Thematische Bibliographien / Host-Guest moleculars

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Auswahl der wissenschaftlichen Literatur zum Thema „Host-Guest moleculars“

Autor: Grafiati

Veröffentlicht am 18. Mai 2024

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Zeitschriftenartikel zum Thema "Host-Guest moleculars"

Malinska, Maura. „Insights into molecular recognition from the crystal structures of p-tert-butylcalix[6]arene complexed with different solvents“. IUCrJ 9, Nr. 1 (16.11.2021): 55–64. http://dx.doi.org/10.1107/s2052252521010678.

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Calixarenes are host molecules that can form complexes with one or more guest molecules, and molecular recognition in calixarenes can be affected by many factors. With a view to establishing molecular recognition rules, the host p-tert-butylcalix[6]arene (TBC6) was crystallized with different guest molecules (cyclohexane, anisole, heptane, toluene, benzene, methyl acetate, ethyl acetate, dichloromethane, tetrahydrofuran and pyridine) and the obtained structures were characterized by X-ray diffraction. With most solvents, 1:1 and/or 1:3 host–guest complexes were formed, although other stoichiometries were also observed with small guest molecules, and crystallization from ethyl acetate produced the unsolvated form. The calculated fill percentage of the TBC6 cavity was ∼55% for apolar guests and significantly lower for polar solvents, indicating that polar molecules can bind to apolar cavities with significantly lower packing coefficients. The most stable crystals were formed by 1:1 host–guest inclusion complexes. The ratio between the apolar surface area and the volume was used to predict the formation of inclusion versus exclusion complexes, with inclusion complexes observed at ratios <40. These findings allow the binding of potential guest molecules to be predicted and a suitable crystal packing for the designed properties to be obtained.

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Chen, Kaifei, Seyed Hesam Mousavi, Ranjeet Singh, Randall Q. Snurr, Gang Li und Paul A. Webley. „Gating effect for gas adsorption in microporous materials—mechanisms and applications“. Chemical Society Reviews 51, Nr. 3 (2022): 1139–66. http://dx.doi.org/10.1039/d1cs00822f.

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External stimuli or host–guest interactions induce structural changes, producing a gating effect in which an adsorbent suddenly becomes accessible to guest molecules. This effect greatly facilitates gas separation, storage, and molecular detection.

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Lebedinskiy, Konstantin, Ivan Barvík, Zdeněk Tošner, Ivana Císařová, Jindřich Jindřich und Radim Hrdina. „Spatial arrangements of cyclodextrin host–guest complexes in solution studied by ¹³C NMR and molecular modelling“. Beilstein Journal of Organic Chemistry 20 (20.02.2024): 331–35. http://dx.doi.org/10.3762/bjoc.20.33.

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13C NMR spectroscopic analyses of Cs symmetric guest molecules in the cyclodextrin host cavity, combined with molecular modelling and solid-state X-ray analysis, provides a detailed description of the spatial arrangement of cyclodextrin host–guest complexes in solution. The chiral cavity of the cyclodextrin molecule creates an anisotropic environment for the guest molecule resulting in a splitting of its prochiral carbon signals in 13C NMR spectra. This signal split can be correlated to the distance of the guest atoms from the wall of the host cavity and to the spatial separation of binding sites preferred by pairs of prochiral carbon atoms. These measurements complement traditional solid-state analyses, which rely on the crystallization of host–guest complexes and their crystallographic analysis.

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Elemans, Johannes A. A. W., Roeland J. M. Nolte und Alan E. Rowan. „Hierarchical self-assembly of a host-guest porphyrin array“. Journal of Porphyrins and Phthalocyanines 07, Nr. 04 (April 2003): 249–54. http://dx.doi.org/10.1142/s1088424603000331.

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The construction of a porphyrin array by a stepwise, hierarchical self-assembly process is described. Four molecular clip host molecules are complexed, in a solid state self-assembly process, to one porphyrin guest molecule. When dissolved in chloroform, the 4:1 host-guest complexes spontaneously self-assemble into an array in which the porphyrins are organized in a cofacial stack. The ensemble is stabilized by a combination of π-π interactions between the porphyrins and between the aromatic surfaces of the host molecules.

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Liang, Guodong, Jacky W. Y. Lam, Wei Qin, Jie Li, Ni Xie und Ben Zhong Tang. „Molecular luminogens based on restriction of intramolecular motions through host–guest inclusion for cell imaging“. Chem. Commun. 50, Nr. 14 (2014): 1725–27. http://dx.doi.org/10.1039/c3cc48625g.

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Suzuki, Akira, Yuya Miyake, Ryoga Shibata und Kazuyuki Takai. „Spin and charge interactions between nanographene host and ferrocene“. Beilstein Journal of Organic Chemistry 20 (02.05.2024): 1011–19. http://dx.doi.org/10.3762/bjoc.20.89.

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Ferrocene (FeCp2) was introduced as a non-magnetic guest molecule to activated carbon fibers (ACFs) as a nanographene-based host having localized spins originating from zigzag edges of graphene. The introduction of the guest molecule was confirmed by FTIR for ACFs-FeCp2 introduced at 55 (150) °C (FeCp2-ACFs-55(150)). The appearance of satellite Fe2p peaks and the increase in shake-up peak intensity of the C1s in the XPS spectrum proved the emergence of charge-transfer host–guest interaction in FeCp2-ACFs-150, supported by the red-shift of the G-band in the Raman spectrum. The six-times enhancement in the spin concentration in FeCp2-ACFs-150 compared with ACFs indicates the spin magnetism of the non-magnetic guest FeCp2+ molecule induced by a charge-transfer host–guest interaction in the nanographene host. The larger ESR linewidth than that expected from the dipolar interaction estimated by the localized spin concentration suggests the exchange interaction between the nanographene and FeCp2 spins. The narrowing of the ESR linewidth of FeCp2-ACFs-55 upon higher excitation microwave power suggests the inhomogeneity of the environment for FeCp2+ molecules in the nanographene host. The observed induction of spin magnetism by the interfacial interactions between the nanographene host and the guest molecules will be a promising strategy for developing a new class of molecular magnets.

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Sun, Zhaoxi, Qiaole He, Zhihao Gong, Payam Kalhor, Zhe Huai und Zhirong Liu. „A General Picture of Cucurbit[8]uril Host–Guest Binding: Recalibrating Bonded Interactions“. Molecules 28, Nr. 7 (31.03.2023): 3124. http://dx.doi.org/10.3390/molecules28073124.

