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Dissertationen zum Thema „Organic groups“
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1
Dunlop, J. E. "Coordinated leaving groups in organic synthesis." Thesis, Bucks New University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374820.
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2
Mouselmani, Rim. "Reduction of Organic Functional Groups Using Hypophosphites." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1241/document.
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Récemment, les exigences en chimie ont évolué rapidement, car le développement durable a retenu plus d'attention. Les principes de la chimie verte ont encouragé les chimistes à développer des produits chimiques et des procédés qui réduisent ou éliminent les substances dangereuses. Les travaux de recherche décrits dans cette thèse portent sur le développement de nouveaux systèmes réducteurs en utilisant des hypophosphites comme substituts aux agents réducteurs toxiques traditionnels.Pour atteindre cet objectif, les nitriles aromatiques ont été réduits en aldéhydes correspondants par la formation du gaz de l’hydrogène et de nanoparticules de nickel en combinant un précurseur de nickel avec de l'hypophosphite de calcium en présence d'une base dans un milieu biphasique. De plus, les nitriles aromatiques ont été réduits en amines primaires en utilisant de l'hypophosphite de calcium et le catalyseur hétérogène palladium sur le carbone. La nature du catalyseur métallique, les additifs, les solvants, la température et les concentrations ont été étudiés en détail.D'autre part, l'amination réductrice directe des cétones aliphatiques et aromatiques a été réalisée pour la première fois en utilisant du palladium hétérogène sur du carbone et de l'hypophosphite d'ammonium qui agit comme une source d'ammoniac et un agent réducteur en même temps. Au cours de l'optimisation, des différents paramètres ont été étudiés<br>Recently, requirements in chemistry are changing fast, since sustainable development has retained more attention. Green chemistry principles have promoted chemists to develop chemical products and processes that reduce or eliminate hazardous substances. The research work described in this thesis is focused on the development of new reducing systems using hypophosphites as substitutes for traditional toxic reducing agents.In order to achieve this goal, aromatic nitriles were reduced into the corresponding aldehydes by the formation of hydrogen gas and nickel nanoparticles upon combining a nickel precursor with calcium hypophosphite in the presence of base in a biphasic medium. Moreover, aromatic nitriles were reduced into primary amines using calcium hypophosphite and the heterogeneous catalyst palladium on carbon. The nature of the metal catalyst, additives, solvents, temperature, and concentrations were studied in details.On the other hand, the well-known direct reductive amination of aliphatic and aromatic ketones was done for the first time using heterogeneous palladium on carbon, and ammonium hypophosphite which acts as a source of ammonia and as a reducing agent at the same time. During optimization different parameters were studied
3
Nomura, Glenn Sterling. "Derivatives of 4-ketoperhydroazulene with bridgehead methyl groups." Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/27064.
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4
Lee, Duckhee. "The design of organosilyl groups to control organic reactions." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624740.
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5
Ahmed, K. M. "Diels-Alder reaction of quinones carrying electron-withdrawing groups." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234154.
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6
Hussain, Firasat [Verfasser]. "Hybrid organic-inorganic polyoxometalates functionalized by diorganotin groups / Firasat Hussain." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2008. http://d-nb.info/1034891162/34.
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7
Longstaff, Peter A. "Novel side chain protecting groups for solid phase peptide synthesis." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/15232.
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8
Korzycka, Karolina Anna. "Two-photon sensitive protecting groups for biological application." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:7e895ed2-04a5-4c0b-9105-74461eae8796.
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Caged compounds are a class of photosensitive reagents used to stimulate cells with spatial control down to a sub-cellular level, and millisecond temporal control. They comprise of biologically important molecule which is modified with a photolabile protecting group. In the absence of light, caged compounds are physiologically silent but irradiation with light induces the release of biologically active species. Illumination under two-photon conditions is particularly advantageous as it enables restriction of the photolysis volume to ~1 fL and it provides deeper penetration into scattering samples. This thesis reports the development of new protecting groups for two-photon uncaging in neuroscience. Mechanistically, the deprotection in these novel groups is designed to operate via an intramolecular photoinduced electron transfer (PeT) between the absorbing unit (electron-donor) and the release module (electron-acceptor). The modular design of these cages ensures separation of absorption and release steps, and allows each process to be tuned and optimized independently. Chapter 1 provides an introduction to the two-photon absorption phenomenon and a historic overview of the uncaging technique. It also discusses recent advances in the development of two-photon sensitive probes used in neuroscience. Chapter 2 describes the exploration of molecular designs for novel protecting groups. A two-photon absorbing dye (electron-donor; fluorene dye) and three different release units (electron-acceptors; nitrobenzyl, pyridinium and phenacyl) were identified as suitable building blocks for the current project. Efficiency of the intramolecular electron transfer between chosen units was evaluated using model dyads which constitute covalently linked electron-donor and acceptor species. Chapter 3 is devoted to the synthesis and photophysical evaluation of nitrobenzyl-based protecting group. Chapter 4 describes the preparation of pyridinium-derived protecting group and demonstrates PeT-mediated release of tryptophan and GABA under one- and two-photon excitation. Hydrolytic instability of pyridinium esters is highlighted. Chapter 5 reports the synthesis, hydrolytic stability and one-photon uncaging efficiency of phenacyl-based derivatives. Chapter 6 discusses properties of developed caged compounds and compares them with other compounds reported in literature. It contains overall conclusions and outlook for the current project. Chapter 7 details the experimental procedures and the characterization of compounds synthesized during this work.
9
He, Chaobin. "Synthesis and structure of rigid chain polyamides with bulky side groups." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/273003.
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10
Deodhar, Bhushan S. "Towards the development of rotaxanes with two functional blocking groups." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1311690891.
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11
Wood, Martin William. "The Modules We Live By in Groups: Individual Differences in Orientations toward Coordinating Action in Groups." Thesis, Griffith University, 2019. http://hdl.handle.net/10072/386549.
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A growing body of literature is beginning to examine how individuals engage and interact with others within group contexts. However, no research has examined how individuals’ orientations toward coordinating action in groups, their relational orientations, alter their behaviour within group interactions. This thesis asserts that this gap has potentially been driven by the absence of a framework that captures all facets of the relational modules individuals use to coordinate action in groups. In turn, existing measures of relational orientations cannot necessarily be applied within the intragroup domain. This thesis represents an attempt to bridge this gap. First, a description of individual differences in orientations towards coordinating action in groups informed by Durkheim (1893/2014) is presented. The description outlines that two distinct collections of relational orientations exist, mechanical and organic. Second, across five studies this thesis presents the development and preliminary evidence of a measure that may capture individual variation in people’s orientations toward coordinating action in groups according to a mechanical or organic relational module, the Mechanical and Organic Orientations Scales or MOOS for short.
