Experimental and theoretical investigation on piperazine-1,4-diium bis (2,5-dichlorophenoxyacetate) single crystal: A potential candidate for nonlinear optical applications

Abstract

Organic nonlinear optical (NLO) piperazine-1,4-diium bis (2,4-dichlorophenoxyacetate) (PDCPA) single crystals are grown by slow evaporation technique. The single crystal X-ray diffraction analysis is carried out to determine the cell parameters of the grown crystal. A combined experimental and theoretical quantum chemical calculation has been accomplished to examine the geometry, vibrational wavenumber, electronic transition and NLO activity of the molecule. The computational study is carried out by employing the DFT method using the B3LYP/6-311G(d,p) basis set. Natural bond orbital (NBO) analysis is performed to identify charge delocalization, hyperconjugative and hydrogen bonding interaction. HOMO-LUMO and chemical reactivity descriptor analysis is carried out to predict the chemical stability and reactivity of the molecule. The optical transmittance and the band gap energy of the PDCPA single crystal are recorded and analysed employing UV-visible transmittance spectral analysis. Hole-electron analysis is carried out to show charge transfer in the molecule. The emission behaviour of PDCPA single crystal has been scrutinized by fluorescence spectral analysis. The NLO activity of the molecule is determined theoretically and experimentally by the DFT method and Z-scan technique.