Facile in Situ Transformation of NiOOH into MOF-74(Ni)/NiO OH Heterogeneous Composite for Enchancing Electrocatalytic Methanol Oxidation.

A new MOF-74(Ni)/NiOOH heterogeneous composite was synthesized via NiOOH microsphere precursor. The electrocatalytic methanol oxidation reactions' (MOR) performance was assessed. The as-prepared MOF-74(Ni)/NiOOH exhibited excellent activity with high peak current density (27.62 mA·cm-2) and high mass activity (243.8 mA·mg-1). The enhanced activity could be a result of the synergistic effect of the MOF-74(Ni)/NiOOH heterocomposite providing more exposed active sites, a beneficial diffusion path between the catalyst surface and electrolyte, and improved conductivity, favorable for improving MOR performance.

Solvatochromism and mechanochromism observed in a triphenylamine derivative.

A donor-π-acceptor fluorescent dye, 4-[N,N-di(4-phenyl)amino]benzaldehyde 4-chlorobenzoyl hydrazone (TPA-CBH), based on a triphenylamine derivative (TPA) and 4-chlorobenzoyl hydrazine (CBH) was designed and synthesized. The optical properties of this luminogen were investigated in solutions as well as in the solid states. In the intramolecular charge-transfer (CT) mechanism, TPA-CBH exhibits solvatochromism when dissolved in various polar solvents. Aggregation-induced emission was observed with the changes of tetrahydrofuran/water ratios. In the solid state, mechanochromic fluorescence is observed when the samples are stressed under different conditions. Based on structural analyses and theoretical calculations, it is found that intra- and intermolecular CT processes play a key role in the diversity of fluorescent properties.

Tunable AIEE fluorescence constructed from a triphenylamine luminogen containing quinoline - application in a reversible and tunable pH sensor.

Herein, tunable emissions in aggregation processes of triphenylamine derivatives (TPAQs) and their protonated cations, as well as protonated processes have been described. In this study, three triphenylamine-based compounds (TPAQs) were synthesized and their optical properties were investigated. Initially, the TPAQs displayed aggregation-induced emission enhancement (AIEE) properties via the restricted intramolecular charge transfer (ICT) state. Interestingly, the single-branched fluorophore (STPAQ) and its protonated cation emitted different color fluorescence in the solution and aggregation state. They emitted green fluorescence, which originated from the intramolecular charge transfer (ICT) state in a strong polar solvent, but the fluorescence bands turned blue, which was attributed to the LE state in the aggregated state. However, the cations of triple-branched fluorophores (TTPAQs) exhibited an inverse tunable emission process from bluish violet fluorescence of the LE state in a weak polar solvent (e.g., THF) to green fluorescence of the ICT state in the aggregated state. In a THF/water mixture solution (fw = 10%), the STPAQ could switch its emission between blue and green in the pH range of 10.0-0.5. This phenomenon enabled STPAQ to serve as a fluorescent pH sensor in solution. In the powder state, double-branched fluorophores (DTPAQs) could be used as a fluorescent sensor for the detection of acidic and basic organic vapors in the solid state.

Aggregation-induced emission and intermolecular charge transfer effect in triphenylamine fluorophores containing diphenylhydrazone structures.

Three new chromophores incorporating acceptor-π-donor-π-acceptor structural motifs and mono-, di- and tri-branched diphenylsulfone base linked to triphenylamine through a hydrazone π-bridge were synthesized, and the photoluminescence properties of the three chromophores were studied in solutions as well as in aggregated states. All the fluorophores emitted strong blue fluorescence in THF. Mono- and di-branched triphenylamine both exhibited increasing blue fluorescence and displayed an AIEE effect in the aggregated state. Tri-branched triphenylamine emitted green fluorescence and presented the AIE effect in the aggregated state. These interesting phenomena have been interpreted by a molecular stacking mode with molecular dynamics (MD) and DFT calculations. The unique propeller shaped molecular configuration of triphenylamine prevented face to face π-π stacking and induced the hindered rotation, which resulted in the AIEE or AIE effect in the aggregated state. The enlarged coplanarity of diphenylhydrazone chains increased the conjugation of tri-branched triphenylamine, which was beneficial to the formation of ICT and AIE and resulted in emitting green ICT fluorescence in the aggregated state. Fluorescent microscope imaging and the fluorescent pictures of the powder states certified the strong AIEE effect or AIE effect in the solid.

Asymmetric Construction of Spiro[thiopyranoindole-benzoisothiazole] Scaffold via a Formal [3 + 3] Spiroannulation.

An enantioselective formal thio[3 + 3] spiroannulation reaction of indoline-2-thiones to 1-azadienes has been developed by the use of a quinine-derived bifunctional tertiary amine-thiourea catalyst, which furnished a series of optically active spiro[thiopyranoindole-benzoisothiazole] heterocycles with a spiro quaternary C-N/C-S stereogenic centers in high yields with good to excellent diastereo- and enantioselectivities.

