Method to determine quadruple points of a two-component system containing a simple hydrate phase and behavior of the system near these points

A method for determining quadruple points of a two-component system containing a simple hydrate phase is proposed. This method utilizes the quasi-static change of the system along three-phase equilibrium lines and was proved to be able to determine the quadruple points as accurately as the conventional method. By using this method, even though some preparation is necessary, a quadruple point can be determined in just a single experimental run. The behavior of the system near the quadruple points was also examined experimentally, for both the quasi-static and the irreversible change cases. At the quadruple points, the temperature and pressure of the system were kept constant for a while, as at the triple point of water. In both cases, the representative point of the state of the system passed through the quadruple point on a p–T diagram.     

Surface-Degenerate Semiconductor Photocatalysis for Efficient Water Splitting without Sacrificial Agents via a Reticular Chemistry Approach

The production of green hydrogen through photocatalytic water splitting is crucial for a sustainable hydrogen economy and chemical manufacturing. However, current approaches suffer from slow hydrogen production (<70 μmol ⋅ g_cat⁻¹ ⋅ h⁻¹) due to the sluggish four-electrons oxygen evolution reaction (OER) and limited catalyst activity. Herein, we achieve efficient photocatalytic water splitting by exploiting a multifunctional interface between a nano-photocatalyst and metal–organic framework (MOF) layer. The functional interface plays two critical roles: (1) enriching electron density directly on photocatalyst surface to promote catalytic activity, and (2) delocalizing photogenerated holes into MOF to enhance OER. Our photocatalytic ensemble boosts hydrogen evolution by ≈100-fold over pristine photocatalyst and concurrently produces oxygen at ideal stoichiometric ratio, even without using sacrificial agents. Notably, this unique design attains superior hydrogen production (519 μmol ⋅ g_cat⁻¹ ⋅ h⁻¹) and apparent quantum efficiency up to 13-fold and 8-fold better than emerging photocatalytic designs utilizing hole scavengers. Comprehensive investigations underscore the vital role of the interfacial design in generating high-energy photoelectrons on surface-degenerate photocatalyst to thermodynamically drive hydrogen evolution, while leveraging the nanoporous MOF scaffold as an effective photohole sink to enhance OER. Our interfacial approach creates vast opportunities for designing next-generation, multifunctional photocatalytic ensembles using reticular chemistry with diverse energy and environmental applications.     

Testing the semi-explicit assembly model of aqueous solvation in the SAMPL4 challenge

Here, we test a method, called semi-explicit assembly (SEA), that computes the solvation free energies of molecules in water in the SAMPL4 blind test challenge. SEA was developed with the intention of being as accurate as explicit-solvent models, but much faster to compute. It is accurate because it uses pre-simulations of simple spheres in explicit solvent to obtain structural and thermodynamic quantities, and it is fast because it parses solute free energies into regionally additive quantities. SAMPL4 provided us the opportunity to make new tests of SEA. Our tests here lead us to the following conclusions: (1) The newest version, called Field-SEA, which gives improved predictions for highly charged ions, is shown here to perform as well as the earlier versions (dipolar and quadrupolar SEA) on this broad blind SAMPL4 test set. (2) We find that both the past and present SEA models give solvation free energies that are as accurate as TIP3P. (3) Using a new approach for force field parameter optimization, we developed improved hydroxyl parameters that ensure consistency with neat-solvent dielectric constants, and found that they led to improved solvation free energies for hydroxyl-containing compounds in SAMPL4. We also learned that these hydroxyl parameters are not just fixing solvent exposed oxygens in a general sense, and therefore do not improve predictions for carbonyl or carboxylic-acid groups. Other such functional groups will need their own independent optimizations for potential improvements. Overall, these tests in SAMPL4 indicate that SEA is an accurate, general and fast new approach to computing solvation free energies.     

Redox‐Driven Symmetry Change for Terbium(III) Bis(porphyrinato) Double‐Decker Complexes by the Azimuthal Rotation of the Porphyrin Macrocycles

Molecular structures for three oxidation forms (anion, radical, and cation) of terbium(III) bis(porphyrinato) double‐decker complexes have been systematically studied. We found that the redox state controls the azimuthal rotation angle (φ) between the two porphyrin macrocycles. For [Tb^III(tpp)₂]ⁿ (tpp: tetraphenylporphyrinato, n=?1, 0, and +1), φ decreases at each stage of the oxidation process. The decrease in φ is due to the higher steric repulsion between the phenyl rings on the porphyrin macrocycle and the β hydrogen atoms on the other porphyrin macrocycle, which results from the shorter interfacial distance between the two porphyrin macrocycles. Conversely, φ=45° for both [Tb^III(oep)₂]^?1 and [Tb^III(oep)₂]⁰ (oep: octaethylporphyrinato), but φ=36° for [Tb^III(oep)₂]⁺¹. Theoretical calculations suggest that the smaller azimuthal rotation angle of the cation form is due to the electronic interaction in the doubly oxidized ligand system.     

Direct Estimation of the Surface Location of Immobilized Functional Groups for Concerted Catalysis Using a Probe Molecule

The location of active sites during concerted catalysis by a metal complex and tertiary amine on a SiO₂ surface is discussed based on the interaction between the functionalized SiO₂ surface and a probe molecule, p‐formyl phenylboronic acid. The interactions of the probe molecule with the surface functionalities, diamine ligand, and tertiary amine, were analyzed by FT‐IR and solid‐state ¹³C and ¹¹B MAS NMR. For the catalyst exhibiting high 1,4‐addition activity, the diamine ligand and tertiary amine base exist in closer proximity than in the catalyst with low activity.     

Synthesis,Structure, Optical,and Electrochemical Properties of Triple‐ and Quadruple‐Decker Co‐facial Tetrathiafulvalene Arrays

Understanding the details of the electronic structure in face‐to‐face arranged tetrathiafulvalenes (TTFs) is very important for the design of supramolecular functional materials and superior conductive organic materials. This article is a comprehensive study of the interactions among columnar stacked TTFs using trimeric (trimer) and tetrameric (tetramer) TTFs linked by alkylenedithio groups (‐S(CH₂)_nS‐, n=1–4) as models of triple‐ and quadruple‐decker TTF arrays. Single‐crystal X‐ray analyses of neutral trimeric TTFs revealed that the three TTF moieties are oriented in a zigzag arrangement. Cyclic voltammetry measurements (CV) reveal that the trimer and tetramer exhibited diverse reversible redox processes with multi‐electron transfers, depending on the length of the ‐S(CH₂)_nS‐ units and substituents. The electronic spectra of the radical cations, prepared by electrochemical oxidation, showed charge resonance (CR) bands in the NIR/IR region (1630–1850 nm), attributed to a mixed valence (MV) state of the triple‐ and quadruple‐decker TTF arrays. In the trimeric systems, the dicationic state (+2; 0.66 cation per TTF unit) was found to be a stable state, whereas the monocationic state (+1) was not observed in the electronic spectra. In the tetrameric system, substituent‐dependent redox processes were observed. Moreover, π‐trimers and π‐tetramers, which show a significant Davydov blueshift in the spectra, are formed in the tricationic (trimer) and tetracationic (tetramer) state. In addition, these attractive interactions are strongly dependent on the length of the linkage unit.