Formation of a copper-copper bond in coordination of a cyclotriphosphazene ligand toward Cu(II): Structural, spectral and docking studies

Two cyclotriphosphazene compounds, [HMPAP](2)[SO4]center dot 2CH(3)OH (1), MPAP: 2,2,4,4,6,6-hexakis(2-methyl-1 lambda(4)-pyridin-1-yl)-1,3,5,2 lambda(5),4 lambda(5),6 lambda(5)-triazatriphosphinine and [Cu(mu-OAc)(2)(MPAP)](2) (2), were prepared and identified by elemental analysis, FT-IR, Raman spectroscopy and single-crystal X-ray diffraction. In the crystal structure of 1, one nitrogen atom of the cyclotriphosphazene ring has been protonated. The copper complex (2) is binuclear formed by four bridging acetato ligands containing one Cu-Cu bond in the center of the complex. Each copper atom has a Cu(O4NCu) environment with octahedral geometry which is distorted owing to the Jahn-Teller effect. In the crystal network of the compounds, in addition to hydrogen bonds and hydrogen bond motifs (only in 1), pi-pi stacking interactions between phenyl rings further stabilize the crystal network. Based on the docking studies on the MPAP and its copper complex (2) with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II, B-DNA), the binding ability of the MPAP ligand toward biomacromolecules is significantly higher than the copper complex and doxorubicin drug and can be considered a biologically active compound. (C) 2020 Elsevier B.V. All rights reserved.