Global supply of 1,3-butadiene (abbreviated as BD) is faced with problems such as unstable price of petrochemicals and variation of chemical feedstock in recent years. Many research works have been conducted to produce BD from some renewable resources instead of petroleum. Among them, biomass-derived C4 alcohols such as 1,3-butanediol (1,3-BDO), 2,3-butanediol (2,3-BDO), and 1,4-butanediol (1,4-BDO) have been considered as alternative resources to produce BD. Direct dehydration of butanediols (BDOs) into BD, however, needs high reaction temperatures while the dehydration into their corresponding unsaturated alcohols (UOLs) such as 3-buten-2-ol (3B2OL), 2-buten-1-ol (2B1OL), and 3-buten-1-ol (3B1OL) proceeds at rather low temperatures over specific catalysts. The latter step of BDO dehydration, dehydration of UOLs to BD, is readily catalyzed by solid acids even at lower temperatures than those at which BDOs are dehydrated completely. Thus, efficient formation of UOLs from BDOs would be a key process to produce BD with high selectivity. We summarize the BD production from C4 alcohols as well as the dehydration of BDOs to UOLs, in addition to the BD production via ethanol dimerization.
The serious side effects of aminoglycosides and the spread of aminoglycoside-resistant strains have restricted the clinical application of aminoglycosides. A compound with the identical mode of action with aminoglycosides and with different molecular skeleton would be an alternative drug for aminoglycosides. In this study, we constructed an SPR-based high-throughput screening system for the discovery of such compounds.
CuSn-codoped CdS (CdS:CuSn) quantum dots (QDs) with different Cu(I) and Sn(IV) doping levels have been successfully synthesized by a simple one-pot procedure. It was found that the doping ratio of Cu(I) and Sn(IV) in CdS QDs significantly affected the photoluminescence (PL) quantum yields (QYs), Stokes shifts, and emission window of as-prepared QDs. Compared to single Cu doping, CuSn codoping further significantly improved the PL QYs of as-prepared QDs (up to 24.6%). The CdS:CuSn QDs may be used as potential emitters in the PL industry.
Thiol-ene photopolymerization has been a versatile tool for polymer synthesis. However, deep photopolymerization of the thiol-ene system still remains a great challenge due to the light-intensity gradient. Using near-infrared light as an excitation source and upconversion nanoparticles as internal lamps, we report a generic and efficient strategy to realize deep thiol-ene photopolymerization. More than 8 cm of photopolymerization depth combined with high functionality conversion was obtained in 40 s. The maximum temperature of about 110 °C during upconversion nanoparticle (UCNP)-assisted photopolymerization is comparable to or lower than that of some reported frontal photopolymerizations applied in the preparation of functional polymer composites and biomaterials.
A novel molecular heterospin system composed of high-spin MnII (S = 5/2) and (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical (PyBTM; S = 1/2) was developed. The MnII ion formed distorted octahedral coordination geometry with two PyBTM radicals coordinated in the trans configuration. Magnetic studies disclosed an intramolecular antiferromagnetic exchange interaction between the spins on PyBTM and MnII with JR–Mn/kB of −9.7 K. The antiferromagnetic interaction was confirmed by broken-symmetry density functional theory calculations. This study reveals the definite intramolecular exchange interaction in the MnII–triarylmethyl radical system for the first time.
In the present study, electrochemical oxidation of 4-aminophenol (1a) has been studied in the presence of cyanoacetate derivatives 3a and 3b as nucleophile in a mixture of ethanol and phosphate buffer solution (0.15 M, pH 7) as green media using cyclic voltammetry and controlled-potential coulometry techniques. The obtained results indicate that the corresponding 4-iminocyclohexa-2,5-dienone (2a) formed from 4-aminophenol (1a) participates in the Michael addition reaction to yield new N- and O-heterocycles. The electrosynthesis of these new heterocycle compounds has been performed successfully in an undivided cell in good to excellent yields and high purity under mild conditions without any catalyst and toxic solvent.