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Atomic-level understanding of the dynamic feature of host–guest interactions remains a central challenge in supramolecular chemistry. The remarkable guest binding behavior of the Cucurbiturils family of supramolecular containers makes them promising drug carriers. Among Cucurbit[n]urils, Cucurbit[8]uril (CB8) has an intermediate portal size and cavity volume. It can exploit almost all host–guest recognition motifs formed by this host family. In our previous work, an extensive computational investigation of the binding of seven commonly abused and structurally diverse drugs to the CB8 host was performed, and a general dynamic binding picture of CB8-guest interactions was obtained. Further, two widely used fixed-charge models for drug-like molecules were investigated and compared in great detail, aiming at providing guidelines in choosing an appropriate charge scheme in host-guest modelling. Iterative refitting of atomic charges leads to improved binding thermodynamics and the best root-mean-squared deviation from the experimental reference is 2.6 kcal/mol. In this work, we focus on a thorough evaluation of the remaining parts of classical force fields, i.e., the bonded interactions. The widely used general Amber force fields are assessed and refitted with generalized force-matching to improve the intra-molecular conformational preference, and thus the description of inter-molecular host–guest interactions. The interaction pattern and binding thermodynamics show a significant dependence on the modelling parameters. The refitted system-specific parameter set improves the consistency of the modelling results and the experimental reference significantly. Finally, combining the previous charge-scheme comparison and the current force-field refitting, we provide general guidelines for the theoretical modelling of host–guest binding.

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Yoshida, Hiroaki, Ken Kikuta und Toshiyuki Kida. „Fabrication of supramolecular cyclodextrin–fullerene nonwovens by electrospinning“. Beilstein Journal of Organic Chemistry 15 (09.01.2019): 89–95. http://dx.doi.org/10.3762/bjoc.15.10.

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Direct electrospinning of small molecules has great potential to fabricate a new class of fiber materials because this approach realizes the creation of various functional materials through the numerous molecular combinations. In this paper, we demonstrate a proof-of-concept to fabricate supramolecular fiber materials composed of cyclodextrin (CD)–fullerene inclusion complexes by electrospinning. Similar to the molecular state of fullerenes in solution, the resulting fibers include molecularly-dispersed fullerenes. We believe such a concept could be expanded to diverse host–guest complexes, opening up supramolecular solid materials science and engineering.

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Archana Sumohan Pillai, Sivaraj Ramasamy, Varnitha Manikandan, Aleyamma Alexander und Israel V.M.V. Enoch. „Anticancer Activity of the Host-Guest Complex of Camptothecin with β-Cyclodextrin-Folate Conjugate. Encapsulation and Efficacy“. International Journal of Research in Pharmaceutical Sciences 11, SPL4 (21.12.2020): 1286–91. http://dx.doi.org/10.26452/ijrps.v11ispl4.4294.

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Cyclodextrins are cyclic oligosachcharides that act as molecular hosts and accommodate drug molecules forming host: guest complexes. They aid in the sustained release of the encapsulated drugs through diffusion in solution and protect their unstable forms. In this paper, we report the synthesis of a β-cyclodextrin-folate by a simple coupling reaction. The compound is characterized using IR, NMR, and mass spectroscopic techniques. The amide carbonyl band is observed at 1680 cm-1. The mass spectrum shows the molecular ion peak of the β-cycloxetrin-folate conjugate at an m/z value of 1615.35. An inclusion complex of the anticancer drug, camptothecin, with the β-cycloxetrin-folate is formed on the stepwise addition of the β-cycloxetrin-folate to the guest molecule. The complex formation is studied using UV-visible and fluorescence spectroscopy. The formation of host: guest complexes is known to enable the sustained release of the encapsulated drug molecule. Herein, we examined the in vitro anticancer activity of the host: guest complex against cervical cancer (HeLa) cells. The host: guest complex formation results in enhanced efficacy of the drug. Dose-dependent cytotoxicity is observed for the β-cyclodextrin-folate: camptothecin complex. The cytotoxicity is more for the complex than for the free drug in solution.

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Wen, Huimin, Wengang Li, Jiewei Chen, Gen He, Longhua Li, Mark A. Olson, Andrew C. H. Sue, J. Fraser Stoddart und Xuefeng Guo. „Complex formation dynamics in a single-molecule electronic device“. Science Advances 2, Nr. 11 (November 2016): e1601113. http://dx.doi.org/10.1126/sciadv.1601113.

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Single-molecule electronic devices offer unique opportunities to investigate the properties of individual molecules that are not accessible in conventional ensemble experiments. However, these investigations remain challenging because they require (i) highly precise device fabrication to incorporate single molecules and (ii) sufficient time resolution to be able to make fast molecular dynamic measurements. We demonstrate a graphene-molecule single-molecule junction that is capable of probing the thermodynamic and kinetic parameters of a host-guest complex. By covalently integrating a conjugated molecular wire with a pendent crown ether into graphene point contacts, we can transduce the physical [2]pseudorotaxane (de)formation processes between the electron-rich crown ether and a dicationic guest into real-time electrical signals. The conductance of the single-molecule junction reveals two-level fluctuations that are highly dependent on temperature and solvent environments, affording a nondestructive means of quantitatively determining the binding and rate constants, as well as the activation energies, for host-guest complexes. The thermodynamic processes reveal the host-guest binding to be enthalpy-driven and are consistent with conventional 1H nuclear magnetic resonance titration experiments. This electronic device opens up a new route to developing single-molecule dynamics investigations with microsecond resolution for a broad range of chemical and biochemical applications.

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Dissertationen zum Thema "Host-Guest moleculars"

Moncelsi, Giulia. „Stimuli-responsive host-guest systems decorated with hemithioindigo and spiropyran units“. Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668163.

