Functional molecular models of photosynthesis.

This perspective focuses on functional models of photosynthesis to achieve molecular photocatalytic systems that mimic photosystems I and II (PSI and PSII). A long-lived and high-energy electron-transfer state of 9-mesityl-10-methylacridinium ion (Acr-Mes) has been attained as a simple and useful model of the photosynthetic reaction center. Acr-Mes has been used as an effective photoredox catalyst for photocatalytic hydrogen evolution and regioselective reduction of NAD(P) from plastoquinone analogs as a molecular functional model of PSI.

Identification, Characterization, and Electronic Structures of Interconvertible Cobalt-Oxygen TAML Intermediates.

The reaction of Li[(TAML)Co]·3HO (TAML = tetraamido macrocyclic tetraanionic ligand) with iodosylbenzene at 253 K in acetone in the presence of redox-innocent metal ions (Sc(OTf) and Y(OTf)) or triflic acid affords a blue species , which is converted reversibly to a green species upon cooling to 193 K. The electronic structures of and have been determined by combining advanced spectroscopic techniques (X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), X-ray absorption spectroscopy/extended X-ray absorption fine structure (XAS/EXAFS), and magnetic circular dichroism (MCD)) with theoretical studies. Complex is best represented as an = 1/2 [(Sol)(TAML)Co---OH(LA)] species (LA = Lewis/Brønsted acid and Sol = solvent), where an = 1 Co(III) center is antiferromagnetically coupled to = 1/2 TAML, which represents a one-electron oxidized TAML ligand.

Thermal stability analysis of nitrile additives in LiFSI for lithium-ion batteries: An accelerating rate calorimetry study.

Although lithium-ion batteries (LIBs) are extensively used as secondary storage energy devices, they also pose a significant fire and explosion hazard. Subsequently, thermal stability studies for LiPF- and LiFSI-type electrolytes have been conducted extensively. However, the thermal characteristics of these electrolytes with thermally stable additives in a full cell assembly have yet to be explored.

Artificial Photosynthesis for Regioselective Reduction of NAD(P) to NAD(P)H Using Water as an Electron and Proton Source.

In photosynthesis, four electrons and four protons taken from water in photosystem II (PSII) are used to reduce NAD(P) to produce NAD(P)H in photosystem I (PSI), which is the most important reductant to reduce CO. Despite extensive efforts to mimic photosynthesis, artificial photosynthesis to produce NAD(P)H using water electron and proton sources has yet to be achieved. Herein, we report the photocatalytic reduction of NAD(P) to NAD(P)H and its analogues in a molecular model of PSI, which is combined with water oxidation in a molecular model of PSII.

Electronic Structure and Reactivity of Mononuclear Nonheme Iron-Peroxo Complexes as a Biomimetic Model of Rieske Oxygenases: Ring Size Effects of Macrocyclic Ligands.

We report the macrocyclic ring size-electronic structure-electrophilic reactivity correlation of mononuclear nonheme iron(III)-peroxo complexes bearing -tetramethylated cyclam analogues (-TMC), [Fe(O)(12-TMC)] (), [Fe(O)(13-TMC)] (), and [Fe(O)(14-TMC)] (), as a model study of Rieske oxygenases. The Fe(III)-peroxo complexes show the same δ and pseudo-σ bonds between iron and the peroxo ligand. However, the strength of these interactions varies depending on the ring size of the -TMC ligands; the overall Fe-O bond strength and the strength of the Fe-O δ bond increase gradually as the ring size of the -TMC ligands becomes smaller, such as from 14-TMC to 13-TMC to 12-TMC.

Mononuclear Non-Heme Manganese-Catalyzed Enantioselective -Dihydroxylation of Alkenes Modeling Rieske Dioxygenases.

The practical catalytic enantioselective -dihydroxylation of olefins that utilize earth-abundant first-row transition metal catalysts under environmentally friendly conditions is an important yet challenging task. Inspired by the -dihydroxylation reactions catalyzed by Rieske dioxygenases and non-heme iron models, we report the biologically inspired -dihydroxylation catalysis that employs an inexpensive and readily available mononuclear non-heme manganese complex bearing a tetradentate nitrogen-donor ligand and aqueous hydrogen peroxide (HO) and potassium peroxymonosulfate (KHSO) as terminal oxidants. A wide range of olefins are efficiently oxidized to enantioenriched -diols in practically useful yields with excellent -dihydroxylation selectivity and enantioselectivity (up to 99% ee).

Network and Computational Drug Repurposing Analysis for c-Myc Inhibition in Burkitt Lymphoma.

