The distribution of cocatalysts on a water splitting photocatalyst was investigated using electron microscopy combined with energy dispersive X-ray spectroscopy. Pt, Cr, and Co cocatalyst components were dispersed on the surface of an Al-doped SrTiO3 photocatalyst by stepwise photodeposition. It was found that the Pt/Cr2O3 cocatalyst for hydrogen evolution and the CoOOH cocatalyst for oxygen evolution were selectively deposited on different crystal facets, indicating anisotropic charge transport.
The foam stability of an aqueous solution containing a high concentration of ethanol (60 vol.%) was assessed under the combined addition of an anionic surfactant, a long-chain alcohol, and an inorganic electrolyte. The addition of the electrolyte resulted in a decreased surface tension and an increased surface viscosity, leading to an enhanced foam stability. This study proposes a new strategy for formulating foam-type disinfectants with increased stability containing high concentrations of ethanol.
The total synthesis of racemic azaspirene was accomplished over 12 steps in a 17% overall yield via a convergent strategy featuring the coupling of isocyanate and 3(2H)-furanone and an intramolecular aldol reaction to construct the spiro core. Later, a complete conversion was achieved via the crystallization-induced diastereomer transformation of the kinetically favored epimer—produced primarily via spirocyclic construction—to the thermodynamically stable and desirable epimer. Finally, a stereoselective hydration produced the target azaspirene.
In this study, we investigated the photophysical properties of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) in a single crystal (SC) state. We found that the forward intersystem crossing (ISC) and reverse ISC rate constants (kISC and kRISC) of a 4CzIPN-SC are one order magnitude higher than that of the amorphous film. Further, an unusual long-lived emission component was observed in 4CzIPN-SC, indicating that the excitons generated by optical excitation spontaneously dissociate into free carriers in 4CzIPN-SC.
Potassium manganese hexacyanoferrate (MnHCF) is a promising cathode material in aqueous zinc-ion batteries (ZIBs) due to its high capacity and operating potential. This study improves its electrochemical performance by using ethanol (EA) as the electrolyte solvent, which can effectively inhibit the dissolution of Mn ions and crystalline phase transformation of MnHCF. This study is of great significance for improving the cycling stability of ZIBs.
We synthesized poly(9,10-anthryleneethynylene)s bearing benzyl ether dendrimers with alkoxy peripheral groups at the 2- and 6-positions of anthracene by polymerization of the corresponding dibromoanthracenes and bis(3-hydroxy-3-methylbutynyl)anthracenes in the presence of a Pd(PPh3)4 catalyst and an appropriate base. The average degree of polymerization reached DPn = 50 by improving the solubility of poly(anthryleneethynylene)s. The UV–vis and CD spectra of poly(9,10-anthryleneethynylene)s bearing chiral menthoxy groups in addition to the dendritic side groups proved their ordered aggregation state in solution.
To unambiguously establish the stereostructure of the marine cytotoxic bromotriterpenoid iubol, a member of the thyrsiferol family, asymmetric chemical synthesis has been carried out. The synthesis features a one-pot process for the tetrahydropyranyl D ring construction through a stoichiometric Sharpless asymmetric epoxidation of allylic alcohols followed by titanium chelation-assisted 6-exo oxacyclization. In this paper, we report the asymmetric total synthesis of iubol, revision of the proposed structure to the C22-epimer, and preliminary cytotoxic activities of synthetic compounds against some tumor cells.
The carrier transport properties of solar cells fabricated with colloidal AgBiS2 nanocrystals (NCs) are affected by the type of ligands adsorbed on the nanoparticle surface, the coverage, and the coordination state. We focus on halide ions (F−, Cl−, Br−, and I−) to passivate the surface of AgBiS2 NCs and investigate their adsorption behavior using X-ray photoelectron spectroscopy (XPS) in this study. The adsorption strength of ligands was a useful figure of merit that could explain the correlation between the ligand type and solar cell performance. The Br ligand achieved the best NC passivation among the four halide ligands. Therefore, the cell with a Br ligand shows the highest solar cell performance.
