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Cycloheptatrienyl (tropyl) molecules are representative non‐alternant hydrocarbons that offer interesting chemistry because of their unique structures and properties. However, there have been a limited number of polycyclic aromatic tropyl cations and radicals reported in the literature. Herein, we report the synthesis of a series of azahomocorannulene derivatives, where the key reactions are a 1,3‐dipolar cycloaddition of polycyclic aromatic azomethine ylides with dibenzotropone and a subsequent palladium‐catalyzed cyclization. X‐ray diffraction analysis revealed that the obtained azahomocorannulenyl cation and radical adopt planar structures and exhibit unique packing structures. Their electronic and optical properties were investigated experimentally and theoretically to reveal their aromatic character. [ABSTRACT FROM AUTHOR]

Cycloheptatrienyl (tropyl) molecules are representative non‐alternant hydrocarbons that offer interesting chemistry because of their unique structures and properties. However, there have been a limited number of polycyclic aromatic tropyl cations and radicals reported in the literature. Herein, we report the synthesis of a series of azahomocorannulene derivatives, where the key reactions are a 1,3‐dipolar cycloaddition of polycyclic aromatic azomethine ylides with dibenzotropone and a subsequent palladium‐catalyzed cyclization. X‐ray diffraction analysis revealed that the obtained azahomocorannulenyl cation and radical adopt planar structures and exhibit unique packing structures. Their electronic and optical properties were investigated experimentally and theoretically to reveal their aromatic character. [ABSTRACT FROM AUTHOR]

Deprotonation of 1‐mesityl‐4,5‐diphenyl‐2‐imidazole 1 with nBuLi, followed by salt metathesis reaction with GeCl2·dioxane complex, led to the formation of the chlorogermyliumylidene 2 bearing two Ge–Cl units, which has been isolated and fully characterized by standard spectroscopic and X‐ray diffraction analysis. Structural and NMR spectroscopic data as well as computational studies revealed that the positive charge mainly resides on the Ge atom between two nitrogen atoms. Reduction of 2 with an excess amount of lithium metal resulted in Ge–Ge bond formation concomitant with elimination of one of the Ge atoms of 2, to give rise to the digermylenedilithium compound 3 involving intramolecular coordination of the imines and the lone pairs to the Li atoms. [ABSTRACT FROM AUTHOR]

The addition of phenyl lithium (PhLi) to an aromatic 1,3,2,5-diazadiborinine (1) afforded isolable ionic species 2, which can be deemed as an inorganic analogue of a Janovsky complex. X-ray diffraction analysis and DFT studies of 2 indicate the delocalization of π-type electrons mainly over the C–B–C unit in the central B2C2N2 six-membered ring. The reactions of 2 with methyl iodide (MeI) and chloro(tricyclohexylphosphine)gold(i) (Cy3PAuCl) gave 3 bearing a B–Me bond and 4 featuring a B–Au bond, respectively, demonstrating the nucleophilic properties of the tricoordinate boron center in 2. [ABSTRACT FROM AUTHOR]

A zwitterionic boraalkenyl boronium 3 was synthesized by reduction of cyclic (alkyl)(amino)carbene (cAAC) and trimethylphosphine (PMe3)-coordinated tetrabromodiborane 2 with KC8 in the presence of PMe3. Further reduction of 3 led to the formation of neutral allenic diborene 4. X-ray diffraction and computational studies revealed that 4 features the cumulated C=B and B=B double bonds. The reaction of 4 with four isonitrile molecules afforded a heterocycle 5 with the B2C3 five-membered ring, via a complete scission of the B=B bond of 4. [ABSTRACT FROM AUTHOR]

Reaction of cyclic (alkyl)(amino)phosphorous chloride 3 with GaCl 3 followed by the treatment with Me 3 NO afforded trimethylamine-stabilized oxophosphonium ion 5 , which was fully characterized by NMR spectroscopy and X-ray diffraction analysis. Computational study using DFT calculations indicates that the incorporation of a carbon atom next to the P center accumulates electron density on the P center. Oxophosphonium ion 5 is air and moisture stable but undergoes thermal decomposition to afford a phosphorus oxychloride 7 as well as a few single crystals of the by-product 8 . Reaction mechanisms for the formation of 7 and 8 may involve a Lewis base free oxophosphonium ion 6 . [ABSTRACT FROM AUTHOR]

Abstract: Catalytic synthesis of ethylbenzene by alkylation of benzene with diethyl oxalate was carried out over HZSM-5 with Si/Al ratios from 50 to 250. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ammonia temperature-programmed desorption (NH3-TPD) and pyridine IR techniques. As revealed by the results of NH3-TPD and pyridine IR spectra, a significant decrease in acidic strength and the number of acidic sites is observed with increasing Si/Al ratio from 50 to 250. The benzene conversion and ethylbenzene selectivity increases obviously with increasing Si/Al ratio from 50 to 200. With a further increase in Si/Al ratios, a slight decrease in the conversion of benzene and selectivity for ethylbenzene is detected, indicating that a proper acidic strength was required in this reaction. In addition, the effects of temperature and feed ratio on the catalytic activity and product distributions are also investigated in this study. [Copyright &y& Elsevier]

