Assessment of long-range corrected and conventional DFT functional for the prediction of second – Order NLO properties and other molecular properties of N-(2-cyanoethyl)-N-butylaniline – A vibrational spectroscopy study

• FT-IR and FT-Raman spectra of N-(2-cyanoethyl)-N-butylaniline recorded and analyzed.
• MEP surface provided the information about donor and acceptor atoms in the molecule.
• Charge transfer characteristics were examined by HOMO–LUMO and NBO analysis.
• Global reactivity and local reactivity descriptors have been calculated.
• Solvent effect & frequency dependent second order NLO property also studied.

Vibrational spectral analysis and quantum chemical computations based on density functional theory have been performed on the N-(2-cyanoethyl)-N-butylaniline. The geometry, structural properties, intermolecular hydrogen bond, and harmonic vibrational frequencies of the title molecule have been investigated with the help of DFT (B3LYP) and LC-DFT (CAM-B3LYP) method. Molecular electrostatic potential (MEP) have been performed. The various intramolecular interactions have been exposed by natural bond orbital analysis. The distribution of atomic charges and bending of natural hybrid orbitals also reflect the presence of intramolecular hydrogen bonding. Global reactivity and local reactivity descriptors of the title molecule have been calculated. The analysis of the electron density of HOMO and LUMO gives an idea of the delocalization and low value of energy gap indicated the electron transport in the molecule and thereby NLO activity. The effect of solvent on second-order NLO properties has been studied using polarized continuum model (PCM) in the tetrahydrofuran (THF) solution. The solvent leads to a slight enhancement of the NLO responses for the studied complexes relevant to their NLO responses in gas phase. The electronic absorption spectra were investigated by the TDDFT methods. The frequency-dependent first hyperpolarizabilities of the N-(2-cyanoethyl)-N-butylaniline were also evaluated. The 1H and 13C NMR chemical shifts have been calculated by gauge-indepedent atomic orbital (GIAO) method with B3LYP/6-311++G(d, p) approach.

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