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Transformacje strukturalne w kryształach wywołane reakcjami fotochemicznymi

100%

Turowska-Tyrk I. , Bąkowicz J.

Wiadomości Chemiczne

2014

tom [Z] 68, 5-6

381--402

Structural changes induced in crystals by photochemical reactions were presented. The changes concern: a) the distances between neighbouring reactant molecules and their mutual orientation in the case of intermolecular reactions, b) the distances and angles between fragments of a molecule for intramolecular reactions, c) the position of molecules in crystals, d) geometry of hydrogen bonds, e) cell constants, and f) the content of product molecules in crystals. For most intramolecular reactions, the distances between reactive atoms are constant for a long time in phototransformation and decrease rapidly at its end (Figs. 3 and 5). In the case of intermolecular reactions, the distances between reactive atoms of reactant molecules decrease linearly along with the phototransformation of crystals (Fig. 7). Additionally, unreacted molecules become, to a certain degree, similar to product molecules in terms of their shape (Figs, 4 and 8). Reactant and product molecules do not assume a fixed place in crystals. Product molecules change their orientation towards that of which is observed in a pure product crystal and reactant molecules gradually move away from the position they took in pure reactant crystals. All this has an influence on the geometry of hydrogen bonds existing in crystals (Fig. 9). The above-mentioned structural transformations find their expression in values of cell constants (Fig. 10). The factors influencing the photoreactivity of molecules in crystals were also described. Knowledge of crystal and molecular structures of partly reacted crystals, determined thanks to X-ray structure analysis which is a branch of crystallography, reveals the behaviour of molecules in crystals in which photochemical reactions proceed and helps to understand a pathway of these reactions.

Monitoring Structural Transformations in Crystals. Part 10. Monitoring Molecular and Crystal Structures During a Yang Photocyclization Reaction – Comparative Studies

80%

Turowska-Tyrk I. , Łabęcka I. , Scheffer J. , Xia W.

Polish Journal of Chemistry

2007

tom Vol. 81, nr 5-6

813-824

Structural changes in a crystal, brought about by the Yang photocyclization of the 2-(4-carboxybenzoyl)-2-methyl-endo-bicyclo[2.1.1]hexyl salt with (S)-(–)--phenylethylamine, were monitored by means of X-ray structure analysis. The changes taking place in the reaction centre, as well as changes inmolecular orientation and cell constants are discussed. Analysis of the geometrical parameters describing the reaction centre enabled an evaluation of the possibility of formation of the opposite enantiomer in a crystal. The results are compared with data for other intramolecular photochemical reactions.

N-(E)-2-Stilbenyloxymethylenecarbonyl substituted hydrazones of ortho, meta and para hydroxybenzaldehydes

80%

Wyrzykiewicz E. , Błaszczyk A. , Turowska-Tyrk I.

Bulletin of the Polish Academy of Sciences. Chemistry

2000

tom Vol. 48, No. 3

213-229

Twelve unknown N-(E)-2-stilbenyloxymethylenecarbonyl substituted hydra-zones of acetone and ortho, meta and para hydroxybenzaldehydes have been prepared. The N-substituted hydrazones occur as E geometrical isomers and cis/trans amide conformers (1) H NMR estimations). Crystal structures of N-(E)-2-stilbenyloxymethylenecarbonyl sub-stituted hydrazone of ortho hydroxy-benzaldehyde 10 and N-(E)-2/-(4/-chlorostilbenyloxy-methylenecarbonyl)-substituted hydrazone of meta hydroxybenzaldehyde 14 have been determined as E geometrical isomers and trans amide conformers with intra- (10) and intermolecular (14) hydrogen bonds.