A visible-light-induced cascade reaction of etherification/C-C cyclization: efficient synthesis of dibenzo[b,d]oxepin-7(6H)-ones.

A visible-light-induced palladium-catalyzed cascade reaction was developed by etherification/C-C coupling cyclization of α-bromoacetophenones with phenols. A series of dibenzo[b,d]oxepin-7(6H)-one derivatives were efficiently synthesized by using this method in good yields. Furthermore, this method was applied to the synthesis of protosappanin A. The protocol has advantages such as simple reaction conditions, wide range of substrates and high reaction efficiency.

Construction of highly-stable covalent organic framework with combined enol-imine and keto-enamine linkages.

A novel covalent organic framework (COF) (Tp-BI-COF) with combined ketimine-type enol-imine and keto-enamine linkages was prepared through a cascade of ketimine condensation followed by aldimine condensation and characterized by XRD, solid state 13C NMR, IR, TGA and BET. Tp-BI-COF showed high stability toward acid, organic solvent, and boiling water. The 2D COF exhibited photochromic properties after being irradiated with a xenon lamp. The stable COF, with aligned one-dimensional nanochannels, provided nitrogen sites on pore walls, which confine and stabilize the H3PO4 in the channel via hydrogen-bonding interactions. After loading with H3PO4, the material showed excellent anhydrous proton conductivity.

catena-Poly[[(5-phenyl-2,2'-bipyridine-κN,N')copper(I)]-µ-thio-cyanido-κN:S].

The title compound, [Cu(NCS)(C(16)H(12)N(2))](n), was synthesised under hydro-thermal conditions. The Cu(I) ion shows distorted tetra-hedral geometry being coordinated by two N atoms from a 5-phenyl-2,2'-bipyridine ligand and by the N and S atoms from two different thio-cyanate anions. The Cu(I) ions are bridged by thio-cyanide groups, forming a one-dimensional coordination polymer along the b axis. The crystal packing is through van der Waals contacts and C-H⋯π inter-actions.

Metal-organic framework bearing new viologen ligand for ammonia and Cr2O7 2- sensing.

Three anionic metal-organic frameworks (MOFs) {[Zn3(BTEC)2(H2O)(4-BCBPY)]·(H2O)} n (1-3) (BTEC4- = 1,2,4,5-benzenetetracarboxylic acid anion, 4-BCBPY2+ = 1,1'-bis(4-cyanobenzyl)-4,4'-bipyridinium dication) were synthesized in the reaction of 1,2,4,5-benzenetetracarboxylic acid with different metal salts such as ZnNO3, ZnCl2, and ZnSO4, under solvothermal conditions in the presence of 1,1'-bis(4-cyanobenzyl)-4,4'-bipyridinium chloride. Single crystal X-ray diffraction analysis shows that compounds 1, 2 and 3 have MOF structures based on binuclear metal building units, which are connected by two protonated BTEC4- ligands and three zinc ions, and the viologen cation 4-BCBPY2+ is located in the channel to achieve charge balance. Compounds 1, 2 and 3 have good photosensitivity, respond to sunlight, UV light and blue ray, and turn blue. The D-A distance and π-π stacking distance of the discolored samples (1P, 2P and 3P) changed. In addition, the three compounds showed visible color changes to ammonia vapor, rapidly changing from white to blue. At the same time, the three compounds exhibited fluorescence quenching to ammonia vapor and Cr2O7 2-. It is further proved that compounds 1, 2 and 3 are fluorescent sensors with a low detection limit (for Cr2O7 2-: 10-5 M) and high sensitivity for ammonia vapor and Cr2O7 2-. It was found that photochromic behavior, ammonia sensing properties can be tuned by the nature of metal salts.

Poly[penta-kis-(µ-cyanido-κN:C)tris-(5-phenyl-2,2'-bipyridine-κN,N')penta-copper(I)].