In an initial pilot study (Chapter 2) preliminary items created to capture mechanical and organic orientations are submitted to factor analytic methods to examine the underlying structure of the items. While the results of this pilot study were promising, a number of issues suggested that further refinement of the items was needed. A series of studies were then conducted using a revised set of items (Chapter 3). In Study 1, an exploratory factor analysis using the revised set of items was conducted. Although the item factor loadings were moderate, the results provided some support for a two factor model of relational group orientations reflecting the two predicted mechanical and organic orientations, with nine items in each factor. Study 2 then sought to confirm the factor structure observed in Study 1. The results demonstrated good indices of fit. The factor structure and loading of items were also shown to be consistent through a series of multigroup measurement invariance models. Study 2 also sought to establish the convergent and divergent validity of the MOOS from measures that capture people’s life-guiding principles. The results provided support for the validity of the MOOS, with associations demonstrating that the MOOS captures a dimension of sociality that is different to but nonetheless related to broad socially organising principles. Study 3 was then conducted to further establish the construct validity of the MOOS from existing measures of people’s relational orientations. Only tentative support for the MOOS was obtained in this study. While the patterns of convergence and divergence found in Study 3 suggested that the MOOS are related to existing relational orientation measures, the patterns of results were paradoxical to what theory outlined in Chapter 1 would suggest. A considerable discussion is also provided to discuss why these paradoxical patterns may have emerged. In Study 4, associations between the MOOS and the ties people seek to form with others in their own social networks were examined. Again, only weak support for the validity of the MOOS was obtained. Although the MOOS do appear to be associated with group level phenomena (i.e., how people form their interdependencies with others), some of these associations were non-significant. The results of Study 4 were taken to provide only preliminary support to the validity of the MOOS. Study 4 also noted that further research is needed before the MOOS can be fully utilised in contemporary research.
The general discussion (Chapter 4) then draws upon the findings of the five studies to propose that while there is some evidence to suggest that people’s relational group orientations may be relevant to the way people coordinate action in groups, further research is necessary to establish the validity of the MOOS. With the recognition that further improvements are necessary, the theoretical and practical implications of an improved MOOS are then discussed. Specifically, this discussion draws attention to the relevance of these findings for research in relationship science and group dynamics, and provides examples of how an improved MOOS may be used to inform theory and practice within these domains. Limitations of the research program are discussed and suggestions for future research exploring mechanical and organic orientations are also outlined.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Applied Psychology<br>Griffith Health<br>Full Text
12
Yeats, Keith. "An investigation into the synthesis and crosslinking of some polymers containing cyclopropyl groups." Thesis, Durham University, 1990. http://etheses.dur.ac.uk/6051/.
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The thesis describes an investigation into the use of polymers containing cyclopropyl groups as network forming materials. The initial route investigated involved the synthesis and homopolymerization of novel acrylate and methacrylate monomers containing cyclopropyl groups. Preliminary crosslinking experiments revealed the unsuitability of this approach. The second route examined involved the synthesis of a series of all hydrocarbon copolymers containing pendant cyclopropyl groups. Crosslinking experiments using a variety of initiators demonstrated the feasibility, in principle, of the proposed network forming system. In order to provide a practical crosslinking system further investigation into suitable initiators would be required.
13
Rudd, Martin D. "Macrocyclic complexation of cationic f-block (lanthanide) and p-block (groups 14 and 15) metal species." Thesis, University of Warwick, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282539.
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14
楊小雯 and Siu-man Yeung. "The synthesis and reactions of 3H-pyrroles bearing methyl and aryl groups." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31210119.
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15
Saito, Hayate. "Development of Silyl Groups Bearing Bulky Alkoxy Unit and Their Application to Organic Synthesis." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263488.
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16
Christian, Karen. "Content-Related Interactions and Methods of Reasoning within Self-Initiated Organic Chemistry Study Groups." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145096.
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Students often use study groups to prepare for class or exams; yet to date, we know very little about how these groups actually function. This study looked at the ways in which undergraduate organic chemistry students prepared for exams through self-initiated study groups. We sought to characterize the methods of social regulation, levels of content processing, and types of reasoning processes used by students within their groups. Our analysis showed that groups engaged in predominantly three types of interactions when discussing chemistry content: co-construction, teaching, and tutoring. Although each group engaged in each of these types of interactions at some point, their prevalence varied between groups and group members. Our analysis suggests that the types of interactions that were most common depended on the relative content knowledge of the group members as well as on the difficulty of the tasks in which they were engaged.Additionally, we were interested in characterizing the reasoning methods used by students within their study groups. We found that students used a combination of three content-relevant methods of reasoning: model-based reasoning, case-based reasoning, or rule-based reasoning, in conjunction with one chemically-irrelevant method of reasoning: symbol-based reasoning. The most common way for groups to reason was to use rules, whereas the least common way was for students to work from a model. In general, student reasoning correlated strongly to the subject matter to which students were paying attention, and was only weakly related to student interactions.Overall, results from this study may help instructors to construct appropriate tasks to guide what and how students study outside of the classroom. We found that students had a decidedly strategic approach in their study groups, relying heavily on material provided by their instructors, and using the reasoning strategies that resulted in the lowest levels of content processing. We suggest that instructors create more opportunities for students to explore model-based reasoning, and to create opportunities for students to be able to co-construct in a collaborative manner within the context of their organic chemistry course.
17
Ritchie, Jason Duane. "The distribution of charge and acidic functional groups in natural organic matter the dependence on molecular weight and pH /." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-08252005-125918/.
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Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2006.<br>Michael Bergin, Committee Member ; E. Michael Perdue, Committee Chair ; Ching-Hua Huang, Committee Member ; Ellery Ingall, Committee Member ; Martial Taillefert, Committee Member. Vita. Includes bibliographical references.
18
Grudzien, Rafal M. "Synthesis and characterization of ordered cage-like siliceous mesostructures with organic pendant and bridging groups." [Kent, Ohio] : Kent State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1226507948.
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Thesis (Ph.D.)--Kent State University, 2008.<br>Title from PDF t.p. (viewed Dec. 17, 2009). Advisor: Mietek Jaroniec. Keywords: mesoporous, FDU-1, SBA-16, organosilicas, pendant groups, bridging groups, adsorption, isocyanurate, template removal, cage-like structures. Includes bibliographical references (p. 219-238).
19
Malmstrom, Rex R. "Contributions of abundant bacterial groups to the flux of dissolved organic matter in the ocean." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.42 Mb.,170 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3200540.
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20
Mizori, Farhad G. "Transmetallation from zirconium to boron : the synthesis and conjugate addition of mixed unsymmetrical tricoordinate organoboranes containing phenyl and methyl groups /." Diss., Connect to a 24 p. preview or request complete full text in PDF formate. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3138868.
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21
Dell'angela, Martina. "Organic molecules at metal surfaces: the role of functional groups in self-assembly and charge transfer." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3071.
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2007/2008<br>The understanding of the interaction of organic molecules with metal surfaces
is crucial for tailoring the desired properties of future devices that can be
employed for molecular electronics or biomedical applications. Self-assembly
of complex supramolecular structures and charge transfer through molecular
films or even through single molecules are some of the properties that have
recently attracted much interest both for possible applications and for more
fundamental studies.
The molecule-surface interaction takes place thanks to the functional
groups that constitute the molecule. The choice of appropriate functional
groups of the molecules allows their use as building blocks in the fabrication
of complicate architectures [1]. In fact, the functional entities can influence
molecule-molecule and molecule-surface interactions, governing the
self-assembly of the molecules on the surface.