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L’objectiu del treball de recerca d’aquesta tesis doctoral és el disseny i síntesis de contenidors moleculars que responguin a estímuls externs mitjançant la incorporació d’unitats foto-isomeritzables (photoswitchable units (PUs) en anglès) a les estructures tant del receptor com de la molècula reconeguda. S’han utilitzat dos tipus de PUs amb propietats diferenciades, hemitioindigos i espiropirans, incorporats a dos tipus de macrocicles, calix[4]arè i calix[4]pirrole. S’ha estudiat la isomerització de les PUs mitjançant la irradiació amb llum i el tractament àcid-base així com l’efecte d’aquesta en les propietats d’enllaç i encapsulació tant dels receptors unimoleculars com de les capsules supramoleculars. Primerament es descriu la síntesis i la caracterització fotoquímica de dos hemitioindigos que presenten un grup N-òxid terminal. S’ha demostrat la isomerització Z/E sota llum visible (λ = 450 nm) i s’ha estudiat en detall la constant d’enllaç dels dos isomers Z/E en la cavitat aromàtica polar d’un receptor calix[4]pirrole super aril-extès en dissolvents orgànics. Seguidament, s’han dissenyat i sintetitzat dos calixarens tetra-urea decorats amb quatre unitats hemitioindigo al cèrcol superior. S’ha descrit la seva síntesis i s’ha investigat la seva dimerització en dissolvents orgànics no-polars en presència de salts de tetrametilfosfoni. També es descriuen els intents de foto-isomerització tant dels monòmers com dels agregats de les tetra-ureas. Finalment, s’ha sintetitzat un calixarè tetra-urea amb quatre grups espiropirà al cèrcol superior. S’ha estudiat el seu auto-assemblatge en capsules homo- i hetero- dimèriques, aquesta última en presència d’un calix[4]pirrole i un N-òxid. S’han realitzat estudis d’auto-assemblatge, “self-sorting”, estudis foto- i acido- cròmics de les capsules en dissolvents clorats. Els resultats suggereixen que els tractaments àcid-base de les capsules són reversibles i pronostiquen bons resultats en el transport i alliberament controlat de molècules.
El objetivo del trabajo de investigación incluido en esta tesis es el diseño y síntesis de sistemas receptor-huésped capaces de responder a estímulos externos. Estos sistemas cuentan con interruptores moleculares fotosensibles unidos covalentemente al receptor o al huésped. Los interruptores moleculares presentados son hemitioindigos y espiropiranos, mientras que las estructuras macrocíclicas están basadas en calix[4]arenos y calix[4]pirroles. Se estudió cómo la irradiación con luz y el tratamiento acido-base inducen la isomerización del interruptor molecular, así como el efecto que este proceso tiene en la afinidad de enlace y las propiedades de encapsulación de los receptores unimoleculares y las cápsulas supramoleculares. Se describe la síntesis de dos hemitioindigo N-oxidos. Se investigó su fotoisomerización reversible Z/E con luz visible (λ = 450 nm) al mismo tiempo que se realizó un estudio detallado de la interacción 1:1 y su efecto en la isomerización Z- y E-HTI en la cavidad aromática polar de un calix[4]pirrol super aril-extendido en disolvente orgánico. A continuación, se diseñaron y sintetizaron dos calix[4]arenos tetraurea decorados con cuatro hemitioindigos en su parte superior. Se describen los intentos de sintetizar dichos receptores y su dimerización en una variedad de disolventes orgánicos apolares y en presencia de tetrametil fosfonio. También se describe la fotoisomerización de las tetraureas en su estado monomérico y formando agregados. Finalmente, se sintetizó un calix[4]areno con unidades tetraurea capaz de responder a estímulos externos que cuenta con cuatro espiropiranos en su parte superior. Este receptor se auto ensambla formando capsulas homo- y heterodiméricas, esta última en presencia de un calix[4]pirrol similar y un N-oxido adecuado. Se discuten los estudios de auto-ensamblaje, “self-sorting”, foto- y acidocrómicos de dichos sistemas capsulares en disolventes clorados. Los resultados apuntan a que el tratamiento acido-base es reversible y predicen un buen comportamiento para su uso como transportadores y liberación de moléculas.
The aim of the research work included in this doctoral thesis is the design and synthesis of stimuli-responsive host-guest systems in which photoswitchable units are covalently incorporated into either the receptor’s or the guest’s scaffold. We use two photoswitches with distinct properties, hemithioindigos and spiropyrans, and two types of macrocyclic scaffolds based on calix[4]arene and calix[4]pyrrole. We study how light-irradiation and acid-base treatments induce the isomerization of the molecular switch. We were especially interested in coupling the isomerization processes with the binding affinity and the encapsulation properties of unimolecular receptors and supramolecular capsules, respectively. First, we describe the synthesis and photochemical characterization of two hemithioindigos featuring a terminal N-oxide moiety. We probe their Z/E reversible photoisomerization with visible light (λ = 450 nm) and we provide a detailed study of the 1:1 binding and its effect on the switching of the Z- and E-HTI isomers into the polar aromatic cavity of a super aryl-extended calix[4]pyrrole receptor in organic solvent. Next, we design and synthesize two tetraurea calix[4]arenes decorated with four hemithioindigo units at the upper rim. We describe the synthetic efforts to obtain these receptors and we investigate their dimerization in a variety of non-polar organic solvents and in the presence of tetramethyl phosphonium salts. We also report the tentative photoisomerization of the tetraureas in the monomeric state and involved in aggregates. Finally, we synthesize a stimuli-responsive tetraurea calix[4]arene featuring four appended spiropyran groups at its upper rim, which self-assembles into a homo- or heterodimeric capsule, the latter in the presence of a calix[4]pyrrole counterpart and a suitable N-oxide templating guest. The self-assembly, self-sorting, photo- and acidochromic studies of the capsular systems in chlorinated solvents are discussed. Our results suggest that the acid-base treatments are reversible and augur well for the transport and release of molecular cargo.

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Bouanga, Boudiombo Jacky Sorrel. „Molecular selectivity by host-guest methods“. Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33667.

