Academic literature on the topic 'Metal-Molecule-Metal structure'
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Journal articles on the topic "Metal-Molecule-Metal structure"
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Kučera, Jan, and Axel Groß. "Influence of water on the properties of an Au/Mpy/Pd metal/molecule/metal junction." Beilstein Journal of Nanotechnology 2 (July 12, 2011): 384–93. http://dx.doi.org/10.3762/bjnano.2.44.
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The geometric and electronic structure of the metal–molecule interface in metal/molecule/metal junctions is of great interest since it affects the functionality of such units in possible nanoelectronic devices. We have investigated the interaction between water and a palladium monolayer of a Au(111)/4-mercaptopyridine/Pd junction by means of DFT calculations. A relatively strong bond between water and the palladium monolayer of the Au/Mpy/Pd complex is observed via a one-fold bond between the oxygen atom of the water molecule and a Pd atom. An isolated H2O molecule adsorbs preferentially in a flat-lying geometry on top of a palladium atom that is at the same time also bound to the nitrogen atom of a Mpy molecule of the underlying self-assembled monolayer. The electronic structure of these Pd atoms is considerably modified which is reflected in a reduced local density of states at the Fermi energy. At higher coverages, water can be arranged in a hexagonal ice-like bilayer structure in analogy to water on bulk metal surfaces, but with a much stronger binding which is dominated by O–Pd bonds.
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Orpen, A. Guy. "Metal Complex Geometries in Small-Molecule Crystals." Acta Crystallographica Section D Biological Crystallography 54, no. 6 (November 1, 1998): 1194–98. http://dx.doi.org/10.1107/s0907444998007744.
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The origins, scope and utility of compilations of metal–ligand and intraligand bond lengths based on the Cambridge Structural Database are discussed. The limitations on the apparent uncertainty of metal–ligand bond lengths derived from crystallographic data and recent evidence of metal-assisted hydrogen bonding involving ligands are reviewed in the light of the transferability of bond-length values from one crystal structure determination.
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Maio, U., K. Dolag, B. Ciardi, and L. Tornatore. "Metal and molecule cooling in simulations of structure formation." Monthly Notices of the Royal Astronomical Society 379, no. 3 (August 11, 2007): 963–73. http://dx.doi.org/10.1111/j.1365-2966.2007.12016.x.
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Willenbockel, M., D. Lüftner, B. Stadtmüller, G. Koller, C. Kumpf, S. Soubatch, P. Puschnig, M. G. Ramsey, and F. S. Tautz. "The interplay between interface structure, energy level alignment and chemical bonding strength at organic–metal interfaces." Physical Chemistry Chemical Physics 17, no. 3 (2015): 1530–48. http://dx.doi.org/10.1039/c4cp04595e.
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Kim, Do-Hyun, Hyoyoung Lee, and Taehyoung Zyoung. "Transport mechanism of self-assembled D-σ-A-thiol monolayers in metal-molecule-metal structure." Synthetic Metals 152, no. 1-3 (September 2005): 293–96. http://dx.doi.org/10.1016/j.synthmet.2005.07.160.
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Mondal, Monosij, Maicol A. Ochoa, Maxim Sukharev, and Abraham Nitzan. "Coupling, lifetimes, and “strong coupling” maps for single molecules at plasmonic interfaces." Journal of Chemical Physics 156, no. 15 (April 21, 2022): 154303. http://dx.doi.org/10.1063/5.0077739.
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The interaction between excited states of a molecule and excited states of a metal nanostructure (e.g., plasmons) leads to hybrid states with modified optical properties. When plasmon resonance is swept through molecular transition frequency, an avoided crossing may be observed, which is often regarded as a signature of strong coupling between plasmons and molecules. Such strong coupling is expected to be realized when 2|⟨ U⟩|/ ℏΓ > 1, where ⟨ U⟩ and Γ are the molecule–plasmon coupling and the spectral width of the optical transition, respectively. Because both ⟨ U⟩ and Γ strongly increase with decreasing distance between a molecule and a plasmonic structure, it is not obvious that this condition can be satisfied for any molecule–metal surface distance. In this work, we investigate the behavior of ⟨ U⟩ and Γ for several geometries. Surprisingly, we find that if the only contributions to Γ are lifetime broadenings associated with the radiative and nonradiative relaxation of a single molecular vibronic transition, including effects on molecular radiative and nonradiative lifetimes induced by the metal, the criterion 2|⟨ U⟩|/ ℏΓ > 1 is easily satisfied by many configurations irrespective of the metal–molecule distance. This implies that the Rabi splitting can be observed in such structures if other sources of broadening are suppressed. Additionally, when the molecule–metal surface distance is varied keeping all other molecular and metal parameters constant, this behavior is mitigated due to the spectral shift associated with the same molecule–plasmon interaction, making the observation of Rabi splitting more challenging.
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Rojanasuwan, Sunit, Pakorn Prajuabwan, Annop Chanhom, Anuchit Jaruvanawat, Adirek Rangkasikorn, and Jiti Nukeaw. "The Effect of the Central Metal Atom on the Structural Phase Transition of Indium Doped Metal Phthalocyanine." Advanced Materials Research 717 (July 2013): 146–52. http://dx.doi.org/10.4028/www.scientific.net/amr.717.146.
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We investigate the effect of central metal atom on the phthalocyanine (Pc) molecular crystals as intercalated with indium. As dopant, indium has physical interaction with some atom in the ring of Pc molecule and there is charge transfer between indium atom and Pc ring atom. Since In-doped Pc is a hole doping which increase positive charge carriers and the HOMO of ZnPc, CuPc, NiPc and MgPc are localized on the phthalocyanine ring, then, the central metal atom e.g. Zn, Cu, Ni and Mg are not directly involved with the charge transfer between indium dopant and their Pc molecule. The structural phase transition from α phase to β phase of ZnPc upon doping with indium is another evidence for the existing of charge transfer between dopant atom and matrix Pc molecule. A comparative experiment of optical absorption spectrum of each metal Pc reveals that the central metal atom will affect the forming of crystal structure whether will be α phase or β phase as intercalated with indium.
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Sartain, Hope T., Richard J. Staples, and Shannon M. Biros. "Crystal structure of pentakis(ethylenediamine-κ2N,N′)lanthanum(III) trichloride–ethylenediamine–dichloromethane (1/1/1)." Acta Crystallographica Section E Structure Reports Online 70, no. 11 (October 29, 2014): 424–26. http://dx.doi.org/10.1107/s1600536814023289.
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We report here the crystal structure of a ten-coordinate lanthanum(III) metal coordinated by five bidentate ethylenediamine ligands, [La(C2H8N2)5]Cl3·C2H8N2·CH2Cl2. One free ethylenediamine molecule and three Cl−anions are also located in the asymmetric unit. The overall structure is held together by an extensive hydrogen-bonding network between the Cl−anions and the NH groups on the metal-bound ethylenediamine ligands. The free ethylenediamine molecule is held in an ordered position by additional hydrogen bonds involving both the chlorides and –NH groups on the metal-bound ligands. One highly disordered molecule of dichloromethane is located on an inversion center; however, all attempts to model this disorder were unsuccessful. The electron density in this space was removed using the BYPASS procedure [van der Sluis & Spek (1990).Acta Cryst.A46, 194–201].
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Chu, Yu-Ming, Muhammad Abid, Muhammad Imran Qureshi, Asfand Fahad, and Adnan Aslam. "Irregular topological indices of certain metal organic frameworks." Main Group Metal Chemistry 44, no. 1 (January 1, 2021): 73–81. http://dx.doi.org/10.1515/mgmc-2021-0009.