An optically active poly(diphenylacetylene) with a pendant amide functional group was synthesized by a macromolecular reaction of the optically inactive poly(diphenylacetylene) bearing carboxy groups with (S)-1-phenylethylamine. The obtained polymer showed good chiral recognition ability towards diverse racemates when used as a chiral stationary phase for high-performance liquid chromatography. The chiral recognition ability was substantially influenced by the chiral conformation, probably preferred-handed helical conformation, which was induced by thermal annealing in dimethylformamide after introducing optically active pendants through the macromolecular reaction.
Metal phthalocyanines (MPcs; M = Co, Ni, Cu, Zn) with α-phase powders were obtained at the interface between hydrophilic and hydrophobic solutions starting from β-phase powders. This method was also applied to the deposition of a highly dispersed α-phase MPc on a carbon substrate, which showed high electrochemical activity for oxygen reduction.
Treatment of diaryloxy- and triaryloxybenzenes in the presence of a Pd(TFA)2 catalyst and an AgOAc oxidant produces the corresponding benzobis- and benzotrisbenzofurans in good yields through double and triple intramolecular C–H/C–H coupling reactions, respectively.
Dissolution of water-insoluble curcumin at a high concentration (>100 µM) is achieved by femtosecond-laser ablation in an aqueous solution containing cyclodextrin compounds at room temperature. The curcumin solution is freeze-dried to yield an orange powder, which is also highly soluble in water (ca. 1 mM). The dissolved curcumin compound has cytotoxic activity toward lung cancer cells.
There is a fundamental demand for organic fluorescent nanoparticles due to their great significance in the bioimaging field. Herein, we report a facile fabrication of bovine serum albumin nanoparticles loaded with flavonoid dyes via the classic desolvation method. The as-prepared nanoparticles were characterized by fluorescence spectroscopy, dynamic light scattering, scanning electron microscopy, etc. The nanoparticles exhibited several advantages over their counterpart dyes, such as enhanced fluorescent intensity, good photostability, and long-term bioimaging property. This work provided a versatile strategy applying fluorescent dye-loaded biopolymer nanoparticles into bioimaging applications.
A novel 5-fluorouracil (5-FU)-based anticancer prodrugs consisting of pyrene and oligonucleotide trimer having 5-halouracils were designed. The UVA-induced electron injection from photoexcited pyrene followed by the radical-induced C1′ hydrogen abstraction of 5-fluoro-2′-deoxyuridine is expected to cause the elimination of 5-FU. Since the prodrug clearly suppressed the proliferation of HeLa cells in an UVA-responsive manner, we have successfully developed a novel 5-FU prodrug.
Aggregation-induced emission (AIE)-based probes for biomolecules have gained much attention due to their fluorescence properties including turn-on type chemosensing and high quantum yield. We herein developed cationic and anionic tetraazacyclophane–tetraphenylethylene conjugates 1 and 2, respectively, as a new class of AIE-based probe, and evaluated their sensing ability toward calf thymus DNA (ctDNA) and proteins (BSA, HSA, lysozyme, and trypsin). Cationic 1 responded to ctDNA with high sensitivity. In contrast, anionic 2 showed strong AIE in the presence of BSA and HSA.
Sperm whale myoglobin mutant, F43Y Mb, with Tyr43 forming a novel crosslink to the heme 4-vinyl group, was found to exhibit dramatically enhanced dehaloperoxidase activity compared to that of wild-type Mb (ca. 115-fold), which is even beyond the catalytic efficiency of the native dehaloperoxidase from Amphitrite ornata (ca. 9-fold), indicating a potential application for bioremediation.