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The Host-Guest inclusion crystallization method has long been used for the separation of closely related compounds. Especially for the separation of isomers which presented difficulties in techniques like distillation or chromatography. In this study, different host systems were used to separate isomers of trimethoxybenzenes, lutidines, methylacetophenones and xylenols. Isomers are compounds with the same molecular formula but different arrangement of their atoms. They are often produced as mixtures when synthesised in large quantities by various industries and are more valuable as purified single components. Thus, it is important to separate them into their individual components. The process of Host-Guest method is dependent on the phenomenon of molecular recognition between the host and guest molecules, and this, in turn, relies on the sum of non-bonded, secondary interactions which impinge on the final crystalline product. This is especially the case for enantiomers which are isomers with the same boiling points and melting point. However, enantiomers differ by their ability to diffract polarised light. Although countless methods have been used for their separation, one method that has been proven to be certainly successful on this path was the “family method”. The “Dutch resolution method” or the “family method” makes use of the crystallization technique by mixing similar host compounds to separate enantiomers. However, the improvement of the end results was not understood. In fact, the whole process has been done just on results and no analysis of the actual activity occurring at the molecular level was investigated. In this research, the Host-Guest chemistry method was applied with the aim of separating several isomers compounds in the intention of understanding the selectivity characteristics of a particular host. For the purpose of the analysis, structural isomers with close boiling points were selected. Competition experiments were set to survey which of the isomers were a better fit for a particular host. After analysis of the different crystal material obtained from crystallization experiments with NMR techniques, various trends were observed. X-Ray crystallography was employed to elucidate the crystal structures of the different compound formed by Host-Guest chemistry. The new complexes were further analysed by thermal analysis (TGA, DSC), kinetics of desolvation, Hirshfeld surface analysis, and activation energy of desolvation-analysis techniques. During the separation of the trimethoxybenzene (TMB) isomers, cholic acid and deoxycholic acid' hosts were used in chapter 3. It was found that each host separated the isomers differently. That was independent of the closeness of their molecular structures. The difference in selectivity was attributed to the arrangement of each host in the structure obtained with the guest compounds. Separation of lutidines was carried out in chapters 4 and 5. The first separation consisted of the study of the fifteen pairwise combinations of the isomers with 3,3′-bis(9-hydroxy-9- fluorenyl)2−2′- binaphthyl which is presented in chapter 4. The second analysis was carried out with host 2,2'bis(1-hydroxy-4,5-dihydro-2,3:6,7-dibenzocycloheptatrien-1-yl)-biphenyl. Nevertheless, both hosts preferred 3,4-lutidine. Four additional hosts were used to simulate the “Dutch resolution method” in chapter 5. Further analysis of torsion angles was performed over the five hosts for the complexes formed with 2,4-lutidine and 3,5-lutidine. The host characterized by unbridged phenyl moieties and the one characterized by bulky tert-butyl groups was found to prefer 3,5-lutidine. In chapter 6, deoxycholic acid resolved the 2-methylcyclohexanone (2MCH) but not 3- methylcyclohexanone (3MCH) during the separation of methylcyclohexanone isomers. However, during the competition experiment, it was found that when 2MCH was mixed with 3MCH, the latter was resolved as an S-enantiomer. Kinetics of desolvation studied resulted in the determination of the activation energies of the Host-Guest complexes and was like the trend observed by 1H NMR analysis. Chapter 7 was focused on the synergistic effect of mixed hosts system. This was to emphasize the impact that a mixture of compounds with similar structural composition may provide. Competition experiments were done with the 15 pairs of xylenol isomers with 4,4'- isopropylidene Bisphenol. Three of these pairs were selected for further analysis with two similar bisphenol hosts. One interesting structure was obtained with 4,4-isopropylidene Bisphenol and 4,4'-(9-Fluorenylidene) Bisphenol with a guest mixture. This is an unusual result as crystal structures comprising two hosts with two guests are rare.

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Bezuidenhout, Charl Xavier. „Polar ordering of guest molecules in host-guest inclusion complexes“. Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18107.

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Thesis (MSc)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: 2,7-dimethylocta-3,5-diyne-2,7-diol forms inclusion complexes with various guests molecules, where the guest molecules are polar-ordered. A Cambridge Structural Database (CSD) search revealed ten inclusion complexes where the guest molecules were polar-ordered. Using Density Functional Theory (DFT) computational methods (in the absence of the host), we evaluated the intra-channel and lateral guest-guest interactions between the guest molecules. Two polar-ordered inclusion complexes ((1,4,7-cyclohexane-1,2,4,5,7,8-hexaoxonane)·CHCl3 and (2,4,6-(endolongifolyl)-1,3,5-trioxane)·CDCl3) were singled out in the CSD search for further studies along with 2,7-dimethylocta-3,5-diyne-2,7-diol. Synthesis of any 1,2,4,5,7,8-hexaoxonane and 1,3,5-trioxane derivatives was attempted to establish whether the polar-ordering ability extends into the family of compounds. We managed to produce three new polar-ordered inclusion complexes with 2,7-dimethylocta-3,5-diyne-2,7-diol (ClC(CH3)3, BrC(CH3)3 and IC(CH3)3), thus extending the series to six guest polar-ordered systems. We were only able to synthesise 1,4,7-cyclohexane-1,2,4,5,7,8-hexaoxonane and produce the CHCl3 inclusion complex and one new polar-ordered inclusion complex (CHBr3). Three 1,3,5-trioxanes was synthesised (the cyclohexyl, cyclohex-3-en-1-yl and cyclopentyl derivatives), which did not include any solvents. However, these 1,3,5-trioxanes also form polar-ordered crystals. These compounds and inclusion complexes were analysed by means of single crystal X-ray diffraction to determine their crystal structures. All the crystal structures could be solved and refined to adequate accuracy (except for 2,4,6-tri(cyclopentyl)-1,3,5-trioxane) with no disorder of the guest molecules (where applicable) and their polar-ordering property investigated. Due to their vast molecular differences, these compounds were studied separately by means of visual crystal structure analysis and computational modelling techniques (Density functional theory, molecular mechanics, molecular dynamics and molecular quench dynamics).
AFRIKAANSE OPSOMMING: 2,7-dimetielokta-3,5-diyn-2,7-diol vorm insluitingskomplekse met verskeie molekules as gaste, waar die gas-molekules polêr georden is. 'n Cambridge Struktuur Databasis (CSD) soektog lewer tien insluitings komplekse waarvan die gas-molekules polêr georden is. Deur gebruik te maak van Digtheidsfunksionele teorie (DFT) berekeninge (in die afwesigheid van die gasheer) het ons die inter-kanaal en wedersydse gas-gas interaksies tussen die gas molekules geëvalueer. Twee polêr geordende insluitingskomplekse ((1,4,7-sikloheksaan-1,2,4,5,7,8-heksaoksonaan)·CHCl3 en (2,4,6-(endolongifolyl)-1,3,5-trioksaan)·CDCl3) is uitgesonder uit die CSD soektog vir verdere studies saam met 2,7-dimetielokta-3,5-diyn-2,7-diol. Aanslag was gemaak om enige 1,2,4,5,7,8-heksaoksonaan en 1,3,5-trioksaan derivate te sintetiseer en vas te stel of die polêre ordensvermoë oor die familie van verbindings strek. Ons het daarin geslaag om drie nuwe polêr geordende insluitingskomplekse op te lewer met 2,7-dimetielokta-3,5-diyn-2,7-diol (Cl(CH3)3, BrC(CH3)3 en I(CH3)3), en sodoende die reeks uitgebrei na ses gaste wat polêr geordende insluitingskomplekse vorm. Net 1,4,7-sikloheksaan-1,2,4,5,7,8-heksaoksonaan kon gesintetiseer word en dit lewer twee polêr geordende insluitingskomplekse (CHCl3 en CHBr3 (nuut)). Drie 1,3,5-trioksane is gesintetiseer (die sikloheksiel, sikloheks-3-een-1-iel en siklopentiel derivate) en het nie enige oplosmiddels (gaste) ingesluit nie. Nietemin vorm hiedie 1,3,5-trioksane ook polêr geordende kristalle. Hierdie verbindings en insluitingskomplekse is geanaliseer deur middel van enkelkristal X-straal diffraksie om hul kristalstrukture te bepaal. Alle kristalstrukture was opgelos en verwerk tot voldoende akkuraatheid (behalwe vir 2,4,6-tri(siklopentiel)-1,3,5-trioxane) met geen wanorde in die gas molekuul posisies nie (waar van toepassing) en hul polêre ordensvermoë is ondersoek. As gevolg van groot verskille in hul molekulêre strukture, is hierdie verbindings afsonderlik bestudeer deur middel van molekulêre modellerings metodes (Digtheidsfunksionele teorie, molekulêre meganika, molekulêre dinamika en molekulêre stakings dinamika).

