Transition-Metal-Complex-Directed Synthesis of Hybrid Iodoargentates with Single-Crystal to Single-Crystal Structural Transformation and Photocatalytic Properties

Abstract

We synthesized and characterized three types of isostructural iodoargentates, [TM(phen)₃]Ag₂I₄·3DMF (TM = Co (<b>1</b>), Ni (<b>2</b>), Zn (<b>3</b>)), [TM(phen)₃]Ag₃I₅·DMF (TM = Co (<b>4</b>), Ni (<b>5</b>), Zn (<b>6</b>)), and [TM(phen)₃]₂Ag₈I₁₂·7DMF (TM = Co (<b>7</b>), Ni (<b>8</b>), Zn (<b>9</b>)) (phen = 1,10-phenanthroline, DMF = dimethylformamide) using transition-metal (TM) complexes as the structure-directing agents. Compounds <b>1</b>-<b>3</b> and compounds <b>4</b>-<b>6</b> feature zero-dimensional anionic [Ag₄I₈]^4- and [Ag₆I₁₀]^4- clusters, respectively. All of the [TM(phen)₃]²⁺ cations in compounds <b>1</b>-<b>6</b> are arranged into a two-dimensional (2D) (6,3) net layer. Interestingly, compounds <b>1</b>-<b>3</b> are kinetically unstable in the mother solution, and they can be converted to compounds <b>4</b>-<b>6</b> via irreversible single-crystal to single-crystal transformation processes, respectively, with distinct changes in the crystal morphology and structure. Compounds <b>7</b>-<b>9</b> feature one-dimensional (1D) zigzag chains constructed from [Ag₈I₁₂]^4- units. The UV-vis diffuse reflectance measurements demonstrate that compounds <b>1</b>-<b>9</b> possess the characteristics of semiconductors with band gaps of 2.58-2.71 eV and visible-light-irradiation-induced photocatalytic activities. Especially, compound <b>3</b> possesses higher photocatalytic degradation activity toward crystal violet (CV) and rhodamine B (RhB) in comparison to P25 under identical conditions. Moreover, the mechanism study reveals that the TM complex cations make a great contribution to the photocatalytic activity.