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Tungsten disulfide nanotubes (WS 2 -NTs), with their cylindrical structure composed of rolled WS 2 sheets, have attracted much interest because of their unique physical properties reflecting quasi-one-dimensional chiral structures. They exhibit a semiconducting electronic structure regardless of their chirality, and various semiconducting and optoelectronic device applications have been demonstrated. The development of techniques to fabricate arrayed WS 2 -NTs is crucial to realizing the highest device performance. Since the discovery of WS 2 -NTs, various synthesis techniques have been reported; however, horizontally arrayed WS 2 -NTs have never been successfully synthesized. Here, we demonstrate a simple technique to synthesize arrayed WS 2 -NTs. Through precise temperature and gas control, W 18 O 49 nanowires are grown along the [1̅101] direction on an r-plane sapphire substrate, and the nanowires are converted into nanotubes via sulfurization under optimized conditions. The demonstrated synthesis technique for arrayed WS 2 -NTs will play a central role in the fabrication of devices using transition-metal dichalcogenide nanotubes.

Runt-related transcription factor (RUNX) proteins are considered to play various roles in cancer. Here, we evaluated the anticancer activity of Chb-M' , a compound that specifically and covalently binds to the consensus sequence for RUNX family proteins, in p53 -mutated non-small cell lung cancer cells. Chb-M' killed the cancer cells by inducing apoptosis. The compound showed an anticancer effect comparable to that of the clinically used drugs alectinib and ceritinib in vivo. Notably, Chb-M' extended the cancer-free survival of mice after ending treatment more effectively than did the other two drugs. The results presented here suggest that Chb-M' is an attractive candidate as an anticancer drug applicable to the treatment of non-small cell lung cancer and various other types of cancers.

Triplet repeat diseases are caused by the abnormal elongation of repeated sequences comprising three bases. In particular, the elongation of CAG/CTG repeat sequences is thought to result in conditions such as Huntington's disease and myotonic dystrophy type 1. Although the causes of these diseases are known, fundamental treatments have not been established, and specific drugs are expected to be developed. Pyrrole imidazole polyamide (PIP) is a class of molecules that binds to the minor groove of the DNA duplex in a sequence-specific manner; because of this property, it shows promise in drug discovery applications. Earlier, it was reported that PIP designed to bind CAG/CTG repeat sequences suppresses the genes that cause triplet repeat diseases. In this study, we performed an X-ray crystal structure analysis of a complex of double-stranded DNA containing A-A mismatched base pairs and a cyclic-PIP that binds specifically to CAG/CTG sequences. Furthermore, the validity and characteristics of this structure were analyzed using in silico molecular modeling, ab initio energy calculations, gel electrophoresis, and surface plasmon resonance. With our direct observation using atomic force microscopy and DNA origami, we revealed that the PIP caused structural changes in the DNA strands carrying the expanded CAG/CTG repeat. Overall, our study provides new insight into PIP from a structural perspective., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

A method for aromatic halogenation using a combination of elemental sulfur (S 8 ) and N -halosuccinimide has been developed. A catalytic quantity of elemental sulfur (S 8 ) with N -bromosuccinimide (NBS) and N -chlorosuccinimide (NCS) effectively halogenated less-reactive aromatic compounds, such as ester-, cyano-, and nitro-substituted anisole derivatives. No reaction occurred in the absence of S 8 , underscoring its crucial role in the catalytic activity. This catalytic system was also applicable to aromatic iodination with 1,3-diiodo-5,5-dimethylhydantoin.

The runt-related transcription factor (RUNX) family is known to play important roles in the progression of cancer. Conjugate 1 , which covalently binds to the RUNX-binding sequences, was reported to inhibit the binding of RUNX proteins to their target sites and suppress cancer growth. Here, we evaluated the anticancer effects of 1 and its analogs 2 - 4 against p53 -mutated PANC-1 pancreatic cancer cells. We found that they possessed different DNA-alkylating properties in vitro . And conjugates 1 - 3 were shown to have anticancer effects by inducing apoptosis in PANC-1 cells. Furthermore, conjugates 2 and 3 suppressed cancer growth in PANC-1 xenograft mice, with activity equivalent to a 50-fold dose of gemcitabine. Especially, 3 showed the highest alkylation efficiency, specificity, and better anticancer effects against pancreatic cancer than 1 in vivo without significant body weight loss. Our results revealed the potential of our compounds as new candidates for cancer therapy.