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Grotzfeld, Robert M. (Robert Martin). „Studies in molecular recognition : self-assembling molecular host-guest sytems“. Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10865.

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HOUSE, BRIAN EDWARD. „HOST-[2] ROTAXANES: GUEST RECOGNITION AND CELLULAR TRANSPORT“. University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155826127.

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Montalvo, Acosta Joel José. „Computational approaches to molecular recognition : from host-guest to protein-ligand binding“. Thesis, Strasbourg, 2018. http://www.theses.fr/2018STRAF051/document.

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La reconnaissance moléculaire est un problème très intéressant et surtout un défi actuel pour la chimie biophysique. Avoir des prévisions fiables sur la reconnaissance spécifique entre les molécules est hautement prioritaire, car il fournira un aperçu des problèmes fondamentaux et suscitera des applications technologiques pertinentes. La thèse présentée ici est centrée sur une analyse quantitatif de la reconnaissance moléculaire en solution pour la liaison l'hôte-invité, la liaison protéine-ligand et la catalyse. Le cadre de la mécanique statistique utilisé pour décrire l'état de la technique de liaison récepteur-ligand est un point d'inflexion pour le développement de nouvelles méthodes améliorées. En fait, un modèle très performant et précis a été obtenu pour l'analyse de la liaison hôte-invité. Enfin, les modèles présentés ont été utilisés comme outils prédictifs fiables pour la découverte de nouvelles entités chimiques destinées à améliorer la catalyse en solution
Molecular recognition is a very interesting problem, and foremost, a current challenge for biophysical chemistry. Having reliable predictions on the specific recognition between molecules is highly priority as it will provide an insight of fundamental problems and will raise relevant technological applications. The dissertation presented here is centered on a quantitative analysis of molecular recognition in solution for host-guest, protein-ligand binding and catalysis. The statistical mechanics framework used to describe the state-of-the-art for receptor-ligand binding is an inflection point for the developing of new improved and methods. In fact, a highly performanced and accurate model was obtained for the analysis of host-guest binding. Finally, the presented models were used as a reliable predictive tools for discovering new chemical entities for enhance catalysis in solution

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MacGillivray, Leonard R. „Self-assembly for the construction of discrete and infinite host-guest architecture /“. free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924903.

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SMUKSTE, INESE. „ARTIFICIAL RECEPTORS FOR MOLECULAR RECOGNITION OF AMINO ACIDS, PEPTIDES AND CARBOHYDRATES“. University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1029757614.

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García, Simón Cristina. „Synthesis of molecular nanocapsules for supramolecular host-guest chemistry and enzyme-like catalysis“. Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/289567.