In particular, in the thesis I will report on the characterization by means of
Helium Atom Scattering (HAS), X-ray Photoemission Spectroscopy (XPS),
Near Edge X-ray Absorption Fine Structure (NEXAFS) and Scanning Tunneling
Microscopy (STM) of the self-assembly in ultra high vacuum (UHV)
conditions of L-methionine molecules on different metal substrates (Ag(111),
Cu(111), Au(111), Au(110)). L-methionine is an amino acid with three functional
groups which can interact with the substrate or with other molecules:
the amino (-NH2), the carboxyl (-COOH) and the thioether (-S-). Moreover,
the first two can change their charge state in a protonated amino group
(-NH+
3 ) and a deprotonated carboxyl group (-COO−): the molecules are
called zwitterionic and it is allowed the formation of hydrogen bonds between
them. Hydrogen bonding between zwitterionic molecules is responsible for
the crystallization in the solid state. In the thesis I have studied how, depending
on the choice of the substrate and the growth conditions, L-methionine
molecules form assemblies with different morphologies and different chemical
states of the building blocks. L-methionine molecules deposited on Ag(111)
and Au(111) are in the zwitterionic state and interact strongly via hydrogen
bonding forming dimers of molecules. The weak interaction with the
substrate allows the organization of these dimers in extended bidimensional
nanogratings composed of chains of length extending in the micrometer range
and with tunable periodicity across the chains. At temperatures below 270K,
L-methionine on Cu(111) forms short aggregates of zwitterionic dimers. By
increasing the substrate temperature above 300K the charge state of the
amino group changes and also the interaction with the surface. Molecules
are anionic (-NH2 and -COO−) and form again charged nanogratings. The
anionic state of the molecules can also be obtained on the Au(110) surface,
where the interaction of the amino and thioether groups with the gold inhibits
the formation of zwitterionic dimers via hydrogen bonding.
The functional groups in the molecules can also influence their transport
properties. The final goal of miniaturization in molecular electronics research
is the formation and characterization of a nanoelectronic device in which a
molecule between two electrodes plays the role of an active conducting element.
In such a device the interaction between the functional groups anchoring
the molecule to the electrodes and the electrodes is a crucial element
in order to understand and control the conduction. Recent STM-break junction
experiments [2] have shown that Au-molecule-Au contacts with amino (-
NH2) terminated molecules are better defined than Au-molecule-Au contacts
formed with thiol (-SH) terminated molecules [3]. The strong interaction of
thiols with gold surfaces is well known in literature and the self-assembly of
thiolated molecules is widely employed in many applications. In contrast, the
weak interaction of amino terminated molecules with gold is poorly studied.
Theoretical calculations suggest that the amine lone pair is responsible for
bonding and that it prefers to bind to undercoordinated gold atoms. Within
this framework, in the thesis I report on the study of growth of thin films of
1,4-benzenediamine and p-toluidine on two different Au surfaces, where the
atoms present different coordination: Au(111) and Au(110). Both molecules
interact more strongly with the low coordination (110) surface. By means of
Resonant Photoemission Spectroscopy (RPES) it has been possible to disentangle
molecular orbitals and determine the ones involved in the charge
transfer at the surface. In both cases the charge transfer involves states localized
also on the nitrogen atoms indicating a possible interaction of the
molecule with the surface through nitrogen atoms. I also studied the assembly
of three benzene substituted diamines on Au(111). These results
complement very well the results obtained from conduction experiments of
different amine-terminated molecules and combined with theoretical investigations
can help understanding the basics of the molecular charge transport
mechanism.
[1] Barth J.V., Costantini G., Kern K., Nature, 437 (2005) 671
[2] Venkataraman L., Klare J. E., Nuckolls C., Hybertsen M. S., Steigerwald
M. L., Nature, 442 (7105), 904 (2006)
[3] Schreiber F., Progress in Surface Science, 65 (5-8) (2000) 151<br>Lo studio dell’interazione di molecole organiche con superfici metalliche è
di fondamentale importanza per la progettazione di futuri dispositivi che
possiedano proprietà ben controllabili in modo tale che possano essere usati
per l’elettronica molecolare o per applicazioni biomediche. L’autoassemblaggio
di complesse strutture ”supramolecolari” e il trasferimento di carica attraverso
film molecolari o anche attraverso singole molecole sono alcune delle proprietà
che hanno attratto di recente grande interesse sia per le possibili applicazioni
future che per studi di tipo più fondamentale.
L’interazione molecola-superficie avviene attraverso i gruppi funzionali
che costituiscono le molecole. Molecole con appropriate funzionalizzazioni
possono essere usate come mattoni elementari nella fabbricazione di architetture
complesse [1]. Infatti, tali gruppi funzionali possono influenzare le
interazioni del tipo molecola-molecola e molecola-superficie che governano
l’autoassemblaggio delle molecole sulla superficie.
In particolare, in questa tesi riporter`o circa la caratterizzazione mediante
diffrazione di atomi di elio (HAS), spettroscopia di fotoemissione di raggi
X (XPS), misure di assorbimento di raggi X (NEXAFS) e microscopia ad
effetto tunnel (STM) dell’autoassemblaggio in condizioni di ultra alto vuoto
(UHV) di molecole di L-metionina su diversi substrati metallici (Ag(111),
Cu(111), Au(111), Au(110)). La molecola di L-metionina `e un amminoacido
che presenta tre gruppi funzionali i quali possono interagire con il substrato
o con altre molecole: il gruppo amminico (-NH2), il gruppo carbossilico (-
COOH) e il gruppo tioetere (-S-). I primi due possono inoltre cambiare il
loro stato di carica originando un gruppo amminico protonato (-NH+
3 ) e un
gruppo carbossilico deprotonato (COO−): in tal caso le molecole sono dette
zwitterioniche ed è permessa la formazione di legami a idrogeno tra esse.
I legami a idrogeno tra molecole zwitterioniche sono responsabili della loro
cristallizzazione nello stato solido. In questa tesi ho studiato come, a seconda
della scelta del substrato e delle condizioni di cescita, le molecole di
L-metionina formino strutture assemblate che presentano diverse morfologie
e diversi stati chimici delle molecole costituenti. Le molecole di L-metionina
depositate su Ag(111) e Au(111) sono zwitterioniche e interagiscono fortemente
tra di loro tramite legami a idrogeno a formare dimeri di molecole sulla
superficie. La debole interazione con il substrato permette l’organizzazione
di questi dimeri in estesi reticoli bidimensionali di dimensione nanometrica
composti da catene di lunghezza nel range micrometrico e con spaziatura tra
le catene controllabile. A temperature sotto 270K, le molecole di L-metionina
su Cu(111) formano corti aggregati di dimeri zwitterionici. Aumentando la
temperatura del substrato oltre 300K lo stato di carica del gruppo amminico
cambia e quindi l’interazione con la superficie. Le molecole sono anioniche
(-NH2 e COO−) e formano di nuovo reticoli carichi. Lo stato anionico delle
molecole si può ottenere anche sulla superficie di Au(110) dove l’interazione
dei gruppi amminico e tioetere con l’oro inibisce la formazione di dimeri
zwitterionici via legami a idrogeno.
