Synthesis and Photophysical Properties of Emissive Silver(I) Halogenido Coordination Polymers Composed of {Ag₂X₂} Units Bridged by Pyrazine, Methylpyrazine, and Aminopyrazine

Luminescent silver(I) coordination polymers having a {Ag2(μ-X)2} rhombic core (X = I, Br) were prepared using pyrazine (pyz), methylpyrazine (Mepyz), and aminopyrazine (ampyz) as bridging ligands. Photophysical measurements show that the complexes were strongly luminescent in the solid state at room temperature; further, the emissive excited state of the pyz and Mepyz complexes was a triplet charge-transfer (3CT) excited state, similar to that of their copper(I) congeners, whereas that of the ampyz complex was a intraligand (3IL) excited state. The energy of the 3CT excited state of a silver halogenido complex was revealed to be ca. 5000 cm-1 higher than that of the corresponding copper complex.