A 4,8,12-triazatriangulene (TATA) cation derivative bearing tetra(ethylene glycol) group was synthesized by direct functionalization of the TATA framework at the 2-, 6-, and 10-positions. Emission properties of the amphiphilic TATA derivative in three different environments—in the monomer state, in aggregates formed in aqueous media, and in the solid state—were carefully analyzed based on the radiative (kf) and nonradiative (knr) rate constants. We found that the fluorescence quenching of the TATA cation derivative upon aggregation is dominantly attributed to the decrease in the kf value but not to the change in the knr value.
We observe that etching approximately 6 nm spherical gold nanoparticles (AuNPs) with cysteine produces assembled AuNPs with approximately 2 nm of particle size, which specifically exhibit a new absorption band around 377 nm. The absorption band possesses an optical activity reflecting the chirality of cysteine attached on the AuNPs. We also observe that the decrease in the chiral purity of cysteine used from 100% to 60% enantiomeric excess (ee) enhances the optical rotation of the plasmonic band. The anomalous enhancement of the optical rotation is caused by the recovery of the net optical rotation of the assemblies of the AuNPs because the decrease in the chiral purity of cysteine decreases the size of the disordered assemblies. Since disordered assemblies cancel their inherent optical rotation of the AuNP components, the decrease in their size recovers the net optical rotation of the assemblies. Our results demonstrate that control of the chiral purity of optically active thiols etching AuNPs is a potential method to fabricate assemblies of AuNPs with unique optical activity.
We employed an oxygen-pressure method as a novel approach to improve the emission intensity of a Ca14Zn6Al10O35:Mn4+ phosphor. With this new approach, the Ca14Zn6Al10O35:Mn4+ phosphor exhibited near-infrared emission under excitation at 450 nm, and the emission intensity of a Ca14Zn6(Al0.97Mn0.03)10O35 phosphor was effectively enhanced by approximately 143% compared with that of a Ca14Zn6(Al0.97Mn0.03)10O35 phosphor synthesized by a conventional solid-state reaction method in air.
This paper describes a new approach to novel proton-conducting organic–inorganic nanohybrid materials by surface modification of a large amount of SiOH groups on nanoporous glass with silane coupling reagent containing double SH groups, based on pore surface analysis and first principle calculations.
To determine the reaction rate coefficient of volatile organic compounds (VOCs) with ozone, the reduction of ozone through a flow-tube reactor was measured by a sensitive chemiluminescent detector. In this study, temperature dependence of the rate constant of ozone with linalool, k(T) = A exp(−B/T), was explored (T = 299–322 K). Consequently, temperature-dependent parameters A and B were experimentally determined as (1.6 ± 0.4) × 10−15 cm3 molecule−1 s−1 and 396 ± 26 K, respectively, for the first time. The rate constant of linalool + O3 reaction varied by 10% with changes in temperatures from 299 to 322 K.
Liquid crystals (LCs) of large macrocyclic compounds are a plausible platform in which to organize included guest molecules regularly in a flowable medium. Herein, a series of metallomacrocycles with different peripheral alkyl chains were synthesized through a 3:3 self-assembly based on metal complexation between naphthalene-2,7-dihydroxamic acid and Cu2+ ions. The crystallinity and liquid crystallinity of the macrocycles sharply depend on the structure of the peripheral alkyl chains. The metallomacrocycle with six hexyl chains has only the crystalline phase, whereas the metallomacrocycles with more and longer side chains exhibit LC mesophases. Most notably, oligo(ethylene glycol) side chains effectively assemble the macrocycle into an ordered lamellar structure.
A well-defined, light-responsive copolymer poly(spiropyrane)-block-poly(ethylene glycol) (PSP-b-PEG) was synthesized by RAFT polymerization. The final copolymer can self-assembled into spherical micelles with a hydrophilic PEG corona and a hydrophobic spiropyrane core in aqueous solution. Moreover, the properties of micelles in aqueous solution were detected by fluorescence spectroscopy, UV–vis spectroscopy, dynamic light scattering (DLS), and scanning electron microscope (SEM). Model drug Nile Red was then encapsulated into the micelles and its light-controlled release was studied. In addition, an MTT assay provided the evidence for the low cell cytotoxicity of PSP-b-PEG micelles. The results demonstrate that the spherical micelles of PSP-b-PEG possess a potential application in smart drug delivery.