The coronavirus disease 2019 (COVID-19) pandemic has necessitated the development of antiviral agents against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). 3C-like protease (3CL pro ) is a promising target for COVID-19 treatment. Here, we report a new class of covalent inhibitors of 3CL pro that possess chlorofluoroacetamide (CFA) as a cysteine-reactive warhead. Based on an aza-peptide scaffold, we synthesized a series of CFA derivatives in enantiopure form and evaluated their biochemical efficiency. The data revealed that 8a ( YH-6 ) with the R configuration at the CFA unit strongly blocks SARS-CoV-2 replication in infected cells, and its potency is comparable to that of nirmatrelvir. X-ray structural analysis showed that YH-6 formed a covalent bond with Cys145 at the catalytic center of 3CL pro . The strong antiviral activity and favorable pharmacokinetic properties of YH-6 suggest its potential as a lead compound for the treatment of COVID-19.

Monoamine oxidase B (MAO-B) metabolizes monoamines such as dopamine regarding neural transmission and controls its level in the mammalian's brain. When MAO-B metabolizes dopamine abnormally, normal neurotransmission does not occur, and central nervous system disorders such as Parkinson's disease may develop. Although several MAO inhibitors have been developed, most of them have no selectivity between monoamine oxidase A (MAO-A) and MAO-B, or they work irreversibly against the enzyme. This report describes the first case of screening of N -arylated heliamine derivatives to develop novel MAO-B selective inhibitors that can be synthesized concisely by microwave-assisted Pd nanoparticle-catalyzed Buchwald-Hartwig amination. We discovered that the derivatives 4h , 4i , and 4j display inhibitory activity against MAO-B with IC 50 values of 1.55, 13.5, and 5.08 μM, respectively., Competing Interests: The authors declare no competing financial interest., (© 2022 American Chemical Society.)

The optical near field refers to a localized light field near a surface that can induce photochemical phenomena such as dipole-forbidden transitions. Recently, the photodissociation of the S-S bond of dimethyl disulfide (DMDS) was investigated using a scanning tunneling microscope with far- and near-field light. This reaction is thought to be initiated by the lowest-energy highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) transition of the DMDS molecule under far-field light. In near-field light, photodissociation proceeds at lower photon energies than in far-field light. To gain insight into the underlying mechanism, we theoretically investigated the excited states of DMDS adsorbed on Cu and Ag surfaces modeled by a tetrahedral 20-atom cluster. The frontier orbitals of the molecule were delocalized by the interaction with the metal, resulting in narrowing of the HOMO-LUMO gap energy. The excited-state distribution was analyzed using the Mulliken population analysis, decomposing molecular orbitals into metal and DMDS fragments. The excited states of the intra-DMDS transitions were found over a wider energy range, but at low energies, their oscillator strengths were negligible, which is consistent with the experimental results. Sparse modeling analysis showed that typical electronic transitions differed between the higher and lower excited states. If these low-lying excited states are efficiently excited by near-field light with different selection rules, the S-S bond dissociation reaction can proceed.

Cyanobacteriochromes (CBCRs) belong to the phytochrome superfamily of photoreceptors, the members of which utilize a linear tetrapyrrole (bilin) as a chromophore. RcaE is a representative member of a green/red-type CBCR subfamily that photoconverts between a green-absorbing dark state and red-absorbing photoproduct (Pr). Our recent crystallographic study showed that the phycocyanobilin (PCB) chromophore of RcaE adopts a unique C15- E , syn configuration in the Pr state, unlike the typical C15- E , anti configuration for the phytochromes and other CBCRs. Here, we measured Raman spectra of the Pr state of RcaE with 1064 nm excitation and explored the structure of PCB and its interacting residues under physiologically relevant aqueous conditions. We also performed measurements of RcaE in D 2 O as well as the sample reconstituted with the PCB labeled with 15 N or with both 13 C and 15 N. The observed Raman spectra were analyzed by quantum mechanics/molecular mechanics (QM/MM) calculations together with molecular dynamics simulations. The Raman spectra and their isotope effects were well-reproduced by the simulated spectra of fully protonated PCB with the C15- E , syn configuration and allowed us to assign most of the observed bands. The present vibrational analysis of the all syn bilin chromophore using the QM/MM method will advance future studies on CBCRs and the related proteins by vibrational spectroscopy.