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Abstract It is interesting to study the molecular topology that provides a base for relationship of physicochemical property of a definite molecule. The topology of a molecule and the irregularity of the structure plays a vital character in shaping properties of the structure like enthalpy and entropy. In this article, we are interested to calculate some irregular topological indices of two classes of metal organic frameworks (MOFs) namely BHT (Butylated hydroxytoluene) based metal (M = Co, Fe, Mn, Cr) organic frameworks (MBHT) and M1TPyP-M2 (TPyP = 5, 10, 15, 20-tetrakis (4-pyridyl) porphyrin and M1, M2, = Fe and Co) MOFs. Also we compare our results graphically.
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Pengmanayol, S., and Tanakorn Osotchan. "Optical Properties of Metal Free and Metal Phthalocyanine by Molecular Band Calculation." Advanced Materials Research 55-57 (August 2008): 677–80. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.677.
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The optical properties of metal-free and metal phthalocyanine were calculated by using density functional theory with various metals including copper, zinc, cobalt, iron and manganese. The polymorphic form of these crystals was employed only for β from. The molecules were optimized with the symmetry of D4h. For the alignments of the molecule in the crystal structures of this polymorphic form which have not been reported in detail, the variation of total energy was examined as a function of the align angles. The align angle at minimum total energy was used for the band calculation. The density functional theory and plane-wave pseudopotential method were used to calculate the energy band structure and electron density of state. The calculated band structures of various metal phthalocyanines can be divided in two groups according to the peak wavelength of the maximum absorption. The first group with the peak wavelength at about 230 nm consists of β-CuPc, β-H2Pc, and β-MnPc while the wavelength of another group for β-CoPc, β-FePc, and β-ZnPc occurs at 350 nm. From the density of state calculation, it indicates that these two transitions originate from the different band and the ratio of the absorption between these states depending on the type of metal in phthalocyanine. The optical absorption was derived to examine the absorption spectra for various metal compositions while the variation in intrinsic electrical conductivity can be estimated from the shape of the band. The phonon and infrared spectra were also determined in order to investigate the vibration mode of molecule in the crystals
Dissertations / Theses on the topic "Metal-Molecule-Metal structure"
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Campos, Otero Alfredo. "Optics and structure of metal clusters at the atomic scale." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS401/document.
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Il est bien connu que les propriétés optiques des nanoparticules de métaux nobles, en particulier d'or et d'argent, s'écartent fortement de celles de métaux macroscopiques. Pour les tailles comprises entre dix et quelques centaines de nanomètres, elles sont dominées par les plasmons de surface (SP) décrites par des modèles purement classiques. En revanche, les agrégats de quelques dizaines d’atomes se comportent comme des systèmes quantiques, ce qui induit des comportements optiques nouveaux. La structure des nanoparticules et l'environnement diélectrique peuvent affecter les propriétés optiques. Dans cette thèse, j'ai utilisé un microscope électronique à transmission à balayage (STEM) équipé d'un spectromètre à perte d'énergie des électrons (EELS) pour mesurer, en parallèle, les propriétés optiques et structurales de nanoparticules individuelles. Je présente comment des expériences complémentaires (STEM-EELS et absorption optique) sur de petites nanoparticules d'argent triées en taille et encapsulées dans une matrice de silice donnent au premier abord des résultats incohérents: tandis que, d’une part, l'absorption optique ne montre aucun effet de taille entre quelques atomes et environ 10 nm, un décalage en énergie est observé dans les mesures STEM-EELS. Notre interprétation quantitative, fondée sur un modèle mixte classique/quantique qui prend en compte tous les effets quantiques pertinents, a résolu les apparentes contradictions non seulement dans nos données expérimentales, mais également dans celles de la littérature. Notre modèle décrit comment l'environnement local est le paramètre crucial contrôlant la manifestation ou l'absence d'effets de taille quantique. En second lieu, je me suis intéressé à la région purement classique à travers des structureslithographiées de quelques centaines de nanomètres. Bien que les cavités plasmoniques triangulaires aient été largement étudiées dans la littérature, une classification en termes de modes de respiration et de bords plasmoniques manquait. Dans cette étude, les résultats expérimentaux de STEM-EELS, des modèles analytiques et des simulations classiques nous ont permis de décrire la nature des différents modesIt is well known that the optical properties of nanoparticles of noble metals, in particular gold and silver, deviate strongly from those of macroscopic metals. For sizes between ten and a few hundred nanometers, they are dominated by surface plasmons (SPs) described by purely classical models. On the other hand, clusters of a few tens of atoms behave like quantum systems inducing new optical behaviors. The structure of the nanoparticles and the dielectric environment can affect the optical properties. In this thesis I used a scanning transmission electron microscope (STEM) fitted with an electron energy loss spectrometer (EELS) to measure, in parallel, the optical and structural properties of individual nanoparticles. I present how complementary experiments (STEM-EELS and optical absorption) on sizeselected small silver nanoparticles embedded in silica yield at first inconsistent results: while optical absorption shows no size-effect in the range between only a few atoms and ~10 nm, a clear spectral shift is observed in STEM-EELS technique. Our quantitative interpretation, based on a mixed classical/quantum model which takes into account all the relevant quantum effects, resolves the apparent contradictions, not only within our experimental data, but also in the literature. Our comprehensive model describes how the local environment is the crucial parameter controlling the manifestation or absence of quantum size effects. Secondly, I was interested in the purely classical region through lithographed structures of a few hundred nanometers. Although triangular plasmonic cavities have been widely studied in the literature, a classification in terms of plasmonic modes of breathing and edge was missing. In this study, experimental STEM-EELS results, analytical models and classical simulations enabled us to describe the nature of the different modes
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DIMONTE, ALICE. "Nanogap structures for molecular electronics and biosensing." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506146.
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Molecular transport characterization is an active part of the research field in nanotechnology. In this interesting branch the self-assembly approach is highly exploited; it consists in spontaneous formation of highly ordered monolayers
on various substrate surfaces. Self-assembled monolayers (SAMs) have found their applications in various areas, such as nanoelectronics, surface engineering, biosensing, etc. An important area in biosensing is the electrochemical detection, that enables sensing of dierent biomarkers with an important role, for many dierent applications in biomedical diagnostics or in monitoring of biological systems. Various test structures have been developed in order to carry out characterizations of self-assembled molecules, and numerous reports have been published in the past several years on the transport characteristics.
This thesis' purpose is the single protein biomolecular sensing, that could become the starting point for monitoring drugs, developing clean energy systems,
realizing bio-opto-electronic transistors... The possibility to cover so many fields is related to the kind of proteins, molecules, bioelements that will be inserted inside sensors. Biomolecular sensing has to be thought in order to reach a result with the better compromise between instrumentation versatility and measurements precision. The main underlying idea is to use single molecules as active elements in nano-devices. As a consequence, the proper realization of a molecule-electrode contact is a crucial issue. What is needed by author is something versatile, precize, cheap, at single molecule level and able to record measurements in few time in order to do statistical characterizations. The final goal of this work is a platform system adapt for both industry and research field.
