Two new one-dimensional luminescent silver(I) and lead(II) coordination polymers containing the flexible ligand 2-(1H-imidazole-1-yl)acetic acid

The free ligand, 2-(1H-imidazole-1-yl)acetate (Hima, 1), was crystallized from the mixture solution of 1. Two new coordination polymers, [Ag(Hima)(NO3)] (2) and {[Pb(Hima)2(NO3)](NO3)}n (3), are achieved by reaction of a flexible Hima, AgNO3 and Pb(NO3), respectively. In 2, the silver(I) atom is coordinated by four oxygen atoms from three carboxylate groups and one nitrate ion in a distorted tetrahedral environment. The free ligand Hima acts as the tridentate coordination mode, which bridges the silver atoms into a zigzag chain featuring a rare [Ag2(carboxylato-O,O′)(carboxylato-μ1,1-O)] six-membered ring. The intra-dimer Ag···Ag distance is 2.966(l) Å. In 3, Pb(II) atom exhibits an eight-coordinated dodecahedral coordination geometry, in which a unique 1-D chain structure with dicubane-like can be observed. In two polymers, the ligand Hima exhibits new and unique coordination modes. Solid-state fluorescence spectra reveal that the emission bands of complex 2 center at 462 and 510 nm (λex = 280 nm). In 3, the emission peaks locate at 465 and 547 nm upon excitation at 280 nm. In addition, they have been characterized by IR spectra and TG analysis.