Montmorillonite (MMT), a layered clay mineral, was dispersed in ionic liquids (ILs) to prepare MMT-IL dispersions. After several weeks of standing, MMT-IL dispersions separated into an upper transparent layer and a lower birefringent (liquid crystalline) turbid layer, in which MMT was present as stacked layers of particles intercalated with ILs, not as exfoliated single layers. MMT-IL liquid crystals were sufficiently aligned under a magnetic field of 0.5 T in strength.
Exposure of 1-substituted cyclopropanols to excess Et2Zn promotes its dimerization to afford 2-methylcyclopentane-1,3-diol derivatives as meso compounds in a diastereoselective fashion. The reaction likely proceeds via aldol reaction between two molecules of zinc homoenolate and subsequent intramolecular alkylzinc addition to the carbonyl group. Dehydration of the present product allows for facile preparation of 1,2,3-trisubstituted cyclopentadiene and its transition metal complex.
We synthesized a new type of asymmetric binuclear Ag(I) complex, [Ag2(dppaO2)2(dppbz)] (1), consisting of two chelating dppaO2− ligands (dppaO2− = N,N-bis(diphenylphosphino)amide-dioxide) and one bridging dppbz ligand (dppbz = 1,2-bis(diphenylphosphino)-benzene). According to X-ray crystal structure analysis, the two Ag(I) ions were adjacent to each other and were bridged by both the dppbz ligands and one of the oxygen atoms in the dppaO2− ligands. Complex 1 showed relatively strong green luminescence in the solid state.
An iron(II) complex of a novel tripodal 2,2′-bipyridine ligand bearing perfluoroalkyl linkers showed anion-dependent fac/mer isomerization. In the complexes with bromide and triflate anions, the mer isomer was preferentially formed. The bistriflimide anion shifted the equilibrium to the fac isomer. The different isomerization behaviors were probably caused by difference in the hydrogen bond modes of the isomers with anions.
Graphene oxide (GO) membranes have received widespread attention. However, GO membranes exhibit low structural stability in water. We attempted to solve this problem by cross-linking GO with silica. The water permeance of a silica/GO membrane, which was prepared with a tetraethyl silicate/GO mass ratio of 190 and a reaction time of 3 h, was six times that of an unmodified GO membrane. The molecular weight cutoff of the silica/GO membrane was 800, which was almost the same as that of the unmodified GO membrane.
Inspired by the energy conversion processes through the discrete 120° rotation by ATPase, here we newly developed a multiblock amphiphilic triptycene that can be incorporated into the lipid bilayers. The incorporation was confirmed by microscopy and spectroscopy techniques. We also found that depending on the concentration, multiblock amphiphilic triptycene assembled within the lipid bilayers.
The helix-hairpin-helix (HhH) motif in prokaryote and eukaryote DNA binding proteins is involved in non-sequence-specific DNA binding. Several studies have examined various HhH binding interactions, but the effect of stereochemistry on non-sequence-specific DNA binding by HhH peptides remains unresolved. Here, we analyzed stereochemistry-specific interactions between DNA structures and HhH motif peptides derived from NAD+-dependent DNA ligase, which is a promising target for developing new antibiotics. We synthesized l- and d-forms of single HhH motif peptides and found that both the native l-HhH-N peptide and d-HhH-N peptide bind bubble DNA and the peptides were changed to α-helical structure. Moreover, the d-HhH-N peptide showed different interaction properties against single-stranded and double-stranded DNA when compared with the l-HhH-N peptide. This study provides insights into non-sequence-specific DNA binding of d-peptides for developing d-peptide drugs.
Silica-coated ZSM-5 with high crystallinity and related hierarchical catalysts using simultaneous generation of ZSM-5 and mesoporous silica with gel skeletal reinforcement exhibited high selectivity for p-xylene among a xylene mixture in catalytic cracking of low-density polyethylene, which reached more than 95%. A linear relationship appeared between mesoporous pore volume and the relative activity per acidic site calculated by the conversion and NH3-TPD, suggesting that the formation of hierarchical structure would increase the activity per active site.