Synthesis, spectral characterisation and cytotoxic effect of metal complexes of 2-(2-(4-carboxyphenyl)guanidino) acetic acid ligand

Abstract

A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Sr(II), Hg(II), Ag(I), Tl(I) and UO2(II) complexes of 2-(2-(4-carboxyphenyl)guanidino)acetic acid ligand have been synthesised and characterised by elemental analyses, IR, UV-Vis spectra, mass spectra (ligand and its zinc(II) complex), 1H NMR spectra (ligand and its mercury(II) complex), magnetic moments, conductances, thermal analyses (DTA and TGA) and ESR measurements. The IR data show that, the ligand behaves as neutral tridentate, (2), [(H2L)3Cu2(OAc)4(H2O)2], neutral bidentate, (3), [(H2L)Cu(OAc)2].1/2H2O, (13), [(HL)2CuCl2(H2O)2], (17), [(H2L)Cu(OOSO2)(H2O)3], dibasic hexadentate, (4), [(L) Ni4(OAc)6(H2O)10].4H2O, (5), [(L)Mn4(OAc)6(H2O)10].4H2O, (6), [(L)Co4(OAc)6(H2O)10] .4H2O, monobasic bidentate, (7), [(HL)(UO2)(OAc)(H2O)3], (12), [(HL)2Cu], (15), [(HL)2Fe2(Cl4)(H2O)2].7H2O, (16), [(HL)2Cr2(Cl4)(H2O)2].7H2O, (21), [(H2L)Cd (OOSO2)(H2O)3].2H2O, monobasic tridentate, (8), [(L)2Hg2(OAc)2 (H2O)6].H2O, (9), [(L)2Zn2(OAc)2(H2O)6].H2O, (10), [(L)2Cd2(OAc)2(H2O)6].H2O, (11), [(L)Tl4(OAc)3 (H2O)6], (18), [(HL)(OH)Cr2(SO4)2(H2O)5].H2O, (19), [(HL)3Ag3NO3], or dibasic tridentate, (14), [(L) Sr(Cl)20(H2O)24], (20), [(L)3Cu (H2O)2]. Molar conductances in DMF indicate that, the complexes are non-electrolyte. The ESR spectra of Cu(II) complexes (2), (3) and (20) at room temperature show axial type symmetry with g// > g- > 2.00, indicating a d(x2-y2) ground state with significant covalent bond character in an octahedral or square planar geometry. However, Cu(II) complexes (12) and (13) show isotropic type, indicating square planar and octahedral structure. Complexes Mn(II) (5) and Co(II) (6) show broad signals in the low field region indicating spin exchange interaction take place between metal(II) ion. Hg(II) complex (9), Tl(I) complex (11), Cr(III) complex (16), Cu(II) complex (17) and Cd(II) complex (21) showed potential antiproliferative activity where they showed inhibitory effect on breast carcinoma (MCF-7 cell line) in comparing with the standard drug.