Spelling suggestions: "subject:"spiropyran"" "subject:"spiropyrans""
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Properties of metastable linkage NO isomers in Na2[Fe(CN)5NO]·2H2O incorporated in mesopores of silica xerogelsTahri, Zakaria, Lepski, Robert, Hsieh, Kuan-Ying, Bendeif, El-Eulmi, Pillet, Sebastien, Durand, Pierrick, Woike, Theo, Schaniel, Dominik 07 April 2014 (has links) (PDF)
We study the properties of photoinduced metal–nitrosyl linkage isomers in sodium nitroprusside (SNP) as a function of particle size. By embedding the molecular complex at various concentrations into mesopores of silica xerogels the size of the particles can be adjusted. The ground state is characterized by X-ray diffraction, absorption and infrared spectroscopy. The physical properties of the photoswitched molecules were analysed by steady-state low-temperature absorption, infrared spectroscopy and by nanosecond transient absorption spectroscopy. The electronic structure as well as the activation energies of the metastable linkage isomers are independent of the particle size down to single isolated molecules, indicating that the SNP complexes are quasi-free inside the pores of the gel. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Properties of metastable linkage NO isomers in Na2[Fe(CN)5NO]·2H2O incorporated in mesopores of silica xerogelsTahri, Zakaria, Lepski, Robert, Hsieh, Kuan-Ying, Bendeif, El-Eulmi, Pillet, Sebastien, Durand, Pierrick, Woike, Theo, Schaniel, Dominik January 2012 (has links)
We study the properties of photoinduced metal–nitrosyl linkage isomers in sodium nitroprusside (SNP) as a function of particle size. By embedding the molecular complex at various concentrations into mesopores of silica xerogels the size of the particles can be adjusted. The ground state is characterized by X-ray diffraction, absorption and infrared spectroscopy. The physical properties of the photoswitched molecules were analysed by steady-state low-temperature absorption, infrared spectroscopy and by nanosecond transient absorption spectroscopy. The electronic structure as well as the activation energies of the metastable linkage isomers are independent of the particle size down to single isolated molecules, indicating that the SNP complexes are quasi-free inside the pores of the gel. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Le rôle des matériaux hybrides à base d'argiles dans la protection des œuvres d'art / The role of clay-based hybrid materials in the protection of works of artGuillermin, David 08 October 2018 (has links)
Le travail de cette thèse s’intéresse à la stabilisation de plusieurs pigments hybrides.Une première partie traite de pigment obtenu à l’aide de l’acide carminique et de la montmorillonite, une argile commune. Un procédé d’inversion de la charge de surface de l’argile avec un polymère cationique, ou l’utilisation d’argiles modifiées par des polycations de Titane et d’Aluminium, permettent l’élaboration du pigment. La résistance des pigments à la photodégradation est alors testée. Les techniques couplées de RMN, DRX, FTIR et d’EPR permettent d’éclairer l’agencement des molécules organiques sur la surface minérale, et également de suivre le processus de dégradation du colorant.La description de pigments hybrides obtenus à l’aide d’un spiropyrane vient compléter l’étude. Le composé, qui joue le rôle de colorant organique, est ajouté à différentes matrices minérales : l’argile, modifiée ou non, ainsi que la co-précipitation avec des organo-silanes. Ces synthèses permettent d’observer la variété de couleur obtenus en mélangeant un même colorant avec plusieurs matrices de nature différente. / The work of this thesis focuses on the stabilization of several hybrid pigments.The first part deals with pigment obtained with carminic acid and montmorillonite, a common clay. A method of reversing the surface charge of the clay with a cationic polymer, or the use of clays modified with titanium and aluminum polycations, allows the elaboration of the pigment. The resistance of the pigments to photodegradation is then tested. Coupled NMR, DRX, FTIR and EPR techniques help to illuminate the arrangement of organic molecules on the mineral surface, and also to follow the dye degradation process.The description of hybrid pigments obtained using a spiropyran completes the study. The compound, which plays the role of organic dye, is added to different mineral matrices: clay, modified or not, and co-precipitation with organosilanes. These syntheses make it possible to observe the variety of color obtained by mixing the same dye with several matrices of different nature.
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Vliv fotochromního aditiva na optické a elektrické vlastnosti polymerních matric / Influence of photochromic additives on the optical and electrical properties of polymer matricesTumová, Šárka January 2017 (has links)
This thesis is focused on the photochromic molecule of spiropyran, which changes its structure as well as physical and chemical properties after UV irradiation. These changes are reversible, the molecule thermally restore its initial structure. For the study, the molecule SP1 with the systematic name 1',3'-dihydro-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2'-(2H)-indole] was used. This molecule was incorporated within polymers PVK, Tg PPV, PCBTDPP and PCDTBT and the method of UV-VIS spectroscopy was used to observe the photochromic activity within these matrices. The influence of matrices to the ability to undergo UV induced photochromic conversion as well as to the reverse conversion to the initial structure induced by heat was monitored. Furthermore, the influence of spiropyran to the electrical properties of individual matrices was studied. The effect of photochromic conversion to both, the mobility of charge carriers and to the photogeneration was observed. For this purpose, the method of current-voltage measurement was used.
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Exploiting Substituent Effects to Control the Mechanochromic Response of Spiropyran-containing CopolymersKempe, Fabian 18 May 2021 (has links)
Mechanochromic polymers respond to external force by changing their color. This can be achieved by the incorporation of a molecular switch such as spiropyran (SP) into polymers. SPs can be isomerized by mechanical force from their colorless form into colored merocyanines. Main chain copolymerization of spiropyrans allows investigation of their mechanochromic behavior and potential use as force sensors.
So far, several covalent polymer matrices have been used to investigate the mechanochromic response of SPs, among them poly(ε caprolactone) (PCL). Less investigated is how the mechanochromic response can be fine-tuned by substituent effects. First, PCL with differently substituted spiropyrans at the chain’s midpoint were used in order to investigate the effect of different substituents and their regiochemistry on the isomerization behavior of SPs under mechanical stress. A low activation barrier was observed for NO2 substitution of “ortho”-spiropyrans compared to no substitution (R = H).
In order to investigate phenyl-substituted “para,para” spiropyrans, a newly developed kinked polyarylene was employed as covalent matrix material. This new polyarylene (PmmpP) has a meta,meta,para connection in its backbone and exhibits excellent mechanical properties. Its high strength allows the isomerization of this molecular switch with a large activation barrier. The phenyl-substituted “para,para” spiropyran showed transient mechanochromism and was switched 25 times in force-and-release cycles. The synthesis of PmmpP was carried out by a Suzuki polycondensation in three steps from commercial starting materials.
To further capitalize on the simplicity and properties of PmmpP, a two step synthesis of a semifluorinated kinked polyarylene was demonstrated by direct arylation polycondensation with tetrafluorobenzene (F4). This partially fluorinated PmmpF4 was synthesized with a variety of side-chains. Resulting polymers exhibited a large range of glass transition temperatures, allowing for the production of tailor-made smart materials.
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Towards the Development of Photoresponsive Static and Dissipative AssembliesCreemer, Cassidy January 2020 (has links)
No description available.
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