Redox active extended networks constructed from the three-fold symmetrical TPymT ligand [2,4,6-Tris(2-pyrimidyl)-1,3,5-triazine] and silver(I) ions

Abstract

Two new three-dimensional coordination polymers, with the general formula [Ag4(TPymT)(CN)4]n (1) and [Ag5(TPymT)(CN)5]n (2), were obtained by reacting K[Ag(CN)2] complex with Fe(BF4)2 and polydentate TPymT ligands (TPymT ​= ​2,4,6-Tris(2-pyrimidyl)-1,3,5-triazine). The unexpected dissociation of the diacyanoargentate(I) ion in solution released Ag(I) ions that prevented the in situ coordination of Fe(II) to the TPymT ligand and favored the obtaining of silver(I) complexes, green- and yellow-orange colored compounds 1 and 2, respectively. X-ray diffraction on single crystals shows the formation of a chiral three-dimensional (3-D) structure for 1, and for 2, the molecular structure consists of two types of two-dimensional (2-D) networks that interact through argentophilic interactions and weak Ag–N coordinate bonds which leads to a 3-D structure. In 1, the four crystallographically independent silver(I) ions exhibit distorted seesaw, square-pyramidal and trigonal prism environments. The asymmetric unit in 2 contains five silver(I) ions penta-, tetra- and tricoordinated, in square-pyramidal, rare distorted square-planar, and trigonal surroundings. Room temperature photoluminescence spectra recorded on the ligand and the two complexes show broad emissions for TPymT ligand, for λexc ​= ​265 ​nm, attributed to π-π∗ intra-ligand fluorescence, whereas 1 and 2 show similar bands with lower intensity. Circular dichroism for 1 confirms the presence of the vast majority of P65 crystals. Electrochemical properties of 1 and 2 were also investigated, and for 1 a promising response to dopamine analyte was noticed.