A facile synthesis and structural elucidation for furfural based chromophores: Prediction of linear and nonlinear optical properties

A facile condensation reaction between thiosemicarbazide and furfural was accomplished to synthe-size thiosemicarbazone derivatives: TMOH, FMOH, TMEH, FMEH, DCFH and DCMH with good yields as 73%, 70%, 72%,71%, 74% and 74%, respectively. They were characterized by spectroscopic techniques as UV-Vis, FT-IR, 1 H and 13CNMR. Furthermore, density functional theory (DFT) analysis was per-formed by applying M06 level with 6-311G(d,p) basis set for geometry optimization, natural bond or-bitals (NBOs), linear and nonlinear optical (NLO) and vibrational analyses. Time-dependent DFT ap-plying M06/6-311G(d,p) level of theory was used for computing frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP) and UV-Vis analyses. Experimental values of vibrational wave number and Amax values were seen in good correspondence with the DFT-based results. NBO in-vestigation revealed that title compounds were found with prominent hyper-conjugative interac-tions having stabilization energies as 57.72, 62.66, 59.95, 58.54, 63.59 and 45.6 kcal/mol, respectively, which are probably the main reasons for their stability. The descending order of Egap was found as DCMH >DCFH >TMOH >TMEH >FMEH >FMOH. Therefore, FMOH, exhibiting the smallest energy gap of 4.416 eV , can be regarded as an efficiently polarized structure, possessing a high capacity for electron transfer. MEP analysis describes the involvement of various reaction sites in chemical reactivity, at differ-ent portions of spread electronic cloud over the molecule. The decrease in values of (alpha) for title com-pounds are found as DCFH >DCMH >FMOH >TMOH >FMEH >TMEH. Moreover, beta tot values are found with this order DCFH >DCMH >TMOH >TMEH >FMEH >FMOH. It can be seen that DCMH exhibits a larger NLO response with (alpha) and beta tot figured as 300.51 and 2614.07 a.u., respectively. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

A facile condensation reaction between thiosemicarbazide and furfural successfully synthesized thiosemicarbazone derivatives with good yields, which were further characterized and analyzed using spectroscopic techniques and density functional theory. The prominent hyper-conjugative interactions between structures were found to be the main reason for stability, while the descending order of energy gaps determined the electron transfer properties.