The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Vishal Modi - One of the best experts on this subject based on the ideXlab platform.
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Mesogenic bent-shaped nitrooxadiazoles and thiadiazoles
Liquid Crystals, 2011Co-Authors: A. K. Prajapati, Vishal ModiAbstract:The mesomorphism of three series of compounds has been studied. Compounds in Series I [4-nitrobenzoic acid N′-(4′-n-alkoxybenzoyl)hydrazides] were synthesised by the Schotten–Baumann Reaction of 4-nitrobenzhydrazide with 4-n-alkoxybenzoyl chloride in dry pyridine. The resulting compounds were cyclised using phosphoryl chloride to give bent-shaped mesogenic 2-(4′-nitrophenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-oxadiazoles (Series II) or, using phosphorus pentasulphide, 2-(4′-nitrophenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-thiadiazoles (Series III). These compounds have been characterised using a combination of elemental analysis and spectroscopic techniques. The mesomorphic properties of the three series were compared with one other and with other structurally related compounds. The effect of different heterocyclic moieties and terminal substituents on mesomorphism has been evaluated.
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Bent-shaped mesogenic oxadiazole and thiadiazole derivatives from rod-shaped mesogenic hydrazide containing polar chloro group
Liquid Crystals, 2010Co-Authors: A. K. Prajapati, Vishal ModiAbstract:Rod-shaped mesogenic hydrazide (series I) derivatives have been synthesised by the Schotten-Baumann Reaction of 4-chlorobenzhydrazide with 4-n-alkoxybenzoyl chloride using pyridine as a solvent. Rod-shaped mesogenic hydrazide (series I) have been cyclised to bent-shaped mesogenic oxadiazole (series II) and thiadiazole (series III) derivatives using POCl3 and P2S5, respectively. The synthesised compounds are characterised by a combination of elemental analysis and standard spectroscopic methods. All the compounds of present series I–III exhibit smectic A mesophase. The mesomorphic properties of the present series I–III are compared with each other and with the other structurally related mesogenic homologous series to evaluate the effect of bent-shape and different heterocyclic moiety on mesomorphism.
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Bent-shaped mesogenic oxadiazoles and thiadiazoles with terminal methyl group
Phase Transitions, 2010Co-Authors: A. K. Prajapati, Vishal ModiAbstract:Rod-shaped 4-methylbenzoic acid-N′-(4′-n-alkoxybenzoyl) hydrazide (series I) have been synthesized by the Schotten–Baumann Reaction of 4-methylbenzhydrazide with 4-n-alkoxy benzoyl chloride using dry pyridine, as a solvent. The series I compounds have been cyclized to bent-shaped mesogenic 2-(4′-methylphenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-oxadiazoles (series II) and 2-(4′-methylphenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-thiadiazole (series III) using POCl3 and Lawesson's reagent, respectively. The synthesized compounds are characterized by the combination of elemental analysis and standard spectroscopic methods. In series II, lower and middle members are non-mesogenic. n-Dodecyloxy to n-hexadecyloxy derivatives exhibit enantiotropic nematic mesophase. In series III, all the compounds synthesized exhibit enantiotropic nematic mesophase. n-Tetradecyloxy and n-hexadecyloxy derivatives also exhibit enantiotropic SmA mesophase. The mesomorphic properties of the series II and III used in this study are compared with eac...
Fernando Catalina - One of the best experts on this subject based on the ideXlab platform.
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Solid fluorescence sensors obtained by functionalization of photocrosslinked water-swollen acrylic membranes with 4-piperazine naphthalimide derivatives
Polymer, 2017Co-Authors: S. Fernández-alonso, Teresa Corrales, Jesús L. Pablos, Fernando CatalinaAbstract:Abstract A photocrosslinked membrane (M-Cl) based on vinyl-pyrrolidone/butyl acrylate containing ethylene glycol dimethacrylate as a crosslinking agent and methacryloyl chloride as reactive monomer has been prepared for further functionalization. A series of hydroxy substituted piperazine naphthalimide compounds have been synthetized as pH sensitive Off-On fluorescence probes using two methods: microwave and reflux. Three of the derivatives were selected to be anchored to the M-Cl membrane through the acid chloride groups by the Schotten-Baumann Reaction. All the obtained water-swollen membranes were characterized using different techniques. Photo-induced electron transfer (PET) and its pH-dependent optical changes were investigated and various photochemical parameters were determined by using pH-dependent absorption and fluorescence spectroscopies. In the pH range of 9.0–4.0, these solid sensors undergo PET process from the piperazine to the naphthalimide moiety leading to a fluorescence quenching. However, in the pH range of 4.0–1.0, the PET is inhibited to give a fluorescence enhancement. The sensitivity of the functionalized membranes to pH changes depended on the size and position of the naphthalimide substituents.
A. K. Prajapati - One of the best experts on this subject based on the ideXlab platform.
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Mesogenic bent-shaped nitrooxadiazoles and thiadiazoles
Liquid Crystals, 2011Co-Authors: A. K. Prajapati, Vishal ModiAbstract:The mesomorphism of three series of compounds has been studied. Compounds in Series I [4-nitrobenzoic acid N′-(4′-n-alkoxybenzoyl)hydrazides] were synthesised by the Schotten–Baumann Reaction of 4-nitrobenzhydrazide with 4-n-alkoxybenzoyl chloride in dry pyridine. The resulting compounds were cyclised using phosphoryl chloride to give bent-shaped mesogenic 2-(4′-nitrophenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-oxadiazoles (Series II) or, using phosphorus pentasulphide, 2-(4′-nitrophenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-thiadiazoles (Series III). These compounds have been characterised using a combination of elemental analysis and spectroscopic techniques. The mesomorphic properties of the three series were compared with one other and with other structurally related compounds. The effect of different heterocyclic moieties and terminal substituents on mesomorphism has been evaluated.
