Substituent effect investigation at 13C NMR chemical shifts in CDCl3 solution of novel thiadiazole derivatives with SSP, DSP, DSP-NLR equations

Kara Y. S., Tekin N., Ussenov N.

Journal of Molecular Structure, vol.1346, 2025 (SCI-Expanded, Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 1346
  • Publication Date: 2025
  • Doi Number: 10.1016/j.molstruc.2025.143180
  • Journal Name: Journal of Molecular Structure
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Chemical Abstracts Core, Chimica, Compendex, INSPEC
  • Keywords: DSP analyses, DSP-NLR analyses, Excellent correlation, Reverse substituent effect, Thiadiazole ring
  • Kocaeli University Affiliated: Yes

Abstract

In this study, novel 4-(substituted phenyl)-3-phenyl-1,2,4-thiadiazol-5(4H)-ones were synthesized through the rearrangement reaction of a series of 1,2,4-oxadiazol-5(4H)-thione derivatives with copper powder. The thiadiazole derivatives were characterized using infrared (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, and high-resolution mass spectrometry (HRMS). The substituent-induced 13C chemical shift (SCS) values for the thiadiazole derivatives were correlated with various substituent constants through different linear free energy relationships (LFER) using both single and multiple regression analyses. The LFER models applied included the single, dual, and dual-nonlinear resonance substitution parameter methods (SSP, DSP, and DSP-NLR, respectively). In all correlation analyses, a reverse substituent effect was observed, indicated by negative ρ values. A statistical analysis of the SCS values for the studied carbon atoms revealed that the highest numerical results were obtained when employing the DSP-NLR method, demonstrating an excellent correlation (r ≥ 0.99).