Porphyrin-Polyoxotungstate Molecular Hybrid as a Highly Efficient, Durable, Visible-Light-Responsive Photocatalyst for Aerobic Oxidation Reactions.

Organic-polyoxometalate (POM) hybrids have recently attracted considerable interest because of their distinctive properties and wide-ranging applications. For the construction of organic-POM hybrids, porphyrins are promising building units owing to their optical properties and reactivity, including strong visible-light absorption and subsequent singlet-oxygen (1O2*) generation. However, the practical utilization of porphyrins as photocatalysts and photosensitizers is often hindered by their own degradation by 1O2*. Therefore, there is a substantial demand for the development of porphyrin-derived photocatalysts with both high efficiency and durability. Herein, we present a porphyrin-polyoxotungstate molecular hybrid featuring a face-to-face stacked porphyrin dimer (I) fastened by four lacunary polyoxotungstates. Hybrid I exhibited remarkable efficiency and durability in photocatalytic aerobic oxidation reactions, and the selective oxidation of various dienes, alkenes, sulfides, and amines proceeded using just 0.003 mol % of the catalyst. Mechanistic investigations suggested that the high activity of I stems from the efficient generation of 1O2*, resulting from the heavy-atom effect of POMs. Furthermore, despite its high efficiency in 1O2* generation compared to free porphyrins, I exhibited superior durability against 1O2*-induced degradation under photoirradiation.

Chiroptical Response Inversion and Enhancement of Room-Temperature Exciton-Polaritons Using 2D Chirality in Perovskites.

Although chiral semiconductors have shown promising progress in direct circularly polarized light (CPL) detection and emission, they still face potential challenges. A chirality-switching mechanism or approach integrating two enantiomers is needed to discriminate the handedness of a given CPL; additionally, a large material volume is required for sufficient chiroptical interaction. These two requirements pose significant obstacles to the simplification and miniaturization of the devices. Here, room-temperature chiral polaritons fulfilling dual-handedness functions and exhibiting a more-than-two-order enhancement of the chiroptical signal are demonstrated, by embedding a 40 nm-thick perovskite film with a 2D chiroptical effect into a Fabry-Pérot cavity. By mixing chiral perovskites with different crystal structures, a pronounced 2D chiroptical effect is accomplished in the perovskite film, featured by an inverted chiroptical response for counter-propagating CPL. This inversion behavior matches the photonic handedness switch during CPL circulation in the Fabry-Pérot cavity, thus harvesting giant enhancement of the chiroptical response. Furthermore, affected by the unique quarter-wave-plate effects, the polariton emission achieves a chiral dissymmetry of ±4% (for the emission from the front and the back sides). The room-temperature polaritons with the strong dissymmetric chiroptical interaction shall have implications on a fundamental level and future on-chip applications for biomolecule analysis and quantum computing.

Better Peptides via Chemical Glycosylation: Somatostatin Analogues Having a Human Complex-Type N-Glycan with Improved Drug Properties.

Somatostatin (somatotropin release-inhibiting factor, SRIF) is a growth hormone inhibitory factor in the form of a 14- or 28-amino acid peptide. SRIF affects several physiological functions through its action on five distinct SRIF receptor subtypes (sst1-5). Native SRIF has only limited clinical applications due to its rapid degradation in plasma. To overcome this obstacle, we have developed glycosylated SRIF analogues that possess not only metabolic stability but also high affinity to all five receptor subtypes by attaching human complex-type oligosaccharides. Such glycosylated SRIF analogues with improved pharmacokinetic profiles could be potent and novel therapeutic drugs for SRIF-related diseases in which several SRIF receptor subtypes are closely involved, and also shed light on new indications. Our results show that chemical glycosylation can be a powerful tool for the development of peptide and protein analogues superior to the original molecules with enhanced drug properties.

Two-photon, red light uncaging of alkyl radicals from organorhodium(III) phthalocyanine complexes.

A stepwise two-photon, red light excitation of organorhodium(III) phthalocyanine complexes was found to induce the activation of the axial metal-carbon bond to generate alkyl radicals/aldehydes. The cooperative action of the photouncaging reaction and the photochemical generation of reactive oxygen species were indicated to induce the cell deaths.

Organic deliquescence: organic vapor-induced dissolution of molecular salts.

