Conductivity and photoconductivity in a two-dimensional zinc bis(triarylamine) coordination polymer

We report the synthesis and characterization of a 2D semiconductive and photoconductive coordination polymer. [Zn(TPPB)(Cl₂)]·H₂O (1) (TPPB = N ¹,N ¹,N ⁴,N ⁴-tetrakis(4-(pyridin-4-yl)phenyl)benzene-1,4-diamine) consists of a TPPB redox-active linker with bis(triarylamine) as the core. It consists of two redox sites connected with a benzene ring as a bridge. Thus, this forms an extended conjugation pathway when the TPPB ligand is coordinated with the Zn²⁺ metal ions. The single crystal conductivity measurement revealed conductivity of 1 to be in the range of 0.83 to 1.9 S cm^-1. Band structure analysis predicted that 1 is a semiconductor from the delocalization of electronic transport in the network. The computational calculations show the difference in charge distribution between holes and electrons, which led to spatial separation. This implies a long charge carrier lifetime as indicated by lifetime measurement. Incorporating a bis(triarylamine)-based redox-active linker could lead to a new semiconductive scaffold material with photocatalytic applications.