Background/aim: The treatment rate of Burkitt lymphoma (BL) is still low in low-income countries and among elderly patients. The c-Myc dysregulation induced by mutations is one of the characteristics of BL. However, studies on the downstream signaling pathways of c-Myc are still lacking.

Generation, Spectroscopic Characterization, and Computational Analysis of a Six-Coordinate Cobalt(III)-Imidyl Complex with an Unusual = 3/2 Ground State that Promotes N-Group and Hydrogen Atom-Transfer Reactions with Exogenous Substrates.

We report the synthesis and characterization of a mononuclear nonheme cobalt(III)-imidyl complex, [Co(NTs)(TQA)(OTf)] (), with an = 3/2 spin state that is capable of facilitating exogenous substrate modifications. Complex was generated from the reaction of Co(TQA)(OTf) with PhINTs at -20 °C. A flow setup with ESI-MS detection was used to explore the kinetics of the formation, stability, and degradation pathway of in solution by treating the Co(II) precursor with PhINTs.

A dual stimuli-responsive smart soft carrier using multi-material 4D printing.

This paper proposes a 4D printed smart soft carrier with a hemispherical hollow and openable lid. The soft carrier is composed of a lid with a slot (with a shape of 4 legs), a border, and a hemisphere. The soft carrier is fabricated by 4D printing using smart hydrogels.

The elusive active species in nickel(II)-mediated oxidations of hydrocarbons by peracids: a Ni-oxyl species, an aroyloxy radical, or a Ni-peracid complex?

Nonheme nickel(II)-mediated oxidations of hydrocarbons by -chloroperbenzoic acid (CPBA) show promising activity and selectivity; however, the active species and the reaction mechanism of these reactions are still elusive after decades of efforts. Herein, a novel free radical chain mechanism of the Ni(II)-mediated oxidation of cyclohexane by CPBA is investigated using density functional theory calculations. In this study, we rule out the involvement of a long speculated Ni-oxyl species.

Redox catalysis photoinduced electron transfer.

This perspective article highlights redox catalysis of organic and inorganic molecules photoinduced electron transfer, which is well exploited for a number of important photoredox reactions including hydrogen evolution, water oxidation and a number of synthetic applications. Organic and inorganic photoredox catalysis is also combined with thermal transition metal redox catalysis to achieve overall photocatalytic redox reactions, which would otherwise not be possible by using photoredox catalysis or thermal redox catalysis alone. Both thermodynamic and kinetic data are discussed to understand the photoinduced electron-transfer processes of organic and inorganic photoredox catalysts in the light of the Marcus theory of electron transfer, providing a comprehensive and valuable guide for employing organic and inorganic redox catalysts photoinduced electron transfer.

A Manganese Compound I Model with a High Reactivity in the Oxidation of Organic Substrates and Water.

A high-valent manganese(IV)-hydroxo porphyrin π-cation radical complex, [Mn(IV)(OH)(Porp)(X)], was synthesized and characterized spectroscopically. The Mn porphyrin intermediate was highly reactive in alkane hydroxylation and oxygen atom transfer reactions. More importantly, the Mn porphyrin intermediate reacted with water at a fast rate, resulting in the dioxygen evolution.

High-sensitivity NH gas sensor using pristine graphene doped with CuO nanoparticles.

A highly sensitive and selective NH gas sensor was developed based on single-layer pristine graphene doped with copper(II) oxide (CuO) nanoparticles of a specific size. High-quality single-layer graphene was grown using chemical vapor deposition. Approximately 15 nm-sized CuO colloidal nanoparticles were fabricated by a microwave-assisted thermal method using copper acetate as the precursor, and dimethylformamide as the reducing and stabilizing agent.

Thermal and Mechanical Characterization of Epoxy/Polyimide Blends via Postcuring Process.

In this study, the effects of polyimide (PI) content and postcuring on thermal and mechanical properties in PI and epoxy (EP) blending systems were investigated. EP/PI (EPI) blending reduced the crosslinking density and improved the flexural and impact strength due to ductility. On the other hand, in the postcuring of EPI, the thermal resistance improved due to the increased crosslinking density and the flexural strength increased by up to 57.

Use of Singlet Oxygen in the Generation of a Mononuclear Nonheme Iron(IV)-Oxo Complex.

Nonheme iron(III)-superoxo intermediates are generated in the activation of dioxygen (O) by nonheme iron(II) complexes and then converted to iron(IV)-oxo species by reacting with hydrogen donor substrates with relatively weak C-H bonds. If singlet oxygen (O) with ca. 1 eV higher energy than the ground state triplet oxygen (O) is employed, iron(IV)-oxo complexes can be synthesized using hydrogen donor substrates with much stronger C-H bonds.

