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.

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 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.

Bis(4-{2-[4-(diethyl-amino)-phen-yl]ethen-yl}pyridine-κN)diiodidozinc.

In the title compound, [ZnI2(C17H20N2)2], the Zn(II) atom is four-coordinated by two I atoms and the N atoms of two pyridine rings belonging to different ligands in a distorted tetra-hedral geometry. The coordinating pyridine rings are oriented in an almost perpendicular fashion, making a dihedral angle of 83.7 (5)°.

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.

Methyl 3-(pyridin-4-yl-methyl-idene)di-thio-carbazate.

There are two independent mol-ecules in the asymmetric unit of the title mol-ecule, C8H9N3S2, both of which exhibit an E conformation with the pyridine ring and di-thio-carbazate fragment located on opposite sides of the C=N bond. The pyridine ring and di-thio-carbazate group are approximately coplanar, with dihedral angles of 4.74 (1) and 8.77 (1)° between their planes in the two mol-ecules. In the crystal, mol-ecules are linked to each other via N-H⋯N hydrogen bonds, forming zigzag chains parallel to [10-1].

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 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.

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.

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.

IR spectroelectrochemical cyclic voltabsorptometry and derivative cyclic voltabsorptometry.

In this paper, we report the IR (infrared) CVA (cyclic voltabsorptometry) and DCVA (derivative cyclic voltabsorptometry) spectroelectrochemical techniques to elucidate an electrochemical mechanism. First we set potassium ferrocyanide as an example to explain the validity of this method. Then the electrochemical redox of two compounds, 1,4-benzoquinone and 1,4-bis(2-ferrocenylvinyl)benzene, was selected to be examined with this method. 1,4-Benzoquinone exhibits two single-electron waves in the cyclic voltammetric (CV) experiment, whereas two electroactive groups (Fc) are contained in p-(Fc-CH=CH)(2)BZ, but only one redox wave is observed. IR CVA results show that three IR absorption peaks in 1,4-benzoquinone, 1232 cm(-1) (the absorption of final production), 1656 cm(-1) (the absorption of original reactant), and 1510 cm(-1) (the absorption of intermediate), and two IR absorption peaks in 1,4-bis(2-ferrocenylvinyl)benzene, 1620 cm(-1) (the absorption of final oxide production) and 1589 cm(-1) (the absorption of intermediate), can be used to track the electron transfer. On the basis of the IR absorbance at the appropriate monitored wavelength (mentioned above), we can analyze simultaneously the concentration change of the corresponding redox transition during CV scans. Also the combination of the DCVA spectroelectrochemical technique with theory analysis allows reconstructing the current-potential (i-E) curve for each step of electron transfer. The reconstructed i-E curve can help us to understand the electron-transfer process. We believe IR CVA and DCVA spectroelectrochemical techniques can be applicable to the study of a wide range of complex electrochemistry processes.

Various unique coordination patterns of Hg and DFT calculations to determine the formation of a 3-D supramoleculer framework by covalent and noncovalent interactions.

By combining a large pi-conjugated bidentate ligand L: 3,6-dipyrazole-N-ethylcarbazole with HgI(2), an extraordinary supramolecular coordination polymer, [Hg(4)L(2)I(8)](infinity), has been prepared. The crystal structures of the ligand and its coordination polymer were determined by X-ray crystallography, which shows three varied coordination modes especially the rare asymmetric quadruply bridged trinuclear moieties in [Hg(4)L(2)I(8)](infinity). Density functional theory (DFT) calculations (ADF) performed on model dimers show the roles of covalent and noncovalent interactions in establishing the three-dimensional architecture.

(E)-2-Hydroxy-naphthalene-1-carb-al-de-hyde semicarbazone.

The title compound, C(12)H(11)N(3)O(2), adopts an E or trans configuration with respect to the C=N bond. There is an intra-molecular O-H⋯N hydrogen bond involving the hydroxyl H atom and an N atom of the hydrazine group. In the crystal structure, mol-ecules are connected via N-H⋯O hydrogen bonds, forming a three-dimensional network.

[Synthesis, characterization, spectroscopy and theoretical calculation of two novel carbazole derivatives].

Two novel carbazole derivatives, 3-acetyl-9-n-hexylcarbazole (AHCZ) and 3, 6- diacetyl-9-n-hexylcarbazole (DHCZ) were synthesized through Friedel-Crafts reaction. The compounds were characterized by IR spectra, 1H NMR, MS and elemental analysis. UV-visible spectra of AHCZ and DHCZ were measured and compared with those of their precursors, 9-hexylcarbazole(HCZ) and carbazole(CZ). DHCZ and AHCZ exhibited strong absorption band, revealing the extent of pi conjugation in the system. TD-DFT method was performed to analyze the electronic absorption spectra of AHCZ and DHCZ, and the calculated excitation energies and oscillator strengths were compared with the experimental results.

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.