Crystal structures and antifungal activities of fluorine-containing thioureido complexes with nickel(II).

Ni(II) complexes with N-2-fluorobenzoylpiperidine-1-carbothioimidate (L2-), N-4-fluorobenzoylpiperidine-1-carbothioimidate (L3-), N-2-fluorobenzoylmorpholine- 1-carbothioimidate (L5-) and N-4-fluorobenzoylmorpholine-1-carbothioimidate (L6-)  have been synthesized and characterized by elemental analysis, FTIR and 1H-NMR. The crystal structures of three ligands (HL2, HL3 and HL6) and the corresponding Ni(II) complexes ([Ni(L2)2], [Ni(L3)2] and [Ni(L6)2]) have been determined by X-ray diffraction. The antifungal activities of the Ni(II) complexes together and the corresponding ligands against the fungi Botrytis cinerea, Trichoderma spp., Myrothecium and Verticillium spp. have been investigated. The experimental results showed that the ligands and their complexes have antifungal abilities. When the fluorine was substituted on the para-benzoyl moiety, the antifungal activity of the ligands was obviously increased. Moreover, the ligands were stronger than their complexes in inhibiting fungal activities. The antifungal ability of HL6 is especially strong, and similar to that of the commercial fungicide fluconazole.

Highly efficient chemoselective synthesis of polysubstituted pyrroles via isocyanide-based multicomponent domino reaction.

A multicomponent domino reaction for the chemoselective, catalyst-free synthesis of polysubstituted pyrroles from readily available isocyanides, primary or secondary amines, and gem-diactivated olefins has been developed. Structurally diverse pyrroles were obtained in moderate to good yields under mild conditions.

Synthesis, structures and antibacterial activities of benzoylthiourea derivatives and their complexes with cobalt.

Four new thiocarbonyl fluorobenzamides and their complexes with cobalt have been synthesized and characterized by elemental analysis, FTIR, and (1)H NMR. Five crystal structures of the thioylbenzamides complexes of Co(PTCB)(3), Co(2FPTCB)(3), Co(4FPTCB)(3), Co(2FMTCB)(2) and Co(4FMTCB)(3) have been determined by X-ray diffraction. The antibacterial properties of these compounds against the bacteria, E. coli, Staphylococcus aureus, B. subtilis, P. aeruginosa, and Shewanella sp. were investigated. The experiments showed that both compounds and the complexes had the antibacterial activities against all of the studied bacteria. The thioylbenzamides had stronger controls for the bacteria of E. coli, S. aureus, B. subtilis and P. aeruginosa than their corresponding cobalt complexes. There was the contrary result against the bacteria of Shewanella sp. The para-substitution of fluorine atom increased antibacterial activities, while fluorine atom was substituted on ortho-benzoyl, the antibacterial activity weakened. The thioylbenzamides linked to piperidine instead of a morpholine group may increase the antibacterial activities.

Dependences of water permeation through cyclic octa-peptide nanotubes on channel length and membrane thickness.

Effects of the channel length and membrane thickness on the water permeation through the transmembrane cyclic octa-peptide nanotubes (octa-PNTs) have been studied by molecular dynamics (MD) simulations. The water osmotic permeability (p(f)) through the PNTs of k × (WL)(4)/POPE (1-palmitoyl-2-oleoyl-glycerophosphoethanolamine; k = 6, 7, 8, 9, and 10) was found to decay with the channel length (L) along the axis (~L(-2.0)). Energetic analysis showed that a series of water binding sites exist in these transmembrane PNTs, with the barriers of ~3k(B)T, which elucidates the tendency of p(f) well. Water diffusion permeability (p(d)) exhibits a relationship of ~L(-1.8), which results from the novel 1-2-1-2 structure of water chain in such confined nanolumens. In the range of simulation accuracy, the ratio (p(f)/p(d)) of the water osmotic and diffusion permeability is approximately a constant. MD simulations of water permeation through the transmembrane PNTs of 8 × (WL)(4)/octane with the different octane membrane thickness revealed that the water osmotic and diffusion permeability (p(f) and p(d)) are both independent of the octane membrane thickness, confirmed by the weak and nearly same interactions between the channel water and octane membranes with the different thickness. The results may be helpful for revealing the permeation mechanisms of biological water channels and designing artificial nanochannels.

Novel quadruple fluorescence properties of two benzoylthiourea isomers.

