Impact of substituent position on crystal structure and photoconductivity in 1D and 2D lead(ii) benzenethiolate coordination polymers

Abstract

Coordination polymers containing a sulfur coordination atom (S-CPs) are an emerging class of materials with unique optoelectronic properties resulting from their inorganic metal–sulfur (–M–S–)_n networks. Although the structural dimensionalities of (–M–S–)_n networks govern the semiconductive properties of S-CPs, few systematic investigations have examined the impact of these dimensionalities on their semiconductive nature. In this study, we explored the relationship between the (–Pb–S–)_n dimensionality and photoconductivity. We systematically synthesized Pb(II) S-CPs with the formula [Pb(x-SPhOMe)₂] (x = ortho (KGF-32), meta (KGF-33), and para (KGF-34); HSPhOMe = methoxybenzenthiol). Single-crystal X-ray diffraction showed that KGF-32 and KGF-34 featured holodirected coordination spheres, but 1D (–Pb–S–)_n chains with [PbO₂S₄] octahedra and 2D (–Pb–S–)_n layers with [PbS₆] octahedra, respectively. In contrast, KGF-33 features a 1D (–Pb–S–)_n chain comprising a hemidirected [PbS₅] coordination sphere. Notably, time-resolved microwave conductivity measurements and first-principles calculations revealed that the 2D-extended (–Pb–S–)_n layer with the holodirected [PbS₆] octahedron observed in KGF-34 served as a pathway for electron mobility. The findings of this study provide further design strategies for fabricating highly photoconductive Pb(II) S-CPs.