Ta 3 N 5 is a promising semiconductor photocatalyst which can generate H 2 gas from water under visible light illumination. It is expected that Ta 3 N 5 exhibits a strong anisotropy in its physical properties stemming from its highly anisotropic crystal structure. However, such anisotropic properties have not been verified experimentally due to the difficulty in synthesizing a large single crystal. Here, we report the synthesis of (010)-oriented Ta 3 N 5 single-crystalline thin films by solid phase epitaxy on the (110) plane of perovskite LaAlO 3 substrates. The obtained epitaxial thin films of Ta 3 N 5 exhibited clear optical anisotropy (pleochroism) as predicted by previous first-principles calculations. The optical gap for E ||[100] polarization (∼2.12 eV) was smaller than that for E ||[100] polarization (∼2.27 eV).

b-Series gangliosides are abundant in central nervous tissues and are involved in important nerve processes. However, their functions are complicated because of their properties of forming dynamic domains in cell plasma membranes (PMs), called lipid rafts. In this study, we aim to develop fluorescently labeled b-series gangliosides that are useful for single-molecule imaging. The chemical synthesis of fluorescent GD3 and GQ1b was achieved using sialylation and ganglioside synthetic methods previously developed by our group. Furthermore, biophysical evaluations demonstrated that synthesized fluorescent GD3 and GQ1b behaved as raft molecules on cell PMs, suggesting their applicability to the study of raft-associated interactions.

A portable chemical analysis system for monitoring ambient carbonyl sulfide (COS) was investigated for the first time. COS is paid attention to from the perspectives of photosynthesis tracer, breath diagnosis marker, and new process-use in the manufacture of semiconductors. Recently, the threshold level value of COS was settled at 5 ppm in volume ratio (ppmv) for workplace safety management. In this work, COS was converted to H 2 S by a small column packed with alumina catalyzer at 65 °C. Then, the H 2 S produced was collected in a small channel scrubber to react with fluorescein mercuric acetate (FMA), and the resulting fluorescence quenching was monitored using an LED/photodiode-based miniature detector. The miniature channel scrubber was re-examined to determine its robustness and easy fabrication, and conditions of the catalyzer were optimized. When the FMA concentration used was 1 μM, the limit of detection and dynamic range, which were both proportional to the FMA concentration, were 0.07 and 25 ppbv, respectively. Ambient COS in the background level and even contaminated COS in the nitrogen gas cylinder could be detected. If necessary, H 2 S was removed selectively by reproducible adsorbent columns. COS concentrations of engine exhaust were measured by the proposed method and by cryo-trap-gas chromatography-flame photometric detection, and the results obtained (0.5-5.9 ppbv) by the two methods agreed well ( R 2 = 0.945, n = 19). COS in ambient air and exhaust gases was successfully measured without any batchwise pretreatment., Competing Interests: The authors declare no competing financial interest.

Elucidation of the details of the associating mode is one of the major concerns for the precise design of DNA-binding molecules that are used for gene regulation. Pyrrole-imidazole polyamide (PIP) is a well-established synthetic DNA-binding molecule that has sequence-specificity for duplex DNA. By the design of the sequence of pyrrole, imidazole, and other synthetic units, PIP is bound to the target DNA sequence selectively. Here, we report the X-ray crystal structure of newly synthesized chiral cyclic PIP (cPIP) complexed with DNA at 1.5 Å resolution and reveal that cPIP binds in the reverse orientation in the DNA minor groove. Analysis of the crystal structure revealed that the positions of the hydrogen bonds between the bases and the pyrrole-imidazole moieties of cPIP were similar for both forward- and reverse-binding orientations and that the distortion of the B-form DNA structure caused by cPIP binding was also similar for both orientations. We further found that new hydrogen bonds formed between the amino groups on the γ-turn units and DNA at both ends of the cPIP molecule. Additionally, by comparing the reverse PIP orientation with the forward orientation, we could clarify that the cause of the preference toward the reverse orientation in the S -form cPIP as used in this study is the overall conformation of the cPIP-DNA complex, particularly the configuration of hydrogen bonds. These results thus provide an explanation for the different stereoselectivity of cPIP binding in the minor groove.

