Structural elucidation and spectroscopic studies of acetyl substituted piperazine nucleus tethered with 4, 5-diaryl-1 H-imidazole scaffold: DNA binding, Cu2+and Sn2+ ions sensing and cytotoxicity

Abstract

In this study, we report on synthesis of new imidazole based fluorescentchemosensors2-((4-(5-bromo-2-hydroxy-3-(4,5-diphenyl-1H-imidazol-2-yl)benzyl)piperazine-1-yl)methyl)-4-bromo-6-(4,5-diphenyl-1H-imidazole-2-yl)phenol(1)and2-((4-(2-hydroxy-5-methyl-3-(4,5-diphenyl-1H-imidazol-2-yl)piperazine-1-yl)methyl)-4-methyl-6-(4,5-diphenyl-1H-imidazole-2-yl)phenol(2). The synthesized chemosensors 1 and 2 were characterized by FT-IR, 1H NMR, UV–visible and fluorescence spectral studies. Further, the single crystal X-ray diffraction analysis shows that the chemosensor 1 crystallizes in triclinic system, with space group P-1.Hirshfeld surface analysis and 2D fingerprint maps revealed that 1 have remarkable H…H, C…H/H…C, and O…H/H…O Br…H/H…Br, interactions. The chemosensors have developed for selective and sensitive detection of Sn2+ and Cu2+ions in methanol among other tested cation. A bathochromic shift and color change with respect to the intra-molecular charge transfer transition in the absorption spectra was displayed after the addition of Sn2+ and Cu2+ions. The “Turn-on” fluorescence enhancement to Sn2+ ions and “turn-off” fluorescence quenching response to Cu2+ ions at λmax 450 and 448 nm, respectively, were detected in the fluorescence emission spectra of 1 and 2 upon addition of Sn2+ and Cu2+ions⁻. The receptor senses Sn2+ and Cu2+ ions via the deprotonation of the phenolic O-H unit, which was further confirmed by 1H NMR titration. Moreover, the fluorescence imaging in A549 cells suggested that chemosensors had great potential in the application of bio-imaging. The chemosensors1 and 2 with Sn2+ ions were found to be cytotoxic against A549 cells andthe IC50 of 1 and 2 have value of 107.40 μM and 8.21 μM, respectively and could be used as an anticancer agent.