Molecular Structure, Vibrational Spectra and Potential Energy Distribution of Colchicine Using ab Initio and Density Functional Theory

Shamoon Ahmad SIDDIQUIa, Apoorva DWIVEDIa, Anoop PANDEYa, P. K. SINGHa, Tanveer HASANa, Sudha JAINb and Neeraj MISRAa*

aDepartment of Physics, Lucknow University
226007, India
bDepartment of Chemistry, Lucknow University
226007, India

(Received: October 6, 2008; Accepted for publication: February 10, 2009; Advance publication: April 3, 2009)

   (Note:Author for Correspondence: Neeraj Misra, B-981, sector-A, Mahanagar, Lucknow 226006, India) This work deals with a theoretical study of the molecular structure of colchicine. The equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by the ab initio Hartree-Fock method and the Density Functional B3LYP method employing 6-31G(d) as the basis set, and the vibrational studies were interpreted in terms of the potential energy distribution (P.E.D.). The internal coordinates were optimized repeatedly to maximize the P.E.D. contributions. A detailed interpretation of the infrared and Raman spectra of colchicine is reported. The scaled theoretical wave numbers are in perfect agreement with the experimental values. The FT-IR spectra of colchicine was recorded in solid phase, and the FT-Raman spectra of colchicine have been taken from the literature.

キーワード: FT-IR and FT-Raman Spectra, Molecular structure, P. E. D., Colchicine, Vibrational spectra

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