Electrical nanogap devices are the main character of this work. They have proven good performances as element for detecting small quantities of biomolecules, allowing direct transduction of biomolecular signals into useful
electrical ones such as resistance/impedance, capacitance/dielectric, or field effect. Nanogaps are now one of the most busy area of research in the nanotechnology world. Moreover, these structures do not require feedback to maintain the mutual arrangement (comparing with conducting tip AFM) and are less
stochastic with respect to electrochemical cells. Several techniques can be applied to nanogap fabrication: mechanically broken or positioned junctions, nano-scale lithography by Synchrotron radiation sources, electrochemical deposition and etching, and electromigration. None of these techniques is presently able to give precise control as to thefinal gap size. In this thesis the electromigration approach has been choosen, because of several useful characteristics. It is cost eective, because of the relatively low complexity of the required equipment. It can be embedded into a lab-on-chip
system, thus exploiting the possibility to tailor the gap formation process by means of a digital loop control system. To this end, it just requires a conventional microchip fabrication process. It allows the parallelization with a smart packaging through which it is possible to produce more probes at the same time and perform many measurements in contemporary. The employment of nanogaps, as an instrumentation for the molecular charac-
terization, has also some issues that have to be considered in order to obtain useful measurements. To characterize molecules the leakedge must be not higher than some pA to avoid the noise overcome the signal. Nanogap platform is perfect for molecular electronics. The experiments have been developed in dry way, as a consequence the solutions were evaporated before the measurement starting. This brought several problems cause biochemical analysis requires liquid solution in order to avoid an untimely death of the bio-elements tha has to be characterized. Considering a future developement, an improvement is necessary in terms of a system able to work with salty solutions without damaging the microchip's probes. Therefore it is a necessary a set-up allowing the anchorage
of a microfluidic part. At the same time it is necessary to keep in mind that the presence of a new system has to not overcome the molecule signal, maintaining the leakedge under some tens of pA.
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Temirov, Ruslan [Verfasser]. "Studying complex metal-molecule interface with low temperature scanning tunneling microscope : from electronic structure to charge transport / Ruslan Temirov." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2008. http://d-nb.info/1034984187/34.
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Musetti, Caterina. "SELECTIVE TARGETING OF NUCLEIC ACIDS BY SMALL MOLECULES: A DNA STRUCTURE RECOGNITION APPROACH." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3422045.
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The discovery of new anticancer targets is the key factor for the development of more efficacious therapies. Sequence selective binding of double stranded DNA in the classical B form has been extensively employed to target small molecules to defined polynucleotide portions. More recently, ligand recognition of non canonical DNA foldings has been additionally considered a useful approach to selectively target distinct genomic regions. In this connection, G-quadruplexes represent an interesting system since they are believed to be physiologically significant arrangements. These non-canonical DNA structures are found at the ends of the human chromosomes (telomeres) as well as at promoter regions of several oncogenes where there is a cluster of guanine-rich sequences and they are likely to play important roles in the regulation of biological events. The induction and stabilization of the G-quadruplex arrangement by small molecules can lead to the inhibition of the telomerase activity by interfering with the interaction of the enzyme and its single stranded template. A similar molecular mechanism is likely involved in the transcriptional control that leads to the suppression of the oncogene transcription and, ultimately, in the regulation of the gene expression. As a result, the quadruplex topic is very attractive for the development of a specific anticancer strategy defined by a dramatic reduction of side effects, typical of chemotherapy.
The purpose of this work is to investigate the interactions between novel classes of small molecules and different quadruplex DNA sequences and conformations. These new molecules were properly designed providing systematic atom-wise substitutions based on rational evaluations of previous studied compounds in order to increase their selectivity for G-quadruplex structures and to reduce toxic effects. Biophysical and biological properties of all new derivatives are herein evaluated at molecular and cellular level.
The thesis work is divided into three main sections based on the structural features of the compounds object of study. The first part focuses on heterocyclic dications: upon changing their molecular binding shape, a correlation with G-quadruplex binding have been drawn. In particular it was possible to rationalize a shift in the binding modes, in particular between end stacking and groove recognition. Nevertheless a correlation between biophysical (G-quadruplex affinity) and biological (telomerase inhibition and cytotoxicity) results was not always clear. This feature may suggest the involvement of cellular targets different from the telomere and that are now under investigation.
In Chapter 3, the DNA binding properties of some phenantroline derivatives in presence and in absence of Ni(II) and Cu(II) are investigated. We confirmed that different complex geometries involving one, two or three ligands per metal ion can affect the pattern of DNA recognition by driving nucleic acid conformational changes.
Finally, in Chapter 4 some transplatin derivatives are evaluated. We focused our attention on defining the compounds capability to form adducts, with the nucleic acids, the nature of adducts and the kinetics of adduct formation not only on double strand DNA but also using single strand as well as G-quadruplex as targets. The results showed how different structural modifications can cooperate to greatly affect the potential interaction of the compounds. Interestingly it turned out their preference to react on single stranded DNA portions than to double stranded ones. This is probably due to an unfavourable orientation of the reactive groups when the molecule interacts with the DNA substrate. As a result, they appear to crosslink unpaired strands. By extending these results at cellular level they can reflect distinct distribution of platination site along the genome in comparison to cisplatin and even transplatin.
The results obtained increment the available knowledge of DNA-small molecules interaction. In particular it emerged that a conserved interaction mode is consistent with biological effects. On the other hand, a shift in the binding mode can drive to different cytotoxic effects. This can provide a rationale for subsequent drug structure optimization leading to the development of new efficient and selective anticancer agents.La scoperta di nuovi target anticancro è il fattore chiave per lo sviluppo di terapie sempre più efficaci. Lo studio del legame selettivo a sequenze di DNA a doppia elica nella classica forma B è stato largamente impiegato al fine di direzionare piccole molecole verso porzioni polinucleotidiche definite. Più recentemente, il riconoscimento (da parte di ligandi) di porzioni non canoniche di DNA si può tradurre in un metodo vantaggioso per indirizzare questi composti verso regioni distinte del genoma. A tale proposito, le strutture G-quadruplex rappresentano un sistema interessante poiché sono ritenute fisiologicamente significative. Queste strutture “non-canoniche” di DNA si trovano alle estremità del cromosoma (telomeri) così come in varie regioni promotrici di oncogeni in cui vi è un’abbondante presenza di residui guaninici e sembrano coinvolte nella regolazione di importanti eventi biologici. Pare infatti che l'induzione e la stabilizzazione di strutture G-quadruplex dalle parte di piccole molecole porti all'inibizione dell'attività della telomerasi interferendo con l'interazione tra l’enzima e il suo substrato a singola catena. Un simile meccanismo molecolare è probabilmente coinvolto anche nel controllo della regolazione dell'espressione genica e può portare alla soppressione della trascrizione di un oncogene. Di conseguenza, “l’approccio G-quadruplex” si rivela molto interessante per lo sviluppo di una strategia anticancro specifica caratterizzata anche da una riduzione drammatica degli effetti collaterali, tipici della chemioterapia. Lo scopo di questo lavoro è lo studio delle interazioni tra nuove famiglie di piccole molecole e diverse conformazioni di DNA G-quadruplex. Queste nuove molecole sono state opportunamente progettate apportando sostituzioni di atomi o gruppi funzionali basate sulla valutazione di composti precedentemente studiati al fine di aumentare la loro selettività per strutture G-quadruplex e di ridurre gli effetti tossici. Le proprietà biofisiche e biologiche di tutti i nuovi derivati sono state valutate al livello molecolare e cellulare. Il lavoro di tesi si divide in tre parti in base alle caratteristiche strutturali dei composti. La prima parte è dedicata alla studio di dicationi eterociclici: si è cercato correlare modifiche nella conformazione molecolare con l’affinita’ verso strutture G-quadruplex. In particolare è stato possibile razionalizzare cambiamenti della modalità di legame in base alla struttura dei composti esaminati. Tuttavia una correlazione fra i risultati biofisici (affinità G-quadruplex) e biologici (inibizione della telomerasi e citotossicità) non è risultata sempre definita. Ciò può suggerire il coinvolgimento di bersagli cellulari diversi dal telomero umano. Nel capitolo 3, sono state studiate le proprietà di legame al DNA di alcuni derivati fenantrolinici in presenza ed in assenza di Ni (II) e Cu (II). Abbiamo confermato che complessi caratterizzati da diverse geometrie che coinvolgono una, due o tre molecole per ione possono compromettere o meno il riconoscimento del DNA o determinare cambiamenti conformazionali dell'acido nucleico. Per concludere, il capitolo 4 è dedicato allo studio di derivati del transplatino. In particolare ci siamo focalizzati nel definire la capacità dei composti di formare addotti, la natura dei complessi e la cinetica di formazione del complesso non solo con DNA a doppio filamento ma utilizzando anche substrati a singola catena come il G-quadruplex. I risultati hanno dimostrato come diverse modifiche strutturali possano avere un ruolo importante nell’interazione dei composti con gli acidi nucleici. E’ risultata interessante la loro preferenzialità a reagire con porzioni di DNA a singolo filamento rispetto a sequenze a doppia elica. Ciò è probabilmente dovuto ad uno sfavorevole orientamento dei gruppi reattivi quando la molecola interagisce con il substrato di DNA. Di conseguenza, i composti sembrano formare un cross-link tra due filamenti non appaiati. A livello cellulare, questi risultati riflettono una distinta distribuzione del sito di platinazione all’interno del genoma rispetto al cisplatino e perfino rispetto al transplatino. I risultati ottenuti incrementano la conoscenza disponibile sull’interazione tra DNA e piccole molecole. In particolare è emerso che la conservazione della modalità di interazione si correla con effetti biologici definiti. Al contrario, una variazione della modalità di legame può portare a effetti citotossici differenti. Ciò può fornire una spiegazione razionale per una successiva ottimizzazione della struttura dei composti finalizzata allo sviluppo di nuovi agenti antitumorali efficaci e selettivi.
