Vibrational assignment, HOMO – LUMO, first-hyperpolarizability and Mulliken’s charge analysis of 2,7-dinitrofluorene

Abstract

The experimental and theoretical study on molecular structure and vibrational spectra of 2,7-dinitrofluorene (DNF) have been investigated. The FTIR and FT-Raman experimental spectra of the molecule have been recorded in the range 4000–50 cm^-1 and 3500-50 cm^-1, respectively. Making use of the recorded data, the complete vibrational assignments are made and analysis of the observed fundamental bands of molecule is carried out. The experimental determination of vibrational frequencies has been compared with those obtained theoretically from DFT quantum mechanical calculations using B3LYP/6-311+G(d,p) and 6-311++G(d,p) basis sets. The HOMO-LUMO analysis explains the charge transfer taking place within the molecule. The predicted first-hyperpolarizability value of DNF (5.5058<img src='/image/spc_char/cross.gif' border=0>10^-30 esu) suggests that the title molecule is an attractive object for future studies of non-linear optical property. Thermodynamic properties like entropy, heat capacity and zero-point energy have been calculated for the molecule. The total energy distribution (TED) values obtained reflect the correctness of the vibrational assignments.