Perovskite oxynitrides have been studied with regard to their visible light-driven photocatalytic activity and novel electronic functionalities. The assessment of the intrinsic physical and/or electrochemical properties of oxynitrides requires the epitaxial growth of single-crystalline films. However, the heteroepitaxy of perovskite oxynitrides has not yet matured compared to the progress realized in work with perovskite oxides. Herein, we report the heteroepitaxial growth of CaTaO 2 N thin films with (100) pc , (110) pc , and (111) pc crystallographic surface orientations (where the subscript pc denotes a pseudocubic cell) on SrTiO 3 substrates using reactive radio frequency magnetron sputtering, along with investigations of crystallinity and surface morphology. Irrespective of surface orientation, stoichiometric CaTaO 2 N epitaxial thin films were grown coherently on SrTiO 3 substrates and showed clear step and terrace surfaces in the case of low values of film thickness of approximately 20 nm. A (110) pc -oriented film was also more highly crystalline than (100) pc - and (111) pc -oriented specimens. This relationship between crystallinity and surface orientation is ascribed to the number of inequivalent in-plane rotational domains, which stems from the symmetry mismatch between the orthorhombic CaTaO 2 N and cubic SrTiO 3 . A CaTaO 2 N thin film grown on a lattice- and symmetry-matched orthorhombic DyScO 3 substrate exhibited a significant crystallinity and a clear step and terrace surface even though the film was thick (∼190 nm). These results are expected to assist in developing the heteroepitaxial growth of high-quality perovskite oxynitride thin films., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Small extracellular vesicles (sEVs) are reliable biomarkers for early cancer detection; however, conventional detection methods such as immune-based assays and microRNA analyses are not very sensitive and require sample pretreatments and long analysis time. Here, we developed a molecular imprinting-based dynamic molding approach to fabricate antibody-conjugated signaling nanocavities capable of size recognition. This enabled the establishment of an easy-to-use, rapid, sensitive, pretreatment-free, and noninvasive sEV detection platform for efficient sEV detection-based cancer diagnosis. An apparent dissociation constant was estimated to be 2.4 × 10 -16 M, which was ∼1000 times higher than that of commercial immunoassays (analysis time, 5 min/sample). We successfully used tears for the first time to detect cancer-related intact sEVs, clearly differentiating between healthy donors and breast cancer patients, as well as between samples collected before and after total mastectomy. Our nanoprocessing strategy can be easily repurposed for the specific detection of other types of cancer by changing the conjugated antibodies, thereby facilitating the establishment of liquid biopsy for early cancer diagnosis.

Pyrrole-imidazole polyamides (PIPs) bind to predetermined double-stranded DNA sequences and selectively target a large variety of DNA sequences. Although the forward-binding (5'-3'/N-C) orientation, in which the N-terminus of PIPs faces the 5'-terminus of DNAs, is considered to be the main binding manner of PIPs, a reverse-binding (5'-3'/C-N) orientation, in which the C-terminus of PIPs faces the 3'-terminus of DNAs, sometimes causes unintended binding. Here, we synthesized optical or structural isomers of previously reported cyclic PIPs (cPIPs), which differ in the position of the amino groups in the γ-turn units, and we investigated their binding affinities both in the forward- and reverse-binding orientation. We show that cPIPs with ( R )-α-amino-γ-turn units prefer the forward orientation as do hairpin PIPs. More importantly, we document for the first time the remarkable reverse-binding preference of cPIPs with ( S )-α-amino-γ-turns. These results indicate that the orientation preference of cPIPs can be controlled by the position of the amino groups on the γ-turn units, which may markedly increase the number of DNA sequences that can be targeted by PIPs.

We developed a mild aromatic halogenation reaction using a combination of N-halosuccinimide and PhSSiMe 3 or PhSSPh. Less reactive aromatic compounds, such as methyl 4-methoxybenzoate, were brominated with PhSSiMe 3 or PhSSPh and N-bromosuccinimide in high yields. No reaction was observed in the absence of PhSSiMe 3 or PhSSPh. This method is also applicable to chlorination reactions using N-chlorosuccinimide and PhSSPh.

Phytochrome and cyanobacteriochrome utilize a linear methine-bridged tetrapyrrole (bilin) to control numerous biological processes. They show a reversible photoconversion between two spectrally distinct states. This photocycle is initiated by a C═C double-bond photoisomerization of the bilin followed by its thermal relaxations with transient and/or stationary changes in the protonation state of the pyrrole moiety. However, it has never been identified which of the four pyrrole nitrogen atoms is deprotonated. Here, we report a resonance Raman spectroscopic study on cyanobacteriochrome RcaE, which has been proposed to contain a deprotonated bilin for its green-absorbing 15 Z state. The observed Raman spectra were well reproduced by a simulated structure whose bilin B ring is deprotonated, with the aid of molecular dynamics and quantum mechanics/molecular mechanics calculations. The results revealed that the deprotonation of B and C rings has the distinct effect on the overall bilin structure, which will be relevant to the color tuning and photoconversion mechanisms of the phytochrome superfamily. Furthermore, this study documents the ability of vibrational spectroscopy combined with the advanced spectral analysis to visualize a proton of a cofactor molecule embedded in a protein moiety.