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Rossi, François-Noël. "Etude théorique des collisions non réactives entre atomes alcalins et molécules d'hydrogène ou de deuterium : Calcul et analyse des surfaces de potentiel, application aux transitions de structure fine du rubidium." Paris 13, 1986. http://www.theses.fr/1986PA132015.
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Calcul des courbes de potentiel adiabatiques pour les géométries colinéaires et perpendiculaires, à l'aide d'un pseudopotentiel dépendant du moment orbital électronique et d'une approche à deux centres; bon accord avec les calculs ab initio existants. Examen des différentes symétries de ces systèmes dans le formalisme de la théorie des groupes, afin d'étudier les valeurs propres et facteurs propres de l'hamiltonien électronique. Calcul quantique des sections efficaces relatives des transitions de structure fine de Rb induites par collision avec H(2) ou D(2). En tenant compte des niveaux rotationnels moléculaires, obtention d'un très bon accord avec les résultats expérimentaux et interprétation de l'effet isotopique
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Duan, Sai. "Geometrical and Electronic Structures at Molecule-Metal Interfaces from Theoretical Modeling." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94120.
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In this thesis, we focus on theoretical investigations on metal interfaces where many heterogeneous chemical reactions take place. Surface-enhanced Raman scattering (SERS) spectroscopy and the modern electrochemical methods are important in-situ techniques that have been widely employed for a variety of applications. Theoretical simulations have become an indispensable tool to infer the molecular details of interfacial structures that are not directly accessible from experimental measurements. In this context, we have proposed several new theoretical models for both SERS and interfacial electrochemistry, which allow us to provide molecular-level understanding of the interfacial structures under the realistic experimental conditions. The first part of the thesis has addressed the basic theory of SERS that offers the vibrational structure of the interfacial molecules. It is well known that the huge enhancement of Raman intensity in this technique can be attributed to two independent factors, namely the physical and chemical enhancements. The former is resulted from the enhanced electromagnetic field induced by the plasmonic excitations, while the latter comes from the changing of interaction between the molecule and the surface. The interplay between these two enhancement factors, which has long been an issue of debate, is revealed in this thesis. They are coupled through molecular polarizability. A practical computational approach is proposed and used to demonstrate the importance of the coupling on different molecular systems. It is found that for certain systems the coupling factor can be as large as 106. This finding is of great importance towards a comprehensive understanding of the SERS mechanisms and a quantitative prediction of the enhancement factor. The other part of the thesis is devoted to the theory of interfacial electrochemistry, in particular the effects of water solution. A novel protocol that combines classical molecular dynamics (MD) and the first principles density functional theory (DFT) calculations is proposed to address the statistical behavior of interfacial properties. Special attention has been paid to the work function of Pt(111) surface and CO adsorption energy on Pt(111) surface in aqueous solution. It has been found that in this case the work function of Pt surface illustrates a surprisingly broad distribution under the room temperature, sheds new light on the understanding of reaction activity of the surface. The proposed protocol is able to provide results in very good agreement with experiments and should be applied routinely in future studies.QC 20120515
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Houwaart, Torsten. "Cobalt porphyrins on coinage metal surfaces - adsorption and template properties." Thesis, Lyon, École normale supérieure, 2014. http://www.theses.fr/2014ENSL0927.
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Cette thèse est une étude théorique sur la interface de porphyrine de cobalt avec des surfaces métalliques avec le code VASP DFT. Le cadre DFT nécessaire a été introduit dans le chapitre 1. La structure de la jBardeen, une programme ecrit en Java, pour la simulation de la STM est expliqué dans le chapitre 2 et le code source est jointe en annexe. Une étude de l'adsorption de CoTPP sur les surfaces métalliques a été entrepris dans le chapitre 3. Différents paramètres de calcul ont été évalués: Le site d'adsorption et de la géométrie à la fois la molécule et la surface ont été étudiés par rapport à la xc-fonctionnel et correction de la dispersion utilisée. Une adsorption site le plus stable est identifié. Par conséquent, ce site plus stable a été étudiée pour sa structure électronique. Calculés images STM avec le code jBardeen ont été comparés avec une experimentation de CoTPP Cu sur une surface (111) avec une couverture sous monocouche. Dans le chapitre 4, un adatome Fe a été présenté à la CoTPP sur Ag système (111). Trois sites de liaison symétrique différentes pour l'atome Fe ont été identifiés sur le macrocycle, marqué les , bi-, brd- et bru-positions. Un moment magnétique pouvait être attestée qui a été principalement situé sur l'atome Fe. Voies possibles entre les quatre, symétriquement équivalentes, sites bi- ont été étudiées avec des méthodes différentes. Simples calculs dans le vacuum et calculs de la “Nudged Elastic Band” (NEB) de l'ensemble du système a révélé une hauteur de barrière légèrement au-dessus de 0,2 eV allant de position bi à la posititon brd. Une analyse de vibration a montré que la commutation de l'atome Fe est susceptible, lorsqu'il est perturbé hors d'équilibre dans les positions brd et bruThis thesis is a theoretical study on the cobalt porphyrin - coinage metal surface interface with the DFT code VASP. The necessary DFT framework has been introduced in chapter 1. The structure of the Java program jBardeen for STM simulation is explained in chapter 2 and the source code is attached as Appendix. A study of the adsorption of CoTPP on coinage metal surfaces has been undertaken in chapter 3. Different parameters of the calculation have been evaluated: the adsorption site and the geometry of both the molecule and surface have been investigated with respect to the xc-functional and dispersion correction used. A most stable adsorption site -bridge down- is identified. Consequently, this most stable site was investigated for its electronic structure. Calculated STM images with the jBardeen code were compared with an experiment of CoTPP on a Cu(111) surface with sub monolayer coverage. In chapter 4 an Fe adatom was introduced to the CoTPP on Ag(111) system. Three symmetrically different binding sites for the Fe atom were identified on the macrocycle, labelled the bi-, brd- and bru-positions for bisector, bridge down and bridge up respectively. A magnetic moment could be evidenced which was mainly located on the Fe atom. Possible pathways between the four symmetrically equivalent bisector sites were investigated with different methods. Single point calculations in vacuum and Nudged Elastic Band (NEB) of the whole system revealed a barrier height of slightly above 0.2 eV going from bi- to the brd-position. A vibrational analysis showed that switching of the Fe atom is likely, when perturbed out of equilibrium in the brd- and bru- positions
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Hliwa, Mohamed. "Traitement simplifie des interactions moleculaires en chimie quantique." Toulouse 3, 1988. http://www.theses.fr/1988TOU30038.
