1,2,3-triazole Ligands and their Cu(II), Zn(II), Pt(II), and Ru(II) Complexes' DNA Binding Characteristics

In this study, novel 1,2,3-triazole-based ligands were designed and synthesized to explore their coordination behavior with transition metals and to evaluate the DNA-binding properties of their metal complexes. Two novel 1,2,3-triazole-based compounds (4c, 4d) were created in this work using a click reaction and thoroughly examined using FTIR, NMR, and mass spectrometry. UV-Vis absorption and fluorescence spectroscopy were then used to create their Cu(II), Zn(II), Pt(II), and Ru(II) complexes (5c–8d) and examine their DNA binding characteristics. The ligands and complexes had moderate to strong interactions with DNA, as shown by their binding constants (Kb), which varied from 2.67 to 5.7 ×104 M⁻¹. Compared to the free ligands and Pt(II) complex, the Cu(II), Zn(II), and Ru(II) complexes showed greater binding affinities. Cu(II) complexes displayed a strong hyperchromic effect with a slight red shift (2–3 nm), indicating that groove or electrostatic binding stabilized the DNA helix. A tiny red shift (1–2 nm) and hyperchromicity (29.82–40%) were seen in the titration of Ru(II)( η6-p-cymene). When we examined the absorption spectra of Pt(II) and Zn(II) complexes in the absence and presence of DNA, a strong absorption band at 280 nm, indicating π–π* transitions due to the aromatic ring in their structures, appeared in the spectra of the complexes. Fluorescence quenching studies further confirmed the DNA binding behaviour, with compound 4d (Ksv = 6.82 x104 M-1) and compound 7c (Ksv = 10.33 x10⁴ M⁻¹) showing the highest quenching efficiencies. Compound 8c exhibited a Ksv value of 5.84 × 10⁴ M⁻¹, indicating efficient fluorescence quenching and a notable interaction with DNA. This result suggests that 8c has a considerable affinity toward DNA, supporting its potential as a DNA-binding agent.