Synthesis, characterization, anticancer activity and DNA interaction studies of new 2-aminobenzothiazole complexes; crystal structure and DFT calculations of [Ag(Habt)2]ClO4

•New transition metal simple and mixed complexes of 2-aminobenzothiazole are reported.•Salts of Zn+2, Pd+2, Pt+2, Rh+3, Ru+2, Os+6, Ir+4, Ag+ and Au+3 are obtained.•Crystal structure and DFT calculations of [Ag(Habt)2]ClO4 are determined.•Complexes were tested against breast (MDA-MB231) and ovarian (OVCAR-8) cancer cells.•DNA-binding of some complexes were studied using CD spectroscopy.

The synthesis and characterization of new complexes of 2-aminobenzothiazole (Habt), [M(Habt)3Cl]Cl, [M(L)(abt)]Cl (M(II) = Pd, Pt; L = bpy, phen), [Ir(Habt)3(H2O)Cl2]Cl, [Ru(Habt)3(H2O)Cl2], [Rh(Habt)3Cl3], [OsO2(Habt)2(OH)2], [Zn(bpy)(Habt)Cl]Cl, [Zn(PPh3)(Habt)2Cl]Cl, [Ag(Habt)2]ClO4, [Ag(L)(Habt)]ClO4 (L = bpy, phen, PPh3) and [Au(Habt)3Cl]Cl2 are reported. The structures are discussed on the bases of IR, Raman, UV–Vis, NMR (1H, 13C and 31P) and mass spectroscopy, elemental analysis, molar conductivity and thermal degradation measurements. In the X-ray crystal structure of the linear [Ag(Habt)2]ClO4 complex, Habt coordinates Ag(I) in a monodentate manner through the benzothiazol nitrogen atom. A theoretical study on [Ag(Habt)2]ClO4 was undertaken through DFT conformational analysis. The in vitro anticancer activity was evaluated against human breast cancer (MDA-MB231) and human ovarian cancer (OVCAR-8) cell lines. The complexes, [Ag(Habt)(PPh3)]ClO4, [Ag(phen)(Habt)]ClO4, [Pt(Habt)3Cl]Cl and [Pd(abt)(phen)]Cl, are more cytotoxic than is cisplatin to these cell lines, with mean IC50 values of 1.38, 1.78, 4.15 and 5.06 (MDA-MB231), and 1.26, 1.45, 4.04 and 5.20 (OVCAR-8) μM, respectively. The DNA-binding properties of some of these complexes were studied using circular dichroism (CD) spectroscopy. The results indicate that the complexes may have intercalative CT-DNA binding capabilities.

Graphical abstractSynthesis and characterization of new complexes of 2-aminobenzothiazole (Habt), [M(Habt)3Cl]Cl, [M(L)(abt)]Cl (M(II) = Pd, Pt; L = bpy, phen), [Ir(Habt)3(H2O)Cl2]Cl, [Ru(Habt)3(H2O)Cl2], [Rh(Habt)3Cl3], [OsO2(Habt)2(OH)2], [Zn(bpy)(Habt)Cl]Cl, [Zn(PPh3)(Habt)2Cl]Cl, [Ag(Habt)2]ClO4, [Ag(L)(Habt)]ClO4 (L = bpy, phen, PPh3) and [Au(Habt)3Cl]Cl2 are reported. The crystal structure and DFT conformational analysis of [Ag(Habt)2]ClO4 are determined. The free Habt and some complexes have been tested as anti-cancer agents against human breast cancer (MDA-MB231) and human ovarian cancer (OVCAR-8) cell lines. DNA-binding properties of some of the reported complexes were studied using circular dichroism (CD) spectra.Figure optionsDownload full-size imageDownload as PowerPoint slide