Pervoskite oxynitrides exhibit rich functionalities such as colossal magnetoresistance and high photocatalytic activity. The wide tunability of physical properties by the N/O ratio makes perovskite oxynitrides promising as optical and electrical materials. However, composition-dependent variation of the band structure, especially under partially substituted composition, is not yet well understood. In this study, we quantitatively analyzed the composition-dependent variation of band structure of a series of SrNbO 3- x N x (0 ≤ x ≤ 1.02) epitaxial thin films. Electrical conductivity decreased along with the increase of N content x as a result of an increase in Nb valence from 4+ to 5+. Optical measurements revealed that the N 2p band is formed at a critical composition between 0.07 < x < 0.38, which induces charge-transfer transition (CTT) in the visible-light region. These variations in the band structure were explained by first-principles calculations. However, the CTT energy slightly increased at higher N contents (i.e., lower carrier density) on contrary to the expectation based on the rigid-band-like shift of the Fermi level, which suggests a complex combination of the following band-shifting effects induced by N-substitution: whereas (1) reduction of the Burstein-Moss effect causes CTT energy reduction, (2) enhancement of hybridization between Nb 4d and N 2p orbitals and/or (3) suppression of many-body effects enlarge the band gap energy at larger N content. The band structure variation in perovskite oxynitride as presently elucidated would be a guidepost for future material design.

A novel transformation reaction of methylene acetals, using a combination of trimethyl(phenylthio)silane (PhSTMS) and N-bromosuccinimide (NBS) under mild reaction conditions, is described. Various methylene acetals were converted to their corresponding bromoformates in good to high yields. Under the given conditions, the reaction proceeded via a radical pathway. Further transformation of bromoformates to their corresponding epoxides was achieved by treatment with NaOMe.

Mixed-anion perovskites such as oxynitrides, oxyfluorides, and oxyhydrides have flexibility in their anion arrangements, which potentially enables functional material design based on coordination chemistry. However, difficulty in the control of the anion arrangement has prevented the realization of this concept. In this study, we demonstrate strain engineering of the anion arrangement in epitaxial thin films of the Ca 1-x Sr x TaO 2 N perovskite oxynitrides. Under compressive epitaxial strain, the axial sites in TaO 4 N 2 octahedra tend to be occupied by nitrogen rather than oxygen, which was revealed by N and O K-edge linearly polarized X-ray absorption near-edge structure (LP-XANES) and scanning transmission electron microscopy combined with electron energy loss spectroscopy. Furthermore, detailed analysis of the LP-XANES indicated that the high occupancy of nitrogen at the axial sites is due to the partial formation of a metastable trans-type anion configuration. These results are expected to serve as a guide for the material design of mixed-anion compounds based on their anion arrangements.

Perovskite nickel oxides are of fundamental as well as technological interest because they show large resistance modulation associated with phase transition as a function of the temperature and chemical composition. Here, the effects of fluorine doping in perovskite nickelate NdNiO 3 epitaxial thin films are investigated through a low-temperature reaction with polyvinylidene fluoride as the fluorine source. The fluorine content in the fluorinated NdNiO 3-x F x films is controlled with precision by varying the reaction time. The fully fluorinated film (x ≈ 1) is highly insulating and has a bandgap of 2.1 eV, in contrast to NdNiO 3 , which exhibits metallic transport properties. Hard X-ray photoelectron and soft X-ray absorption spectroscopies reveal the suppression of the density of states at the Fermi level as well as the reduction of nickel ions (valence state changes from +3 to +2) after fluorination, suggesting that the strong Coulombic repulsion in the Ni 3d orbitals associated with the fluorine substitution drives the metal-to-insulator transition. In addition, the resistivity of the fluorinated films recovers to the original value for NdNiO 3 after annealing in an oxygen atmosphere. By application of the reversible fluorination process to transition-metal oxides, the search for resistance-switching materials could be accelerated.

The cyclization of amphiphiles has emerged as an attractive strategy for inducing remarkable properties in these materials without changing their chemical composition. In this study, we successfully synthesized three cyclic polyoxyethylene dodecyl ethers (c-POEC12's) with different ring sizes and explored the effects of their topology on their surface and self-assembly properties related to their function, comparing them with those of their linear counterparts (l-POEC12's). The surface activity of the c-POEC12's remained almost constant despite the change in their hydrophobic and hydrophilic balance (HLB) value, while that of the l-POEC12's decreased with an increase in the HLB value as general surfactants. In contrast to the normal micelles seen in the case of the l-POEC12's (3.4-9.7 nm), the cyclization of the POEC12's resulted in the formation of large spherical structures 72.8-256.8 nm in size. It also led to a dramatic decrease of 28 °C in the cloud point temperature. Furthermore, the cyclization of the POEC12's markedly suppressed the rate of protease hydrolysis caused by the surfactants. The initial rate of reduction of a detergent enzyme from Bacillus licheniformis was increased by more than 40% in the case of c-POE600C12 and c-POE1000C12, even though they exhibited surface activities almost equal to or higher than those of their linear counterparts. These results suggest that cyclization induces unusual aqueous behaviors in POEC12, making the surfactant milder with respect to detergent enzymes while ensuring it exhibits increased surface activity.

