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1. ipso ‐Arylative Ring‐Opening Polymerization as a Route to Electron‐Deficient Conjugated Polymers

   https://doi.org/10.1002/anie.201809610  

   Shih, Feng‐Yang ; Choi, Deokkyu ; Wu, Qin ; Nam, Chang‐Yong ; Grubbs, Robert B. ( December 2018 , Angewandte Chemie International Edition)

   ipso‐Arylative ring‐opening polymerization of 2‐bromo‐8‐aryl‐8H‐indeno[2,1‐b]thiophen‐8‐ol monomers proceeds to M_nup to 9 kg mol⁻¹with conversion of the monomer diarylcarbinol groups to pendent conjugated aroylphenyl side chains (2‐benzoylphenyl or 2‐(4‐hexylbenzoyl)phenyl), which influence the optical and electronic properties of the resulting polythiophenes. Poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to have lower frontier orbital energy levels (HOMO/LUMO=−5.9/−4.0 eV) than poly(3‐hexylthiophene) owing to the electron‐withdrawing ability of the aryl ketone side chains. The electron mobility (ca. 2×10⁻³ cm² V⁻¹ s⁻¹) for poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to be significantly higher than the hole mobility (ca. 8×10⁻⁶ cm² V⁻¹ s⁻¹), which suggests such polymers are candidates for n‐type organic semiconductors. Density functional theory calculations suggest that backbone distortion resulting from side‐chain steric interactions could be a key factor influencing charge mobilities.

    

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2. ipso ‐Arylative Ring‐Opening Polymerization as a Route to Electron‐Deficient Conjugated Polymers

   https://doi.org/10.1002/ange.201809610  

   Shih, Feng‐Yang ; Choi, Deokkyu ; Wu, Qin ; Nam, Chang‐Yong ; Grubbs, Robert B. ( December 2018 , Angewandte Chemie)

   ipso‐Arylative ring‐opening polymerization of 2‐bromo‐8‐aryl‐8H‐indeno[2,1‐b]thiophen‐8‐ol monomers proceeds to M_nup to 9 kg mol⁻¹with conversion of the monomer diarylcarbinol groups to pendent conjugated aroylphenyl side chains (2‐benzoylphenyl or 2‐(4‐hexylbenzoyl)phenyl), which influence the optical and electronic properties of the resulting polythiophenes. Poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to have lower frontier orbital energy levels (HOMO/LUMO=−5.9/−4.0 eV) than poly(3‐hexylthiophene) owing to the electron‐withdrawing ability of the aryl ketone side chains. The electron mobility (ca. 2×10⁻³ cm² V⁻¹ s⁻¹) for poly(3‐(2‐(4‐hexylbenzoyl)phenyl)thiophene) was found to be significantly higher than the hole mobility (ca. 8×10⁻⁶ cm² V⁻¹ s⁻¹), which suggests such polymers are candidates for n‐type organic semiconductors. Density functional theory calculations suggest that backbone distortion resulting from side‐chain steric interactions could be a key factor influencing charge mobilities.

    

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3. Solid state photodimerization of 9- tert -butyl anthracene ester produces an exceptionally metastable polymorph according to first-principles calculations

   https://doi.org/10.1039/C8CE01985A  

   Beran, Gregory J. ( January 2019 , CrystEngComm)

   Molecular crystal engineering seeks to tune the material properties by controlling the crystal packing. However, the range of achievable properties is constrained by the limited energy range of polymorphs which can be crystallized. Here, computational modeling highlights that a solid-state crystal-to-crystal chemical reaction in 9- tert -butyl anthracene ester (9TBAE) nanorods [Al-Kaysi et al. , J. Am. Chem. Soc. , 2006, 128 , 15938] imparts “synthetic memory” into the crystal structure that allows reproducible formation of a highly metastable, yet long-lived polymorph. Specifically, whereas the vast majority of known polymorphs exhibit lattice energy differences below 10 kJ mol −1 , the conformational polymorph formed via solid state reaction chemistry lies 14 kJ mol −1 higher in energy than the form grown from solution, according to calculations that combine a dispersion-corrected second-order Møller–Plesset perturbation theory (MP2D) treatment of the monomer and photodimer with a density functional theory treatment (B86bPBE-XDM) of the intermolecular interactions in the crystal. Moreover, the solid-state reaction environment traps a highly unstable intramolecular photodimer conformation which defies the conventional wisdom surrounding conformational polymorphs. These observations suggest that solid-state reaction chemistry represents an under-appreciated strategy for producing polymorphs that would likely be unobtainable otherwise. 

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4. Prediction of p K a s of Late Transition‐Metal Hydrides via a QM/QM Approach

   https://doi.org/10.1002/jcc.26057  

   Patel, Prajay ; Wang, Jiaqi ; Wilson, Angela K. ( September 2019 , Journal of Computational Chemistry)

   Three implicit solvation models, the conductor‐like polarizable continuum model (C‐PCM), the conductor‐like screening model (COSMO), and universal implicit solvent model (SMD), combined with a hybrid two layer QM/QM approach (ONIOM), were utilized to calculate the pK_avalues, using a direct thermodynamic scheme, of a set of Group 10 transition metal (TM) hydrides in acetonitrile. To obtain the optimal combination of quantum methods for ONIOM calculations with implicit solvation models, the influence of factors, such as the choice of density functional and basis set, the atomic radii used to build a cavity in the solvent, and the size of the model system in an ONIOM scheme, was examined. Additionally, the impact of Grimme's empirical dispersion correction and exact exchange was also investigated. The results were calibrated by experimental data. This investigation provides insight about effective models for the prediction of thermodynamic properties of TM‐containing complexes with bulky ligands. © 2019 Wiley Periodicals, Inc.

    

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5. Two-way wave–vortex interactions in a Lagrangian-mean shallow water model

   https://doi.org/10.1017/jfm.2022.889  

   Maitland-Davies, Cai ; Bühler, Oliver ( January 2023 , Journal of Fluid Mechanics)

   We derive and investigate numerically a reduced model for wave–vortex interactions involving non-dispersive waves, which we study in a two-dimensional shallow water system with an eye towards applications in atmosphere–ocean fluid dynamics. The model consists of a coupled set of nonlinear partial differential equations for the Lagrangian-mean velocity and the wave-related pseudomomentum vector field defined in generalized Lagrangian-mean theory. It allows for two-way interactions between the waves and the balanced flow that is controlled by the distribution of Lagrangian-mean potential vorticity, and for strong solutions it features a desirable exact energy conservation law for the sum of wave energy and mean flow energy. Our model goes beyond standard ray tracing as we can derive weak solutions that contain discontinuities in the pseudomomentum field, using the theory of weakly hyperbolic systems. This allows caustics to form without predicting infinite wave amplitudes, as would be the case in the standard ray-tracing theory. Suitable wave forcing and dissipation terms are added to the model and a numerical scheme for the model is implemented as a coupled set of pseudo-spectral and finite-volume integrators. Idealized examples of interactions between wavepackets and simple vortex structures are presented to illustrate the model dynamics. The unforced and non-dissipative simulations suggest a heuristic rule of ‘greedy’ waves, i.e. in the long run the wave field always extracts energy from the mean flow. 

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