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

The construction of coordination polymers is of great interest due to their intriguingtopologies and potential applications as functional materials by using single metal andpolynuclear metal centers as building blocks. Silver（I）-ethynide complexes have also beenintensively investigated to prepare giant silver clusters and luminescent materials andserve as novel polynuclear building units to assemble organometallic networks. Recently itwas proposed that silver-ethynide complexes could be modified by the incorporation ofcoordination groups, such as pyridyl or pyrimidyl rings to become bifunctional buildingblocks to rationally assemble two-demensional （2D） and three-demensional （3D）coordination networks through Ag-N coordination bonds and argentophilic andsilver-ethynide interactions.Therefore one could imagine that phenylethynide ligands bearing carboxylate groupscould make a silver（I） phenylethynide complex unit interact with more silver（I） ions orsilver-ethynide complex units and thus lead to diverse and high-level organometallicarchitectures. In this work, three phenylethynes bearing carboxylic groups were utilized asligands to construct silver-organic networks and to investigate the relationship between thestructure of the network and the number of carboxylate groups attached to thephenylethynide ligands. Three phenylethynes bearing methyl carboxylate （HL1）,monocarboxylate （H₂L2）, and dicarboxylate （H₂L3） groups were utilized as ligands tosynthesize a new class of organometallic silver（I）-ethynide complexes as bifunctionalbuilding units to assemble silver（I）-organic networks. X-ray crystallographic studiesrevealed that in [Ag₂（L1）₂^<sub>AgNO₃]∞（1）（L1=4-C₂C₆H₄CO₂CH₃）, In [Ag₂（L2）·3AgNO₃·H₂O]∞（2）（L2=4-CO₂C₆H₄C₂）, the ethynide group coordinates to four silver ions toform a building unit （Ag4C₂C₆H₄CO₂）, which interacts through silver（I）-carboxylatecoordination bonds to generate a wave-like2D network and is subsequently connected bynitrate anions as bridging ligands to aford a three-dimensional （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 unitsinteract through silver（I）-carboxylate coordination bonds to directly generate a3D network. The obtained results showed that as a building unit, silver（I）-ethynide complexesbearing carboxylate groups exhibit diverse binding modes, and an increase in the numberof carboxylate groups in the silver（I）-ethynide complex unit leads to higher levelarchitectures. In the solid state, all of the complexes （1,2, and3） are photoluminescent atroom temperature and their emissions mainly originate from intraligand nâ†'л*andÏ€â†'Ï€*transitions.