Metal-organic framework-177 (MOF-177) is one of the most porous materials whose structure is composed of octahedral Zn4O(-COO)6 and triangular 1,3,5-benzenetribenzoate (BTB) units to make a three-dimensional extended network based on the qom topology. This topology violates a long-standing thesis where highly symmetric building units are expected to yield highly symmetric networks. In the case of octahedron and triangle combinations, MOFs based on pyrite (pyr) and rutile (rtl) nets were expected instead of qom. In this study, we have made 24 MOF-177 structures with different functional groups on the triangular BTB linker, having one or more functionalities. We find that the position of the functional groups on the BTB unit allows the selection for a specific net (qom, pyr, and rtl), and that mixing of functionalities (-H, -NH2, and -C4H4) is an important strategy for the incorporation of a specific functionality (-NO2) into MOF-177 where otherwise incorporation of such functionality would be difficult. Such mixing of functionalities to make multivariate MOF-177 structures leads to enhancement of hydrogen uptake by 25%.

The electrocatalytic activity for CO 2 reduction is greatly enhanced for Co complexes with pyridyldiimine-based ligands through the stepwise integration of three synergistic substituent effects: extended conjugation, electron-withdrawing ability, and intramolecular electrostatic effects. The stepwise incorporation of these effects into the catalyst structures results in a series of complexes that show an atypical inverse scaling relationship for CO 2 reductionthe maximum activity of the resulting catalysts increases as the onset potentials are driven positive due to the ligand electronic substituent effects. Incorporating all three effects simultaneously into the catalyst structure results in a Co complex [Co(PDI-PyCH 3 + I − )] with dramatically enhanced activity for CO 2 reduction, operating with over an order of magnitude higher activity (TOF cat = 4.1 × 10 4 s −1 ) and ∼0.2 V more positive catalytic onset (E onset = −1.52 V vs Fc +/0 ) compared to the parent complex, an intrinsic activity parameter TOF 0 = 6.3 × 10 −3 s −1 , and >95% Faradaic efficiency for CO production in acetonitrile with 11 M water. This makes [Co(PDI-PyCH 3 + I − )] among the most active molecular catalysts reported for the CO 2 reduction reaction. Our work highlights a promising catalyst design strategy for molecular CO 2 RR catalysts in which catalytic ability is enhanced by tuning three synergistic substituent effects simultaneously in a single catalyst structure.

In situ X-ray absorbance spectroscopy measurements show that encapsulating cobalt phthalocyanine within coordinating polymers leads to axial ligation of Co and results in enhanced rates for electrocatalytic CO2 reduction.