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Calculs ab initio sur le systeme hautement degenere cr h: mise en evidence d'un fort couplage entre etats ioniques et neutres et analyse des fonctions d'onde dans une description diabatique. Proposition d'une methode perturbative pour calcul des energies de dispersion entre un systeme versatil a (decrit dans une grande base) et un systeme quasi passif b (traite a l'approximation en coeur gele et caracterise par sa polarisabilite); calcul scf + ci de (a + b gele), du champ electrique exerce par a sur b, et de ses fluctuations, a l'aide d'un hamiltonien effectif; application a l'etude des courbes de potentiel des premiers etats excites des molecules diatomiques de ar avec na, k ou mg. Emploi de la theorie des pseudopotentiels et des potentiels modeles pour le calcul de potentiels impulsifs d'atomes inertes transferables a des systemes moleculaires; a partir de ces potentiels, calcul d'energies de dispersion applicable a la spectroscopie d'atomes alcalins en matiere de gaz rare
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Martin, Claudia. "Density functional study of the electronic and magnetic properties of selected transition metal complexes." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-134958.
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Die vorliegende Promotionsarbeit “Density functional study of the electronic and magnetic properties of selected transition metal complexes” beschäftigt sich mit dem Zusammenhang zwischen strukturellen Merkmalen sowie elektronischen und magnetischen Eigenschaften von Einzelmolekül-Magneten. Im Wesentlichen konnte dabei gezeigt werden, dass die magnetischen Eigenschaften sowohl von strukturellen Merkmalen als auch von den elektronischen Eigenschaften bestimmt werden. Des Weiteren ergab sich, dass verschiedene Kenngrößen der magnetischen Eigenschaften (im speziellen der magnetische Grundzustand S sowie die magnetische Anisotropie D) miteinander korreliert sind. Dies ist im Besonderen für eine mögliche Anwendung von Einzelmolekül-Magneten im Bereich der Datenspeicherung von Bedeutung.
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Haghjoo, Farhad. "The synthesis and structural characterisation of a series of iodides and dipyridyl ketone based metal complexes with relevance to the Grätzel photovoltaic cell and single molecule magnets." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/the-synthesis-and-structural-characterisation-of-a-series-of-iodides-and-dipyridyl-ketone-based-metal-complexes-with-relevance-to-the-gratzel-photovoltaic-cell-and-single-molecule-magnets(18f7cd83-fa41-46b9-a5c8-a28e95a9b184).html.
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The Grätzel photovoltaic cell is described in the introductory chapter and the main experimental method used in this study, X-ray crystallography, in the second chapter. The work described in chapter 3 and 4 was inspired by the Grätzel cell namely, the synthesis and characterisation of iodide and poly-iodides in chapter 3 and transition metal complexes synthesised using 2,2’-dipyridyl ketone in chapter 4.Chapter five looks in detail at a series of tri-angular lanthanide complexes, a chance discovery made while synthesising the 2,2’-dipyridyl ketone complexes described in chapter 4. These tri-angular clusters have interesting magnetic properties that are also described.
Books on the topic "Metal-Molecule-Metal structure"
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Unimolecular and supramolecular electronics: Chemistry and physics meet at metal-molecule interfaces. Heidelberg: Springer, 2012.
Find full textBook chapters on the topic "Metal-Molecule-Metal structure"
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Ueno, Nobuo, Satoshi Kera, and Kaname Kanai. "Fundamental Electronic Structure of Organic Solids and Their Interfaces by Photoemission Spectroscopy and Related Methods." In The Molecule-Metal Interface, 173–217. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2013. http://dx.doi.org/10.1002/9783527653171.ch7.
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Petek, H., M. Feng, and J. Zhao. "Electronic Structure of Metal–Molecule Interfaces." In Current-Driven Phenomena in Nanoelectronics. Pan Stanford Publishing, 2010. http://dx.doi.org/10.1201/b11114-2.
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Enoki, Toshiaki, Morinobu Endo, and Masatsugu Suzuki. "Surface Properties and Gas Adsorption." In Graphite Intercalation Compounds and Applications. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195128277.003.0010.
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It is well known that alkali metal binary GICs adsorb gaseous species (H2, N2, Ar, CH4, etc.) physisorptively at low temperatures, where physisorbed gaseous molecules are accommodated in the interstitials of the alkali metal lattice within the graphitic galleries (Lagrange and Hérold, 1975; Lagrange et al., 1972, 1976; Watanabe et al., 1971, 1972, 1973). The capacity for hydrogen adsorption, which is estimated at 144 cm3/g in KC24, for example, is large and comparable to the capacity in other adsorbers such as zeolite or activated charcoal. Interestingly, the physisorption phenomenon in alkali metal GICs has different features from that in conventional adsorbents such as zeolite or activated charcoal; that is, guest molecules in alkali metal GICs are not simply bonded to the adsorbents through weak van der Waals forces without any change in the electronic structures. Here we discuss the gas physisorption phenomenon in alkali metal GICs from general aspects, in relation to their specific features. Then in subsequent sections, we will give details of actual cases. Hydrogen is a typical gaseous molecule adsorbed in alkali metal GICs. Hydrogen physisorption takes place at low temperatures below about 200 K, where hydrogen molecules are accommodated in the graphitic galleries and are not dissociated into atomic hydrogen species. When the temperature is increased to over 200 K, the alkali metal GICs work as catalysts to hydrogen, resulting in the occurrence of hydrogen chemisorption. Hydrogen physisorption will be discussed in Section 8.1.2, hydrogen chemisorption and related issues have been discussed partly in Sections 2.2.1 and 5.4.1 from the viewpoints of structure and electronic properties, and will be discussed again in Section 8.1.2. Figure 8.1 represents the composition dependence of the amount of physisorption of hydrogen molecules in KCm at 77 K (Lagrange and Hérold, 1975). The composition of 1/m = 1/8 corresponds to the stage-1 compound and the composition 1/m = 1/24 to the stage-2 compound; intermediate compositions between 1/8 and 1/24 are considered to have a mixed structure of stage-1 and stage-2 compounds. The stage-1 compound does not adsorb hydrogen at all.
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"Bio-Mediated Synthesis of Metal Nanomaterials for SERS Application." In Materials Research Foundations, 118–54. Materials Research Forum LLC, 2021. http://dx.doi.org/10.21741/9781644901571-5.
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The discovery of nanomaterials (NMs) caused a great revolution in the field of science especially in material science. The highly exotic and tunable size and shape of NMs have devoted more interest due to their unique physiochemical properties. There are various methods and methodologies involved to prepare NMs in a desired morphology. Among these, the fabrication of bio-molecules mediated NMs are highly attractive because their size and shape can be easily tuned by simple, eco-friendly and reliable way. Deoxyribonucleic acid (DNA) is considered to be one of the most promising and well-studied bio-molecule in the fabrication of various types of NMs. The rich functionalities with the double-helix structure of DNA facilitate to accommodate a higher number of metal ions on its surface and results in perfect chain-like nano-assemblies. Moreover, the DNA mediated NMs can be highly useful for the Surface Enhanced Raman Scattering (SERS) studies with appropriate analytes. The SERS technique provides the fingerprint information of the analyte molecules even at very low concentration (such as even in ppm levels). The SERS intensity is greatly influenced by the size and shape of the NMs prepared using DNA scaffolds due to their assembly in a close proximity and generation of higher number of ‘hot spots’. In this present book chapter, we elaborated the numerous methodologies involved for the synthesis of DNA-based NMs considering their size, shapes, and also highlighted the possible mechanism involved for their growth with DNA scaffolds. In-addition, the possible application of DNA mediated NMs towards SERS studies has also been detailed in this book chapter.