I gruppi funzionali nelle molecole possono anche influenzare le loro proprietà di trasporto. Lo scopo finale della miniaturizzazione nella ricerca nel
campo dell’elettronica molecolare è la formazione e caratterizzazione di un
dispositivo nanoelettronico in cui una molecola immobilizzata tra due elettrodi
gioca il ruolo di elemento conduttivo attivo. In tale dispositivo il controllo
dell’interazione tra i gruppi funzionali che tengono la molecola attaccata
gli elettrodi e gli elettrodi è un elemento cruciale per la comprensione e il
controllo della conduzione. Recenti esperimenti del tipo STM break junction
[2] hanno motrato che contatti del tipo Au-molecola-Au con molecole con terminazioni
amminiche (NH2) sono meglio definiti che contatti del medesimo
tipo con molecole con terminazione tiolica (-SH) [3]. La forte interazione
dei tioli con superfici d’oro è ben nota in letteratura e l’autoassemblaggio
di molecole con terminazione tiolica è largamente utilizzato in molte applicazioni.
In contrasto, la debole interazione di molecole con terminazione
amminica con superfici d’oro è stata poco studiata. Recenti calcoli teorici
hanno previsto che le molecole si legano alla superficie d’oro attraverso il
”lone pair” localizzato sull’azoto e che sono preferiti i legami con atomi di
oro di bassa coordinazione. In particolare, nella tesi riporterò i risultati dello
studio della crescita di film sottili di 1,4-benzenediamina e p-toluidina su
due diverse superfici d’oro, i cui atomi di superficie presentano diversa coordinazione:
Au(111) e Au(110). Ambedue le molecole interagiscono più
fortemente con la superficie di bassa coordinazione (110). Tramite la tecnica
di fotoemissione risonante (RPES) è stato possibile individuare gli orbitali
molecolari e determinare quelli coinvolti nel trasferimento di carica
all’interfaccia. In ambedue i casi il trasferimento di carica coinvolge stati
che sono localizzati anche sull’atomo di azoto, il che indica una possibile interazione
della molecola con la superficie attraverso i gruppi amminici. Ho
anche studiato l’assemblaggio su Au(111) di tre diverse benzene-diamine con
vii
diversi sostituenti legati all’anello. Questi risultati sono un complemento ai
risultati ottenuti da esperimenti di conduzione di molecole con diverse terminazioni
amminiche e combinati con le investigazioni teoriche possono aiutare
nella comprensione dei fondamenti dei meccanismi di trasporto di carica nelle
molecole.
[1] Barth J.V., Costantini G., Kern K., Nature, 437 (2005) 671
[2] Venkataraman L., Klare J. E., Nuckolls C., Hybertsen M. S., Steigerwald
M. L., Nature, 442 (7105), 904 (2006)
[3] Schreiber F., Progress in Surface Science, 65 (5-8) (2000) 151<br>XXI Ciclo<br>1981
22
Wild, Peter Gareth. "The use of immobilised crown ethers as in-situ protecting groups for organic synthesis within flow reactors." Thesis, University of Hull, 2008. http://hydra.hull.ac.uk/resources/hull:1180.
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Organic synthesis often requires one functional group of a bifunctionalised compound to be rendered temporarily inert to allow the selective reaction of another moiety. While protecting groups are used to remove the problem of the functional group incompatibility, they also raise other issues such as increasing the length of the synthetic pathway (by at least two steps – protection and deprotection), generally leading to an increase in cost and a decrease in yield. The protecting group is often selected based upon the deprotection conditions, leading to the requirement for orthogonal protecting groups. Crown ethers are commonly associated with the complexation of metal ions, but the 18-crown-6 species also readily bind ammonium ions with complexation occurring via hydrogen bonding. As discussed in Chapter 1, crown ethers have previously been employed for N-protection in this way, to successfully facilitate the reaction of bifunctional compounds, though they have exhibited very little selectivity and reaction control. Isolation of the desired product from the resulting reaction mixture has also proven to be problematic.Over recent years there has been a large increase in the volume of organic protocols conducted in micro and continuous flow reactors. Utilising the high surface to volume ratio obtained under these reaction conditions, greater reaction control of many common and specialised organic syntheses has been reported. Building upon literature precedent, the work herein reports the immobilisation of an 18-crown-6 ether derivativeonto a solid-support and its incorporation into a continuous flow reactor to enable sequestration of the primary amine salt of a bi-functionalised compound. This effectively affords a non-covalent N-protection strategy allowing the selective reaction of the remaining moiety. The desired product is subsequently recovered as the free amine by a simple process of decomplexation using an organic base.
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Thenna, Hewa Kosala R. S. "Applications Focused Synthetic Modification on Photoremovable Protecting Groups (PRPG) & Photochemical Analysis on Organic Azides and Isoxazoles." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511858669354976.
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Macklin, Todd Kristopher. "The development of sulfamates as latent directed metalation groups. Total synthesis of schumanniophytine. Divergent synthesis of substituted chromone 3- and 8-carboxamides." Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/925.
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Webb, Lauren J. Gray Harry B. "Chemical characterization and charge carrier dynamics of crystalline silicon(111) surfaces modified with surface-bound organic functional groups /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05262005-123044.
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Mogemark, Mickael. "Solid-phase glycoconjugate synthesis : on-resin analysis with gel-phase ¹9F NMR spectroscopy." Doctoral thesis, Umeå University, Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-438.
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<p>An efficient and versatile non-destructive method to analyze the progress of solid-phase glycoconjugate synthesis with gel-phase <sup>19</sup>F NMR spectroscopy is described. The method relies on use of fluorinated linkers and building blocks carrying fluorinated protective groups. Commercially available fluorinated reagents have been utilized to attach the protective groups. </p><p>The influence of resin structures for seven commercial resins upon resolution of gel-phase <sup>19</sup>F NMR spectra was investigated. Two different linkers for oligosaccharide synthesis were also developed and successfully employed in preparation of α-Gal trisaccharides and a n-pentenyl glycoside. Finally, reaction conditions for solid-phase peptide glycosylations were established.</p>
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Bonner, Grady Gregg 1965. "Synthesis, pharmacology, and structural analysis of opioid peptides: Cyclic somatostatin analogs which include unusual amino acids with conformationally restricted side-chain groups." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282318.
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This work relates the activities of Somatostatin-derived opioid peptides to their 3-dimensional structures. Due to the flexability of peptides, they adopt multiple conformations. This flexibility leads to ambiguity in the development of structure-activity profiles. Here flexibility is reduced by incorporation of amino acids with conformationally restricted side-chain groups. These groups are restricted to certain topographies by cyclization or biased through substitution at the beta carbon. The opioid activities of these peptides are determined by brain binding radioligand competition assay, in vitro activity in the mouse vas deferens (MVD) and guinea pig ileum (GPI) smooth muscle twitch-height inhibition assays, and in vivo in the mouse warm water tail-flick latency assay. Their 3-dimensional structures were determined through a variety of 2D 1H NMR including TOCSY, ROESY, DQF-COSY, and COSY-35, as well as molecular modeling including energy minimization and molecular dynamics. By knowing the activity of the peptides, and their preferred conformations, a reasonably confident structure-activity profile was generated.
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Sigstad, Emma Elizabeth. "Extraction of 1:1 electrolytes and some organic molecules by resins containing dibenzo-18-crown-6 as anchor groups." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/843414/.
