Boosting activity of γ-alumina-supported vanadium catalyst for isobutane non-oxidative dehydrogenation via pure V3.

The vanadium-based dehydrogenation (DH) catalyst is becoming a promise alternative to the industrial used Pt- and Cr-based catalysts, due to lower cost and less environmental threat. However, the low DH activity hampered the industrial application of vanadium-based catalysts. Herein, for the first time, we introduce a method to prepare high-efficiency vanadium-based catalyst by constructing pure V3+ species on γ-Al2O3 through treatment of as-prepared thiovanadate. The V3+ species contributes to not only enhancing the DH activity, but also fabricating the V3+-O/S acid-base pair with ideal strength and stability. The isobutene yield can reach as high as 56.9 wt%. Only Lewis acid is recognized on V3+/Al2O3 catalyst, while no Brønsted acid remains. The side-reactions are consequently inhibited, and the selectivity to isobutene is improved. Besides, with the increase of vanadium loadings, the Lewis acid content increases at first and then decreases, and the content of acid sites in middle strength keeps decreasing. Though the deposited coke on V3+/Al2O3 was just 2.5 wt% during 8.5 h consecutive DH reaction, the valence state of vanadium was still influenced and the fraction of inert V4+ species increased steadily. This study will improve the potential for industrial application of vanadium-based DH catalyst, and offer theoretical guidance for optimization of ideal DH catalysts.

Novel two-photon absorption compounds with different organic cations: facile synthesis, photophysical properties, detection of viscosity, and selective imaging of the endoplasmic reticulum in living cells.

Three novel imidazole-based two-photon absorption compounds bearing different organic cations (1PIPy, 2PIQu, and 3PIIm) were facilely synthesized and fully characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. The linear and nonlinear photophysical properties of the target compounds were systematically investigated in various solvents, supplemented with the density functional theory calculations to shed light on their structure-property relationships. The maximum two-photon action cross-sections (Φ × Î´max) were determined to be 22.4-98.2 (CH2Cl2), 9.6-41.3 (DMF), and 3.9-11.8 (H2O) GM. It is found that 3PIIm shows significant viscosity sensitivity with a sharp 27-fold increase in fluorescence intensity. Its fluorescence intensity also exhibits a linear relationship with the viscosity of the media in a logarithmic plot. The Φ × Î´max value of 3PIIm in highly viscous glycerol was found to be 107.5 GM. Cytotoxicity tests indicate that these compounds have relatively low cytotoxicity. All the target compounds were successfully characterized by one- and two-photon fluorescence imaging in living cells. The colocalization experiments reveal that 1PIPy and 3PIIm are specially located in the endoplasmic reticulum (ER) with the Pearson's coefficients above 0.90. 3PIIm can also monitor the fluctuation of ER viscosity during etoposide-induced apoptosis.

Novel red light-emitting two-photon absorption compounds with large Stokes shifts for living cell imaging.

Three novel donor-π-acceptor two-photon absorption compounds (1PZPy, 2PZIm, 3CZPy) bearing the 10-butyl-10H-phenothiazine (9-butyl-9H-carbazole) donor, the pyridinium (benzimidazolium) acceptor, and the 2,5-divinylthiophene π-bridge were synthesized and fully characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. The linear and nonlinear photophysical properties were systematically investigated. Their absorption properties show a strong solvent dependence, while the emission properties are nearly independent of solvent polarity. All of them possess large Stokes shifts (Δλ=149-190 nm in H2O). 1PZPy and 3CZPy exhibit red fluorescence emission centered at about 635 and 660 nm, respectively. The two-photon absorption cross-sections measured by the open aperture Z-scan technique are determined to be 486 (1PZPy), 601 (2PZIm), and 753 GM (3CZPy) in DMF. The density functional theory calculations were further carried out to reveal their electronic structures. All the target compounds are verified to have low cytotoxicity in the working solution and good capability for one- and two-photon excitation fluorescence imaging, suggesting their potential application in bioimaging. Moreover, they show the organelle targeting ability in living cells with the high Pearson's coefficients above 0.94 for the endoplasmic reticulum.