Hydrogen Bonding-Assisted and Nonheme Manganese-Catalyzed Remote Hydroxylation of C-H Bonds in Nitrogen-Containing Molecules.

The development of catalytic systems capable of oxygenating unactivated C-H bonds with excellent site-selectivity and functional group tolerance under mild conditions remains a challenge. Inspired by the secondary coordination sphere (SCS) hydrogen bonding in metallooxygenases, reported herein is an SCS solvent hydrogen bonding strategy that employs 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a strong hydrogen bond donor solvent to enable remote C-H hydroxylation in the presence of basic aza-heteroaromatic rings with a low loading of a readily available and inexpensive manganese complex as a catalyst and hydrogen peroxide as a terminal oxidant. We demonstrate that this strategy represents a promising compliment to the current state-of-the-art protection approaches that rely on precomplexation with strong Lewis and/or Brønsted acids.

Seeing the -Dihydroxylating Intermediate: A Mononuclear Nonheme Iron-Peroxo Complex in -Dihydroxylation Reactions Modeling Rieske Dioxygenases.

The nature of reactive intermediates and the mechanism of the -dihydroxylation of arenes and olefins by Rieske dioxygenases and synthetic nonheme iron catalysts have been the topic of intense research over the past several decades. In this study, we report that a spectroscopically well characterized mononuclear nonheme iron(III)-peroxo complex reacts with olefins and naphthalene derivatives, yielding iron(III) cycloadducts that are isolated and characterized structurally and spectroscopically. Kinetics and product analysis reveal that the nonheme iron(III)-peroxo complex is a nucleophile that reacts with olefins and naphthalenes to yield -diol products.

Preparation and Characterization of a Formally Ni-Oxo Complex with a Triplet Ground State and Application in Oxidation Reactions.

High-valent first-row transition-metal-oxo complexes are important intermediates in biologically and chemically relevant oxidative transformations of organic molecules and in the water splitting reaction in (artificial) photosynthesis. While high-valent Fe- and Mn-oxo complexes have been characterized in detail, much less is known about their analogues with late transition metals. In this study, we present the synthesis and detailed characterization of a unique mononuclear terminal Ni-O complex.

A Contrasting Effect of Acid in Electron Transfer, Oxygen Atom Transfer, and Hydrogen Atom Transfer Reactions of a Nickel(III) Complex.

There have been many examples of the accelerating effects of acids in electron transfer (ET), oxygen atom transfer (OAT), and hydrogen atom transfer (HAT) reactions. Herein, we report a contrasting effect of acids in the ET, OAT, and HAT reactions of a nickel(III) complex, [Ni(PaPy*)] () in acetone/CHCN (v/v 19:1). was synthesized by reacting [Ni(PaPy*)] () with magic blue or iodosylbenzene in the absence or presence of triflic acid (HOTf), respectively.

Dendrite Suppression by Lithium-Ion Redistribution and Lithium Wetting of Lithium Zeolite Li(AlSiO) in Liquid Electrolytes.

Lithium metal is considered a next-generation anode material for high-voltage, high-energy-density batteries; however, its commercialization is limited because of dendrite formation during charging, which leads to short-circuiting and fire. Li metal is coated with a lithium zeolite Li(AlSiO) (bikitaite - BKT) for dendrite suppression. The BKT-coated Li metal anode exhibits enhanced cycle performance for both Li/LMO (over 982 cycles) and Li/Li cells (over 2000 h at 0.

Triphenyl phosphate activates estrogen receptor α/NF-κB/ cyclin D1 signaling to stimulate cell cycle progression in human Ishikawa endometrial cancer cells.

Objective: Triphenyl phosphate (TPHP) is one of the most commonly used organophosphorus flame retardants that may accumulate in the environment. However, its effects on human reproductive organs have not been well studied. We aimed to investigate the in vitro effects of TPHP in human Ishikawa endometrial cancer cells to elucidate how TPHP exposure disrupts intracellular signaling and cell proliferation in reproductive tissues.

Comparison of pharmacologic therapies alone versus operative techniques in combination with pharmacologic therapies for postoperative analgesia in patients undergoing laparoscopic cholecystectomy: A randomized controlled trial.

Background: Laparoscopic cholecystectomy (LC) causes moderate pain. Various operative analgesic techniques and pharmacologic treatments can reduce postoperative pain. This single-center, single-surgeon randomized controlled study aimed to assess the efficacy of combined operative analgesic techniques and pharmacologic analgesia in decreasing pain in patients undergoing LC.