The subject of this work was the study of thermally and photochemically stimulated « isomerization and hydrazo « azo tautomerism of and -isomers of isatin arylhydrazones and ((arylamino)methylene)indolin-2-ones and their anions. Using NMR, UV-Vis spectroscopy, kinetic measurements, and HPLC, we studied the relationship of structure, ( and isomers), of these compounds and hydrazo=azo tautomerism. The ON/OFF functionality of these compounds and their anions using light to stimulate switching between ON and OFF states was investigated.
View Article and Find Full Text PDFThe photoswitching properties of three readily accesible benzoylpyridine hydrazones were investigated. Interestingly, replacing classical stirring with ultrasound wave activation results in pure thermodynamically less stable E isomer crystallization at room temperature. The studied benzoylpyridine hydrazones exhibit both P- and T-photochromic behaviour, depending on the benzoyl substituent, and improved addressability compared to most of the previously published pyridyl based hydrazones and 2-pyridylcarboxaldehyde acylhydrazones.
View Article and Find Full Text PDFFour novel isatin hydrazones containing bipyridyl fragments were synthesized as potential ON/OFF switches. Hydrazone -isomers exhibit high thermal stability. The characteristic photochemical reaction for all studied hydrazones is the - isomerization in CHCl.
View Article and Find Full Text PDFThe photoswitching properties of two easily synthesized isatin 4-nitrophenylhydrazones were investigated. Although the parent isatin 4-nitrophenylhydrazones exhibit low addressability which hampers their photochromic applications, the addition of strongly basic anions to phenylhydrazone solutions creates a new Vis-Vis photochromic system with the unusual azo/azine-to-hydrazone photo-tautomerization process as the photoswitching mechanism. To the best of our knowledge, this is the first report related to the anion-assisted azo/azine-to-hydrazone photo-tautomerism.
View Article and Find Full Text PDFFive novel hydrazones derived from substituted isatins were synthesized as potential anion sensors. Using UV-VIS, FTIR, NMR and fluorescence spectroscopy, these compounds' tautomeric equilibrium and - photoisomerization were studied in DMF and CHCl₃, depending on the hydrazone concentrations, the presence of basic anions and light stimulation. Anion recognition aspects (PF₆, HSO₄, Br, Cl, NO₃, F and CH₃COO) and these receptors' detection limits were also studied.
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