THEORETICAL STUDIES OF MOLECULAR STRUCTURE AND VIBRATIONAL SPECTRA OF THE ASYMMETRIC SQUARAINE [(2-DIMETHYLAMINO-4-ANILINO)SQUARAINE]

Abstract

The molecular geometry and vibrational frequencies of asymmetric squaraine [(2-dimethylamino-4-anilino squarine)squaraine] (ADTCH3) in the ground state have been calculated using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-31++G(d) basis set. The optimized geometric bond length and bond angles are in good agreement with the x-ray data. The vibrational spectra of the asymmetric squaraine (ADTCH3), which is calculated by the HF and B3LYP methods, reproduces vibrational wave numbers with an accuracy which allows reliable vibrational assignments. The asymmetric squaraine have been studied theoretically in the 4000-200 cm(-1) region and the assignments of all the observed bands have been made. The analysis of the infrared spectra indicated that there are some structure-spectra correlations. These methods are proposed as a tool to be applied in the structural characterization of the ADTCH3.