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Torres-Santillan, Esther, Selene Capula-Colindres, Gerardo Teran, Carmen M. Reza-San German, Miriam Estrada Flores, and Oscar Guadalupe Rojas Valencia. "Synthesis of Pt-Mo/WMCNTs Nanostructures Reduced by the Green Chemical Route and Its Electrocatalytic Activity in the ORR." In Carbon Nanotubes - Recent Advances, New Perspectives and Potential Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106396.
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Platinum (Pt) and molybdenum (Mo) nanoparticles were supported on multiwall carbon nanotubes (MWCNTs) by a green chemical route. Different relations of Pt:Mo (10:0, 8:2, 5:5, 2:8, and 0:10, respectively) in weight percent were compared to their electrocatalytic activity in the oxygen reduction reaction (ORR) in an acid medium. The morphologies and the structure were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The rotary disc electrode (RDE) and linear voltammetry (LV) techniques were employed to observe the electron transfer and mass transport phenomena. The surface activation of the samples was conducted by cyclic voltammetry (CV) technique According to the TEM analysis. The TEM analysis, shows that Mo and Pt nanoparticles have a good dispersion on the tubular carbon support, with sizes between 3.94 and 10.97 nm. All Pt-containing ratios had exhibited a first-order transfer in the ORR without inhibition of the reaction. Molybdenum is a reducing agent (oxyphilic metal) that benefits the adsorption of oxygenated species. The Pt:Mo 8:2 wt.% ratio presents the maximum benefits in the kinetic parameters. The Mo10/MWCNTs nanostructure inhibits the ORR due to the strong bonds it presents with oxygen. Molybdenum at low concentrations with platinum is conducive to oxygen molecule adsorption-desorption by increasing the ORR’s electroactivity.
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Shajkumar, Aruni, and Ananthakumar Ramadoss. "Recent Advancements in Photocatalytic Nanocomposites." In Research Anthology on Synthesis, Characterization, and Applications of Nanomaterials, 952–72. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8591-7.ch039.
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Photocatalysts utilize light energy or photons to catalyze a reaction. The most significant characteristics of a photocatalyst lies in its ability to simultaneously oxidize a donor molecule and reduce an acceptor through the electron-hole pair generated upon excitation. With the emergence of nanotechnology, the utilization of nanomaterials for their photocatalytic properties has gained a new pace. TiO2 and ZnO nanoparticles are exploited widely for their photocatalytic properties. The recent trends concentrate on devising composite nanostructures that utilize both the properties of the photocatalyst and supporting materials such as graphene, carbon nanotubes, or noble metal nanoparticles to enhance the photocatalytic properties of the semiconductor metal oxide. The main areas of application of such structures lie in the field of water purification and energy harvesting. This chapter outlines an overview of the photocatalytic process and the existing technologies followed by the application areas and the recent advancements lying in that area.
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Shajkumar, Aruni, and Ananthakumar Ramadoss. "Recent Advancements in Photocatalytic Nanocomposites." In Diverse Applications of Organic-Inorganic Nanocomposites, 136–61. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-1530-3.ch006.
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Photocatalysts utilize light energy or photons to catalyze a reaction. The most significant characteristics of a photocatalyst lies in its ability to simultaneously oxidize a donor molecule and reduce an acceptor through the electron-hole pair generated upon excitation. With the emergence of nanotechnology, the utilization of nanomaterials for their photocatalytic properties has gained a new pace. TiO2 and ZnO nanoparticles are exploited widely for their photocatalytic properties. The recent trends concentrate on devising composite nanostructures that utilize both the properties of the photocatalyst and supporting materials such as graphene, carbon nanotubes, or noble metal nanoparticles to enhance the photocatalytic properties of the semiconductor metal oxide. The main areas of application of such structures lie in the field of water purification and energy harvesting. This chapter outlines an overview of the photocatalytic process and the existing technologies followed by the application areas and the recent advancements lying in that area.
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Lowenstam, Heinz A., and Stephen Weiner. "Some Nonskeletal Functions in Biomineralization." In On Biomineralization. Oxford University Press, 1989. http://dx.doi.org/10.1093/oso/9780195049770.003.0012.
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The functions of mineralized hard parts are often self-evident. In many of the tables throughout the book we note the assigned or very often assumed functions of many different mineralized bodies. Often, however, assumed functions do not stand up to closer examination. A good example is the study of the cells of the hepatopancreas of gastropods (Howard et al. 1981). These glands have numerous cells containing intracellular mineralized granules. It was generally assumed that they all functioned as transient storage sites for calcium ions, until it was found that a subpopulation forms granules of a different type, which are used for heavy metal detoxification. Granules can be used in other ways as well. Certain polychaete worms, for example, strengthen their muscles by packing them with granules (Gibbs and Bryan 1984). Spicules are also commonly formed by many organisms and their functions are often not understood. They tend to have elaborate morphologies and mineralogies that are species specific, implying that they do perform specialized functions. These are just a few of many examples in which the functions of mineralized bodies still need to be determined. In this chapter we describe four different cases in which the functions are fairly well established. They have been investigated in some detail and, thus, provide good guidelines as to the various approaches by which function can be investigated. Some gravity receptors have been closely examined with respect to neuroanatomy and function, but not with respect to the specific adaptations of structure and mineralogy of the ubiquitous “heavy bodies.” Studies of biologic magnetic field receptors, in contrast, have focused on the mineral, and virtually nothing is known about the neuroanatomy. The molecular structure of the iron storage molecule ferritin is known with a resolution of a few Angstroms. Ferritin provides us with a glimpse of the insights that can be gained into function from such detailed structural information. Finally, some studies on the control of proteins on ice crystal formation represent the first application of the powerful techniques of molecular biology to determining function in biomineralization. These are undoubtedly the forerunners of many function-oriented studies using molecular biological techniques.
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Harris, Nadine, Logan K. Ausman, Jeffrey M. McMahon, David J. Masiello, and George C. Schatz. "Computational Electrodynamics Methods." In Computational Nanoscience, 147–78. The Royal Society of Chemistry, 2011. http://dx.doi.org/10.1039/bk9781849731331-00147.
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This chapter has focused on a number of commonly used analytical and numerical electrodynamics methods that can be used to model the optical properties of plasmonic nanostructures, with emphasis on nonconventional applications of these methods to problems that have been recently been of interest in the surface spectroscopy field, especially surface-enhanced Raman scattering (SERS). A dipole reradiation (DR) methodology was added to the analytical approach of Mie theory to DR effects in SERS intensities, which is a more accurate expression for the electromagnetic enhancement theory than the commonly used plane-wave (PW) enhancement expression. We show that DR/PW differences can be significant for certain choices of detector locations due to interference and multipole effects, and generally the DR enhancements are smaller than PW. The numerical 2D finite-difference time-domain (FDTD) method was modified through the incorporation of the hydrodynamic Drude model dielectric constant, enabling the calculation of spatially nonlocal dielectric responses for arbitrarily shaped nanostructures. Nonlocal effects become important when structural features extend below around 10 nm where the dielectric constant becomes a function of both the wavevector and the frequency. The importance of including nonlocal effects was demonstrated by calculating the optical response of cylindrical and triangular nanowires. The discrete dipole approximation (DDA) provides an alternative method for determining nanoparticle optical properties that uses a similar grid to FDTD, but with different convergence characteristics. We show that for cube-shaped particles the two methods have similar convergence behavior, but accuracy is a problem for DDA, while representing the frequency dependence dielectric constant is a problem for FDTD. A general many-body formalism describing plasmon-enhanced linear spectroscopies was developed by linking the numerical DDA method with electronic structure theory based on Q-Chem. This methodology allows the calculation of the linear-response and scattering properties between a molecule, which is described quantum mechanically, interacting with a classically described metal nanostructure. To demonstrate this formalism the linear response and scattering of a pyridine–Ag spheroidal system was calculated as a function of excitation energy and aspect ratio.
