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1. Role of curvature in acridone for ¹O₂ oxidation of a natural product homoallylic alcohol: A novel iso ‐hydroperoxide intermediate

   https://doi.org/10.1111/php.13843  

   Lapoot, Lloyd ; Jabeen, Shakeela ; Durantini, Andrés M. ; Greer, Alexander ( August 2023 , Photochemistry and Photobiology)

   A density functional theoretical (DFT) study is presented, implicating a¹O₂oxidation process to reach a dihydrobenzofuran from the reaction of the natural homoallylic alcohol, glycocitrine. Our results predict an interconversion between glycocitrine and aniso‐hydroperoxide intermediate [R(H)O⁺–O⁻] that provides a key path in the chemistry which then follows. Formations of allylic hydroperoxides are unlikely from a¹O₂‘ene’ reaction. Instead, the dihydrobenzofuran arises by¹O₂oxidation facilitated by a 16° curvature of the glycocitrine ring imposed by a pyramidalN‐methyl group. This curvature facilitates the formation of theiso‐hydroperoxide, which is analogous to theisospecies CH₂I⁺–I⁻and CHI₂⁺–I⁻formed by UV photolysis of CH₂I₂and CHI₃. Theiso‐hydroperoxide is also structurally reminiscent of carbonyl oxides (R₂C=O⁺–O⁻) formed in the reaction of carbenes and oxygen. Our DFT results point to intermolecular process, in which theiso‐hydroperoxide's fate relates to O‐transfer and H₂O dehydration reactions for new insight into the biosynthesis of dihydrobenzofuran natural products.
2. Mono ‐ and Bis ‐Alkylated Lumazine Sensitizers: Synthetic, Molecular Orbital Theory, Nucleophilic Index and Photochemical Studies

   https://doi.org/10.1111/php.13310  

   Sosa, María José ; Urrutia, María Noel ; Schilardi, Patricia L. ; Quindt, Matías I. ; Bonesi, Sergio M. ; Denburg, Dobrushe ; Vignoni, Mariana ; Greer, Alexander ; Greer, Edyta M. ; Thomas, Andrés H. ( August 2020 , Photochemistry and Photobiology)

   Mono‐ andbis‐decylated lumazines have been synthesized and characterized. Namely,mono‐decyl chain [1‐decylpteridine‐2,4(1,3H)‐dione]6aandbis‐decyl chain [1,3‐didecylpteridine‐2,4(1,3H)‐dione]7aconjugates were synthesized by nucleophilic substitution (S_N2) reactions of lumazine with 1‐iododecane inN,N‐dimethylformamide (DMF) solvent. Decyl chain coupling occurred at theN¹site and then theN³site in a sequential manner, without DMF condensation. Molecular orbital (MO) calculations show ap‐orbital atN¹but notN³, which along with a nucleophilicity parameter (N) analysis predict alkylation atN¹in lumazine. Only after the alkylation atN¹in6a, does ap‐orbital onN³emerge thereby reacting with a second equivalent of 1‐iododecane to reach the dialkylated product7a. Data from NMR (¹H,¹³C, HSQC, HMBC), HPLC, TLC, UV‐vis, fluorescence and density functional theory (DFT) provide evidence for the existence ofmono‐decyl chain6aandbis‐decyl chain7a. These results differ to pterinO‐alkylations (kinetic control), whereN‐alkylation of lumazine is preferred and then to dialkylation (thermodynamic control), with an avoidance of DMF solvent condensation. These findings add to the list of alkylation strategies for increasing sensitizer lipophilicity for use in photodynamic therapy.
3. Highly Active and Abundant MAB Phases Ni _n+1 ZnB _n ( n  = 1, 2) toward Hydrogen Evolution

   https://doi.org/10.1002/aesr.202100052  

   Rezaie, Amir A. ; Lee, Eunsoo ; Yapo, Johan A. ; Fokwa, Boniface P. T. ( May 2021 , Advanced Energy and Sustainability Research)