We demonstrate the electron transfer from the conduction band of tantalate nanosheets to that of tungstate nanosheets depending on the interlayer distance in the alternate-stacked structure prepared by the thiol-ene click reaction of thiol-grafted tantalate nanosheets and alkene-grafted tungstate nanosheets. The interlayer distance is precisely controlled from 0.93 to 1.64 nm by changing the methylene chain number of the organic bridges. The logarithm of the rate constant of the electron transfer decreases linearly with the distance.
A phenylene-linked copper(II) porphyrin–zinc(II) porphyrin dimer exhibits near-IR emission, the lifetime of which is 310 ns at 300 K in toluene. Based on transient absorption measurements and emission temperature dependence, the observed emission was ascribed to phosphorescence from the trip-doublet state of copper porphyrin, which is thermally activated with an energy gap of 430 cm−1 from the zinc(II) porphyrin triplet state. The zinc–porphyrin triplet state acts as a reservoir and emission lifetime of the dimer is prolonged by ten times compared to the copper–porphyrin monomer, of which the lifetime is 30 ns.
Triple-shelled Co3O4 hollow spheres were successfully prepared using a facile solvothermal method and the following calcinations. Benefitting from the unique hollow structure, triple-shelled Co3O4 hollow spheres exhibited much higher specific reversible capacity (923.1 mA h g−1) than that of bare Co3O4 particles (206.9 mA h g−1) after 50 cycles, as well as superior rate capability. This is because of the porous shells, which can accommodate volume change during charging/discharging process and enable easy infiltration of electrolyte when used as anodes in lithium ion batteries.
A homogeneous coprecipitate of a samarium/barium solution with saturated sodium tetraborate has been air-fired. The product was confirmed to be barium octoborate by X-ray diffraction. The reaction process reduced samarium from the trivalent state to form divalent samarium. The samarium(II) emission is consistent with that of samarium-doped barium octoborate prepared by ceramic methods. The Raman scattering exhibited by the product proved extremely useful. The formation of this species by this method has not been reported.
We prepared novel cerium meso-tetrathienylporphyrin double-decker complexes with 2-thienyl and 3-thienyl substituents. The X-ray structures show that the porphyrin rings are distorted in a half-pipe fashion, which seems to be a common type of distortion for double-decker complexes of tetraarylporphyrins. The side-arm thienyl groups rotate more than two orders of magnitude faster than the phenyl groups of the corresponding double-decker complex of meso-tetraphenylporphyrin in solution at room temperature because of the lower rotational barriers.
A push–pull porphyrin dimer with multiple electron-donating groups has been synthesized as a sensitizer with an excellent light-harvesting ability in the near-infrared region for dye-sensitized solar cells (DSSCs). The DSSC based on the sensitizer exhibited the photocurrent generation exceeding a wavelength of 900 nm, together with a power conversion efficiency of 6.21% under AM 1.5 condition.
Novel calamitic liquid crystals having an electron-deficient isoquino[8,7-h]isoquinoline moiety as a core, 2,8-didecylisoquino[8,7-h]isoquinoline (10-IQIQ-10) and 2,8-didodecylisoquino[8,7-h]isoquinoline (12-IQIQ-12), were prepared, and their phase transition behaviors, HOMO and LUMO levels, and charge carrier transport properties were investigated. 12-IQIQ-12 showed a highly ordered smectic H phase at around 140 to 150 °C and a low-lying LUMO level of −3.33 eV. Time-of-flight measurements revealed field-independent ambipolar transport characterized by mobility on the order of 10−4 cm2 V−1 s−1 at the highly ordered smectic phase.