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Resins containing dibenzo-18-crown-6 (phiDB18C6) as anchor groups have been prepared according to the procedure suggested by Blasius and the total capacity, CT, determined by micro analysis. The effective capacity, CE, of phiDB18C6 towards the alkali-metal salts using water as reaction media was obtained from saturation experiments. The electrolyte concentration dependence of the distribution ratio of 1:1 electrolytes between phiDB18C6 and water at 298K was studied and the results used to determine the concentration range at which a maximum separation factor between two ions could be achieved. The rational equilibrium constant, log K'ex, corrected for activity in the solution phase and the derived apparent free energy change, DeltaG'ex for the process taking place when phiDB18G6 is equilibrated with an aqueous or non-aqueous solutions (s) of the different M+A- electrolytes as represented by are calculated. The results obtained clearly reflect the influence of the anions on the extraction of cations by the resin containing the macrocyclic ligand. For aqueous solutions of electrolytes containing a common cation and different anions the selectivity found is in the order Pi→SCN→I→Br→C1-. An enhancement of selectivity by a factor of 1.55x104, 8.91x103, 2.09x103 and 1.55x103 is found for the picrate salts relative to the chloride, bromide, iodide and thiocyanate, respectively. The heats associated with the interaction of phiDB18C6 and 1:1 electrolytes in aqueous solutions were measured calorimetrically at 298K and the apparent enthalpy change evaluated. Combination of the free energy and enthalpy changes yield the corresponding entropy changes. The contribution of the enthalpy and entropy terms to the free energy suggests that the process of extraction of 1:1 electrolytes from the aqueous I s solution to the resin phase is enthalpically controlled. An interesting relationship is obtained when values for the effective capacity of the resin towards the different 1:1 electrolytes are plotted against the apparent enthalpies(DeltaH'ex) obtained for the different electrolytes in water. Distribution data for the 1:1 electrolytes and phiDB18C6 were obtained in solvents such as N,N-dimethylformamide (DMF), propylene carbonate (PC), acetonitrile, (AN), methanol (MeOH) and water (H2O), in an attempt to evaluate the reaction media effects on the extraction of 1:1 electrolytes by these resins. Distribution ratios decrease in the order AN→PC→MeOH→DMF→H2O. Interaction between organic molecules in aqueous solutions (urea, thiourea, and phenol) and phiDB18C6 were also studied. Effective capacity measurements as determined by saturation experiments at 298K using thiourea and phenol indicate that the 1:1 organic molecule crown ether ratio obtained for the former compound is altered to a 4:1 ratio in the case of phenol. A possible mechanism based on hydrogen bond formation in the resin phase is suggested.
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Kulikov, Anton V. "DEVELOPMENT OF PHOTOCLEAVABLE LINKER GROUPS FOR APPLICATION TO PHOTOCLEAVAGE OF LIPOSOMES AND OF CAGING ALCOHOLS AND CARBOXYLIC ACIDS." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1150729530.
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Zhao, Qun. "Palladium-catalyzed directed introduction of α-CF3-vinyl and SCF3 groups by C-H bond functionalization". Thesis, Normandie, 2017. http://www.theses.fr/2017NORMIR15.
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Ces dernières années ont été témoin de l'énorme développement de la chimie organique du fluor. Notamment, l'introduction de groupements fluorés émergents sur des « briques » moléculaires variées a attiré l'attention de la communauté scientifique en raison de leurs propriétés particulières. De plus, la stratégie de fonctionnalisation dirigée de la liaison C-H par catalyse par les métaux de transition, a conduit à une révolution dans le développement de méthodologies synthétiques originales. Par conséquent, la conception de nouvelles approches synthétiques pour l'introduction de groupements fluorés par fonctionnalisation de la liaison C-H catalysée par les métaux de transition est particulièrement attirante. Dans cette thèse, nous nous sommes concentrés sur le développement de nouvelles méthodologies d'introduction directe des groupements fluorés sur des arènes et des oléfines par fonctionnalisation directe de liaison C(sp2)-H catalysée par les métaux de transition. En particulier, nous avons tourné notre attention sur le 2-bromo-3,3,3-trifluoropropène (BTP), un réactif fluoré bon marché et provenant de déchets de l'industrie. Ce dernier est utilisé comme agent de remplacement de halon pour la suppression des incendies et, utilisé comme « brique » moléculaire en synthèse organique (Chapitre 1). La première partie de cette thèse est dédiée au développement de nouvelles méthodologies pour l'introduction directe du groupement CF3-vinyl sur des arènes et des oléfines par fonctionnalisation de la liaison C(sp2)-H catalysée par le palladium. Ensuite, cette approche a été étendue à la fonctionnalisation d'esters α,β- insaturés, bien qu'un mécanisme différent soit probablement impliqué (Chapitre 2). Dans la seconde partie de cette thèse, nous avons développé une nouvelle méthodologie pour l'introduction directe du groupement SCF3 sur des arènes et des oléfines par fonctionnalisation de la liaison C(sp2)-H catalysée par le palladium, utilisant le réactif de Munavalli (Chapitre 3)<br>Recent years have witnessed a great development of the organofluorine chemistry field. In particular, the introduction of emergent fluorinated moieties onto various scaffolds has attracted attention of the scientific community because of their special properties. Besides, transition metal-catalyzed directed C-H bond functionalization strategy has brought a revolution in the development of original synthetic methodologies, since it allows straightforward and more atom-economical processes. Thus, the design of new synthetic approaches for the introduction of fluorinated moieties by transition metal-catalyzed C-H bond functionalization pathway is particularly appealing. Therefore, in this Ph.D. thesis, we focused on the development of new methodologies for the direct introduction of fluorinated moieties onto arenes and olefins by transition metal catalyzed directed C(sp2)-H bond functionalization. In particular, we turned our attention to the 2-bromo-3,3,3-trifluoropropene (BTP), an inexpensive fluorinated reagent coming from industry waste, used as a potential halon replacement for fire suppression and as a fluorinated building block in organic synthesis (Chapter 1). The first part of this Ph.D. thesis was dedicated to the development of new methodologies for the direct introduction of a CF3- vinyl moiety onto arenes and olefins by a Pd-catalyzed directed C(sp2)-H bond functionalization with BTP. Then, this approach was extended to the functionalization of α,β-unsaturated esters, although a different reaction pathway is probably involved (Chapter 2). In the second part of this Ph.D. thesis, we developed a new methodology for the direct introduction of the SCF3 group onto arenes and olefins by Pd-catalyzed directed C(sp2)-H bond functionalization using the Munavalli reagent (Chapter 3)
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Elacqua, Elizabeth. "Supramolecular chemistry of molecular concepts: tautomers, chirality, protecting groups, trisubstituted olefins, cyclophanes, and their impact on the organic solid state." Diss., University of Iowa, 2012. https://ir.uiowa.edu/etd/3447.
