Synthesis, Spectroscopic and Quantum Chemical Studies of N-Pentylhydrazinylthiazole Derivatives

Abstract

Herein, a series of N-pentylhydrazinylthiazole based compounds (EP1–EP7) were synthesized via three step synthetic strategy. The intermediates (TH1–TH7) were prepared with Hantzsch’s approach followed by N-pentylation through substitution reaction to obtain targeted N-pentylhydrazinylthiazoles (EP1–EP7). The proposed structures were established with different spectroscopic methods like FTIR, 1H-, 13C-NMR, and HRMS. Further, the non-linear optical (NLO) effect of established structures was explored via quantum chemical investigations. NLO, ultraviolet–visible (UV–Vis), natural population analysis (NPA), global reactivity parameters (GRPs), and natural bond orbital (NBO) investigations were executed at M06/6-311G(d,p) level of density functional theory (DFT). UV–Vis analysis revealed that the yielded systems (EP1–EP7) exhibited absorption wavelength in UV–Vis spectrum in the range of 328.61–389.58 nm. EP1 exhibited the highest λ max value (389.58 nm) among all examined compounds due to its minimal E gap of 4.028 eV. The widening of the energy gap was observed from EP1 to EP7 (4.028–4.492 eV) as elucidated by Frontier molecular orbital (FMO) investigation. The GRPs were correlated with the results of energy gap. As EP1 depicted the minimum band gap (4.028 eV), so it exhibited the highest value of softness (0.248 eV−1) along with lower-most value of hardness (2.014 eV). NBO analysis revealed valuable insights into the charge delocalization and stability of the compounds (EP1–EP7). The dipole moment ( average linear polarizability <α>, first and second order hyperpolarizabilities ( and ) were also executed for EP1–EP7 at the above-mentioned level. Consequently, the maximum (2.10 × 10−29 esu) and (9.31 × 10−35 esu) values were depicted by EP1 and EP3, respectively. Thus, all these outcomes unveiled that EP1 depicted robust response and proved to be the best NLO candidate for various hi-tech applications such as signal processing, fiber optics and data storage.