Control of Emissive Excited States of Silver(I) Halogenido Coordination Polymers by a Solid Solution Approach

Luminescent silver­(I) halogenido coordination polymers [Ag2X2(PPh3)2(bpy)] n (X = I, Br, Cl) have been prepared. The iodido and bromido complexes exhibit strong blue phosphorescence assignable to the 3π–π*-excited-state of bpy, whereas the chlorido complex shows luminescence thermochromism due to the π–π*-state of bpy and charge transfer from the {Ag2Cl2} core to the bpy π*-orbital. Taking advantage of their structural similarities, we prepared a series of mixed-halogenido silver­(I) complexes [Ag2(X x X′(1–x))2(PPh3)2(bpy)] n (X, X′ = I, Br, Cl) at varying molar fractions as solid solutions. The mixed-halogenido complexes are as strongly luminescent as their parent complexes. The detailed study of their structure and emissive properties revealed smooth energy migration between the luminescent units and modification of the luminescence properties based on the planarity of bpy.