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The research presented in this thesis is founded upon the ability to mimic Nature by using highly directional forces to influence self-assembly, while achieving the formation of desired supramolecular structures. The successful engineering of such solids relies upon a full comprehension of supramolecular synthons, so as to apply them to design complex architectures. We have studied synthon formation in multifunctional pharmaceutical solids. Through the formation of salts and co-crystals, we uncovered a role of tautomers in the salt – co-crystal continuum. From a solid-state perspective, one can envisage that tautomers could promote co-crystal formation since an inherent flexibility to interconvert can accommodate geometries of different co-formers, as well as increase the number of synthons able to support a multicomponent solid. We have also employed co-crystallization to ibuprofen as a means to exploit solid-state properties. We have shown that co-crystallization with bipyridines can result in the formation of both co-crystal solid solutions and co-crystal conglomerates.
Supramolecular chemistry can also be utilized to construct target organic and metal-organic frameworks. Solid-state synthesis has emerged as a means to achieve the formation of molecular targets that are usually inaccessible via solution phase synthesis through the exploitation of molecular recognition and self-assembly. In particular, utilizing a combinatorial template strategy can facilitate a [2+2] photodimerization in the solid state. Although the template-directed strategy has helped circumvent problems associated with crystal packing, the solid state is still not routinely used for synthesis, owing, in part, to a lack of expansion to multifunctional olefins and molecular targets.
We have introduced a method to direct the reactivity of multifunctional olefins that contain two robust hydrogen bonding elements to produce heteropolytopic molecules that are of interest for the formation of metal-organic frameworks. Specifically, we developed a protecting group strategy that affords a supramolecular regiochemistry to attain the desired self-assembly. We have also extended our template approach to more conformationally-complex molecules to gain a further understanding of the rules regarding reactivity in highly substituted systems.
The end of this thesis is focused upon the solid-state synthesis of a series of molecular targets known as cyclophanes. Cyclophanes have a very rich history however, their immersion in all aspects of chemistry has suffered from a lack of high yielding synthetic techniques, as well as novel methodologies that target substitution on the aliphatic bridges. We have shown that a series of laterally-substituted [2.2]cyclophanes can be synthesized in quantitative yields utilizing template-directed self-assembly. The cyclophanes also exhibit optical properties that are influenced by a nonconventional internal charge transfer process, stemming from the strained cyclobutane core. We have also developed a sonochemical method to produce nanocrystals of cyclophanes, resulting in enhanced and red-shifted emissions.
Overall, the results described herein detail the use of supramolecular chemistry to achieve the formation of target architectures that differ in topology, connectivity, and/or physiochemical properties. The entirety of this thesis represents the undeveloped interplay between traditional synthetic organic chemistry and supramolecular solid-state chemistry. While the precision afforded by the crystalline phase provides access to molecular targets with high fidelity, expansion to multifunctional molecules that are desirable in the context of emergent properties bodes well for the continued development and exploitation of molecular recognition to generate novel functional materials.
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Selaya, Susan D. "Investigations into the fluorescent covalent labeling of biomolecules utilizing rhodamine dyes, electrophilic leaving groups and mRNA display." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3623.
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The discovery of a method by which proteins of interest can selectively be labeled with a probe of choice intracellularly is a longstanding goal in chemical biology research. Conventional labeling techniques have utilized large domain tags but despite the development of small labeling molecules there have been no short peptide sequences known to covalently label a small molecule without the aid of an enzymatic process or metal chelation. We aimed to find a sequence of nucleophilic peptides that reacted covalently and specifically with electrophilic small labeling molecules using mRNA display. Our goal was to show that an electrophilic small labeling molecule that is brought in proximal distance to a protein of interest via affinity can result in nucleophilic attack by a neighboring nucleophilic amino acid to covalently label the protein of interest. Utilizing affinity between a small labeling molecule and a protein of interest to bring them spatially close to one another maximizes the chance that a covalent reaction can take place and provides selectivity between two components in a complex mixture. Towards this goal, we developed several electrophilic fluorescent small molecules. Covalent labeling was achieved using electrophilic bait in the form of sulfonate esters, a polyethylene oxide linker provided structural flexibility, and a fluorescent affinity tag containing a rhodamine backbone served as the potential binding site to a key peptide sequence encoded within a protein of interest. The synthetic routes to access our electrophilic rhodamine B and sulforhodamine 101 fluorophores were optimized. Key intermediates were produced and served as flexible points of modification to make various analogs of our desired electrophilic fluorophores. The affinity between proteins containing the peptide sequence and the fluorescent electrophiles were determined by fluorescence polarization. Covalent labeling was determined to be both time and concentration dependent. The expected published affinity between the peptides and fluorophore was not high enough to produce selective labeling. However, our small labeling molecules were found to be effective at labeling various proteins in vitro. In addition, our electrophilic fluorophores have been found superior to sulforhodamine 101 in live cell imaging of astrocytes.
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Sobieski, Julian Witold. "Assessing steric bulk of protecting groups via a computational determination of exact cone angle and exact solid cone angle." Kent State University Honors College / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1528385706530151.
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Hartdegen, Vera [Verfasser], and Thomas M. [Akademischer Betreuer] Klapötke. "Energetic polymers and plasticizers based on organic azides, nitro groups and tetrazoles : synthesis and characterization / Vera Hartdegen. Betreuer: Thomas M. Klapötke." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1105374033/34.
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Grabicka, Bogna E. "Microwave-Assisted Synthesis of Ordered Mesoporous Organosilicas with Surface and Bridging Groups." Kent State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=kent1290459085.
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Konosonoks, Armands. "Release of Alcohols Through Photoenolization." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1132334815.
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Schwartz, Rachel E. "Oxidized organic functional groups in aerosol particles from forest emissions measured at mid-mountain and high-elevation mountain sites in Whistler, BC." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p1474776.
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Thesis (M.S.)--University of California, San Diego, 2010.<br>Title from first page of PDF file (viewed April 14, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references.
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Karlsson, Torbjörn. "Complexation of cadmium, copper and methyl mercury to functional groups in natural organic matter : studied by X-ray absorption spectroscopy and binding affinity experiments /." Umeå : Dept. of Forest Ecology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005117.pdf.
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Sattar, A. K. "Catalytic transfer hydrogenation of organic functional groups using Ni, Ru complexes and asymmetric induction using racemic chiral and achiral ligands and synthetic applications." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2005. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2462.
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Yang, Florent. "Electrochemical modification of Si surfaces by methyl groups (CH 3, CD 3), ethynyl derivatives, pyrrole and thiophene." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/16034.