This report demonstrates organic vapor-induced dissolution of several molecular salts (i.e., organic deliquescence), like water vapor-induced deliquescence. Systematic experiments indicate that appropriate organic deliquescent responses to volatile organic compounds can be designed according to the principle, "like dissolves like". The phenomena will be useful for developing agents to collect various volatile organic compounds.

A Red-Light-Driven CO-Releasing Complex: Photoreactivities and Excited-State Dynamics of Highly Distorted Tricarbonyl Rhenium Phthalocyanines.

A complex comprising one [Re(CO)3 ]+ unit and a phthalocyanine (Pc) ligand (Re1 Pc) is shown to function as a photo-induced CO-releasing molecule (photoCORM) in the presence of O2 and a coordinative solvent under irradiation with red light, which can deeply penetrate living tissues. Transient absorption spectroscopic measurements indicate very short excited-state lifetimes and ultrafast intersystem crossing for Re1 Pc and Re2 Pc, which contains two [Re(CO)3 ]+ units. The excited-state properties are ascribed to efficient spin-orbit coupling and large Franck-Condon factors originating from the complexes' distorted structures, that is, unsymmetric coordination of [Re(CO)3 ]+ unit(s), one of which was confirmed by single-crystal X-ray analysis of a symmetrically substituted Pc with two [Re(CO)3 ]+ units. Re1 Pc represents a promising red-light-driven photoCORM that can be applied in biological environments or therapeutic applications.

Chiral Induction in Buckminsterfullerene Using a Metal-Organic Framework.

Chiral induction is an emerging topic of interest in various areas of chemistry because of its relationship to the elusive mechanism of spontaneous symmetry breaking in nature. Buckminsterfullerene (C60 ) with the shape of a highly symmetric truncated icosahedron has rarely been referred for chiral induction due to the difficult symmetry breaking. In this work, we demonstrate that a chiral metal-organic framework (MOF) can provide a key field for chiral induction. C60 could be incorporated into the chiral nanochannels of the MOF using an in situ self-assembly strategy. The circular dichroism spectra of the resulting nanocomposites showed an intense chiral signal in the absorption region of C60 . Experimental and theoretical studies showed that this unprecedented chiral induction of C60 was attributed to hybridization of the molecular orbitals through a close association with the pore surface of the MOF. Our method can endow highly symmetric achiral compounds with chirality, paving the new way toward fabrication of novel chiral nanomaterials.

A Newly Developed Aerosol Exposure Apparatus for Heated Tobacco Products for In Vivo Experiments Can Deliver Both Particles and Gas Phase With High Recovery and Depicts the Time-Dependent Variation in Nicotine Metabolites in Mouse Urine.

INTRODUCTION: There is no standardized aerosol exposure apparatus to deliver heated tobacco products (HTPs) for in vivo experiments. Therefore, we developed a novel HTPs aerosol exposure apparatus for mice and demonstrated that nicotine and other chemicals in HTPs aerosol generated by the apparatus can be delivered to mice which replicate human smoke. AIMS AND METHODS: The amounts of nicotine, tar, and carbon monoxide (CO) in IQOS (Marlboro Regular HeatSticks) aerosol generated by two types of apparatuses were determined. C57BL/6N mice were exposed to IQOS aerosol, followed by determination of the urinary nicotine metabolites. Further, the skin surface temperature of mice was monitored to confirm the vasoconstriction action of nicotine. RESULTS: The amount of chemicals in IQOS aerosol by the novel air push-in inhalation apparatus for HTPs (APIA) was equivalent to that of the analytical vaping machine (LM4E) (1.60 ± 0.08 [APIA] vs. 1.46 ± 0.07 mg/stick [LM4E] in nicotine and 0.55 ± 0.04 [APIA] vs. 0.45 ± 0.01 mg/stick [LM4E] in CO). After mice were exposed to IQOS aerosol by APIA, the urinary nicotine metabolite levels were determined; peak values in cotinine and 3-hydroxycotinine (3-HC) were 6.82 µg/mg creatinine at 1 hour after exposure and 32.9 µg/mg creatinine at 2 hours after exposure, respectively. The skin surface temperature decreased and was lower (33.5°C ± 0.5°C) at 30 minutes than before exposure (37.6°C ± 0.8°C). CONCLUSIONS: The new apparatus for HTPs aerosol exposure to mice showed good performances in terms of both chemical analysis of collected aerosol and fluctuations in the urinary nicotine metabolites. IMPLICATIONS: The APIA reported in this study can expose small animals to HTPs aerosol, including nicotine and other chemical substances as same amounts as LM4E and replicate actual human smoking process by in vivo experiments. Therefore, the experiments using APIA can provide evidence to assess the health risks of HTPs use.

