Two- and Three-Dimensional Silver(I)-Organic Networks Generated from Mono- and Dicarboxylphenylethynes

Three phenylethynes bearing methyl carboxylate (HL1), monocarboxylate (H2L2), and dicarboxylate (H2L3) groups were utilized as ligands to synthesize a new class of organometallic silver(I)-ethynide complexes as bifunctional building units to assemble silver(I)-organic networks. X-ray crystallographic studies revealed that in [Ag2(L1)2·AgNO3]∞ (1) (L1= 4-C2C6H4CO2CH3), one ethynide group interacts with three silver ions to form a complex unit. These units aggregate by sharing silver ions with the other three units to afford a silver column, which are further linked through argentophilic interaction to generate a two-demensional (2D) silver(I) network. In [Ag2(L2)·3AgNO3·H2O]∞ (2) (L2 = 4-CO2C6H4C2), the ethynide group coordinates to four silver ions to form a building unit (Ag4C2C6H4CO2), which interacts through silver(I)-carboxylate coordination bonds to generate a wave-like 2D network and is subsequently connected by nitrate anions as bridging ligands to afford a three-demensional (3D) network. In [Ag3(L3)·AgNO3]∞ (3) (L3 = 3,5-(CO2)2C6H3C2), the building unit (Ag4C2C6H3(CO2)2) aggregates to form a dimer [Ag8(L3)2] through argentophilic interaction. The dimeric units interact through silver(I)-carboxylate coordination bonds to directly generate a 3D network. The obtained results showed that as a building unit, silver(I)-ethynide complexes bearing carboxylate groups exhibit diverse binding modes, and an increase in the number of carboxylate groups in the silver(I)-ethynide complex unit leads to higher level architectures. In the solid state, all of the complexes (1, 2, and 3) are photoluminescent at room temperature.