A quest for supramolecular gelators: silver(i) complexes with quinoline-urea derivatives

Abstract

The quinoline urea derivatives 1,3-di(quinolin-5-yl)urea (DQ5U), 1-phenyl-3-(quinolin-6-yl)urea (PQ6U), 1-(isoquinolin-5-yl)-3-phenylurea (PiQ5U) and 1-phenyl-3-(3,5-bis(pyrid-2-yl)-1,2,4-triazol-4-yl)urea (PPT4U) have been synthesised and structurally characterized by powder and single crystal X-ray diffraction. Their gelator behaviour in the formation of Ag-complexes has been explored. Compound DQ5U proved capable of gelating the mixed solvent EtOH–DMF 1 : 2 (v/v) when mixed with 1 equivalent of AgNO₃. In the case of PQ6U, two polymorphic forms of the complex [Ag(PQ6U)₂]NO₃, plus the solvated form [Ag(PQ6U)₂]NO₃·CH₃CN, were crystallized. Photophysical characterization of the ligands has been conducted in solution, while fluorescence microscopy has been used to examine the microstructure and photophysical properties of the gels formed by PQ5U and DQ5U with AgNO₃.