We developed a technique to fabricate oxide thin films with uniaxially controlled crystallographic orientation and lateral size of more than micrometers on amorphous substrates. This technique is lateral solid-phase epitaxy, where epitaxial crystallization of amorphous precursor is seeded with ultrathin oxide nanosheets sparsely (≈10% coverage) deposited on the substrate. Transparent conducting Nb-doped anatase TiO2 thin films were fabricated on glass substrates by this technique. Perfect (001) orientation and large grains with lateral sizes up to 10 μm were confirmed by X-ray diffraction, atomic force microscopy, and electron beam backscattering diffraction measurements. As a consequence of these features, the obtained film exhibited excellent electrical transport properties comparable to those of epitaxial thin films on single-crystalline substrates. This technique is a versatile method for fabricating high-quality oxide thin films other than anatase TiO2 and would increase the possible applications of oxide-based thin film devices.

Phytochromes are red/far-red photosensory proteins that utilize the photoisomerization of a linear tetrapyrrole (bilin) chromophore to detect the red to far-red light ratio. Cyanobacteriochromes (CBCRs) are distantly related cyanobacterial photosensors with homologous bilin-binding GAF domains, but they exhibit greater spectral diversity. Different CBCR subfamilies have been described, with spectral sensitivity varying across the near-ultraviolet and throughout the visible spectrum, but all known CBCRs utilize photoisomerization of the bilin 15,16-double bond as the primary photochemical event. The first CBCR discovered was RcaE, responsible for tuning light harvesting to the incident color environment (complementary chromatic adaptation) in Fremyella diplosiphon. The green/red RcaE photocycle has recently been described in detail. We now extend this analysis by examining femtosecond photodynamics using ultrafast transient absorption techniques with broadband detection and multicomponent global analysis. Excited-state dynamics in both directions are significantly slower than those recently published for the red/green CBCR NpR6012g4. In the forward reaction, the primary Lumi-G photoproduct arises from the longer-lived excited-state populations, leading to a low photoproduct quantum yield. Using dual-excitation wavelength interleaved pump-probe spectroscopy, we observe multiphasic excited-state dynamics in the forward reaction ((15Z)Pg → (15E)Pr), which we interpret as arising from ground-state inhomogeneity with different tautomers of the PCB chromophore. The reverse reaction ((15E)Pr → (15Z)Pg) is characterized via pump-probe spectroscopy and also exhibits slow excited-state decay dynamics and a low photoproduct yield. These results provide the first description of excited-state dynamics for a green/red CBCR.

Creation of an artificial oscillating gene expression system is one of the most challenging issues in synthetic biology. Here, we constructed a simple system to manipulate gene expression patterns to be circadian, reflecting the intrinsic cellular clock, by fusing a core clock protein, BMAL1 or CLOCK, with a zinc finger-type DNA binding domain. Circadian rhythmic gene expression was induced only when the target gene contained zinc finger-binding sequences. To our knowledge, this simple approach is the first to manipulate gene expression patterns into circadian rhythms and would be applicable to various endogenous genes.

Cyanobacteriochromes are a spectrally diverse photoreceptor family that binds a bilin chromophore. For some cyanobacteriochromes, in addition to the widely conserved cysteine to anchor the chromophore, its ligation with a second cysteine is responsible for a remarkable blue shift. Herein, we report a newly discovered cyanobacteriochrome Tlr1999 exhibiting reversible photoconversion between a blue-absorbing form at 418 nm (P418) and a teal-absorbing form at 498 nm (P498). Acidic denaturation suggests that P418 harbors C15-Z phycoviolobilin, whereas P498 harbors C15-E phycoviolobilin. When treated with iodoacetamide, which irreversibly modifies thiol groups, P418 is slowly converted to a green-absorbing photoinactive form denoted P552. The absorption spectrum of P498 appears to be unaffected by iodoacetamide, but when iodoacetamide modified, it is photoconverted to P552. These results suggest that a covalent bond exists between the second Cys and the phycoviolobilin in P418 but not in P498. Subsequent treatment with dithiothreitol converts P552 into P418, whereas dithiothreitol reduces P498 to yield P420, a photoinactive form. Site-directed mutagenesis shows that the second Cys is essential for assembly of the photoactive holoprotein and that the photoactivity of this inert mutant is partially rescued by β-mercaptoethanol. These results suggest that the covalent attachment and detachment of a thiol, although not necessarily that of the second Cys, is critical for the reversible spectral blue shift and the complete photocycle. We propose a thiol-based photocycle, in which the thiol-modified P552 and P420 are intermediate-like forms., (© 2012 American Chemical Society)

