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 (${\mu }_{\mathrm{tot}}),$ average linear polarizability <α>, first and second order hyperpolarizabilities (${\beta }_{\mathrm{to}t}$ and ${\gamma }_{\mathrm{tot}}$) were also executed for EP1–EP7 at the above-mentioned level. Consequently, the maximum ${\beta }_{\mathrm{tot}}$ (2.10 × 10⁻²⁹ esu) and ${\gamma }_{\mathrm{tot}}$ (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.

Keywords:

• N-Pentylated hydrazinylthiazoles
• hyperpolarizability
• NPA analysis
• non-linear optics
• DFT

Acknowledgments

Dr. Muhammad Khalid gratefully acknowledges the financial support of HEC Pakistan (project no. 20-14703/NRPU/R&D/HEC/2021). Authors are thankful for cooperation and collaboration of A.A.C.B from IQ-USP, Brazil especially for his continuous support and providing computational lab facilities. A.A.C.B. (grant 2015/01491-3) is highly thankful to Fundação de Amparo à Pesquisa do Estado de São Paulo for the cooperation and financial assistance. The authors thank the Researchers Supporting Project number (RSP2023R6), King Saud University, Riyadh, Saudi Arabia.

Ethical approval

Our work is not related to human and/or animal studies therefore this section is not applicable.

Authors’ contributions

Muhammad Haroon: Writing-review article, Data curation; formal analysis. Tashfeen Akhtar: Conceptualization; methodology. Muhammad Khalid: Methodology; software; project administration. Hasnain Mehmood: Data curation. Muhammad Adnan Asghar: Conceptualization; resources. Tansir Ahamad: formal analysis; validation. Sarfraz Ahmed; Conceptualization; Writing-review & editing. Ataualpa A. C. Braga; methodology; software.

Disclosure statement

The authors have no relevant financial or non-financial interests to disclose.

Data availability statement

All data generated or analyzed during this study are included in this published article and its supplementary information files.

Additional information

Funding

Dr. Muhammad Khalid gratefully acknowledges the financial support of HEC Pakistan [project no. 20-14703/NRPU/R&D/HEC/2021). A.A.C.B. [grant 2015/01491-3] is highly thankful to Fundação de Amparo à Pesquisa do Estado de São Paulo for the cooperation and financial assistance. The authors thank the Researchers Supporting Project number (RSP2023R6), King Saud University, Riyadh, Saudi Arabia