Synthesis, crystal structure, and PTPs inhibition activity of a {N, S}-coordinated paddle wheel platinum(II) complex

A dinuclear platinum(II) complex, [Pt₂(μ-L)₃(μ-HL)]·Cl·3H₂O·DMSO (1, HL = 4-Amino-5-pyridin-4-yl-2,4-dihydro-[1,2,4]triazole-3-thione, DMSO = dimethyl sulfoxide), has been synthesized and characterized. The X-ray crystal structural analysis shows that the complex crystallizes in the triclinic, space group \(P\overline{1}\). Each Pt(II) atom is four-coordinated with two N atoms and two S atoms from triazole ligands. The two platinum centers of the complex formed a paddle wheel motif with four N atoms and four S atoms from four chelating triazole ligands as bridges. The complex forms a 3D network structure by intermolecular hydrogen bonds and C-H…π interactions. The inhibition of complex 1 was evaluated against protein tyrosine phosphatase 1B (PTP1B) and T-cell protein tyrosine phosphatase (TCPTP). It has been found that the complex can both inhibit PTP1B and TCPTP with IC₅₀ values of 11 and 17 μM, respectively. By comparing with the other platinum complexes, we found that complex 1 exhibits more effective inhibition to PTP1B and TCPTP than the reported paddle wheel dinuclear platinum(II) complexes and weaker inhibition against the two protein tyrosine phosphatases (PTPs) than the mononuclear platinum(II) complex with Schiff base ligand. It is suggested that both the modification and change of the ligand and the spatial structure of the complex will influence their inhibitory ability against PTPs.