The asymmetric one-pot 6π-azaelectrocyclization of alkenyl vinyl stannane, ethyl (Z)-2-iodo-4-oxobutenoate, and (-)-7-isopropyl-cis-aminoindanol in the presence of a Pd(0) catalyst stereoselectively produced the tetracyclic aminoacetal compounds, resulting from the four-bond formation accompanying by controlling the stereochemistry at the two asymmetric centers. The produced cyclic aminoacetals can be regarded as synthetic precursors of substituted chiral piperidines, and the syntheses of 2,4- and 2,4,6-substituted piperidines were realized from the obtained aminoacetals by the stereoselective hydrogenation of the double bond conjugated with the C-4 ester group and alkylation at the aminoacetal moiety. In addition, the stereoselective synthesis of an indolizidine alkaloid, (-)-dendroprimine, and its three stereoisomers, (+)-7-epidendroprimine, (+)-5-epidendroprimine, and (+)-5,7-epidendroprimine, were achieved.

We succeeded in achieving visible-light responsiveness on a tubular TiO(2) sample through the treatment of a tubular TiO(2) that has a large surface area with an aqueous solution of ammonia or triethylamine at room temperature and subsequent calcination at 623 K, which produced a nitrided tubular TiO(2) sample. It was found that the ease of nitridation is dependent on the surface states; washing the tubular TiO(2) sample with an aqueous acidic solution is very effective and indispensable. This treatment causes the appearance of acidic sites on the tubular TiO(2), which was proved by the following experiments: NH(3) temperature-programmed desorption and two types of organic reactions exploiting the acid properties. The prepared samples, TiO(2-δ)N(δ), efficiently absorb light in the visible region, and they exhibit a prominent feature for the decomposition of methylene blue in an aqueous solution at 300 K under irradiation with visible light, indicating the achievement of visible-light responsiveness on the tubular TiO(2) sample. This type of tubular TiO(2-δ)N(δ) sample has merit in the sense that it has a large surface area and a characteristic high transparency for enabling photocatalytic reactions because it has a tubular structure and is composed of thin walls.

A systematic study of the degree of molecular ordering and swelling of different nanocellulose model films has been conducted. Crystalline cellulose II surfaces were prepared by spin-coating of the precursor cellulose solutions onto oxidized silicon wafers before regeneration in water or by using the Langmuir-Schaefer (LS) technique. Amorphous cellulose films were also prepared by spin-coating of a precursor cellulose solution onto oxidized silicon wafers. Crystalline cellulose I surfaces were prepared by spin-coating wafers with aqueous suspensions of sulfate-stabilized cellulose I nanocrystals and low-charged microfibrillated cellulose (LC-MFC). In addition, a dispersion of high-charged MFC was used for the buildup of polyelectrolyte multilayers with polyetheyleneimine on silica with the aid of the layer-by-layer (LbL) technique. These preparation methods produced smooth thin films on the nanometer scale suitable for X-ray diffraction and swelling measurements. The surface morphology and thickness of the cellulose films were characterized in detail by atomic force microscopy (AFM) and ellipsometry measurements, respectively. To determine the surface energy of the cellulose surfaces, that is, their ability to engage in different interactions with different materials, they were characterized through contact angle measurements against water, glycerol, and methylene iodide. Small incidence angle X-ray diffraction revealed that the nanocrystal and MFC films exhibited a cellulose I crystal structure and that the films prepared from N-methylmorpholine-N-oxide (NMMO), LiCl/DMAc solutions, using the LS technique, possessed a cellulose II structure. The degree of crystalline ordering was highest in the nanocrystal films (approximately 87%), whereas the MFC, NMMO, and LS films exhibited a degree of crystallinity of about 60%. The N,N-dimethylacetamide (DMAc)/LiCl film possessed very low crystalline ordering (<15%). It was also established that the films had different mesostructures, that is, structures around 10 nm, depending on the preparation conditions. The LS and LiCl/DMAc films are smooth without any clear mesostructure, whereas the other films have a clear mesostructure in which the dimensions are dependent on the size of the nanocrystals, fibrillar cellulose, and electrostatic charge of the MFC. The swelling of the films was studied using a quartz crystal microbalance with dissipation. To understand the swelling properties of the films, it was necessary to consider both the difference in crystalline ordering and the difference in mesostructure of the films.