The hydro-thermal reaction of Cu(acetate)(2) and K(3)[Fe(CN)(6)] with 5-phenyl-2,2'-bipyridine (5-ph-2,2'-bpy) in water yields the polymeric title complex, [Cu(5)(CN)(5)(C(16)H(12)N(2))(3)](n), which consists of ribbons along the a axis, constructed from 26-membered {Cu(10)(CN)(8)} rings. In these rings, the metal atoms are bridged by cyanide groups, except for one close Cu⋯Cu contact [2.7535 (12) Å], which can be considered as ligand-unsupported. Within the rings, one Cu atom has a distorted tetra-hedral geometry through the coordination to two N atoms from 5-ph-2,2'-bpy and two N/C atoms from two cyanide groups. Two Cu atoms have a trigonal planar environment being coordinated by three cyanide groups and two other Cu atoms have a distorted square planar geometry through coordination to two N atoms from 5-ph-2,2'-bpy and two N/C atoms from two cyanide groups.

[Density functional theory calculation of SERS spectra of trans-1,2-bis(4-pyridyl)-ethylene on silver].

It has been found that trans-1, 2-bis(4-pyridyl)-ethylene has the best SERS signal and can be employed as a kind of self-assembly ? Im for the exploration of the SERS-active on the silver foil substrate. The shifts in the experiment surface enhanced Raman scattering of trans-1,2-bis(4-pyridyl)-ethylene were simulated by density functional theory calculation with the BP86, BPw91, B3LYP method. The basis set of 6-31++G(d,p) and Lan12dz was used by H, C, N atoms and Ag atom for the t-BPE-Ag complex. The Raman spectra and surface enhanced Raman scattering of trans-1, 2-bis (4-pyridyl)-ethylene were assigned by the calculated results of potential energy distribution The density functional theory calculated results explain that the angles between pyridyl rings for t-BPE-Ag complex holding 0o. Thus, the calculated Raman spectra of trans-1, 2-bis(4-pyridyl)-ethylene and Ag complex accord with observed SERS results of t-BPE. The energy level space between the high occupied molecular orbital and lowest unoccupied molecular orbital is estimated to arise between 415 and 912 nm for trans-1,2-bis(4-pyridyl)-ethylene and Ag complex.

Photocatalytic Degradation of Deoxynivalenol Using Cerium Doped Titanium Dioxide under Ultraviolet Light Irradiation.

Deoxynivalenol (DON) is a major mycotoxin with high toxicity that often contaminates grains, foods and feeds. The traditional approaches for DON removal are difficult to meet industry and agriculture demands due to the high stability of the DON molecule. Therefore, there is an urgent need to develop green and effective strategies for DON degradation. In this study, a batch of photocatalytic nanomaterials of cerium (Ce) doped titanium dioxide (TiO2) were successfully prepared by sol-gel method. The catalysts were systematically characterized by XRD, HRTEM, FT-IR, UV-Vis and XPS. The catalyst 0.5Ce-TiO2 showed superior photocatalytic activity for DON degradation in aqueous solution under ultraviolet light irradiation, better than that of traditional photocatalyst pure TiO2, and 96% DON with initial concentration of 5.0 mg/L could be degraded in 4 h. In addition, the two possible degradation intermediate products C5H8O3 and C17H18O6 were identified, the photocatalytic degradation mechanism and degradation pathway were studied. The results indicate that Ce doped TiO2 photocatalyst can be used to reduce DON effectively.

Visible Light-Induced Decarboxylative Alkylation of Heterocyclic Aromatics with Carboxylic Acids via Anthocyanin as a Photocatalyst.

A visible light-induced decarboxylative alkylation of heterocyclic aromatics with aliphatic carboxylic acids was developed by using anthocyanins as a photocatalyst under mild conditions. A series of alkylated heterocyclic compounds were obtained in moderate to good yields by using the metal-free decarboxylative coupling reaction under blue light. This strategy uses cheap and readily available carboxylic acids as alkylation reagents with good functional group tolerance and environmental friendliness. It is worth noting that this is the first time that anthocyanin has been used to catalyze the Minisci-type C-H alkylation. The mechanism of decarboxylation alkylation was studied by capturing the adduct of alkyl radical and hydroquinone, thus confirming a radical mechanism. This protocol provides an alternative visible light-induced decarboxylative alkylation for the functionalization of heterocyclic aromatics.

Rare gas atomic number dependence of the hyperpolarizability for rare gas inserted fluorohydrides, HRgF (Rg = He, Ar, and Kr).