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Hejczyk, Tomasz, Jarosław Wrotniak, and Wiesław Jakubik. "Numerical Analysis of the Steady State in SAW Sensor Structures with Selected Polymers for Detection of DMMP and CO." In Metal-Oxide Gas Sensors. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.109367.
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The chapter presents the results of the numerical investigation of the SAW gas detector structures with selected polymer layers in steady-state conditions. The effect of SAW velocity changes vs. the surface electrical conductivity of the detector structures is predicted on the base of acoustoelectric elemental theory. The electrical surface conductivity of the rough polymer sensing layer placed above the piezoelectric waveguide depends on the profile of the diffused gas molecule concentration inside the whole detector structure. Numerical results in the steady state conditions for the gas molecules DMMP and polymer layer of (RR)-P3HT have been shown as well as for carbon oxide molecules with thin polyaniline and polypyrrole layer. The main aim of the investigations was to study a thin film’s interaction with targeted gases in the SAW detector configuration based on diffusion equations for polymers. Numerical results for profile concentration in steady state conditions for gas molecules concentration, film thickness, roughness, and interaction temperature have been shown. The results of numerical analyzes allow for selecting better detector design conditions, including the morphology of the detector layer, its thickness, operating temperature, and layer type. The numerical results, based on the code written in Python, were shown.
Conference papers on the topic "Metal-Molecule-Metal structure"
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Wong, Eric K. L., and Geraldine L. Richmond. "Laser excitation spectroscopy: a probe of metal ion binding in polymers." In International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.fg6.
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The structure and the function of many macromolecules and organic polymers are dependent on the specific sites bound to metal ions. Metal binding in some ionic polymers is in the form of ionic clusters. The objective of our laser-induced fluorescence studies is to gain a better understanding of the structure and binding properties of these clusters by using europium ions as probes. Eu(III) has many unique spectral properties which make it a good luminescent probe of the metal binding in polymers. The energy, fluorescence quantum yield, and lifetime of the excited state of the 7F0 → 5D0 transition near 580 nm are very sensitive to the environment of the ions. By studying this transition in detail, it is possible to obtain unique optical information about the metal–molecule interaction. Metal binding in the perfluorosulfonate membrane, Nation (DuPont), has been studied here as function of such parameters as metal ion concentration and pH. The resulting excitation spectra show multiple peaks corresponding to different ionic environments. The results of these experiments are discussed in terms of the known macroscopic binding properties of this film.
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Tomar, Aishwarya, and AK Shankhwar. "Design and Performance Investigation of Symmetrical Dual Gate Doping-less TFET for Biomolecule Recognition." In International Conference on Women Researchers in Electronics and Computing. AIJR Publisher, 2021. http://dx.doi.org/10.21467/proceedings.114.72.
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This manuscript presents a dielectric modulated doping-less dual metal Gate Tunnel Field Effect Transistor (DL-DMG-TFET) sensor. In which a nano-cavity is presented above the tunnelling point to recognize the bio-molecule like amino acids (AAs), protein, and so on the proposed P+ and N+ sections are invented relying on the electrode's work-function on silicon body. The impacts of metal work regulation, cavity length and thickness variety are investigated for improving band-to-band tunnelling probability at the source-channel intersection. The proposed structure shows perceptible affectability results for neutral and charged biomolecules. The sensitivity of the higher dielectric constant bio-molecules are higher as compared to bio-molecule having lower dielectric constant; the drain current sensitivity of the Gelatin (k=12) is assessed as which is 13% and 35% higher than the affectability of Keratin (k=10) and Bacteriophage T7 (k=5) separately at the nano-cavity length of 30 nm.
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Sharma, Brajendra K., Girma Biresaw, and Sevim Z. Erhan. "Adsorption Behavior of Heat Modified Soybean Oil via Boundary Lubrication Coefficient of Friction Measurements." In STLE/ASME 2008 International Joint Tribology Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ijtc2008-71292.
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The frictional behaviors of soybean oil and heat modified soybean oils with different Gardner scale viscosities as additives in hexadecane have been examined in a boundary lubrication test regime (steel contacts) using Langmuir adsorption model. The free energy of adsorption (ΔGads) of various heat modified soybean oils were compared with unmodified soybean oil. It was observed, that relative distribution of unsaturation in the molecule, average molecular weight and thus viscosity can affect adsorption on the metal surface. Heat modified soybean oils consistently have a lower ΔGads values compared to unmodified soybean oil. Lower ΔGads corresponds to stronger adsorption on the metal surface. The heat modification thus provides oils with stronger adsorption and higher viscosities, good for use in industrial lubricant formulations. This information can be used to design suitable lubricant molecules that will have optimum structure for effective metal adsorption as well as exhibit excellent boundary lubrication properties.
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Fei, Haosheng, Xicheng Ai, Li Han, Ruijuan Nie, and Zhenhua Hu. "Surface Effect On The Nonlinear Optical Properties Of Transition Metal-Oxode Microcrystallites." In Nonlinear Optics. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/nlo.1992.we15.
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The size dependent modifications of the optical and electronic properties of microcrystallites have attracted considerable attention recently[1-4]. As the diameter of the microcrystallite approaches its corresponding exciton Bohr diameter, its electronic and optical properties start to change because of the quantum confinement effect, dielectric effect and the effect of the surface[5]. For microcrystallites in such a small size regime, a large percentage of the atomes is on or near the surfaces. The existence of this vast interface between the microcrystallite and the surrounding medium can have a profound effect on the nonlinear optical properties of the microcrystallites. For the first time, we studied the nonlinear optical properties of translation metal-oxide microcrystallites by coating the surface with a layer of organic polar molecule(DBS etc.), and found that the change of the surface environment could alter the optical properties greatly. For Fe2O3 as example, (1) the absorption incresed toward the high energy side, (2) the laser induced luminescence intensity decreased by 2 orders in magnitude, and on the contrary, the Raman signal of the surface was enhanced greatly, (3) the saturable absorption phenomenon disappeared, (4) larger third order susceptibility and faster excited state relaxation were obtained compared with uncoated Fe2O3 microcrystallite. These phenomena are the results of the change of the electronic structure caused by the quantum confinement effect and the effect of the surface, unlike semiconductor microcrystallites in which the delocalized Wannier excitons can be influenced greatly by the quantum confinement effect (such as PbS microcrystallite). Transition metal oxide microcrystallite has more complicated electronic structure in which localized d electrons influence its electronic and optical properties greatly[6], and the small diameter Frenkel exciton in such material was effected little by the quantum confinement effect, therefore, the exciton structure could not be abserved in the absorption spectrum. But the size of the transition metal oxide microcrystallites influence their electronic structure strongly. For Fe2O3 as example, the energy structure can be quantitatively shown as the Figure (at the end of the paper), in which a is d-d transition, b represents charge transfer, c is orbital promotion and d is interband transitions. As the size of the microcrystallite decreases, the 3d and 4sp state couples increasingly, and the 3d-4sp (orbital promotion) state contribution increases correspondingly. To some extend, the d electrons and the Frenkel exciton will be delocalized, and the excited electron-hole pair can be ionized and scattered to the surface rapidly. In particular, when the surface was coated with a layer of organic polar molecule, the 3d-4sp state interaction was enhanced greatly under the strong polar interaction of the surface, and some 3d-4sp hydride state will exist, thus the d electrons and the Frenkel exciton will became more delocalization, and the laser induced electron-hole pairs interect and scatter to the surface very fast, so the surface delocalization state generate, accumulate and relax very rapidly and the electron-electron coherence effect[7] is enhanced greatly. Such changes not only increased the nonlinear response, but also resulted in shorter lifetime and stronger nonraditive process.