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Bent-shaped mesogenic oxadiazole and thiadiazole derivatives from rod-shaped mesogenic hydrazide containing polar chloro group
Liquid Crystals, 2010Co-Authors: A. K. Prajapati, Vishal ModiAbstract:Rod-shaped mesogenic hydrazide (series I) derivatives have been synthesised by the Schotten-Baumann Reaction of 4-chlorobenzhydrazide with 4-n-alkoxybenzoyl chloride using pyridine as a solvent. Rod-shaped mesogenic hydrazide (series I) have been cyclised to bent-shaped mesogenic oxadiazole (series II) and thiadiazole (series III) derivatives using POCl3 and P2S5, respectively. The synthesised compounds are characterised by a combination of elemental analysis and standard spectroscopic methods. All the compounds of present series I–III exhibit smectic A mesophase. The mesomorphic properties of the present series I–III are compared with each other and with the other structurally related mesogenic homologous series to evaluate the effect of bent-shape and different heterocyclic moiety on mesomorphism.
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Bent-shaped mesogenic oxadiazoles and thiadiazoles with terminal methyl group
Phase Transitions, 2010Co-Authors: A. K. Prajapati, Vishal ModiAbstract:Rod-shaped 4-methylbenzoic acid-N′-(4′-n-alkoxybenzoyl) hydrazide (series I) have been synthesized by the Schotten–Baumann Reaction of 4-methylbenzhydrazide with 4-n-alkoxy benzoyl chloride using dry pyridine, as a solvent. The series I compounds have been cyclized to bent-shaped mesogenic 2-(4′-methylphenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-oxadiazoles (series II) and 2-(4′-methylphenyl)-5-(4″-n-alkoxyphenyl)-1,3,4-thiadiazole (series III) using POCl3 and Lawesson's reagent, respectively. The synthesized compounds are characterized by the combination of elemental analysis and standard spectroscopic methods. In series II, lower and middle members are non-mesogenic. n-Dodecyloxy to n-hexadecyloxy derivatives exhibit enantiotropic nematic mesophase. In series III, all the compounds synthesized exhibit enantiotropic nematic mesophase. n-Tetradecyloxy and n-hexadecyloxy derivatives also exhibit enantiotropic SmA mesophase. The mesomorphic properties of the series II and III used in this study are compared with eac...
S. Fernández-alonso - One of the best experts on this subject based on the ideXlab platform.
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Solid fluorescence sensors obtained by functionalization of photocrosslinked water-swollen acrylic membranes with 4-piperazine naphthalimide derivatives
Polymer, 2017Co-Authors: S. Fernández-alonso, Teresa Corrales, Jesús L. Pablos, Fernando CatalinaAbstract:Abstract A photocrosslinked membrane (M-Cl) based on vinyl-pyrrolidone/butyl acrylate containing ethylene glycol dimethacrylate as a crosslinking agent and methacryloyl chloride as reactive monomer has been prepared for further functionalization. A series of hydroxy substituted piperazine naphthalimide compounds have been synthetized as pH sensitive Off-On fluorescence probes using two methods: microwave and reflux. Three of the derivatives were selected to be anchored to the M-Cl membrane through the acid chloride groups by the Schotten-Baumann Reaction. All the obtained water-swollen membranes were characterized using different techniques. Photo-induced electron transfer (PET) and its pH-dependent optical changes were investigated and various photochemical parameters were determined by using pH-dependent absorption and fluorescence spectroscopies. In the pH range of 9.0–4.0, these solid sensors undergo PET process from the piperazine to the naphthalimide moiety leading to a fluorescence quenching. However, in the pH range of 4.0–1.0, the PET is inhibited to give a fluorescence enhancement. The sensitivity of the functionalized membranes to pH changes depended on the size and position of the naphthalimide substituents.
Jesús L. Pablos - One of the best experts on this subject based on the ideXlab platform.
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Solid fluorescence sensors obtained by functionalization of photocrosslinked water-swollen acrylic membranes with 4-piperazine naphthalimide derivatives
Polymer, 2017Co-Authors: S. Fernández-alonso, Teresa Corrales, Jesús L. Pablos, Fernando CatalinaAbstract:Abstract A photocrosslinked membrane (M-Cl) based on vinyl-pyrrolidone/butyl acrylate containing ethylene glycol dimethacrylate as a crosslinking agent and methacryloyl chloride as reactive monomer has been prepared for further functionalization. A series of hydroxy substituted piperazine naphthalimide compounds have been synthetized as pH sensitive Off-On fluorescence probes using two methods: microwave and reflux. Three of the derivatives were selected to be anchored to the M-Cl membrane through the acid chloride groups by the Schotten-Baumann Reaction. All the obtained water-swollen membranes were characterized using different techniques. Photo-induced electron transfer (PET) and its pH-dependent optical changes were investigated and various photochemical parameters were determined by using pH-dependent absorption and fluorescence spectroscopies. In the pH range of 9.0–4.0, these solid sensors undergo PET process from the piperazine to the naphthalimide moiety leading to a fluorescence quenching. However, in the pH range of 4.0–1.0, the PET is inhibited to give a fluorescence enhancement. The sensitivity of the functionalized membranes to pH changes depended on the size and position of the naphthalimide substituents.