Coordination-Driven Fluorescent J-Aggregates in a Perylenetetracarboxylate-Based MOF: Permanent Porosity and Proton Conductivity

Abstract

Here we report the synthesis and structural characterizations of a new 3D functional metal–organic framework {[K8(PTC)2(H2O)1.5]·4H2O}n formed by the self-assembly of KI and chromophoric linker perylenetetracarboxylate (PTC). The structure determination shows a 3D pillared-layer framework, where perylene cores are arranged in an unusual end-to-end off-slipped and zigzag arrangement directed by KI–carboxylate bonding. Photophysical studies revealed a broad absorption band with λmax of 531 nm and bathochromically shifted red emission centered at 655 nm. This characteristic emission has been assigned due to J-coupling of the PTC linkers in the solid state. The framework contains 1D water-filled channel, and the desolvated framework shows permanent porosity, “as realized by type-I CO2 adsorption profile at 195 K. Interestingly, the guest and coordinated water molecules in the framework are connected via H-bonding and based on these characteristics, the framework was further exploited for proton conduction. It shows remarkable conductivity of 1 × 10–3 S cm–1 under ambient conditions (98% RH) with low activation energy.