The three structures of rare gas inserted fluorohydrides HRgF (Rg = He, Ar, and Kr) with all real frequencies are obtained at the QCISD(T)/aug-cc-pVTZ level. The static first hyperpolarizabilities (beta(0)) at the QCISD/aug-cc-pVQZ level are 8 a.u. (HF), 384 a.u. (HHeF), 737 a.u. (HArF), and 465 a.u. (HKrF). The beta(0) value remarkably increases by about 50-90 times from 8 a.u. (HF) to 384-737 a.u. (HRgF) due to the inserted rare gas (Rg). The Rg atomic number dependence of beta(0) for HRgF (Rg = He, Ar, and Kr) is found at the first time. The order of beta(0) is unmonotonic to be HHeFHKrF, but not monotonic (HHeF

Using α-Pinene-Modified Triethoxysilane as the New Cross-Linking Agent To Improve the Silicone Rubber Properties.

α-Pinene-modified triethoxysilane (α-PTES) was synthesized by hydrosilylation in the presence of Karstedt's catalyst. The structure of α-PTES was determined by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Under the catalysis of an organotin catalyst, α-PTES, which was the cross-linking agent, and the hydroxy-terminated poly(dimethylsiloxane) matrix were utilized to prepare the room-temperature vulcanized silicone rubber. Morphology, thermal performance, and mechanical properties of the modified silicone rubber were investigated by scanning electron microscopy, thermal gravimetric analysis, dynamic mechanical analysis, and a universal testing machine. Because of the strong rigidity of the ring structure of α-pinene, the thermal and mechanical properties of modified silicone rubber were improved greatly than those of the silicone rubber, and the cross-linking agent of which was methyltriethoxysilane. Results showed that the tensile strength and the break at elongation increased by 69.2 and 125%, respectively, and they are nearly doubled compared to the unmodified silicone rubber.

Crystal structure of poly[(2,2'-bi-pyridine-κ(2) N,N')tetra-kis-(µ-cyanido-κ(2) N:C)dinickel(II)].

The polymeric title complex, [Ni2(CN)4(C10H8N2)] n , was obtained serendipitously under hydro-thermal conditions. The asymmetric unit consists of one half of an [Ni(CN)4](2-) anion with the Ni(2+) cation situated on an inversion centre, and one half of an [Ni(2,2'-bpy)](2+) cation (2,2'-bpy is 2,2'-bi-pyridine), with the second Ni(2+) cation situated on a twofold rotation axis. The two Ni(2+) cations exhibit different coordination spheres. Whereas the coordination of the metal in the anion is that of a slightly distorted square defined by four C-bound cyanide ligands, the coordination in the cation is that of a distorted octa-hedron defined by four N-bound cyanide ligands and two N atoms from the chelating 2,2'-bpy ligand. The two different Ni(2+) cations are alternately bridged by the cyanide ligands, resulting in a two-dimensional structure extending parallel to (010). Within the sheets, π-π inter-actions between pyridine rings of neighbouring 2,2'-bpy ligands, with a centroid-to-centroid distance of 3.687 (3) Å, are present. The crystal packing is dominated by van der Waals forces. A weak C-H⋯N inter-action between adjacent sheets is also observed.

Surface-enhanced Raman scattering of trans-1,2-bis (4-pyridyl)-ethylene on silver by theory calculations.

Surface-enhanced Raman spectra of trans-1,2-bis (4-pyridyl)-ethylene (t-BPE) on silver foil were detected at laser line of 514.5, 633, 785 and 1064 nm, respectively. The structure of Ag-t-BPE, Ag4-t-BPE, Ag6-t-BPE, Ag10-t-BPE and Ag20-t-BPE complexes has been calculated using a local version of the Amsterdam density functional program package. The Raman spectra and electronic polarizability of t-BPE-Ag at 514.5, 633, 785 and 1064 nm excitation lines were calculated. The Raman bands of t-BPE were assigned according to the calculation of potential energy distribution. The experimental and calculated Raman spectra of t-BPE-Ag at 514.5, 633, 785 and 1064 nm were compared. The relative Raman intensities change at different excitation lines were discussed based on the Raman enhanced mechanism and surface selection rules.