Isobutane dehydrogenation over high-performanced sulfide V-K/γ-Al2O3 catalyst: Modulation of vanadium species and intrinsic effect of potassium.

Compared with industrial used Pt- and Cr-based catalyst in dehydrogenation (DH) of light alkanes, the sulfide V-K/γ-Al2O3 catalyst reported in this study shows lower cost and toxicity, and significant DH performance. The yield to isobutene reached as high as 52.9%, which is among the highest reported to date. We attribute such high isobutene yield to the precise modulation of polymerization degree for vanadium species via doping of potassium and indicating that the synergy between vanadium species and acid sites is critical to enhance the DH performance. Our previous work showed sulfidation promoted the increase of DH performance for vanadium-based catalyst, and we go further in this study to explore the correlation between increased range of DH performance and the added potassium. The different loaded potassium leads to variation in sulfidation degree, affecting the properties of vanadium species and acid properties consequently. The potassium was distributed uniformly on surface of the sulfide vanadium-based catalyst and was predominantly bonded with the vanadium species rather than with the γ-Al2O3 support. With increasing the potassium amount from 0 to 3 wt%, the acid amount kept decreasing, and some specific strong acid sites appeared once adequate sulfur was introduced in the V-K/γ-Al2O3 catalyst. The characterization and DFT results both revealed that the doped potassium contributes to regulating the vanadium species in the oligomeric state. The synergy between vanadium species and acid properties was regulated by the added potassium simultaneously, and thus the DH performance was enhanced. This study provides promising strategy for preparation of environment-friendly model industrial DH catalyst.

An "Umpolung Relay" Strategy: One-Pot, Twice Polarity Inversion Cascade Synthesis of Diversified [60]Fulleroindoles.

An "umpolung relay" strategy, which includes an one-pot, twice polarity inversion cascade of C60 via carbanion and carbocation polarity reversed relay pathway, has been developed for the synthesis of a diverse range of novel [60]fulleroindole derivatives.

A novel flurophore-cyano-carboxylic-Ag microhybrid: Enhanced two photon absorption for two-photon photothermal therapy of HeLa cancer cells by targeting mitochondria.

In this study, a novel two-photon photothermal therapy (TP-PTT) agent based on an organic-metal microhybrid with surface Plasmon resonance (SPR) enhanced two-photon absorption (TPA) characteristic was designed and synthesized using a fluorescent cyano-carboxylic derivative 2-cyano-3-(9-ethyl-9H-carbazol-3-yl) -acrylic acid (abbreviated as CECZA) and silver nanoparticles through self-assembly process induced by the interfacial coordination interactions between the O/N atom of CECZA and Ag+ion at the surface of Ag nanoparticles. The coordination interactions caused electron transfer from the Ag nanoparticles to CECZA molecules at the excited state, resulting in a decreased fluorescence quantum yield. The interfacial coordination interactions also enhanced the nonlinear optical properties, including 13 times increase in the TPA cross-section (δ). The decreased fluorescence quantum yield and increased two photon absorption caused by the SPR effect led excellent two-photon photothermal conversion, which was beneficial for the TP-PTT effect on HeLa cancer cells.

A specific HeLa cell-labelled and lysosome-targeted upconversion fluorescent probe: PEG-modified Sr2YbF7:Tm3+ .

In this study, water-soluble PEG-modified Sr2YbF7:Tm3+ was prepared conveniently by a one-pot solvothermal method, where the molar ratio of Sr2+ to Yb3+ was controlled between 3 : 2 and 1 : 1. The optimum red-light emission at 677-699 nm was modulated via 0.7% Tm3+ doped under irradiation at 980 nm. Interestingly, biological experimental results showed that the PEG-modified Sr2YbF7:Tm3+ with low toxicity, excellent cell membrane permeability and high photostability can not only distinguish HeLa cells from mouse embryonic fibroblasts but also target the subcellular organelle lysosome in HeLa cells; therefore it can be anticipated that the as-prepared material would be a potential tool for cancer diagnosis.

Coordination coupling enhanced two-photon absorption of a ZnS-based microhybrid for two-photon microscopy imaging in HepG2.