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Coordination-driven self-assembly has led to the realization of an increasing number of elegant and sophisticated functional structures, the structural complexity of which would be difficult to achieve using conventional covalent chemistry. The synthesis of three-dimensional coordination capsule-like structures is of particular interest due to their multiple potential applications, particularly their use in selective molecular recognition (host-guest chemistry), reactivity modulation (nanoreactors), molecular sensors or biological applications. The main goal of this doctoral thesis, performed in the QBIS-CAT group from the University of Girona, is the preparation of coordination nanocapsules of different sizes (1 and 2) and their application in the selective recognition of specific molecular substrates. On one hand, the smaller capsule (1) displays high selectivity towards anionic, planar-shaped -guests, whilst on the other hand, the larger nanocapsule (2) is able to encapsulate fullerenes in a rapid manner at room temperature, by simply soaking a solid sample of the capsule in a fullerene containing solution. Strikingly, the larger nanocapsule is shown to be effective for the selective separation of C60 from a mixture of fullerenes using a straightforward washing protocol of a solid sample of fullerene containing nanocapsule. Nowadays, the applications of fullerenes (i.e. in solar cells or in medicine) are limited in origin by their purification which is often tedious and expensive. The results of this investigation may pave the way for the future development of new methodologies for the purification of fullerene mixtures. Finally, the confined inner cavity of the larger nanocapsule, 2, was used to encapsulate a chiral rhodium catalyst which gave amongst the highest selectivities in the asymmetric hydroformylation of styrene for a monoligated rhodium catalyst. The results obtained demonstrate a substantial increase in stereoselectivity upon encapsulation of the catalyst, providing evidence of a selectivity-inducing effect by the secondary coordination sphere reminiscent of enzymatic active sites.
La química d’autoacoblament dirigida per enllaços de coordinació ha facilitat l’obtenció d’una gran varietat d’estructures químiques molt sofisticades, la complexitat de les quals hagués estat molt difícil d’aconseguir mitjançant la convencional química covalent. La síntesis de càpsules de coordinació tridimensionals rep un interès especial degut a la multitud d’aplicacions que aquestes ofereixen, destacant la seva aplicació en el reconeixement selectiu de molècules (química receptor-substrat), modulació de la reactivitat (nanoreactors), sensors moleculars o les seves aplicacions biològiques. El principal objectiu d’aquesta tesi doctoral, que ha estat realitzada al grup QBIS-CAT de la Universitat de Girona, és la preparació de nanocàpsules de coordinació de diferents mides (1 i 2), i la seva aplicació en el reconeixement selectiu de substrats moleculars específics. Per una banda, la nanocàpsula més petita (1) és altament selectiva per substrats plans, aniònics amb sistemes . Per altra banda, la nanocàpsula de majors dimensions (2) pot encapsular ful·lerens de manera ràpida i a temperatura ambient, simplement amarant una mostra sòlida de la nanocàpsula en una dissolució de ful·lerens. A més, la nanocàpsula més gran es va emprar amb èxit en la separació selectiva de C60 d’una barreja de ful·lerens utilitzant un senzill protocol experimental basats en rentats del sistema nanocàpsula-ful·lerè en estat sòlid. Actualment, les aplicacions dels ful·lerens (ex. en cel·les solars o en medecina) es veuen limitades per la purificació d’aquestes molècules, que generalment s’aconsegueix mitjançant processos tediosos i costos. Els resultats d’aquesta investigació podrien facilitar el desenvolupament de noves metodologies per la purificació de barreges de ful·lerens. Finalment, la cavitat interior de la nanocàpsula de majors dimensions, 2, es va utilitzar per encapsular un catalitzador de rodi quiral que va donar alts valors de selectivitat, dels més alts que s’han observat per a un catalitzador de rodi monolligat. Els resultats obtinguts demostren que l’encapsulació del catalitzador incrementa notablement l’estereoselectivitat de la reacció, i indiquen que el confinament del catalitzador dins la caixa causa un efecte d’inducció de la selectivitat similar al que té lloc en els centres catalítics dels enzims.

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Norrehed, Sara. „Modulation of Molecular Properties : Host–Guest Interactions for Structural Analysis and Chemical Reactions“. Doctoral thesis, Uppsala universitet, Syntetisk organisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-207138.

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This thesis concerns the construction, use and modulation of various host–guest systems, from small bispidines for binding of inorganic ions to bisporphyrin clips for supramolecular systems. Small flexible molecules undergo fast conformational movements when in solution. These conformational movements generate time-averaged population-weighted chemical shifts, coupling constants and NOEs when analysed by NMR spectroscopy. A bisporphyrin clip was designed to be used as a host for restriction of conformational movements of small flexible molecules by ditopic metal-ligand binding. Based on conformational analysis in combination with NMR analysis of molecular flexibility in solution (NAMFIS), the relative stereochemistry of flexible alditol-derived diamines containing three or four consecutive stereocentres could be determined. To further explore the idea of conformational deconvolution via host–guest binding, two flexible molecular tweezers with photoswitchable moieties were developed. Upon photoswitching cis/trans isomerisation facilitates the opening and closing of these bisporphyrin hosts. A guest molecule could then be exposed to a “catch and stretch” or “catch and release” effect. Preliminary studies have shown that photoisomerisation of the constructed systems is possible without photodecomposition and preliminary binding studies have been conducted. Controlled modulation of molecular conformations is of interest especially if the conformational steering activates a unit working as a nucleator in a larger structure or facilitates a reaction. The protonation-triggered modulation of bispidine conformations has been investigated. In addition to previously reported conformations we have observed that upon diprotonation a bispidine derivative can be driven into the unusual boat-boat conformation. Finally, the unexpected formation of persistent organic radicals with a cyclophane motif from the reaction of N,N´-diphenyl-1-5-diazacyclooctane and AgBF4 is described. Interestingly, these diradicals exhibit features such as intramolecular π-stacking without lateral displacement and also intramolecular spin pairing.

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Mehr Quellen

Bücher zum Thema "Host-Guest moleculars"

Symposium on Host-Guest Molecular Interactions: from Chemistry to Biology (1990 : Ciba Foundation), Hrsg. Host-guest molecular interactions: From chemistry to biology. Chichester: Wiley, 1991.

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Franco, Laeri, Hrsg. Host-guest-systems based on nanoporous crystals. Weinheim: Wiley-VCH, 2003.

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Chadwick, Derek J., und Kate Widdows, Hrsg. Ciba Foundation Symposium 158 - Host-Guest Molecular Interactions: From Chemistry to Biology. Chichester, UK: John Wiley & Sons, Ltd., 1991. http://dx.doi.org/10.1002/9780470514085.

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Crowe, Declan Brendan. Macrocyclic host molecules designed to selectively bind and transport ammonium and primary ammonium guest cations. Birmingham: University of Birmingham, 1991.

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Tite, Elizabeth Louise. The study of preorganised redox-active host molecules designed to bind neutral and cationic guest species. Birmingham: University of Birmingham, 1989.

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Symposium, CIBA Foundation, Derek J. Chadwick und Kate Widdows. Host-Guest Molecular Interactions: From Chemistry to Biology. Wiley & Sons, Limited, John, 2007.

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Chadwick, Derek J., und Kate Widdows. Host-Guest Molecular Interactions: From Chemistry to Biology. Wiley & Sons, Incorporated, John, 2008.

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McGuiness, C. L., R. K. Smith, M. E. Anderson, P. S. Weiss und D. L. Allara. Nanolithography using molecular films and processing. Herausgegeben von A. V. Narlikar und Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533060.013.23.

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This article focuses on the use of molecular films as building blocks for nanolithography. More specifically, it reviews efforts aimed at utilizing organic molecular assemblies in overcoming the limitations of lithography, including self-patterning and directed patterning. It considers the methods of patterning self-assembled organic monolayer films through soft-lithographic methods such as microcontact printing and nanoimprint lithography, through direct ‘write’ or ‘machine’ processes with a nanometer-sized tip and through exposure to electron or photon beams. It also discusses efforts to pattern the organic assemblies via the physicochemical self-assembling interactions, including patterning via phase separation of chemically different molecules and insertion of guest adsorbates into host matrices. Furthermore, it examines the efforts that have been made to couple patterned molecular assemblies with inorganic thin-film growth methods to form spatially constrained, three-dimensional thin films. Finally, it describes a hybrid self-assembly/conventional lithography (i.e. molecular rulers) approach to forming nanostructures.