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Xiaochuan, Zeng, Li Xuejun, He Cuizhu, and Hu Qiaodan. "First-Principles Study on Adsorption Reaction of Oxygen Molecules on Fe (110) Crystal Surface." In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-92890.
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Abstract The adsorption reaction between oxygen (O2) molecule and ferrum (Fe) (110) crystal surface in the oxidation process of Fe surface was studied by using the first-principles method. The differential charge density analysis of the adsorption sites of oxygen molecule on Fe (110) crystal surface, the calculation of adsorption energy at different sites and the analysis of electronic density of states showed that the stable adsorption position of oxygen molecule was parallel to Fe (110) crystal surface, and the oxygen atom tended to adsorb at the triangular gap of Fe atoms. The electronic structure of the adsorption system showed that the 2p electron orbital of oxygen atom plays a major role in the adsorption, and only O-Fe electron interaction exists when oxygen molecule is adsorbed in the parallel orientation, which makes the whole Fe (110) crystal surface lose electrons, increase the system potential and the risk of electrochemical corrosion. The research conclusions can provide theoretical support for the further insight in the oxidation corrosion mechanism of nuclear metal surface.
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Erhan, Sevim Z., and Brajendra K. Sharma. "Development and Tribochemical Evaluation of Biobased Antiwear Additive." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81444.
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Seed oils are renewable resources, environmentally friendly non toxic fluids, pose no work place health hazards and are readily biodegradable. The amphiphilic character of these oils makes them an excellent candidate as lubricants and as specialty chemicals. Industrial application of seed oils is limited due to poor thermo-oxidative stability, poor low temperature fluidity, and other tribochemical degrading processes that occur under severe conditions of temperature, pressure, shear stress, metal surface and environment. This work describes the development and tribochemical evaluation of seed oil based antiwear additive through chemical modification. The current process retains the seed oil structure, eliminates poly-unsaturation in the molecule, and adds polar functional groups that significantly improve adsorption on metal surfaces. These compounds also contribute to the formation of protective films through chemical reaction during the tribochemical process. Comparative tests with commercial products demonstrate its effectiveness.
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Semenova, S. N. "Functionalization of nickel-carbon nanocomposite with sodium polymethyl naphthalene sulfonate (C-3)." In 2022 33th All-Russian Youth Exhibition of Innovations. Publishing House of Kalashnikov ISTU, 2022. http://dx.doi.org/10.22213/ie022142.
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Effective use of metal-carbon nanocomposite (NC) dispersions in composite materials is a complex task. The results of experimental work on the functionalization of nickel-carbon nanocomposites (Ni/C NC) with sodium polymethyl naphthalene sulfonate (plasticizer C-3) for the modification of the cement matrix are presented. The article presents a comparative analysis of dispersions with different duration of ultrasonic treatment at different temperature conditions. It is revealed that solubilization and stability of the system is achieved at a time of ultrasonic treatment of 15 minutes and a heating temperature of 25 ° C. The infrared spectral analysis of compounds formed under the selected mode of obtaining dispersion was carried out. The obtained spectra indicate the substitution of sodium (Na) and the addition of the carbon structure of Ni/C NC to sulfur oxide (VI) SO 3- in a molecule of sodium polymethylsulfonate.
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McCarthy, Michael C., and R. W. Field. "Application of a sideband oodr Zeeman spectroscopy to diatomic molecules." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.wn2.
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In order to test simple atom-in-molecule concepts in the theory of the electronic structure of transition metal monohydrides and monohalides it is necessary to extract key electronic properties from the spectra of these molecules. Unfortunately, the spectra of diatomic molecules containing an atom with a partially filled d-shell are complex. Consequently, it is desirable to develop spectroscopic techniques and strategies whereby spectra can be simplified and rapid generation of diagnostically important spectral information is possible. Sideband optical-optical double resonance-Zeeman spectroscopy (SOODRZ) is one such technique. SOODRZ is one-laser, two-color, absorption-based technique which presents sub-Doppler Zeeman splittings in a simple, diagnostically useful format. Unlike other sub-Doppler techniques where complex Zeeman splitting patterns obscure the tuning coefficients of either the upper state or lower state, in SOODRZ, only two Zeeman resonance features (single upper and single lower state resonance) are observed. The Zeeman information (J, Q-dependent Zeeman tuning coefficients) can then be used for rotational and electronic assignment, we will illustrate the usefulness of SOODRZ by showing examples from the electronic spectrum of NiH. We will also discuss the lineshape and sensitivity of SOODRZ for a variety of detection schemes using both electro-optic and acousto-optic modulators.
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Oshikiri, Mitsutake, and Mauro Boero. "Water Molecule Adsorption Properties and Electronic Structures of Metal Oxide Photo-catalysts Designed for Water Decomposition." In 2006 International Conference on Nanoscience and Nanotechnology. IEEE, 2006. http://dx.doi.org/10.1109/iconn.2006.340712.
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Reda, M. "The Principle of Nanoengines as a Tool for Designing Alloys and Controlling Corrosion Phenomena." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62043.
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Nanoengine principle is new idea that can be used to design new alloys with any desired properties, simply explain corrosion phenomenon and suggest new solutions and can help understand why alloys and composite undergo failure. Nanoengine principle is based on the simple fact that when alloys are made by mixing different metal and nonmetals together at certain ratio of these components, this will enable the formation of Nanoengine crystal structure both at the interface and at the grain-boundary. It is shown that the polarity and the size of the reactant molecule is important variable for the performance of the Nanoengine as well as the choice of the counter cation of the Heteropolyacid (Nanoengine) can determine the mechanical and thermal stability. For example, for industrial alloys, the protective mechanism of alloying using chromium, Nickel and Molybdenum is mis-understood because it will be shown that for example using about 20% chromium, almost 20% Nickel in combination with roughly 6% molybdenum (Alloy AL-6XN and 254 SMO used in space shuttle) is way too much and such a high content of chromium, Nickel and Molybdenum are not needed. The objective her is to show that it is the ratio of Ni:Cr:Mo:P:Si, the choice of counter cation, as well as the water of hydration are the important factors. This ratio and proper choice of counter cation in combination with proper alloys preparation method (water of Hydration during annealing) should be able to produce the right Nanoengine which has the desired mechanical, chemical and thermal properties. This should help in designing alloys at lower chromium and nickel content. This is based on assuming that the protective mechanism of the Nanaoengines is due to both their ability for Redox transformation combined with heterogeneous catalysis. The principle of Nanoengines can give a very precise scientific definition for the phenomena of passivity.
Reports on the topic "Metal-Molecule-Metal structure"
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Hamers, Robert John. Ultra-stable Molecule-Surface Architectures at Metal Oxides: Structure, Bonding, and Electron-transfer Processes. Office of Scientific and Technical Information (OSTI), December 2013. http://dx.doi.org/10.2172/1109183.
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