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 <i>trans</i>-3-(3′-pyridyl)acrylic acid (3-PAH) and <i>trans</i>-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) (<b>1</b>), [Ag(3-PAH)₂](ClO₄) (<b>2</b>), [Ag(4-PAH)₂](ClO₄)·H₂O (<b>3</b>), [Ag(3-PA)]·1.5H₂O (<b>4</b>), and [Ag(4-PA)] (<b>5</b>). Of these, <b>1–2</b> are isotypical hydrogen-bonded polymers of Ag(I) complexes and <b>3</b> is a hydrogen-bonded dimer, whereas <b>4</b> and <b>5</b> are coordination polymers. Compounds <b>1–4</b> undergo photodimerization in <i>head-to-head</i> fashion in the solid state. The photoreactivity of these compounds in solution was also investigated. The <i>head-to-head</i> 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