Effects of counter anions on intense photoluminescence of 1-D chain gold(I) complexes.

A series of cationic carbene complexes of Au(I) with different types of counteranions, [Au{C(OMe)NHMe}(2)](+)(X(-)) (X(-) = CF(3)SO(3)(-), PF(6)(-), CF(3)CO(2)(-), ClO(4)(-), and I(-)), was synthesized, and their intense photoluminescence was studied. These complexes crystallize in the same space group, and the X-ray crystallographic data of these samples revealed the short Au(I)-Au(I) aurophilic distances (3.263-3.335 A), where planar carbene Au(I) complexes are organized into linear stacks. The aurophilic Au(I)-Au(I) interactions found in the crystalline state give rise to phosphorescence with relatively high emission quantum efficiencies, whereas [Au{C(OMe)NHMe}(2)](+)(X(-)) complexes show no appreciable emission in solutions. The Au(I)-Au(I) distances in the crystal of [Au{C(OMe)NHMe}(2)](+)(X(-)) vary depending on the type of counteranions because the carbene ligands of Au(I) cations are linked through hydrogen bonds with adjacent counteranions. The effects of counteranions on the Au(I)-Au(I) aurophilic interactions allow one to modulate the intense photoluminescence color from blue to yellow by adjusting the counteranions of [Au{C(OMe)NHMe}(2)](+)(X(-)) complexes.