Synthesis, structural and spectroscopic evaluations and nonlinear optical properties of 3,5-bis(4-methoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioic O-acid.

Abstract In this study, we report a combined experimental and theoretical study on 3,5-bis(4-methoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioic O-acid (C 18 H 18 N 2 O 3 S) molecule. The compound crystallizes in the trigonal space group R-3 with a  =  b  = 27.7151(12) A, c  = 12.4866(6) A, α  =  β  = 90.0°, γ  = 120.0° and Z  = 18. The crystal packing is stabilized by O H⋯O and O H⋯S intermolecular hydrogen bonds. These hydrogen bond interactions are also proved by NBO analysis. A detailed spectroscopic investigation is performed by the application of FT-IR and FT-NMR in addition to the theoretical approaches. Small energy gap between the frontier molecular orbitals is responsible for the nonlinear optical activity of the title molecule.