CALCULATION AND COMPARATIVE ANALYSIS OF IR SPECTRA OF (22S,23S)-24-EPIBRASSINOLIDE AND (22S,23S)-28-HOMOBRASSINOLIDE
V. M. Andrianov1, M. V. Korolevich2
1B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk, Belarus
2Belarus State Agrarian Technical University, Minsk, Belarus
Keywords: ИК спектроскопия, анализ нормальных колебаний, абсолютные ИК интенсивности, характеристические частоты, интерпретация ИК спектра, брассиностероиды, брассинолиды, IR spectroscopy, normal mode vibration analysis, absolute IR intensities, characteristic frequencies, interpretation of the IR spectrum, brassinosteroids, brassinolides
Abstract
A consistent calculation of frequencies and intensities of normal vibrations of some steroid phytohormones having biological activity (22S,23S)-24-epibrassinolide and (22S,23S)-28-homobrassinolide molecules) is performed within an original approach combining a classical normal mode vibration analysis by the molecular mechanics method and a quantum chemical estimation of absolute intensities. Based on a comparison of the experimental and theoretical spectral absorption curves the interpretation of IR spectral absorption bands is given for the first time and the effect of structural differences within the side chain of these molecules on the formation of their IR spectra in the range 1500-950 cm–1 is estimated.
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