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Symposium, CIBA Foundation. Host-Guest Molecular Interactions: From Chemistry to Biology - No. 158 (CIBA Foundation Symposia Series). John Wiley & Sons, 1991.

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Buchteile zum Thema "Host-Guest moleculars"

Cram, D. J. „Designed Host-Guest Relationships“. In Design and Synthesis of Organic Molecules Based on Molecular Recognition, 153–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-70926-5_13.

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Blaschke, G. „Stereoselective Guest-Host Relationships“. In Design and Synthesis of Organic Molecules Based on Molecular Recognition, 227–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-70926-5_18.

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Shinkai, Seiji. „Molecular Recognition of Calixarene-Based Host Molecules“. In United States-Japan Seminar on Host-Guest Chemistry, 193–201. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0969-4_22.

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Vögtle, Fritz, Heinz Sieger und Walter Manfred Müller. „Complexation of Uncharged Molecules and Anions by Crown-Type Host Molecules“. In Host Guest Complex Chemistry / Macrocycles, 319–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-70108-5_8.

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Dearden, David V. „Host-Guest Molecular Recognition Without Solvents“. In Physical Supramolecular Chemistry, 229–47. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0317-3_15.

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Baars, Maurice W. P. L., und E. W. Meijer. „Host-Guest Chemistry of Dendritic Molecules“. In Dendrimers II, 131–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/3-540-46577-4_3.

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Cheetham, A. K., und B. K. Peterson. „Computer Simulations of Host-Guest Complexes“. In Inclusion Phenomena and Molecular Recognition, 277–87. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0603-0_29.

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Sutherland, Ian O. „Molecular Recognition by Macropolycyclic Hosts“. In United States-Japan Seminar on Host-Guest Chemistry, 213–26. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0969-4_24.

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Gandour, Richard D. „Molecular Recognition in Carnitine Acyltransferases“. In United States-Japan Seminar on Host-Guest Chemistry, 39–51. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0969-4_6.

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Vinter, J. G., und M. R. Saunders. „Molecular Modelling Approaches to Host-Guest Complexes“. In Novartis Foundation Symposia, 249–65. Chichester, UK: John Wiley & Sons, Ltd., 2007. http://dx.doi.org/10.1002/9780470514085.ch16.

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Konferenzberichte zum Thema "Host-Guest moleculars"

Singer, Kenneth D. „Optical Nonlinearities of Guest-Host-Polymer Structures“. In Nonlinear Optical Properties of Materials. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/nlopm.1988.mb4.

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Until recently, attempts to take advantage of the large second-order optical nonlinearities of certain conjugated organic molecules in devices were limited to neat crystalline materials, since the requirements for a noncentrosymmetric bulk phase could be met with molecular and polymeric crystals that happen to condense in a noncentrosymmetric point group.[1] The large dipoles that are often observed in these molecules made the growth of optical quality and robust crystals difficult. More recently, mixed systems consisting of the nonlinear optical molecules incorporated into polymer glasses, liquid crystals, and liquid crystal polymers have been investigated.[2] The difficulties in processing that are required to obtain optical quality materials are reduced. For second-order nonlinearities, an alignment process, such as electric field poling, is required to break the center of symmetry inherent in these materials. However, the reduction in number density and alignment attainable with realistic poling fields requires molecules with exceptionally large nonlinear optical susceptibilities in order to obtain bulk materials with nonlinear coefficients large enough to produce sensible devices.

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Molis, Steven E., und Robert J. Twieg. „Fourier-transform IR characterization of molecular orientation in poled polymer glasses“. In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.the2.

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The electro-optical activity of organic, nonlinear optical (NLO) systems in part depends on the extent of molecular orientation of the NLO moiety. In this investigation, the technique of using infrared absorption spectroscopy to characterize molecular orientation is introduced as a means of characterizing orientational order in poled polymer glasses. A quantitative understanding of this orientation can be used in modeling the field-induced orientation of a dipole as well as for determining the polarizabilities of new NLO substituents. In this initial investigation the orientation of organic guest molecules in corona-poled guest/host systems is investigated with FTIR spectroscopy. The guest molecules include 2-methyl-4-nitroanaline and 4-aminobenzonitrile. For compatibility, we usually used polymethylmethacrylate (PMMA) as the matrix polymer, and it is interesting that some of the PMMA substituent groups also exhibit field-induced orientation. Molecular orientation parameters and relaxation behavior of these systems will be presented.

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Ikeda, Tomiki, und Osamu Tsutsumi. „Liquid Crystalline Materials for Photonics: Optical Switching by Means of Photochemical Phase Transition of Liquid-Crystalline Azobenzene Films“. In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.wd63.

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Isothermal phase transition of liquid crystals (LCs) can be induced reversibly by photochemical reaction of guest molecules incorporated into the LC phase at concentrations of 1 ~ 5 mol%. Such photoresponsive molecules as azobenzene and spiropyran derivatives have been proved to be effective guest molecules to bring about the photochemical phase transition. 1-5 The mechanism of the photochemical phase transition is interpreted in terms of the change in the molecular shape of the guest molecules by the photochemical reaction. For example, trans-azobenzenes are rod-like shape, stabilizing the LC phase, while cis-azobenzenes are bent, destabilizing the LC phase. When the trans-azobenzene/nematic (N) LC mixtures are irradiated to cause trans-cis photoisomerization of the guest molecules, the LC phase of the mixtures is destabilized in accumulation of the cis form and the N to isotropic (I) phase transition temperature (tNI) is lowered. When tNI is lowered below the irradiation temperature, N-I phase transition of the guest/host mixture is induced isothermally. This process is reversible, and cis-trans back isomerization restores the initial N phase. Time-resolved measurements by the use of a pulsed laser have revealed that the photochemical N-I phase transition takes place in the time region of 50 ~ 200 ms for the nematic hosts of low-molecular-weight (LMW) as well as polymeric LCs.6,7 Propagation of perturbation in the form of the trans-cis isomerization of the guest molecules may require a relatively long time in the LC systems.

