R. N. Singh, Poonam Rawat, S. Sahu
Dec 24, 2013
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Journal
Journal of Molecular Structure
Abstract
Abstract This paper describes the synthesis, spectroscopic 1 H and 13 C NMR, UV–Visible, FT-IR analysis, elemental analysis, structural evaluation and non-linear optical (NLO) properties of newly synthesized compound, ethyl 3,5-dimethyl-4-[(benzenesulfonyl)-hydrazonoethyl]-1 H -pyrrol-2-carboxylate using experimental and quantum chemical techniques. FT-IR spectrum, electronic descriptors, molecular electrostatic potential surface (MEPS) and quantum theory of atoms in molecule (QTAIM) have been used to predict the sites and nature of interactions. A combined experimental and theoretical vibrational analysis identified red shifts in v N H and v C O as result of hydrogen bonding confirming formation of the dimer in the solid phase. The binding energy of dimer has been evaluated as 9.72 kcal/mol. The value of Gibbs free energy change (Δ G ) shows that dimer formation is thermodynamically spontaneous. At room temperature, the equilibrium constant ( K eq ) for dimerization reaction is calculated to be 18.91 i.e. K eq ≫ 1 indicating that dimer formation is more favoured in the forward direction and confirms the formation of dimer at room temperature. The first hyperpolarizability ( β 0 ) values for monomer and dimer are found to be 8.94 × 10 −30 , 4.25 × 10 −30 esu, respectively. The UV–Visible spectrum study reveals that the compound absorbs in the range of 299–244 nm due to π–π * and charge transfer transition and so being transparent in the entire visible region providing criteria to be exploited for NLO applications.