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Silizium (Si) wird für eine breite Palette von Anwendungen wie z.B. in Solarzellen, Mikroelektronik, Biochips und so weiter eingesetzt. In dieser Arbeit wurden neue Hybridsysteme aus Si und organischen Molekülen, bezüglich der Oberflächenpassivierung des Halbleiters und der resultierenden elektronischen Eigenschaften untersucht. Insbesondere wurden Methyl-Gruppen (CH3 und CD3), Ethynyl-Derivate (H−C≡C-, CH3−C≡C-, und C6H5−C≡C-), sowie Pyrrol und Thiophen aus Grignardlösungen untersucht. Bezüglich Stabilität und Defektkonzentration konnte gezeigt werden, dass organisch modifizierte Si-Oberflächen eine höhere Stabilität an Luft haben als Standard wasserstoffpassivierte Si-Oberflächen und dabei eine nur geringfügig höhere Defektkonzentration aufweisen. Untersuchungen mit Infrarot Spektroskopischer Ellipsometrie (IRSE) und Synchrotron Röntgen Photoemissions Spektroskopie (SXPS) zeigen, dass die Oxidationsrate für Oberflächen mit CH3-Terminierung stark reduziert ist. In der vorliegenden Arbeit gelang es erstmalig mittels IRSE die charakteristische „Umbrella“-Schwingungsmode zu beobachten und SXPS Messungen zeigten die Spin-Orbit-Aufspaltung der Si 2p Emission für CH3-passivierte Si-Oberflächen. Die CH3-Gruppen besitzen einen hohen Grad von Ordnung auf der Si(111)-Oberfläche. Das Aufbringen von Ethynyl-Derivaten führt zu extrem dünnen polymerisierten Schichten auf Si durch elektrochemische Radikaloxidation der C≡C Dreifachbindung. Diese Schichten sind homogen und haften sehr gut an der Si-Oberfläche. Weiterhin konnte gezeigt werden, dass die Abscheidung von Ethynyl-Derivaten vom Typ des Halogenatoms im Grignard-Precursor abhängig ist, wobei Br im Vergleich zu Cl zu geringeren Rekombinationsgeschwindigkeiten an der Polymer/Si-Grenzfläche führen. Eine Änderung der Austrittsarbeit von bis zu 0.5 eV und der Bandverbiegung von bis zu 0.24 eV wurde nach der Abscheidung dieser Moleküle gemessen. Diese elektronischen Eigenschaften hängen linear vom Oberflächendipol ab.<br>Organic functionalization of silicon (Si) surfaces has received a tremendous interest in the development of organic/semiconductor hetero-structures for plenty of potential applications from microelectronics, molecular electronics, photovoltaics to bio-applications. In this thesis, tailoring of the electronic properties and passivation properties of such organic hetero-structures have been investigated. Direct grafting of organic layers like methyl groups (CH3 and CD3), ethynyl derivatives (H−C≡C-, CH3−C≡C-, and C6H5−C≡C-), and heterocyclic molecules (pyrrole and thiophene) onto Si(111) surfaces have been performed in a one-step electrochemical process by anodic treatment in Grignard electrolytes. Organically modified Si surfaces show low interface recombination rates as measured by photoluminescence technique and reveal also a much better passivation with respect to stability in ambient air than H-terminated Si surfaces. Grafting of ethynyl derivatives and heterocyclic molecules lead to the formation of ultrathin polymeric layers, where the thickness depends on charge flow applied to the Si electrode, while methyl groups lead to a monolayer on Si(111) surfaces. Only a very small amount of oxidation states of Si has been observed by infrared spectroscopic ellipsometry (IRSE) and synchrotron X-ray photoemission spectroscopy (SXPS). For the first time, IRSE and SXPS measurements reveal the “umbrella” vibrational mode characteristic from methyl groups and a well-defined spin-orbit splitting of the Si 2p core level emission, respectively, in the case of methylated Si(111) surfaces. For all ethynyl derivatives, high-resolution SXPS investigations reveal the incorporation of halogen atoms in the organic layers obtained. Thereby, exchanging Br for Cl in the Grignard compound leads to lower interface recombination rates at the polymer/Si interface. A shift in work function and surface band bending of up to 0.5 and 0.24 eV has been observed, respectively. The electronic properties reveal a linear relation between the work function and the surface dipole.
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Ilic, Ivan [Verfasser], Markus [Akademischer Betreuer] Antonietti, Andreas [Gutachter] Taubert, and Christina [Gutachter] Roth. "Design of sustainable cathodes for Li-ion batteries : understanding the redox behaviour of guaiacyl and catecholic groups in lithium organic system / Ivan Ilic ; Gutachter: Andreas Taubert, Christina Roth ; Betreuer: Markus Antonietti." Potsdam : Universität Potsdam, 2020. http://d-nb.info/1222587696/34.
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Anzicek, Nika. "Studies towards a second-generation synthesis of the aplyronines." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267831.
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The aplyronines are a family of 24-membered macrolides of polyketide origin, isolated from the Japanese sea hare Aplysia kurodai. They exhibit an exceptional biological activity profile, acting through an actin and tubulin dual-targeting mechanism, with subnanomolar growth inhibitory potency against a diverse range of cancer cell lines. These characteristics render the aplyronines ideal payloads for antibody-drug conjugates but their prohibitively low natural abundance calls for an efficient total synthesis to overcome the supply issue. This dissertation describes the efforts towards developing a second-generation Paterson synthesis of the macrocyclic core of the aplyronines, focused on improving the scalability and selectivity of key transformations. Chapter 1 details the isolation, biological background and previous synthetic efforts towards the aplyronines to illustrate their therapeutic potential and the challenges associated with material sourcing by chemical synthesis. Chapter 2 presents the existing body of work on the aplyronine project within the Paterson group, highlighting the lessons learned over the past two decades and shortcomings to be addressed. Chapter 3 discusses a revised protecting group strategy towards the C1-C27 macrocyclic alcohol 159 with fewer manipulation steps. A refined reaction sequence featuring titanium aldol methodology and an enzymatic desymmetrisation process delivered multigram stocks of the C15-C27 aldehyde 161 upon scale- up, testifying to the robustness of the devised route. Synthesis of the C1-C14 northern fragment 253 closely followed the existing boron aldol approach with optimisation of the C11-C12 alkylation step, geared towards enhancing the regioselectivity. Chapter 4 describes the coupling of the two major fragments using an Horner-Wadsworth-Emmons reaction to assemble the C1-C27 backbone of the cyclic aplyronine core and suitably adjusted endgame steps to enable a one-step oxidative unmasking of the macrolactonisation sites. The first-generation intermediate 159 was accessed via site-specific Yamaguchi esterification and orthogonal deprotection of the C27 allyl carbonate. Discussion in Chapter 5 includes the appendage of the C28-C34 side chain 118, prepared by the known sequence, and suggestions for the future direction of the second-generation route with the outlook of linker appendage for the purposes of antibody-drug conjugate development.
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Naulet, Guillaume. "Techniques de protection pour la synthèse de larges arènes polycycliques par réaction de Perkin." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0188/document.