   Whilst MXenes (2D carbides and nitrides) have become highly popular in several research fields including the hydrogen evolution reaction (HER), unfortunately they are not competitive HER electrocatalysts in their bulk form (MAX phases). The related MAB (2D‐like bulk borides) phases and the derived 2D MBenes, however, are less studied but show better HER properties. Herein, two highly HER‐active and abundant MAB phases, Ni_n+1ZnB_n(n = 1, 2), are studied experimentally and computationally. The pressed pellet electrodes from bulk polycrystalline powders of these phases drive a current density of 10 mA cm⁻²at impressive overpotentials ofη₁₀ = −0.171 V (n = 1) andη₁₀= −0.145 V (n = 2) to efficiently produce hydrogen. Density functional theory (DFT) calculations prove that the most active site is the hollow site on the nickel basal plane, showing a free energy value comparable to that of the hollow site of Pt (111). This study paves the way for further development of bulk and nanoscale MAB phases for clean energy applications.
4. Development and test of highly accurate endpoint free energy methods. 1: Evaluation of ABCG2 charge model on solvation free energy prediction and optimization of atom radii suitable for more accurate solvation free energy prediction by the PBSA method

   https://doi.org/10.1002/jcc.27089  

   Sun, Yuchen ; He, Xibing ; Hou, Tingjun ; Cai, Lianjin ; Man, Viet Hoag ; Wang, Junmei ( February 2023 , Journal of Computational Chemistry)

   Accurate estimation of solvation free energy (SFE) lays the foundation for accurate prediction of binding free energy. The Poisson‐Boltzmann (PB) or generalized Born (GB) combined with surface area (SA) continuum solvation method (PBSA and GBSA) have been widely used in SFE calculations because they can achieve good balance between accuracy and efficiency. However, the accuracy of these methods can be affected by several factors such as the charge models, polar and nonpolar SFE calculation methods and the atom radii used in the calculation. In this work, the performance of the ABCG2 (AM1‐BCC‐GAFF2) charge model as well as other two charge models, that is, RESP (Restrained Electrostatic Potential) and AM1‐BCC (Austin Model 1‐bond charge corrections), on the SFE prediction of 544 small molecules in water by PBSA/GBSA was evaluated. In order to improve the performance of the PBSA prediction based on the ABCG2 charge, we further explored the influence of atom radii on the prediction accuracy and yielded a set of atom radius parameters for more accurate SFE prediction using PBSA based on the ABCG2/GAFF2 by reproducing the thermodynamic integration (TI) calculation results. The PB radius parameters of carbon, oxygen, sulfur, phosphorus, chloride, bromide and iodine, were adjusted. New atommore »types,on,oi,hn1,hn2,hn3, were introduced to further improve the fitting performance. Then, we tuned the parameters in the nonpolar SFE model using the experimental SFE data and the PB calculation results. By adopting the new radius parameters and new nonpolar SFE model, the root mean square error (RMSE) of the SFE calculation for the 544 molecules decreased from 2.38 to 1.05 kcal/mol. Finally, the new radius parameters were applied in the prediction of protein‐ligand binding free energies using the MM‐PBSA method. For the eight systems tested, we could observe higher correlation between the experiment data and calculation results and smaller prediction errors for the absolute binding free energies, demonstrating that our new radius parameters can improve the free energy calculation using the MM‐PBSA method.

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5. Single Crystal Microwires of p ‐DTS(FBTTh ₂ ) ₂ and Their Use in the Fabrication of Field‐Effect Transistors and Photodetectors

   https://doi.org/10.1002/adfm.201702073  

   Cui, Qiuhong ; Hu, Yuanyuan ; Zhou, Cheng ; Teng, Feng ; Huang, Jianfei ; Zhugayevych, Andriy ; Tretiak, Sergei ; Nguyen, Thuc‐Quyen ; Bazan, Guillermo C. ( November 2017 , Advanced Functional Materials)

   Single crystal microwires of a well‐studied organic semiconductor used in organic solar cells, namelyp‐DTS(FBTTh₂)₂, are prepared via a self‐assembly method in solution. The high level of intermolecular organization in the single crystals facilitates migration of charges, relative to solution‐processed films, and provides insight into the intrinsic charge transport properties ofp‐DTS(FBTTh₂)₂. Field‐effect transistors based on the microwires can achieve hole mobilities on the order of ≈1.8 cm²V⁻¹s⁻¹. Furthermore, these microwires show photoresponsive electrical characteristics and can act as photoswitches, with switch ratios over 1000. These experimental results are interpreted using theoretical simulations using an atomistic density functional theory approach. Based on the lattice organization, intermolecular couplings and reorganization energies are calculated, and hole mobilities for comparison with experimental measurements are further estimated. These results demonstrate a unique example of the optoelectronic applications ofp‐DTS(FBTTh₂)₂microwires.