Photoconductive Coordination Polymer with a Lead–Sulfur Two-Dimensional Coordination Sheet Structure
Yoshinobu Kamakura, Chinatsu Sakura, Akinori Saeki, Shigeyuki Masaoka, Akito Fukui, Daisuke Kiriya, Kazuyoshi Ogasawara, Hirofumi Yoshikawa, Daisuke Tanaka
Abstract
Coordination polymers with metal–sulfur (M–S) bonds in their nodes have interesting optical properties and can be used as photocatalysts for water splitting. A wide range of inorganic–organic hybrid materials with M–S bonds have been prepared in recent years. However, there is a dearth of structural information because of their low crystallinity, which has hampered the understanding of their underlying chemistry and physics. Thus, we conducted a structural study of a novel, highly crystalline coordination polymer with M–S bonds. Theoretical calculations were performed to elucidate its photoconductivity mechanism. The photoconductive, three-dimensional coordination polymer [Pb(tadt)]n (denoted as KGF-9; tadt = 1,3,4-thiadiazole-2,5-dithiolate) was synthesized and confirmed to have a three-dimensional structure containing a two-dimensional Pb–S framework by single-crystal X-ray diffraction. We also performed diffuse-reflectance ultraviolet–visible–near-infrared spectroscopy, time-resolved microwave conductivity, and photoelectron yield spectroscopy measurements on the bulk powder samples, as well as first-principles calculations. Additionally, direct-current photoconductivity measurements were conducted on a single-crystal sample.