Substituent-Dependent Stimuli Recognition of Luminescent Gold(I) Chloride Complexes Based on Diarsenic Ligands

Stimuli-responsive gold(I) chloride complexes were developed based on a diarsenic ligand, cis-1,4-dihydro-1,4-dimethyl-2,3,5,6-tetrakis(alchoxycarbonyl)-1,4-diarsinine (cis-DHDA). The crystals of the complexes showed intense luminescence due to the aurophilic interactions. Interestingly, methyl- and t-butyl substituted cis-DHDAs offered different stimuli-responsive behaviors accompanied with emission color changes. The crystal samples of the complexes with both ligands changed their emission colors by mechanical stimulus such as grinding in a mortar, but the effect of CH2Cl2-treatment for the recovery of the original emission was dependent on the substituent structures. Furthermore, only the crystals of the complex with t-butyl substituted cis-DHDAs showed vapochromic luminescence. These differences arise from steric hindrance of substituents at the ester groups. Relationship between chemical structure and emission behaviors was studied based on a simple ligand backbone.