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La variante « glyoxylique » de la réaction de Perkin permet de lier entre eux deux fragments aromatiques par un pont maléique. La rigidification de cet intermédiaire flexible mène à des systèmes aromatiques polycycliques étendus par création des liaisons carbone-carbone manquantes. Cette stratégie requiert l'utilisation d'acides arylacétiques et arylglyoxyliques, et l’utilisation d'unités bifonctionnelles a auparavant permis la synthèse de cibles variées allant des phénacènes plans aux (poly)hélicènes très distordus, mais aussi des macrocycles conjugués. Afin d'étendre la taille et la variété des molécules obtenues à l'aide de cette stratégie, des méthodes générales de protection/déprotection sont développées. Une dissymétrisation efficace des unités bifonctionnelles mène à des nouveaux précurseurs monoprotégés qui sont ensuite assemblés par la réaction de Perkin en oligomères de taille contrôlée possédant encore des fonctions chimiques réactives aux extrémités après déprotection. L'utilisation de ces derniers lors d'une deuxième réaction de Perkin donne alors accès à de longs précurseurs flexibles, d’au moins cinq unités, qui donneront ensuite de très longs phénacènes, de grands macrocycles mais aussi des cyclo-tris[5]hélicènes qui présentent une géométrie de Möbius persistante et une aromaticité de Möbius<br>The “glyoxylic” variant of the Perkin reaction allows to link two aromatic fragments by a maleic bridge. The stiffening of the obtained flexible intermediate by the creation of the missing carbon-carbon bonds leads to extended polycyclic aromatic systems. This strategy relies on the use of arylacetic and arylglyoxylic acids, and the use of bifunctional units has previously allowed the synthesis of a variety of targets spanning from flat phenacenes to strongly distorted (poly)helicenes, as well as of conjugated macrocycles. This approach is generalized here by developing protection/deprotection techniques in order to enhance the size and the variety of the molecules that can be obtained by this strategy. These techniques enable an efficient dissymetrization of bifunctional units and the recycling of symmetrical side products. The new monoprotected building blocks are connected by Perkin reactions to yield oligomeric intermediates with reactive functions at their extremities after deprotection. Several of these intermediates are assembled in a second Perkin reaction to obtain long phenacenes, large macrocycles and also cyclo-tris[5]helicenes with persistent Möbius geometry and Möbius aromaticity
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Ericsson, Cecilia. "Synthesis of Tetrahydrofuran and Pyrrolidine Derivatives Utilising Radical Reactions : Organochalcogenides in Reductive, Carbonylative and Group-Transfer Cyclisation." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4018.
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Liu, Jianping. "Part I. Self-assembled, low-dimensional materials composed of both lanthanides and transition metals bridged by cyanate or cyanide groups. Part II. Syntheses and reactivity studies of cyclic organohydroborate anions in organic and organometallic.. /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487943341528842.
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El, Haddad Imad. "Fraction primaire et secondaire de l'aérosol organique : méthodologies et application à un environnement urbain méditerranéen, Marseille." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10029.
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La mise en place de politiques efficaces visant à la réduction des niveaux de concentrations en PM exige la connaissance préalable des sources primaires et secondaires de l’aérosol organique, une fraction majoritaire des PM demeurant encore mal appréhendée. Les travaux réalisés au cours de cette thèse s’inscrivent dans le cadre du projet FORMES qui avait pour principal objectif d’évaluer et de contraindre les principales méthodes de quantification de l’influence des différentes sources de la fraction organique de l’aérosol en milieu récepteur et d’en optimiser les procédures. La caractérisation physico-chimique de l’aérosol s’est articulée autour de deux campagnes de mesures intensives de 15 jours chacune dans deux environnements urbains très contrastés : Marseille en été, et Grenoble en hiver. Ce travail de thèse s’est concentré sur le cas de Marseille, un environnement très complexe, combinant une activité photo oxydante très intense à un ensemble d’émissions primaires qui incluent les sources industrielles et les émissions par les bateaux.L’analyse CMB appliquée sur le cas de Marseille a montré que les sources primaires sont dominées par les émissions véhiculaires contribuant à 17 % du carbone organique (OC). Bien que les sources industrielles contribuent faiblement à la masse de l’aérosol (2.5 % de l’OC), ces émissions contrôlent les concentrations des HAP et de certains métaux lourds. Ces sources contribuent également, en moyenne sur la période, à environ 30% du nombre des particules ultrafines (Dp<50 nm), ce qui augmente probablement leurs effets sanitaires. Contrairement à Grenoble, où la combustion de bois est une source prépondérante (environ 70 % de l’OC), à Marseille ces émissions ne constituent qu’une source minoritaire, contribuant à 0.8 % de l’OC. Toutefois, la principale information révélée par la déconvolution de sources par CMB est que les sources primaires considérées ne permettent d’expliquer, que 22 % de l’OC mesuré ; 78 % du carbone restant non expliqué. Cette fraction est associée majoritairement à l’aérosol organique secondaire (SOA). En combinant les résultats CMB aux mesures 14C, il a été montré que plus que 70% de cet aérosol est très vraisemblablement d’origine biogénique. En conséquence, les contributions du SOA formé à partir de l’isoprène, l’α-pinène et le β-caryophyllène ont été examinées moyennant une approche basée sur les marqueurs de cet aérosol. Le SOA issu de ces précurseurs a été estimé comme contribuant uniquement à 4.3 % de l’OC, laissant une grande fraction de ce carbone non-attribuée. Cette sous-estimation est la conséquence de trois causes : (i) les incertitudes associées à l’approche utilisée, (ii) des précurseurs biogéniques non-considérés et (iii) le vieillissement de l’aérosol secondaire au cours de son transport dans l’atmosphère, comme suggéré par les mesures d’organosulfates et de la fraction polycarboxylique de type HULIS. Cette dernière fraction peut contribuer à près de 40% de l’OC non-attribué<br>Tougher particulate matter regulations around the world and especially in Europe point out the need of source apportionment studies in order to better understand the different primary and secondary sources of organic aerosol, a major fraction of particulate matter that remains not well constrained. The work carried out in this thesis takes part of the FORMES project whose main objective is the source apportionment of the organic aerosol using different approaches, including mainly CMB modelling, AMS/PMF and radiocarbon (14C) measurements. The aerosol characterisation was performed within two intensive field campaigns conducted in two contrasted urban environments: Grenoble during winter and Marseille during summer. The present work focuses on the Marseille case study that presents a particularly complex environment, combining an intense photochemistry to a mixture of primary emissions including shipping and industrial emissions. Primary organic carbon (POC) apportioned using CMB modelling contributed on average for only 22% and was dominated by vehicular emissions accounting on average for 17% of OC. Even though, industrial emissions contribute for only 2.3% of the total OC, they are associated with ultrafine particles and high concentrations of Polycyclic Aromatic Hydrocarbons and heavy metals such as Pb, Ni and V, which most likely relate them with acute health outcomes. Whereas in Grenoble the organic aerosol was dominated by wood burning smoke (70% of OC), this source was negligible in Marseille contributing for less than 1% of OC. The main result from this source apportionment exercise is that 78% of OC mass cannot be attributed to the major primary sources and remains un-apportioned; this fraction is mostly associated with secondary organic aerosol. Radiocarbon measurements suggest that more than 70% of this fraction is of modern origins, assigned predominantly to biogenic secondary organic carbon (BSOC). Therefore, contributions from three traditional BSOC precursors, isoprene, α-pinene and β-caryophellene, were considered using a marker based approach. The aggregate contribution from BSOC derived from these precursors was estimated at only 4.2% of total OC. As a result, these estimates underpredict the high loading of OC. This underestimation can be associated with (i) uncertainties underlying the marker-based approach, (ii) presence of other SOC precursors and (iii) further processing of fresh SOC, as indicated by organosulfates (RSO4) and HUmic LIke Substances (HULIS) measurements. This HULIS can contribute up to 40% of the unattributed OC
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Nokami, Toshiki. "Aqueous Organic Syntheses Using Pyridylsilyl Group as a Removable Hydrophilic Group." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147630.
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Parker, D. C. "The dimethyl(phenyl)silyl group : A masked hydroxyl group for organic synthesis." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372282.
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Naim, A. A. "Polymer end-group studies." Thesis, Lancaster University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376702.
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Chrystiuk, E. "Acyl group transfer mechanisms." Thesis, University of Kent, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374300.
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