Distorted Porphyrins with High Stability: Synthesis and Characteristic Electronic Properties of Mono- and Di-Nuclear Tricarbonyl Rhenium Tetraazaporphyrin Complexes.

Mono- and di-nuclear tricarbonyl Re(I) tetraazaporphyrin complexes (Re1 TAP and Re2 TAP) are investigated and compared with Re(I) phthalocyanine complexes (Re1 Pc and Re2 Pc). Although Re2 Pc is unstable in polar solvents, and easily undergoes demetallation reaction, the coordination of the TAP ligand significantly improves the tolerance toward polar solvents, affording more stability to Re2 TAP. Additionally, the incorporation of [Re(CO)3 ]+ unit(s) and the TAP ligand results in remarkable positive shifts in both oxidation and reduction potentials. Consequently, the more positive oxidation potentials of the ReTAP complexes significantly increase the tolerance toward oxidation, while the reduction potential indicates that Re2 TAP is suitable for a soluble electron acceptor. In contrast to Re1 Pc and Re2 Pc, Re1 TAP and Re2 TAP show unique broad Q bands, which can be attributed to the admixture of the π-π* and metal-to-ligand charge transfer characters, owing to the lowered π orbital energy in the TAP complexes. This study is useful for controlling electronic properties and realizing high stability in Pc analogues.

No evidence for genotoxicity in mice due to exposure to intermediate-frequency magnetic fields used for wireless power-transfer systems.

Time varying magnetic fields (MFs) are used for the wireless power-transfer (WPT) technology. Especially, 85 kHz band MFs, which are included in the intermediate frequency (IF) band (300 Hz - 10 MHz), are commonly used WPT system for charging electric vehicles. Those applications of WPT technology have elicited public concern about health effects of IF-MF. However, existing data from health risk assessments are insufficient and additional data are needed. We assessed the genotoxic effects of IF-MF exposure on erythroid differentiation in mice. A high-intensity IF-MF mouse exposure system was constructed to induce an average whole-body electric field of 54.1 V/m. Blood samples were obtained from male mice before and after a 2-week IF-MF exposure (1 h/day, total: 10 h); X-irradiated mice were used as positive controls. We analyzed the blood samples with the micronucleus (MN) test and the Pig-a mutation assay. No significant differences were seen between IF-MF-exposed and sham-exposed mice in the frequencies of either MN or Pig-a mutations in mature erythrocytes and reticulocytes. IF-MF exposure did not induce genotoxicity in vivo under the study conditions (2.36× the basic restriction for occupational exposure, 22.9 V/m, in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines). The absence of significant biological effects due to IF-MF exposure supports the practical application of this technology.

Vortex-Induced Harmonic Light Scattering of Porphyrin J-Aggregates.

An understanding of macroscopic vortex-induced chirality can provide insights into the origin of the homochirality of life. While circular dichroism measurements in stirred solutions are useful for the analysis of chiral supramolecular structures induced by vortex motion, there are no reports on the application of other spectroscopic methods. To obtain a deeper understanding of macroscopic vortex-induced chirality, it is essential to develop novel in situ spectroscopic methods that provide information about changes in both the size and chirality in stirred solutions. Here, we report the first observation by harmonic light scattering of the mirror-symmetry-breaking process of porphyrin J-aggregates under the rotation of a magnetic stirrer. The chiral supramolecular structure observed during stirring is likely due to the formation of a chiral aggregate that consists of porphyrin J-aggregates. The dissociation of the structure proceeds in two steps (a fast step and a slow step), as indicated by the signal decay rate when stirring was stopped. This novel method is useful for analyzing the supramolecular structural changes of chiral aggregates induced by external stimuli.

Recurrent Cerebral Venous Thrombosis Treated with Direct Oral Anticoagulants in a Japanese Man with Hereditary Protein C Deficiency.

