Exploration and Validation of Force Field Design Protocols through QM-to-MM Mapping

The scale of the parameter optimisation problem in traditional molecular mechanics force field construction means that design of a new force field is a long process, and sub-optimal choices made in the early stages can persist for many generations of the force field. We hypothesise that careful use of quantum mechanics to inform molecular mechanics parameter derivation (QM-to-MM mapping) should be used to significantly reduce the number of parameters that require fitting to experiment and increase the pace of force field development. Here, we design a collection of 15 new protocols for small, organic molecule force field design, and test their accuracy against experimental liquid properties. Our best performing model has only seven fitting parameters, yet achieves mean unsigned errors of just 0.031 g/cm3 and 0.69 kcal/mol in liquid densities and heats of vaporisation, compared to experiment. The software required to derive the designed force fields is freely available at https://github.com/qubekit/QUBEKit.

The Synthesis and Properties of TIPA-Dominated Porous Metal-Organic Frameworks

Metal-Organic Frameworks (MOFs) as a class of crystalline materials are constructed using metal nodes and organic spacers. Polydentate N-donor ligands play a mainstay-type role in the construction of metal−organic frameworks, especially cationic MOFs. Highly stable cationic MOFs with high porosity and open channels exhibit distinct advantages, they can act as a powerful ion exchange platform for the capture of toxic heavy-metal oxoanions through a Single-Crystal to Single-Crystal (SC-SC) pattern. Porous luminescent MOFs can act as nano-sized containers to encapsulate guest emitters and construct multi-emitter materials for chemical sensing. This feature article reviews the synthesis and application of porous Metal-Organic Frameworks based on tridentate ligand tris (4-(1H-imidazol-1-yl) phenyl) amine (TIPA) and focuses on design strategies for the synthesis of TIPA-dominated Metal-Organic Frameworks with high porosity and stability. The design strategies are integrated into four types: small organic molecule as auxiliaries, inorganic oxyanion as auxiliaries, small organic molecule as secondary linkers, and metal clusters as nodes. The applications of ratiometric sensing, the adsorption of oxyanions contaminants from water, and small molecule gas storage are summarized. We hope to provide experience and inspiration in the design and construction of highly porous MOFs base on polydentate N-donor ligands.

A Small Organic molecule Based on Benzothiadiazole for Electrocatalytic Hydrogen Production

A small organic molecule 2,1,3-benzothiadiazole-4, 7-dicarbonitrile (BTDN) is assessed for electrocatalytic hydrogen, showing a hydrogen production faradaic efficiency of 82% in presence of salicylic acid. The key catalytic intermediates of reduced species BTDN−• and protonated intermediates are identified and characterized by using various spectroscopic methods and density functional theory (DFT) based calculations. With the experimental and theoretical results, a catalytic mechanism of BTDN for electrocatalytic H2 evolution is proposed.

A Small Organic Catalyst Based on Benzothiadiazole for Electrocatalytic Hydrogen Production

A small organic molecule 2,1,3-benzothiadiazole-4, 7-dicarbonitrile (BTDN) has been tested as electrocatalyst for hydrogen production. The catalyst shows a hydrogen production faradaic efficiency of 82% in presence of salicylic acid. Some of reaction mediators are identified and characterized by using various spectroscopic methods and density functional theory (DFT) based calculations.

A Small Organic Catalyst Based on Benzothiadiazole for Electrocatalytic Hydrogen Production

A small organic molecule 2,1,3-benzothiadiazole-4, 7-dicarbonitrile (BTDN) has been tested as electrocatalyst for hydrogen production. The catalyst shows a hydrogen production faradaic efficiency of 82% in presence of salicylic acid. Some of reaction mediators are identified and characterized by using various spectroscopic methods and density functional theory (DFT) based calculations.