Our OPLS-2009IL force field parameters (J. Chem. Theory Comput. 2009, 5, 1038-1050) were originally developed and tested on 68 unique ionic liquids featuring the 1-alkyl-3-methylimidazolium [RMIM], N-alkylpyridinium [RPyr], and choline cations. Experimental validation was limited to densities and a few, largely conflicting, heat of vaporization (ΔH) values reported in the literature at the time. Owing to the use of Monte Carlo as our sampling technique, it was also not possible to investigate the reproduction of dynamics. The [RMIM] OPLS-2009IL parameters have been revisited in this work and adapted for use in molecular dynamics (MD) simulations. In addition, new OPLS-AA parameters have been developed for multiple anions, i.e., AlCl, BF, Br, Cl, NO, PF, acetate, benzoate bis(pentafluoroethylsulfonyl)amide, bis(trifluoroethylsulfonyl)amide, dicyanamide, formate, methylsulfate, perchlorate, propanoate, thiocyanate, tricyanomethanide, and trifluoromethanesulfonate. The computed solvent densities, heats of vaporization, viscosities, diffusion coefficients, heat capacities, surface tensions, and other relevant solvent data compared favorably with experiment. A charge scaling of ±0.8 e was also investigated as a means to mimic polarization and charge transfer effects. The 0.8-scaling led to significant improvements for ΔH, surface tension, and self-diffusivity; however, a concern when scaling charges is the potential degradation of local intermolecular interactions at short ranges. Radial distribution functions (RDFs) were used to examine cation-anion interactions when employing 0.8*OPLS-2009IL and the scaled force field accurately reproduced RDFs from ab initio MD simulations.

The Mn-catalyzed C-H alkenylation reactions of indole with terminal- and internal-alkynes have been developed. In the presence of a catalytic amount of acid, the procedure efficiently affords bis/trisubstituted indolyl-alkenes in a highly regio- and stereo-selective manner. Without the addition of acid, the reaction undergoes a [2+2+2] cyclization process to give carbazoles with release of hydrogen gas. Notably, the directing pyrimidyl group can be readily removed. Experimental studies reveal that the reaction is initiated by a C-H activation step and the acid is the selectivity controller via a hydrogen transfer process.

Molecular simulations of ionic liquids can provide deeper insight into the relationship between intermolecular interactions and macroscopic measurements for the solvents. However, many existing force fields have multiple shortcomings, including poor solvent dynamics, the underestimation of hydrogen-bonding strength, and errors in solvent interactions/organization. A new force field, called optimized potentials for liquid simulation-ionic-liquid virtual site (OPLS-VSIL), has been developed for imidazolium-based ionic liquids featuring a novel topology incorporating a virtual site bisecting the nitrogen atoms that offloads negative charge to inside the plane of the ring. Guided by free energy of hydration calculations, an empirically derived set of partial charges and nonbonded Lennard-Jones terms for both 1-alkyl-3-methylimidazolium and 11 different anions provided accurate bulk-phase ionic-liquid properties and produced radial distribution functions nearly indistinguishable from ab initio molecular dynamics simulations. For example, overall mean absolute errors (MAEs) of 3.1-3.4% were computed for the density, heat of vaporization, and viscosity of approximately 20 different ion pair combinations. Additional physical properties, such as, self-diffusion coefficients, heat capacity, and surface tension also gave significant MAE improvements using OPLS-VSIL compared to the existing fixed-charge ionic-liquid force fields. Local interactions, including cation-anion hydrogen bonding and π-π stacking between the imidazolium rings, were also accurately reproduced.

In this work, MIL-68(In) functionalized with various ligand substitutions including amine, hydroxyl, bromine, nitro, and methyl groups was prepared, via a one-pot solvothermal reaction for visible-light photocatalytic ammonia synthesis. The diversity of ligands tunes the morphology, geometry, pore environment, and electronic structure of MIL-68(In)-based photocatalysts due to the polarity and intraframework interactions. Amine-inserted MIL-68(In) outperforms its counterparts, presenting a boosted nitrogen photofixation rate of 140.34 μmol gcat –1 h–1 with an apparent quantum efficiency of 5.69% at 420 nm. Further, the size of the batch solvothermal reactor and the amine group content also influence the photocatalytic activity. The combined experimental and theoretical results reveal that amine substituents improve the chemisorption of nitrogen molecules and the conversion of nitrogen into ammonia follows a dual pathway, i.e., a Mars–van Krevelen process and a ligand-to-metal charge transfer mechanism. This work provides a molecular engineering strategy via dual catalysis toward efficient ammonia production.

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Deep eutectic solvents (DESs) are a class of solvents often composed of ammonium-based chloride salts and a neutral hydrogen bond donor (HBD) at specific ratios. These cost-effective and environmentally friendly solvents have seen significant growth in multiple fields, including organic synthesis, and in materials and extractions because of their desirable properties. In the present work, a new software called genetic algorithm machine learning (GAML) was developed that utilizes a genetic algorithm (GA) approach to facilitate the development of optimized potentials for liquid simulation (OPLS)-based force field (FF) parameters for eight unique DESs based on three ammonium-based salts and five HBDs at multiple salt:HBD ratios. As an initial test of GAML, partial charges were created for 86 conventional solvents based on neutral organic molecules that yielded excellent overall mean absolute deviations (MADs) of 0.021 g/cm 3 , 0.63 kcal/mol, and 0.20 kcal/mol compared to experimental densities, heats of vaporization (ΔH vap ), and free energies of hydration (ΔG hyd ), respectively. FFs for DESs constructed from ethylammonium, N,N-diethylethanolammonium, and N-ethyl-N,Ndimethylethanolammonium chloride salts were then parameterized using GAML with exceptional agreement achieved at multiple temperatures for experimental densities, surface tensions, and viscosities with MADs of 0.024 g/cm 3 , 4.2 mN/m, and 5.3 cP, respectively.

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A new kind of supramolecular organogel system based on dicarboxylic acids and primary alkyl amines (R–NH2) was obtained, in which the aggregation morphology of gelators could be controlled by solvent polarity and tail chain length.