Double Palindrome Water Chain in Cu(II) Theophylline Complex. Synthesis, Characterization, Biological Activity of Cu(II), Zn(II) Complexes with Theophylline

Abstract

Two metal complexes of theophylline were synthesized. Namely, 1 with the formula [Cu(theop)2(H2O)3]·2H2O and 2, [Zn(theop)2]∙H2O (where: theop = theophylline ion). Their properties were thoroughly investigated by the elemental analysis (EA), flame atomic absorption spectrometry (FAAS), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) that were augmented by antimicrobial and antioxidant analyses. Their radical scavenging ability (RSA) is notably higher than that of a pure theophylline itself. Similarly to theophylline complexes already studied by us 3, [Mn(theop)2(H2O)4] 4, [Co(theop)2(H2O)4] and 5, [Ni(theop)2(H2O)4] title compounds are inactive against Gram-negative bacteria, but they show moderate or mild activity against Gram-positive rods. The low temperature, single crystal X-ray diffraction technique determines the crystal structure of 1. Its supramolecular crystal topology is affected by the unique, double palindrome water chain that formed by two conserved and a sole coordinated water molecules. Crystal packing arrangements were characterized by fingerprint plots that were derived from the Hirshfeld surfaces (HS), as calculated for all structures in the series 1, 3, 4, 5.

Keywords

• coordination complex
• theophylline-complex
• crystal structure
• hirshfeld surface analysis
• palindrome water chain
• antioxidant activity