Regulating Charge Transfer of Lattice Oxygen in Single-Atom-Doped Titania for Hydrogen Evolution

Single-atom catalysts have attracted much attention. Reported herein is that regulating charge transfer of lattice oxygen atoms in serial single-atom-doped titania enables tunable hydrogen evolution reaction (HER) activity. First-principles calculations disclose that the activity of lattice oxygen for the HER can be regularly promoted by substituting its nearest metal atom, and doping-induced charge transfer plays an essential role. Besides, the realm of the charge transfer of the active site can be enlarged to the second nearest atom by creating oxygen vacancies, resulting in further optimization for the HER. Various single-atom-doped titania nanosheets were fabricated to validate the proposed model. Taking advantage of the localized charge transfer to the lattice atom is demonstrated to be feasible for realizing precise regulation of the electronic structures and thus catalytic activity of the nanosheets.     

N−H Bond Formation at a Diiron Bridging Nitride

Despite their connection to ammonia synthesis, little is known about the ability of iron-bound, bridging nitrides to form N−H bonds. Herein we report a linear diiron bridging nitride complex supported by a redox-active macrocycle. The unique ability of the ligand scaffold to adapt to the geometric preference of the bridging species was found to facilitate the formation of N−H bonds via proton-coupled electron transfer to generate a μ-amide product. The structurally analogous μ-silyl- and μ-borylamide complexes were shown to form from the net insertion of the nitride into the E−H bonds (E=B, Si). Protonation of the parent bridging amide produced ammonia in high yield, and treatment of the nitride with PhSH was found to liberate NH₃ in high yield through a reaction that engages the redox-activity of the ligand during PCET.     

Single-Molecule Analysis Determines Isozymes of Human Alkaline Phosphatase in Serum

Alkaline phosphatase (ALP) is an important biomarker, as high levels of ALP in blood can indicate liver disease or bone disorders. However, current clinical blood tests only measure the total concentration of ALP but are unable to distinguish enzyme isotypes. Here, we demonstrate a novel and rapid approach to profile various ALP isozymes in blood via a single-molecule-analysis platform. The microarray platform provides enzyme kinetics of hundreds of individual molecules at high throughput. Using these single molecule kinetics, we characterize the different activity profiles of ALP isotypes. By analyzing both healthy and disease samples, we found the single molecule activity distribution of ALP in serum reflects the health status of patients. This result demonstrates the potential utility of the method for improving the conventional ALP test, as well as for analyzing other enzymatic biomarkers, including enzyme isotypes.     

Spatially Responsive Multicolor Lanthanide-MOF Heterostructures for Covert Photonic Barcodes

Micro/nanoscale photonic barcodes based on multicolor luminescent segmented heterojunctions hold potential for applications in information security. However, such multicolor heterojunctions reported thus far are exclusively based on static luminescent signals, thus restricting their application in advanced confidential information protection. Reported here is a strategy to design responsive photonic barcodes with heterobimetallic (Tb³⁺/Eu³⁺) metal—organic framework multicolor heterostructures. The spatial colors could be precisely controlled by thermally manipulating the energy-transfer process between the two lanthanides, thus achieving responsive covert photonic barcodes. Also demonstrated is that spatially resolved responsive barcodes with multi-responsive features could be created in a single heterostructure. These findings offer unique opportunities to purposely design highly integrated responsive microstructures and smart devices toward advanced anti-counterfeiting applications.     

A Fully Non-fused Ring Acceptor with Planar Backbone and Near-IR Absorption for High Performance Polymer Solar Cells

Fused-ring electron acceptors have made significant progress in recent years, while the development of fully non-fused ring acceptors has been unsatisfactory. Here, two fully non-fused ring acceptors, o-4TBC-2F and m-4TBC-2F, were designed and synthesized. By regulating the location of the hexyloxy chains, o-4TBC-2F formed planar backbones, while m-4TBC-2F displayed a twisted backbone. Additionally, the o-4TBC-2F film showed a markedly red-shifted absorption after thermal annealing, which indicated the formation of J-aggregates. For fabrication of organic solar cells (OSCs), PBDB-T was used as a donor and blended with the two acceptors. The o-4TBC-2F-based blend films displayed higher charge mobilities, lower energy loss and a higher power conversion efficiency (PCE). The optimized devices based on o-4TBC-2F gave a PCE of 10.26 %, which was much higher than those based on m-4TBC-2F at 2.63 %, and it is one of the highest reported PCE values for fully non-fused ring electron acceptors.     

