Electronic structure, vibrational spectral and intervening orbital interactions studies of NLO material: Guanidinium 4-nitrobenzoate

•Symmetrically perturbed NH2 groups are the characteristic of GPNB molecule.•Moderate and weak intramolecular NH⋯O hydrogen bonds have been reported.•Intramolecular hydrogen bonds and n → σ∗ and σ → σ∗ interactions monitored the planar molecular structure.•Intervening orbital interactions promoting charge transfers for NLO system is investigated.•Global reactivity descriptors for GPNB are calculated.

Single crystals of guanidinium 4-nitrobenzoate (GPNB) have been grown by slow evaporation method. Grown crystals were characterized by FT-IR, FT-Raman, UV–Vis absorption and UV–Vis transmission spectroscopies. Crystal defects and surface morphology were studied by etching method. Dielectric properties of the crystal such as dielectric constant, dielectric loss and AC electrical conductivity as function of frequency (50 Hz–5 MHz) at two temperatures (35 °C and 100 °C) were measured. The frequency and temperature dependence of dielectric behaviour were investigated. The equilibrium geometry, vibrational spectral analysis, intramolecular charge transfer interactions using NBO method, first order hyperpolarizability, molecular electrostatic potential and frontier molecular orbital analysis for GPNB have been studied using density functional theory at B3LYP/cc-pVTZ level. Vibrational spectral study reveals the presence of moderate and weak NH⋯O bonds in GPNB. NBO analysis also confirms the presence of intramolecular NH⋯O hydrogen bonding and investigates the stability as well as the intervening orbital interactions. The electronic absorption spectrum of the gas and water phases of GPNB were simulated using time dependent density functional theory and NBO transitions for the three lowest excited states were assigned and studied.

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