CO tolerance at pure Pt, Pt-Co, and Pt-Ru alloys was investigated by X-ray photoelectron spectroscopy combined with an electrochemical cell (EC-XPS) in order to discover a hint for designing higher performance anode catalysts. After the electrochemical stabilization and/or CO adsorption, these electrodes were immediately transferred to the XPS chamber without exposure to air to avoid contamination of the surfaces. It was revealed that alloying with Co or Ru modified the electronic structures of Pt atoms, resulting in a positive core level (CL) shift of Pt 4f(7/2) which could weaken the Pt-CO interaction. For the Pt-Co alloy electrode, the Pt 4f(7/2) CL shift remained after the electrochemical stabilization despite Co dissolution and formation of a Pt skin layer. Changes in surface core level shifts (DeltaSCLSs) induced by CO adsorption were evaluated and related to the CO adsorption energy. The values of DeltaSCLS at these alloys were smaller than that of pure Pt, indicating that Ru and Co are effective elements to weaken the bond strength of Pt-CO.

The Bfp-OH, a novel fluorous protecting reagent, was able to be easily prepared. The Bfp group was readily introduced to a carbohydrate, removed in high yield, and recyclable after cleavage. The use of the Bfp group made it possible to synthesize a pentasaccharide by minimal column chromatography purification. Each synthetic intermediate was able to be easily purified only by simple fluorous-organic solvent extraction and monitored by TLC, NMR, and MS., (Copyright 2004 American Chemical Society)

We have developed the total internal reflection ultrafast transient lens (TIR-UTL) method to detect nonradiative chemical processes at interfaces and surfaces with subpicosecond time resolution. In the TIR-UTL measurements, the evanescent field of a pump beam irradiated under the TIR condition generates a refractive index change. The refractive index change is attributed to changes of the molecular electronic state, of density by molecular orientation/structure change, and of temperature by vibrational relaxation processes. The refractive index change is detected as a change of the power intensity of the probe beam adjusted coaxially with the pump beam. At first, we discuss a theoretical principle of a coaxial configuration in the TIR-UTL measurement. This configuration has an advantage of versatility over the established TIR configuration. Then, we evaluate time resolution of TIR-UTL and obtain a value of less than 400 fs. We measure the ultrafast molecular dynamics of the cationic chromophore Auramine O (AuO) at a silica/water interface. Two slow time constants originating from AuO adsorbed on the silica surface are detected by TIR-UTL. These are attributed to AuO, whose twisting motion is strongly hindered by adsorption on a silica surface.

[reaction: see text] Highly stereoselective synthesis of 1,4-bifunctional compounds was accomplished via 1,2-asymmetric induction to alpha-oxyaldehyde followed by regio- and diastereoselective Pd-catalyzed allylic substitution reaction.

The Bfp (bisfluorous chain type propanoyl) group, a novel fluorous protecting reagent, was able to be prepared easily. The Bfp group was readily introduced to carbohydrate, was removed in high yield, and was recyclable after cleavage. Use of the Bfp group made it possible to synthesize a tetrasaccharide by minimal column chromatography purification. Each synthetic intermediate was able to be easily purified by using only simple fluorous-organic solvent extraction and was monitored by NMR, mass spectroscopy, and TLC. [structure: see text]

The photophysical properties of tetra-tert-butylphthalocyaninatosilicon (SiPc) covalently linked to one or two 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radicals (R1, R2) have been studied by fluorescence, transient absorption, and time-resolved electron paramagnetic resonance (TREPR) spectroscopies. It is found that the fluorescence quantum yields and lifetimes of R1 and R2 decrease compared with those of (dihydroxy)SiPc ((dihydroxy)SiPc = 6.8 ns, R1 = 4.7 ns and 42 ps, and R2 = 4.7 ns and <30 ps). Transient absorption measurements indicate that the lifetime of the excited triplet SiPc is markedly dependent on the number of linking TEMPO radicals ((dihydroxy)SiPc = 500 micros, R1 = 7.6 micros, and R2 = 3.7 micros). These short lifetimes of R1 and R2 in the excited states are explained as a result of the interaction with TEMPO changing the ISC between the singlet and triplet states to spin-allowed transitions. Quantitative TREPR investigations have been carried out for the radical-quartet pair mechanism of R1 and the photoinduced population transfer of R2. It is determined that the rise and decay times of these electron spin polarizations denote the spin-lattice relaxation time of the ground state and the lifetime of the excited multiplet state, respectively. This study contributes not only to an elucidation of radical-chromophore interactions but also to a novel approach for controlling magnetic properties by photoexcitation.