Assembly of silver(I) coordination polymers incorporating pyromellitic acid and N-heterocyclic ligands

Abstract

Five mixed ligands coordination polymers [Ag 4(apym) 2(pma)·(H 2O) 2] n ( 1), {[Ag 4(dmapym) 4(pma)·(H 2O) 2]·(H 2O) 6} n ( 2), [Ag 2(apyz) 2(H 2pma)·(H 2O) 4] n ( 3), {[Ag 4(apyz) 2(pma)·(H 2O) 2]·(H 2O) 2} n ( 4) and [Ag 4(NH 3) 8(pma)·(H 2O) 6] n ( 5) (apym = 2-aminopyrimidine, dmapym = 4, 6-dimethyl-2-aminopyrimidine, apyz = 2-aminopyrazine, H 4pma = pyromellitic acid) were synthesized and characterized. For 1 and 2, as the substituents change from H to methyl, the dimensions of 1– 2 decrease from three-dimension (3D) to one-dimension (1D) due to the steric effect of methyl groups. For 3 and 4, as the ratios of Ag 2O/apyz/pma vary from 1:1:1 to 2:1:1, the structure of 3 is a 1D ladder structure built from Ag-apyz double chains and pma anions, while the structure of 4 is a two-dimension (2D) grid. As excess ammonia is added to above four reaction systems, the structure of 5 contains unprecedented {[Ag(NH 3) 2] +} n chains and pma anions. The substituent on the pyrimidyl ring, ratios of reactants, solvent systems and ligand isomers intensively influence the coordination environments of metal ion and the coordination modes of the carboxyl group, and thus determine the structures of the coordination polymers. The photoluminescent properties of 1– 5 were also investigated.