We herein report a case involving a 32-year-old Japanese man with recurrent cerebral venous thrombosis due to hereditary protein C deficiency. He was admitted to our hospital with impaired consciousness. Brain magnetic resonance imaging demonstrated high intensities diffusely along the bilateral sulci and magnetic resonance venography revealed left transverse sinus and superior sagittal sinus stenoses. His father had a history of cerebral infarction and venous thrombosis. The protein C activity level examined by chromogenic synthetic substrate assay was markedly reduced. He was diagnosed with protein C deficiency, and a genetic analysis revealed a heterozygous mutation at exon 3 c.199G>A,p.Glu67Lys on the protein C gene. Four months later, at his second admission, he had transient aphasia, and his protein C activity was under 10%. We switched warfarin to the direct oral anticoagulants edoxaban. He remains fully recovered with no adverse events after the administration of edoxaban for a year. Direct oral anticoagulants may be a new tool for treating cerebral venous thrombosis due to hereditary protein C deficiency.

Novel method for preparing stable near-infrared absorbers: a new phthalocyanine family based on rhenium(i) complexes.

Rational design of near-infrared (NIR) absorbing molecules is crucial for developing photofunctional materials. Here, we synthesized dinuclear and mononuclear Re(i) tricarbonyl phthalocyanine complexes that exhibit a sharp intense Q band in the NIR region. The unsymmetric coordination of electron-deficient metal unit(s) concomitantly produced a remarkable red shift of the Q band and improved the tolerance of the phthalocyanine ring to oxidation. This study presents a simple and effective strategy for the construction of NIR absorbers with high stability.

Direct Observation of the S0 → T2 Transition in Phosphorescent Platinum(II) Octaethylporphyrin, Evidenced by Magnetic Circular Dichroism.

In recent years, the importance of analyzing excited triplet states has increased dramatically because of their relevance in the design and development of photofunctional molecules. Since the second lowest excited triplet (T2) state plays an important role in enhancing the nonradiative intersystem crossing (ISC) process from the lowest excited singlet (S1) state to the lowest excited triplet (T1) state, it is strongly desired to develop direct observation methods for the nonluminescent, short-lived T2 state. In this study, the excited triplet states of platinum(II) octaethylporphyrin (PtOEP), which was used as the first phosphorescent organic light emitting diode and oxygen sensor, are investigated using UV-vis absorption, magnetic circular dichroism, and phosphorescence spectroscopies. At low temperature, in highly concentrated solutions, we observe a distinct Faraday A term for the S0 → T1 transition, as well as for the S0 → T2 transition. The novel spectroscopic methodology applied allows resolution of the excited-state properties of a wide variety of molecular systems.

Recent advances in studies on the magneto-chiral dichroism of organic compounds.

Magneto-chiral dichroism (MChD) is an interesting phenomenon in which the absorbance of a chiral molecule depends on the direction of the magnetic field. As the MChD of two enantiomers is opposite in nature, MChD has received considerable attention for the development of magneto-optical devices and new asymmetric synthetic methods, as well as being an explanation for the origin of the homochirality of life. In this perspective, the theoretical background behind MChD is introduced, and then, the first examples of metal complexes and aromatic π-conjugated systems are discussed. Furthermore, the electronic properties of aromatic π-conjugated systems, such as orbital angular momentum and exciton chirality, are theoretically explained, and the possibility of MChD-based photoresolutions is described.

Transcription of Chirality from Metal-Organic Framework to Polythiophene.

Here, we report an unprecedented chirality transfer from a metal-organic framework (MOF) to a polymer. In this work, unsubstituted polythiophene (PTh) was prepared in the nanochannels of a chiral MOF. Circular dichroism spectroscopy revealed that nanoconfinement of the polymer chains could endow optically inactive PTh with a chiral nature. The thickness of polymer chain assemblies could be controlled by tuning the loading amount of PTh, which resulted in a drastic change in the chiroptical properties. Note that PTh liberated from the host still exhibited chirality even without the chiral support. Remarkably, the recovered PTh presented high thermal stability of chirality up to 250 °C. Our findings show that the encapsulation of the polymer chains in chiral MOFs is a simple and effective methodology not only to express the chirality of polymers but also to elucidate the inter- and intrachain chirality in polymer assemblies.

Chiral Supramolecular Nanoarchitectures from Macroscopic Mechanical Rotations: Effects on Enantioselective Aggregation Behavior of Phthalocyanines.

Fluid dynamics, resulting from the macroscopic mechanical rotation of either a rotary evaporator or a magnetic stirrer, has been shown to selectively induce one of two enantiomers (mirror-image structures) in certain nanoscale supramolecules. As an alternative to giving a chiral twist to synthesized supramolecules or polymers, it is a challenge to reproducibly prepare chiral species by only using macroscopic mechanical rotations. Demonstrated here is a highly reproducible method for rotary-evaporation-induced enantioselective H-aggregation of achiral phthalocyanines. Chiral induction mechanisms are proposed by using the chiroptical-sign-based absolute structures. These results will provide insight to the origin of the homochirality of life, and serves as a pioneering study in a novel scientific field in terms of admixing nanoscale molecular chemistry and macroscopic fluid dynamics.