Coordination coupling induced self-assembly of ZnS microparticles was performed with the help of a π-conjugated sulphur-terminal Zn(ii) complex ZnS2L (L = N-hexyl-3-{2-[4-2,2':6',2''-terpyridin-4'-yl-phenyl]ethenyl}-carbazole). The interactions between ZnS and ZnS2L components at the interface, which were analyzed by far-IR and XPS, resulted in a tunable single-photon excited fluorescence and an enhanced nonlinear optical response, including a two-photon absorption cross section and a two-photon excited fluorescence. Such an enhancement in nonlinear optical properties was triggered by the coordination coupling effect between terminal S atoms of ZnS2L and naked Zn2+ ions at the surface of ZnS particles. Thus, the novel hybrid system displayed a unique two-photon excited fluorescence to facilitate promising two-photon microscopy imaging of HepG2 cells upon NIR light illumination at 840 nm. The hybrid shows a stronger ability to enter the cells than free ZnS2L.

Crystal structure of poly[di-chlorido-(µ-2,5-di-carb-oxy-benzene-1,4-di-carboxyl-ato-κ2O1:O4)bis-[µ-4'-(pyridin-3-yl)-4,2':6',4''-terpyridine-κ2N1:N4']dizinc].

In the title polymeric ZnII complex, [Zn2(C10H4O8)Cl2(C20H14N4)2] n , the ZnII cations are bridged by both 2,5-di-carb-oxy-benzene-1,4-di-carboxyl-ate dianions and 4'-(pyridin-3-yl)-4,2':6',4''-terpyridine ligands, forming ladder-like polymeric chains propagating along [1-10]. The Cl- anion further coordinates the ZnII cation to complete a distorted tetra-hedral environment. In the 4'-(pyridin-3-yl)-4,2':6',4''-terpyridine ligand, the three sideward pyridine rings are twisted with respect to the central pyridine ring by 39.27 (12), 14.89 (13) and 3.36 (13)°, respectively. In the crystal, classical O-H⋯N hydrogen bonds and weak C-H⋯O and C-H⋯Cl hydrogen bonds link the chains into a three-dimensional supra-molecular architecture. π-π stacking is observed between the pyridine and benzene rings of neighbouring polymeric chains, with a centroid-to-centroid distance of 3.7280 (14) Å.

A new series of two-photon blue/violet fluorescent trans-alkenes: Green synthesis and optical properties.

A new series of trans-alkenes (3a-3e) containing different electron-donating groups were synthesized by the solvent-free Horner-Wadsworth-Emmons reaction, and characterized by infrared, hydrogen nuclear magnetic resonance, mass spectrometry and elemental analysis. Their UV-visible absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence were systematically investigated in different solvents. Experimental results show different trends in linear and nonlinear optical properties with different donor units. 3a with triphenylamine donor exhibits the best optical properties. It emits strong blue up-converted fluorescence, and the two-photon absorption cross-section can be as large as 218 GM in DCM.

A zinc(II) metal-organic framework with a novel topology formed from 4,4',4''-nitrilotribenzoate and 4,4'-bipyridine ligands.

A metal-organic framework with a novel topology, poly[sesqui(µ2-4,4'-bipyridine)bis(dimethylformamide)bis(µ4-4,4',4''-nitrilotribenzoato)trizinc(II)], [Zn3(C21H12NO6)2(C10H8N2)1.5(C3H7NO)2]n, was obtained by the solvothermal method using 4,4',4''-nitrilotribenzoic acid and 4,4'-bipyridine (bipy). The structure, determined by single-crystal X-ray diffraction analysis, possesses three kinds of crystallographically independent Zn(II) cations, as well as binuclear Zn2(COO)4(bipy)2 paddle-wheel clusters, and can be reduced to a novel topology of a (3,3,6)-connected 3-nodal net, with the Schläfli symbol {5.6(2)}4{5(2).6}4{5(8).8(7)} according to the topological analysis.

2-((E)-{4-[Bis(4-eth-oxy-phen-yl)amino]-phen-yl}imino-meth-yl)phenol.

