Photoreactivity of Ag(I) Complexes and Coordination Polymers of Pyridyl Acrylic Acids

Abstract

An attempt has been made to orient the C═C bonds in trans-3-(3′-pyridyl)acrylic acid (3-PAH) and trans-3-(4′-pyridyl)acrylic acid (4-PAH) in the hydrogen-bonded coordination complexes and coordination polymers of Ag(I), utilizing the argentophilic interaction. Both neutral and deprotonated ligands were employed to synthesize the following compounds: [Ag(3-PAH)2](BF4) (1), [Ag(3-PAH)2](ClO4) (2), [Ag(4-PAH)2](ClO4)·H2O (3), [Ag(3-PA)]·1.5H2O (4), and [Ag(4-PA)] (5). Of these, 1–2 are isotypical hydrogen-bonded polymers of Ag(I) complexes and 3 is a hydrogen-bonded dimer, whereas 4 and 5 are coordination polymers. Compounds 1–4 undergo photodimerization in head-to-head fashion in the solid state. The photoreactivity of these compounds in solution was also investigated. The head-to-head photodimerized product of 4-PAH, namely, 3,4-bis(4′-pyridyl)cyclobutane-1,2-dicarboxylic acid (HH-4,4-BPCD), has been shown to be a potential ligand for synthesizing coordination polymers, by the isolation of [Ag2(HH-4,4-BPCD)(H2O)]·(2H2O)(1/2MeOH), which has a two-dimensional polymeric structure in the solid state.