| Abstract |
yyy Three new coordination polymers, [Na-1(H2L)(H2O)(3)](n) (1), \[K-1(H2L)(H2O)](8)center dot 13H(2)O\(n) (2), and \[(NiNa2I)-Na-II(HL)(2)(H2O)(8)]center dot 6H(2)O\(n) (3), were assembled from 1,3-dimethyl-5-(p-sulfonic-phenylazo)-6aminouracil (H3L) as a versatile building block. Although azo-coupling reactions generally result in simple azo-compounds, the presence of the sulfonate (-SO3-) group at the ligand frame led to the formation of the Na-I-1D (1) or K-I-3D (2) homometallic coordination polymer with different ligand coordination modes. Moreover, the heterometallic Ni-II/Na-I-1D (3) coordination polymer was obtained while carrying the reaction of 2 with NiCl2 center dot 6H(2)O. The structures of the obtained products were fully established by single crystal X-ray diffraction and confirmed by standard methods. Compounds 1 and 3 possess 1D metal-organic chains with the 2C1 topology, whereas 2 features a very complex 3D metal-organic architecture with an unprecedented topology. The computational study for molecular electrostatic potential (MEP) surface energies revealed an important finding, namely a decrease of the pi-acidity of the uracil ring upon coordination and a consequent increase of the pi-basicity of the phenyl-sulfonate ring, resulting in effective anti-parallel pi-pi stacking interactions in 1 and 2. Finally, a semi-conductive behavior of the obtained compounds was explored using impedance spectroscopy, revealing the very remarkable conductive properties of 1 (2.2 x 10(-4) S cm(-1)), which is a far better conductive material than 2 (7.2 x 10(-6) S cm(-1)) and 3 (4.8 x 10(-7) S cm(-1)). The obtained products represent the first coordination compounds derived from H3L. This study contributes to the design of functional coordination polymers driven by still poorly explored 6-aminouracil building blocks. |