Differential oxidation processes of peroxiredoxin 2 dependent on the reaction with several peroxides in human red blood cells.

Peroxiredoxins (Prxs) detoxify hydrogen peroxide (H2O2), peroxynitrite, and various organic hydroperoxides. However, the differential oxidative status of Prxs reacted with each peroxide remains unclear. In the present study, we focused on the oxidative alteration of Prxs and demonstrated that, in human red blood cells (RBCs), peroxiredoxin 2 (Prx2) is readily reactive with H2O2, forming disulfide dimers, but was not easily hyperoxidized. In contrast, Prx2 was highly sensitive to the relatively hydrophobic oxidants, such as tert-butyl hydroperoxide (t-BHP) and cumene hydroperoxide. These peroxides hyperoxidized Prx2 into oxidatively damaged forms in RBCs. The t-BHP treatment formed hyperoxidized Prx2 in a dose-dependent manner. When organic hydroperoxide-treated RBC lysates were subjected to reverse-phase high performance liquid chromatography, two peaks derived from hyperoxidized Prx2 appeared along with the decrease of that corresponding to native Prx2. Liquid chromatography-tandem mass spectrometry analysis clearly showed that hyperoxidation to sulfonic acid (-SO3H) at Cys-51 residue was more advanced in a newfound hyperoxidized Prx2 compared to another hydrophobic hyperoxidized form previously identified. These results indicate that irreversible hyperoxidation of the Prx2 monomer in RBCs was easily caused by organic hydroperoxide but not H2O2. Thus, it is important to detect the hyperoxidation of Prx2 into sulfinic or sulfonic acid derivates of Cys-51 because hyperoxidized Prx2 is a potential marker of oxidative injury caused by organic hydroperoxides in human RBCs.

Molecular ground-state dissociation in the condensed phase employing plasmonic field enhancement of chirped mid-infrared pulses.

Selective bond cleavage via vibrational excitation is the key to active control over molecular reactions. Despite its great potential, the practical implementation in condensed phases have been hampered to date by poor excitation efficiency due to fast vibrational relaxation. Here we demonstrate vibrationally mediated, condensed-phase molecular dissociation by employing intense plasmonic near-fields of temporally-shaped mid-infrared (mid-IR) pulses. Both down-chirping and substantial field enhancement contribute to efficient ladder climbing of the carbonyl stretch vibration of W(CO)6 in n-hexane solution and to the resulting CO dissociation. We observe an absorption band emerging with laser irradiation at the excitation beam area, which indicates that the dissociation is followed by adsorption onto metal surfaces. This successful demonstration proves that the combination of ultrafast optics and nano-plasmonics in the mid-IR range is useful for mode-selective vibrational ladder climbing, paving the way toward controlled ground-state chemistry.

Global Analysis of Transcriptional Expression in Mice Exposed to Intermediate Frequency Magnetic Fields Utilized for Wireless Power Transfer Systems.

BACKGROUND: Intermediate frequency magnetic fields (IF-MFs) at around 85 kHz are a component of wireless power transfer systems used for charging electrical vehicles. However, limited data exist on the potential health effects of IF-MFs. We performed a comprehensive analysis of transcriptional expression in mice after IF-MF exposure. MATERIALS AND METHODS: We developed an IF-MF exposure system to generate a high magnetic flux density (25.3 mT). The system can expose the IF-MF for a mouse whole-body without considering thermal effects. After 10 days (1 h/day) of exposure, a comprehensive expression analysis was performed using microarray data from both the brain and liver. RESULTS: No significant differences in transcriptional expression were detected in the 35,240 probe-sets when controlling the false discovery rate (FDR) under a fold change cutoff >1.5. However, several differential expressions were detected without FDR-adjustment, but these were not confirmed by RT-PCR analysis. CONCLUSIONS: To our knowledge, this is the first in vivo study to evaluate the biological effects of IF-MF exposure with an intense magnetic flux density 253 times higher than the occupational restriction level defined by the International Commission on Non-Ionizing Radiation Protection guidelines. However, our findings indicate that transcriptional responses in the living body are not affected under these conditions.