Metalloporphyrinic metal-organic frameworks for enhanced photocatalytic degradation of a mustard gas simulant.

Four metalloporphyrinic metal-organic frameworks (MOFs) were successfully synthesized and exhibited enhanced activities for the photooxidation of a sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES). Among them, a Sn-porphyrin functionalized 2D MOF, namely CSLA-21-NH(Sn), showed a half-life of 1.5 min for CEES oxidation under blue LED, featuring as one of the fastest photocatalysts for CEES degradation.

Redox-Active Boron Clusters.

ConspectusIn this Account, we discuss our group's research over the past decade on a class of functionalized boron clusters with tunable chemical and physical properties, with an emphasis on accessing and controlling their redox behavior. These clusters can be thought of as three-dimensional aromatic systems that have distinct redox behavior and photophysical properties compared to their two-dimensional organic counterparts. Specifically, our lab has studied the highly tunable, multielectron redox behavior of B(OR) clusters and applied these molecules in various settings.

Electrochemical Cycling of Redox-Active Boron Cluster-Based Materials in the Solid State.

This work demonstrates the first successful electrochemical cycling of a redox-active boron cluster-based material in the solid state. Specifically, we designed and synthesized an ether-functionalized dodecaborate cluster, B(OCH), which is the smallest redox-active building block in the B(OR) family. This species can reversibly access four oxidation states in solution, ranging from a dianion to a radical cation.

Synthesis and structural properties of a 2D Zn(II) dodecahydroxy--dodecaborate coordination polymer.

In this work, we discuss the synthesis and characterization of a 2D coordination polymer composed of a dianionic perhydroxylated boron cluster, [B(OH)], coordinated to Zn(II)-the first example of a transition metal-coordinated [B(OH)] compound. This material was synthesized cation exchange from the starting cesium salt and then subjected to rigorous characterization prior to and after thermal activation. Numerous techniques, including XRD, FTIR, SEM, TGA, and solid-state NMR revealed a 2D coordination polymer composed of sheets of Zn(II) ions intercalated between planes of boron clusters.

Benchmarking the dynamic luminescence properties and UV stability of BH-based materials.

The dynamic photoluminescence properties, and potential quenching mechanisms, of -BH, 4,4'-Br--BH, and 4,4'-I--BH are investigated in solution and polymer films. UV stability studies of the neat powders show no decomposition occurring after intense 7 day light soaking. In contrast, clusters incorporated into polymer films are found to degrade into smaller borane fragments under the same irradiation conditions.

Tuning Thermal Expansion in Metal-Organic Frameworks Using a Mixed Linker Solid Solution Approach.

Several metal-organic frameworks are known to display negative thermal expansion (NTE). However, unlike traditional NTE material classes, there have been no reports where the thermal expansion of a MOF has been tuned continuously from negative to positive through the formation of single-phase solid solutions. In the system Zn-DMOF-TM, Zn[(bdc)(TM-bdabco)][dabco], the introduction of increasing amounts of TM-bdc, with four methyl groups decorating the benzene dicarboxylate linker, leads to a smooth transition from negative to positive thermal expansion in the - plane of this tetragonal material.

Elucidating the Variable-Temperature Mechanical Properties of a Negative Thermal Expansion Metal-Organic Framework.

We report the first experimental study into the thermomechanical and viscoelastic properties of a metal-organic framework (MOF) material. Nanoindentations show a decrease in the Young's modulus, consistent with classical molecular dynamics simulations, and hardness of HKUST-1 with increasing temperature over the 25-100 °C range. Variable-temperature dynamic mechanical analysis reveals significant creep behavior, with a reduction of 56% and 88% of the hardness over 10 min at 25 and 100 °C, respectively.