# CONFORMATIONAL POLYMORPHISM AND MOLECULAR DYNAMICS OF CRYSTALLINE N-CARBOXYLIC ACIDS

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 dc.creator Makarenko, Svetlana en_US dc.creator Puchkovskaya, G. en_US dc.creator Sekirin, I. V. en_US dc.date.accessioned 2006-06-15T19:07:41Z dc.date.available 2006-06-15T19:07:41Z dc.date.issued 1998 en_US dc.identifier 1998-TD-13 en_US dc.identifier.uri http://hdl.handle.net/1811/19039 dc.description Author Institution: Institute of Physics, National Academy of Sciences of Ukraine en_US dc.description.abstract The IR-spectra for a homologous series of n-carboxylic acids $CH_{3}(CH_{2})_{N}COOH (n=8-22)$ are studied in different crystal modifications. Considerable changes in IR-spectra of these substances during polymorphous transformations were discovered: the change of frequencies and forms of the majority of vibrations, the re-distribution of their intencity, ""disappearance"" of certain bands. The analysis of these changes has shown that during the conversion from one crystal modification into another not only does the packaging of molecules dimers in the crystal change but also their conformation; in particular, the $\varphi$ angle between planes of the dimeric ring and methylene chain changes. A calculation of frequencies and forms of normal vibrations of planar $(\varphi=0,180^{\circ})$ and non-planar $(\varphi=10,30,60,90,120,150^{\circ})$ conformations are performed to explain peculiarities of IR-spectra of different crystal modifications of n-carboxilic acids. The theoretical results agree with the experimental data. en_US dc.format.extent 120666 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title CONFORMATIONAL POLYMORPHISM AND MOLECULAR DYNAMICS OF CRYSTALLINE N-CARBOXYLIC ACIDS en_US dc.type article en_US