Structure and coordination environment of the zinc complex with vanillin of double-stranded helix

The structure and coordination environment of unusually double-stranded helix of complex [Zn(C₈H₇O₃)₂(H₂O)₂] are studied experimentally and by the density functional theory (DFT) method. The Zn²⁺ ion coordinates six oxygen atoms of deprotonated vanillin and water molecules forming an octahedron. The intermolecular hydrogen bonds and π interactions of the vanillin fragments contributed to the formation of the double-stranded helical supramolecular structure in the crystal. Counterpoise geometric parameters of the calculation agree with the crystal structure determined by experiment. The stabilization energy between the donor and acceptor obtained from an analysis of natural bond orbitals of the indicated six ligand oxygen atoms act as electron donor to Zn²⁺ ion. The results of the density functional theory on the complex demonstrate that the different coordinated oxygen atoms, which have different chemical environment, distort the coordination octahedron. The text was submitted by the authors in English.