کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9757096 | 1495293 | 2005 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Vibrational spectral investigation on xanthine and its derivatives-theophylline, caffeine and theobromine
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آنالیزی یا شیمی تجزیه
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چکیده انگلیسی
A normal coordinate analysis has been carried out on four compounds having a similar ring structure with different side chain substitutions, which are xanthine, caffeine, theophylline, and theobromine. Xanthine is chemically known as 2,6-dihydroxy purine. Caffeine, theophylline and theobromine are methylated xanthines. Considering the methyl groups as point mass, the number of normal modes of vibrations can be distributed as Îvib=27Aâ²+12Aâ³ based on Cs point group symmetry associated with the structures. In the present work 15 Aâ² and 12 Aâ³ normal modes are considered. A new set of orthonormal symmetry co-ordinates have been constructed. Wilson's F-G matrix method has been adopted for the normal coordinate analysis. A satisfactory vibrational band assignment has been made by employing the FTIR and FT Raman spectra of the compounds. The potential energy distribution is calculated with the arrived values of the force constants and hence the agreement of the frequency assignment has been checked.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 61, Issues 1â2, 1 January 2005, Pages 117-127
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 61, Issues 1â2, 1 January 2005, Pages 117-127
نویسندگان
S. Gunasekaran, G. Sankari, S. Ponnusamy,