Enantioselective Total Synthesis of (−)-Finerenone Using Asymmetric Transfer Hydrogenation

(−)-Finerenone is a nonsteroidal mineralocorticoid receptor antagonist currently in phase III clinical trials for the treatment of chronic kidney disease in type 2 diabetes. It contains an unusual dihydronaphthyridine core. We report a 6-step synthesis of (−)-finerenone, which features an enantioselective partial transfer hydrogenation of a naphthyridine using a chiral phosphoric acid catalyst with a Hantzsch ester. The process is complicated by the fact that the naphthyridine exists as a mixture of two atropisomers that react at different rates and with different selectivities. The intrinsic kinetic resolution was converted into a kinetic dynamic resolution at elevated temperature, which enabled us to obtain (−)-finerenone in both high yield and high enantioselectivity. DFT calculations have revealed the origin of selectivity.     

Toward universal substituent constants: Model chemistry sensitivity of descriptors from the quantum theory of atoms in molecules

The quantum theory of atoms in molecules (QTAIM) provides a theoretical foundation to determine the properties of functional groups through additive atomic contributions. Many studies have used QTAIM in their analyses with a variety of electronic structure methods, but it is unknown if the properties measured using one model chemistry, the combination of the electronic structure method and basis set, can be compared to those measured by another. Here, we evaluate the sensitivity of QTAIM functional group and bond critical point properties using six functionals and seven basis sets. High-level B2PLYPD3-BJ/aug-cc-pV5Z reference values are provided for 116 functional groups and the property sensitivity with respect to these values are evaluated based on absolute deviations and by assessing linear relationships. Functional group properties, including charges, dipoles, quadrupoles and volumes, were found to be mostly insensitive to choice of computational model chemistry. However, due to structural and topological inconsistencies, the 6-31G(d) basis set is not recommended for use. Bond critical point properties varied with choice of model chemistry, but models incorporating hybrid functionals and triple-ζ basis sets provided values suitable for use in regression studies.     

A density functional theory-time-dependent density functional theory investigation of photo-induced hydrogen bond and proton transfer for 2-(3,5-dichloro-2,6-dihydroxy-phenyl)-benzoxazole-6-carboxylicacid

Given the paramount importance of excited-state relaxation in the photochemical process, excited-state hydrogen bonding interactions and excited-state intramolecular proton transfer (ESIPT) are always hot topics. In this work, we theoretically explore the excited-state dynamical behaviors for a novel 2-(3,5-dichloro-2,6-dihydroxy-phenyl)-benzoxazole-6-carboxylicacid (DDPBC) system. As two intramolecular hydrogen bonds (O1 H2⋯N3 and O4 H5⋯O6) exist in the DDPBC structure, we first check if the double proton transfer form cannot be formed in the S1 state. Then, we explore the changes of geometrical parameters involved in hydrogen bonds, based on which we confirm that the dual intramolecular hydrogen bonds are strengthened on photo-excitation. The O1 H2⋯N3 hydrogen bond particularly plays a more important role in excited state. When it comes to the photo-induced excitation, we find charge transfer and electronic density redistribution around O1 H2 and N3 atom moieties. We verify the ESIPT tendency arising from the O1 H2⋯N3 hydrogen bond. In the analysis of the potential energy curves, along with O1 H2⋯N3 and O4 H5⋯O6, we demonstrate that the ESIPT reaction should occur along with O1 H2⋯N3 rather than O4 H5⋯O6. This work not only clarifies the specific ESIPT mechanism for DDPBC system but also paves the way for further novel applications based on DDPBC structure in the future.     

Intramolecular proton transfer in the isomerization of hydroxyacetone: Characterization based on reaction force analysis and the bond fragility spectrum

The mechanism of isomerization of hydroxyacetone to 2-hydroxypropanal is studied within the framework of reaction force analysis at the M06-2X/6-311++G(d,p) level of theory. Three unique pathways are considered: (a) a step-wise mechanism that proceeds through the formation of the Z-isomer of their shared enediol intermediate, (b) a step-wise mechanism that forms the E-isomer of the enediol, and (c) a concerted pathway that bypasses the enediol intermediate. Energy calculations show that the concerted pathway has the lowest activation energy barrier at 45.7 kcal mol⁻¹. The reaction force, chemical potential, and reaction electronic flux are calculated for each reaction to characterize electronic changes throughout the mechanism. The reaction force constant is calculated in order to investigate the synchronous/asynchronous nature of the concerted intramolecular proton transfers involved. Additional characterization of synchronicity is provided by calculating the bond fragility spectrum for each mechanism.