Understanding the exciton transport process within well-defined 3D solid phases will aid in the design of novel materials for highly efficient directional energy transport. Highlighted by highly-ordered crystal structure and synthetic tunability via crystal engineering, metal organic frameworks (MOFs) allow for precise control of distances and angles between chromophores and their alignment by judicious choice of ligands and metal nodes. In order to probe energy migration within the frameworks, PCN-223 MOFs consisting of mixed linkers - meso-tetrakis(4-carboxyphenyl)porphyrin (H2-TCPP) and Zinc-tetrakis(4-carboxyphenyl)porphyrin (Zn-TCPP), have been synthesized. It is expected that excitation of any of the Zn-TCPP units would lead to singlet-singlet energy transfer across the Zn-TCPP units. The singlet exciton can migrate until it decays or is quenched by a H2-TCPP unit, which acts as an exciton trap. Fluorescence lifetimes of PCN-223 MOFs were probed as a function of Zn-TCPP/H2-TCPP ratio in the MOFs to understand the effects of linker distribution on the efficiency and directionality of energy transfer. To complement experimental results and theoretically analyze the optical properties of MOFs, time-dependent density functional theory (TDDFT) studies have been carried out on cluster models of MOF.

Energy transfer studies on mixed-ligand PCN-223 metal organic frameworks

254th National Meeting (2017)

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