Two benzoylthiourea isomers, N-2-flurobenzoy-N'-4- (N,N-dimethyl)amidophenylthiourea (2FBDAPT) and N-4-fluro-benzoy-N'-4- (N,N-dimethyl)amidophenylthiourea (4FBDAPT) were determined by fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and X-ray diffraction. It was found that intra- and intermolecular hydrogen bonds played an important role in determining their conformations. Electronic spectra of the two compounds were investigated by UV absorption and steady-state fluorescence methods. The intermolecular hydrogen bond between the title compounds and methanol molecules caused the long wavelength absorption bands in methanol to weaken and vanish indeed. Quadruple fluorescence bands in ultraviolet and visible region were observed in the studied solvents upon the variable excitation wavelength. As same as Azumaya's suggestions for benzanilide (BA), F4 fluorescence bands with the maximum wavelength (λ(max)) between 546 nm and 622 nm were characteristic of TICT fluorescence. F3 bands of λ(max) from 434 nm to 483 nm were explained by the ESIPT model of the S1 state of the thiol tautomer to the S1 state of the keto tautomer. The new proposition was that F2 bands with λ(max) at about 365 nm were attributed to ESIPT from the S1 state of the thiol tautomer to the S0 state of the enol tautomer. And F1 fluorescence emissions with λ(max) at about 310 nm originated from the local S1 transitions of the enol tautomer. All experimental results were supported by MP2, CASSCF and CASPT2 quantum chemical calculations.

Water diffusion behaviors and transportation properties in transmembrane cyclic hexa-, octa- and decapeptide nanotubes.

Molecular dynamics simulations have been performed on three transmembrane cyclic peptide nanotubes, i.e., 8 × (WL)(n=3,4,5)/POPE (with uniform lengths but various radii) to investigate the radial dependences of the water-chain structures, diffusions, and transportation properties. The diffusions of individual water molecules and collective coordinates of all the channel-water in the three systems are certified as unbiased Brownian motions. From the very good linear relationships between MSDs and time intervals, the diffusion coefficients and transportation permeabilities have been deduced efficiently. Under the hydrostatic pressure differences across the membrane, a net unidirectional water flow rose up, and the osmotic permeabilities were determined. The ratios of the osmotic and diffusion permeabilities (p(f)/p(d)) were examined for all the three channels.

Molecular dynamics simulation for the structure of the water chain in a transmembrane peptide nanotube.

The structure of the water chain in the 8 x cyclo-(WL)(4) peptide nanotube embedded in the POPE lipid bilayer is studied by molecular dynamics simulations. The distribution profiles of water molecules along the nanotube axis proposes a wavelike pattern of the water chain in the nanotube, arraying in the form of a 1-2-1-2 file, in contrast to the single file in other nanochannels studied widely. Cylindrical distribution functions of water at different zones and potential of mean force of a water molecule along the axis suggest that the primary reason for forming the water-chain pattern is steric constraints. A novel hydrogen bond network in the nanotube is present such that each water in the alpha-plane zones forms two hydrogen bonds (as a donor) with the two water molecules in the adjacent midplane zone, and each water molecule in the midplane zones forms one hydrogen bond with the water molecule in the adjacent alpha-plane zone and a poor hydrogen bond with the carbonyl groups in the nanotube. Strong orientations of the water dipoles near the two opening ends pointing to the opposite directions are found, and the potential energy of a water O or H atom along the axis is explored to explain the water dipole orientations' reversing in the nanotube. Defects of the hydrogen bond network exist in the central gaps of the cyclic peptide nanotube.

[Theoretical studies on fluorescence spectra of polyamic acid and it's grafted derivatives].

A theoretical study on the polyamic acid (PAA) and its derivatives with different side chain (GPAA1-4) by semi-empirical PM3 is presented in this paper. After optimization, the authors get their balanceable geometric configurations. For all optimal geometric configurations, there is no imaginary frequency in vibrational analysis, which proves that the geometric configurations are stable. On this basis, the electronic spectra have been calculated by a single-excitation configuration interaction (CIS) method. Tie calculated results are consistent with experimental values on the whole. The authors found that the fluorescence intensity of polyamic acid (PAA) with p-pi conjugation side chain is enhanced obviously, and the longer the alkyl side chain the more intense the fluorescence will be. This will help us to design and synthesize the polymer fluorescence material.

[Comparison of curative effect between decompression and incision of endolymphytic sac].

OBJECTIVE: We compared the curative effect between endolymphytic sac decompression and incision of endolymphytic sac to explore a simple, effective surgical way with less complication. METHOD: 23 endolymphatic sac decompression and 22 incision of endolymphatic sac were performed routinely under general anesthesia. RESULT: 41 of 45 patients were followed up more than 2 years after the surgical procedure, 21 of which received endolymphatic sac decompression, while others received incision of endolymphatic sac. According to Chinese Meniere disease's diagnosis and curative effect standard evaluation criteria tried out in 1996, 13 got grade A(completely controlled), 4 got grade B (fundamentally controlled), 3 got grade C (partially controlled) while 1 got grade D (not controlled) among 21 patients who received endolymphatic sac decompression. The fully control rate is 61.9%. Among 20 patients who received incision of endolymphatic sac, 12 got grade A (completely controlled), 5 got grade B (fundamentally controlled), 2 got grade C (partially controlled) while 1 got grade D (not controlled). The fully control rate is 60%. CONCLUSION: There is no significant difference between endolymphatic sac decompression and incision of endolymphatic sac in curative effect,but endolymphatic sac decompression is more convenient,safe and has less complication compared with incision of endolymphatic sac. From this,we favor endolymphatic sac decompression in selection of surgical method.