In the title Schiff base mol-ecule, C29H28N2O3, the three terminal benzene rings are twisted by 73.84 (15), 81.25 (16) and 12.1 (2)° with respect to the central benzene ring. An intra-molecular O-H⋯N hydrogen bond occurs. In the crystal, mol-ecules are linked via weak C-H⋯π inter-actions into a three-dimensional supra-molecular architecture.

A tetranuclear organotin compound consisting of a core of three fused Sn2O2 rings.

The crystal structure of the tetranuclear organotin compound 1,1,3,3,5,5,7,7-octabutyl-7-((E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoyloxy)-4,8-dimethyl-2,4,6,8-tetroxa-1,3,5,7-tetrastannatricyclo[4.2.0.0(2,5)]oct-3-yl (E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoate, [Sn4(C4H9)8(C21H19N2O4)2(CH3O)2(µ3-O)2], consists of a core of three fused Sn2O2 rings. The central ring consists of two Sn atoms each coordinated by two n-butyl chains, two µ3-bridging O atoms and one µ2-bridging methanolate O atom. The peripheral Sn2O2 rings consist of one of the central ring Sn atoms, and an Sn coordinated by one µ3-bridging O atom, one µ2-bridging methanolate O atom, two n-butyl chains and the carboxylate O atom of a (E)-2-cyano-3-{9-[2-(2-methoxyethoxy)ethyl]-9H-carbazol-3-yl}prop-2-enoate ligand (L). Despite an apparent centrosymmetric nature, the complex does not crystallize about an inversion centre. The structure packs with π-π interactions between carbazole moieties on adjacent molecules.

Poly[tetrachlorido{µ4-tetrakis[(imidazol-1-yl)methyl]methane-κ4N3:N3':N3'':N3'''}dizinc(II)] exhibiting a three-dimensional diamond topology.

The title novel noncentrosymmetric metal-organic framework, [Zn2Cl4(C17H20N8)]n, was prepared solvothermally using the tetradentate tetrakis[(imidazol-1-yl)methyl]methane (tiym) linker in the presence of zinc nitrate under acidic conditions. The asymmetric unit contains one Zn(II) cation, two Cl(-) anions and a quarter of each of two symmetry-independent tiym ligands. Each Zn(II) cation is four-coordinated by two Cl(-) anions and two imidazole N atoms from two tiym ligands, forming a distorted tetrahedral coordination geometry. The tetrahedral tetradentate tiym linker has a quaternary C atom located on a crystallographic -4 axis. With its four peripheral imidazole N atoms, the linkers are bridged by four [ZnCl2] subunits to generate a three-dimensional diamond topological framework, which is represented by the Schläfli symbol {6(6)}. To the best of our knowledge, the title compound is the first example of a non-interpenetrating diamond net based on the tiym ligand.

Silver(I) supramolecular complexes generated from isophorone-based ligands: crystal structures and enhanced nonlinear optical properties through metal complexation.

By self-assembly of (E)-2-(3-(4-(1H-imidazol-1-yl)styryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile (L(1)) and (E)-2-(3-(4-(1H-1,2,4-triazol-1-yl)styryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile (L(2)) with silver(I) salts, eight new complexes, namely AgL(1)2ClO4 (1), AgL(1)2NO3 (2), [AgL(1)2NO3]·C6H6 (3), [AgL(1)2OOCCF3]·C6H6 (4), [AgL(1)2PF6]·C6H6 (5), AgL(2)2NO3 (6), [AgL(2)OOCCF3]2 (7) and AgL(2)2PF6 (8), are presented along with an analysis of their structural features. The structures are built up through the combination of coordination bonds, Ag···π, Ag···F (or O), hydrogen bonding, and π···π stacking interactions to generate new supramolecular architectures. We observed the formation of two-dimensional coordination polymers for complex 7. Solvent benzene molecules and anions are dispersed in the supramolecular structure and play a vital role in building the supramolecular structures of the complexes. The nonlinear optical (NLO) properties of the complexes were investigated using the Z-scan technique and complexes 1, 2, 3, 4 and 7 show obviously nonlinear absorption compared with ligands (L(1) and L(2)).