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Yagyu, Eiji, Tetsuya Nishltnura und Motomu Yoshimura. „Quantitative and Theoretical Analysis of PHB-Hole Feature under Applying Electric Field.“ In Spectral Hole-Burning and Luminescence Line Narrowing: Science and Applications. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/shbl.1992.pd2.

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We have investigated the stark effect on the spectral hole characteristics in the photochemical hole burning systems of anthraquinone derivatives, such as, 1,4-dihydroxyanthraquinone (HAQ) and 4-amino-2,6-bis(4-butylphenoxy)1,5-dihydroxyanthraquinone (ABDAQ) as guest molecules embedded in host polymers such as 2-hydroxyethyl methacrylate (PHEMA) or poly(vinyl butyral) (PVB)1-3). Consequently, we evaluated the dipole moment differences |δμ| of guest molecules. These dipole moment differences depended on the characteristics of the guest and host molecules. This material dependence of the dipole moment differences was able to be explained qualitatively by Hammett’s substituent constant and the Taft’s polar substituent constant3).

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Santa María, Dolores, R. Claramunt, M. García und M. Farrán. „Molecular Modeling:Prediction of the structure of Host-Guest complexes“. In The 14th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2010. http://dx.doi.org/10.3390/ecsoc-14-00407.

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Wu, J. W., J. F. Valley, M. Stiller, S. Ermer, E. S. Binkley, J. T. Kenney, G. F. Lipscomb und R. Lytel. „Poled polyimides for thermally stable electrooptic material“. In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.fq4.

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We present data indicating that polyimide is a suitable host for nonlinear optical molecules and that the resulting guest-host system, once poled, has a highly thermally stable EO response. This stability requires both poling during curing and coplanar electrodes. First, the poling electric field is applied during the cure process so that the dipole alignment is achieved before imidization and densification; second, the guest molecules are aligned in the same orientation as the conforming morphology of the host polymer. After vacuum soft-baking the spin-coated guest-dye/host-polyimide thin film (Erythrosin/L100), the films were imidized by heating to 250°C with a dc electric poling field applied. After holding the sample at 250°C for 1 h, the sample was further cured at 360°C for 0.25 h for the densification process and then cooled. The dc poling field was removed upon reaching room temperature.

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Deeg, F. W., M. Ehrl und C. Bräuchle. „Dynamics and Guest-host Interactions of Chromophores in Inorganic Cage Structures“. In Spectral Hole-Burning and Luminescence Line Narrowing: Science and Applications. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/shbl.1992.tub5.

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Recent progress in chemical synthesis techniques has made it possible to prepare specifically tailored well-defined inorganic cage and channel structures on an Å-scale, so-called molecular sieves, with encapsulated chromophores [1]. The best-known of these inorganic crystals are zeolites which possess an aluminosilicate framework but many more classes of molecular sieves like e.g. metalloaluminates or aluminophosphates are available. The structural and dynamical properties of chromophores encaged in these porous solids are modified by the spatial restrictions enforced by the environment, see e.g. [2]. In this contribution we report about the application of the sensitive techniques of fluorescence line narrowing and spectral hole-burning to probe chromophore dynamics and interactions of the adsorbate with the lattice in these confined geometries.

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Dogariu, Arthur, Rahul Gupta, Alan J. Heeger, Hailiang Wang, Hideyuki Murata und Zakya H. Kafafi. „Time-resolved Foerster energy transfer in molecular and polymeric guest-host systems“. In SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, herausgegeben von Zakya H. Kafafi. SPIE, 1999. http://dx.doi.org/10.1117/12.372724.

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Sarkas, Harry W., Charles D. Merritt und Zakya H. Kafafi. „Preparation, Optical Spectroscopy, and Fluorescence of Molecular Organic Composites for Light-Emitting Diodes“. In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.md.35.

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Electroluminescence from small organic molecules has been known for some time. Thirty years ago, Helfrich and Schneider reported blue-violet electroluminescence in anthracene with an external quantum efficiency as high as 8%.1 This quantum efficiency is much better than that for the best polymer-based light-emitting diode (LED) reported to date.2 In spite of the superior quantum efficiency of molecular-based electroluminescent devices, no major progress was achieved until fairly recently when Tang and VanSlyke reported the first low-voltage organic LED with an external quantum efficiency of 1% (number of photons per electron).3 The emitting layer in this device consists of a thin layer of the metal complex, tris (8-hydroxyquinolinato) aluminum (AlQ3). Later, Littman and Martie showed an enhancement in the electroluminescence quantum efficiency of AlQ3 by doping it with the highly fluorescent laser dyes, Coumarin 540, Coumarin 343, and DCM.4 The paper focuses on a new class of organic composites consisting of highly fluorescent guest molecules dispersed in AlQ3. The electronic and optical properties of organic nanostructures based on these materials are studied, as functions of the luminescent center concentration, via optical and fluorescence spectroscopies. Photoluminescence quantum yields are measured and used to probe the efficiency of energy transfer between host and guest molecules.

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Ichino, Y., Y. Kanematsu und T. Kushida. „Site-Selective Excitation Spectroscopy of Dye-doped Inorganic Amorphous Hosts Prepared by Sol-Gel Method“. In Spectral Hole-Burning and Related Spectroscopies: Science and Applications. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/shbs.1994.wd11.

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Dye-doped inorganic glasses prepared by a sol-gel method have received much interest during the last decade, especially for the application of optical media such as solid-state dye lasers and high-density optical memories.1-3 In order to obtain a preferable combination of host matrices and guest molecules for optical applications, it is important to know precisely about the electron-phonon interaction of the host-guest system. So far, we have experimentally determined the Debye-Waller factor, the site energy distribution function, and the density of states of low-frequency host vibrational modes weighted by the electron-phonon coupling strength in porphyrindoped polymers using a resonance fluorescence technique.4,5 In this study, sol-gel inorganic matrices, SiO2 and SiO2-TiO2, are examined using a similar method by employing a cationic laser dye, oxazine 4 perchlorate(ox4), as the optical center.

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Berichte der Organisationen zum Thema "Host-Guest moleculars"

Lawandy, Nabil M. (AASERT) Superconductors and Nonlinear Optical Materials Based on Molecular Guest-Host Systems. Fort Belvoir, VA: Defense Technical Information Center, September 1995. http://dx.doi.org/10.21236/ada299480.

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