Progressive framework designing and photocurrent responsive tuning based on tetra(4-pyridyl)-tetrathiafulvalene ligand

Abstract

Although metal−organic frameworks (MOFs) based on redox-active tetrathiafulvalene (TTF) unit show good photocurrent performance, related reports about systematically elucidating the relationship between framework and photocurrent propriety are still scarce. Herein, three topologically and dimensionally tunable MOFs based on the redox active tetra(4-pyridyl)-tetrathiafulvalene (TTF(py)4), terephthalic acid (TPA), 4,4′-biphenyldicarboxylic acid (BDA) and 4,4′-oxybisbenzoic acid (OBA) ligand, namely as [Cd(TTF(py)4)2(TPA)2]n (1), [Zn(TTF(py)4)2(BDA)2]n (2) and {[Zn(TTF(py)4)2(OBA)2] H2O}n (3), were prepared via utilizing solvothermal method. Single crystal diffraction analysis showed that the structural adjustment of auxiliary ligands can realize the supramolecular networks with different dimensions well. The rod-shaped auxiliary ligands can endow MOFs (complex 1 and 2) with better three-dimensional (3D) extension skeleton. As a comparison, the fold-like auxiliary ligand (OBA) enabled complex 3 to extend along the two-dimensional (2D) backbone. In addition, all complexes exhibit redox activity and photocurrent responsive properties. Interestingly, complex 3 linking by fold-like auxiliary ligand shows nearly 10 times higher photocurrent intensity than traditional TTF unit. This work sheds some light on the construction of complexes with high photocurrent response properties through rational tuning of MOFs dimensions.