Synthesis, characterization, cytotoxicity and antibacterial activity of an anthracenyl-linked bis(pyrazolyl)methane ligand and its zinc(II) complexes.

Three novel Zn(II) complexes (1-3) with 1,1'-(anthracen-9-ylmethylene)bis(1H-pyrazole) (L(2)) have been prepared and structurally characterized by X-ray crystallography. Among them, 1 is a binuclear Zn(II) complex while 2 and 3 are mononuclear. The in vitro cytotoxic and antibacterial activities of these complexes were also evaluated. The three complexes exhibit cytotoxic specificity and significant antitumor activity. The MIC50 value of complex 1 against Pseudomonas putida reaching 0.011 µg/mL much lower than that the positive control chloromycin (0.182 µg/mL), indicates that complex 1 is a potent antibacterial agent.

A self-assembled nanohybrid composed of fluorophore-phenylamine nanorods and Ag nanocrystals: energy transfer, wavelength shift of fluorescence and TPEF applications for live-cell imaging.

A fluorophore-phenylamine derivative (L) has been coupled with silver nanocrystals (NCs) to construct an L-Ag nanohybrid. Owing to synergic effects of the L and Ag components, the exciton-plasmon interactions between L and Ag increase the strength of the donor-acceptor interaction within the nanohybrid, a fact that results in an energy-transfer process and further brings about a dramatic redshift of single-photon absorption and fluorescence, and a decreased fluorescence FL lifetime. The coupling effect also leads to enhancement of a series of nonlinear optical properties, including two-photon-excited fluorescence (TPEF), two-photon-absorption (TPA) cross section (δ), two-photon-absorption coefficient (ß), nonlinear refractive index (γ), and third order nonlinear optical susceptibility (χ((3))). The enhanced two-photon fluorescence of the nanohybrid is proven to be potentially useful for two-photon microscopy of live cells, such as HepG2. Moreover, cytotoxicity tests show that the low-micromolar concentrations of the nanohybrid do not cause significant reduction in cell viability over a period of at least 24 h and should be safe for further biological studies.

N,N-Diethyl-4-[1-phenyl-3-(pyridin-2-yl)-4,5-di-hydro-1H-pyrazol-5-yl]aniline.

In the title mol-ecule, C24H26N4, the pyrazoline ring assumes an envelope conformation with the aniline-bearing C atom at the flap position. The benzene ring and the pyridine ring form with the pyrazoline ring dihedral angles of 4.53 (1) and 6.26 (1)°, respectively. In turn, the aniline group is nearly perpendicular to the pyrazoline ring [dihedral angle = 79.96 (1)°]. The ethyl groups of the di-ethyl-amine substituent are disordered over two sets of sites, with an occupancy ratio of 0.624 (8):0.376 (8).

{9-Hexyl-2-[2-phenyl-6-(pyridin-2-yl)pyridin-4-yl]-9H-carbazole}di-iodido-zinc.

In the title compound, [ZnI2(C34H31N3)], the Zn(II) atom is four-coordinated by two I atoms and the pyridine N atoms from the bidentate 6'-phenyl-2,2'-bi-pyridine ligand in a distorted tetra-hedral geometry.

N,N-Di-phenyl-4-(1H-pyrrolo[1,2-f][1,10]phenanthro-lin-2-yl)-aniline ethanol monosolvate.

The title compound, C32H21N4·C2H5OH, crystallized as an ethanol monosolvate. In the mol-ecule of this phenanthroline derivative, the pyridine rings are almost coplanar, making a dihedral angle of 1.54 (13)°. The tri-phenyl-amine group, introduced as an electron donor, shows a propeller-type structure, and the dihedral angles between the benzene rings are 68.71 11), 63.92 (16) and 70.81 (15)°. In the crystal, the phenanthroline mol-ecules are linked via the solvent mol-ecule by N-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds, leading to the formation of zigzag chains propagating along [010]. These chains are linked via C-H⋯N hydrogen bonds, forming undulating two-dimensional networks extending in the a- and b-axis directions.