Abstract: Acidity adjustment of MCM-22 was carried out by hydrothermal treatment of parent MCM-22 with flowing pure steam at high temperature. XRD, SEM and N2 adsorption/desorption results indicated that the crystallinity and pore properties of MCM-22 were affected slightly by hydrothermal treatment at different temperatures. NH3-TPD and FT-IR with pyridine adsorption showed only a slight decrease in Brønsted acid sites, compared with parent MCM-22, with hydrothermal treatment temperature in the range 773–873K. The strength of Brønsted acid sites was reduced severely at hydrothermal treatment temperatures of 973 and 1073K. The Lewis acid sites were only slightly affected by hydrothermal treatment. A substantial improvement in ethylbenzene selectivity along with a slight decrease in benzene conversion was achieved in catalytic synthesis of ethylbenzene by alkylation of benzene with diethyl carbonate over MCM-22 hydrothermally treated at 873K. A sharp decrease in benzene conversion was detected over MCM-22 hydrothermally treated at 973K. The results indicate that alkylation of benzene with diethyl carbonate occurred mainly on Brønsted acid sites, and the effect of Lewis acid sites on the alkylation process is negligible. Reduction of Brønsted acid sites of the catalyst can suppress side reactions and improve selectivity for ethylbenzene. It was found that a particular acid strength of catalyst was required to maintain high benzene conversion and ethylbenzene selectivity. [Copyright &y& Elsevier]

A diastereoselective catalytic asymmetric hydrophosphination reaction was performed using a palladacycle catalyst to produce chiral PCP phosphine ligand with high dr (95:5) and excellent enantioselectivity (>99% ee). Subsequent facile metalation of the chiral ligand with Pt and Pd metal salts yielded the desired pincer complexes. The protonated form of these pincer complexes was also synthesised, and their structures were confirmed through the use of X-ray crystal diffraction and NMR spectroscopy analyses. [ABSTRACT FROM AUTHOR]

An autoionization of germanium dichloride/dioxane complex with an imino-N-heterocyclic carbene ligand ( L) afforded a novel germyliumylidene ion, [( L)GeCl]+[GeCl3]−, which was fully characterized. Reduction of the germyliumylidene ion with potassium graphite produced a cyclic species [( L)Ge], which can be viewed as both a Ge0 species and a mesoionic germylene. X-ray diffraction analysis and computational studies revealed one of the lone pairs on the Ge atom is involved in the π system on the GeC2N2 five-membered ring. It was also confirmed that the nucleophilic behavior of [( L)Ge] as a two lone-pair donor. [ABSTRACT FROM AUTHOR]

Eight diorganotin(IV)-oxo-carboxylates {[R2Sn(O(O)CR′)]2O}2 · Y (R′ = C4H3N2Y = H2OR = nBu 1, Y = 0 R = Me 2, Y = 0 R = C6H53, Y = 0 R = C6H5CH24; R′ = CH2SC4H3N2-2,6Y = 0 R = nBu 5, Y = CH2Cl2R = Me 6, Y = 0 R = C6H57, Y = 0 R = C6H5CH28) have been prepared in 1 : 1 molar ratios by reactions of diorganotin(IV) oxide with 2-pyrazinecarboxylic acid or (2-pyrimidylthio)acetic acid, respectively. All the complexes are characterized by elemental analysis, IR, 1H NMR and 13C NMR spectra. Except for 2, 4 and 7, the complexes are also characterized by X-ray crystallography diffraction analyses, which reveal that the complexes adopt the familiar dicarboxylato tetraorganodistannoxane structural mode. Among them, the evident difference is that weak intramolecular interactions between Sn and N atoms are recognized in complexes 1 and 3. However, for complex 5 two different coordination modes are found in the same lattice. [ABSTRACT FROM AUTHOR]

Abstract: Success in obtaining higher‐order twistarenes with precise structures is very important for fundamentally understanding the relationship between the structures and physical properties/optoelectronic applications. In this research, by using the advantages from a retro‐Diels–Alder process (clean reaction) and the cross‐conjugated nature of the pyrene unit, a novel dodeca‐twistarene was prepared for the first time. Its structure, confirmed by single‐crystal XRD analysis, indicates that it possesses a twisted angle (≈30°), and two neighboring molecules in the crystal lattice are perpendicular to each other because of the twisted character and the strong intermolecular CH–π interactions. However, its basic physicochemical properties suggest its instability in air derives from its elevated HOMO energy level, although NICS calculations confirm that the pyrene units contribution poorly to the π conjugation of the overall molecule. [ABSTRACT FROM AUTHOR]

A facile and simple strategy to prepare ammonia gas-modified graphene oxide (GO) catalysts was successfully established by gas–solid acid–base reaction at room temperature. The catalytic performances of ammonia gas-modified GO samples were examined in Knoevenagel condensation. The samples were characterized by X-ray diffraction, Fourier transform infra-red spectroscopy, X-ray photoelectron spectroscopy, atomic force microscope, NH3 temperature-programmed desorption and elemental analysis. The results indicated that the excellent performances of the ammonia gas-modified GO samples in Knoevenagel condensation should be ascribed to the formation of ammonium ions (NH4+) by the reaction between ammonia gas and the carboxyl groups located on the edge of the GO. [ABSTRACT FROM AUTHOR]

A series of B 2 O 3 /HZSM-5 catalysts were prepared by impregnation of HZSM-5 zeolites with triethyl borate, trimethyl borate and boric acid. The selective synthesis of para -diethylbenzene by alkylation of ethylbenzene with diethyl carbonate was carried out over the B 2 O 3 /HZSM-5 catalysts. The physicochemical properties of the catalysts were characterized by X-ray diffraction, N 2 adsorption–desorption, Fourier-transform infrared spectroscopy with pyridine adsorption and NH 3 temperature programmed desorption. The characterization results indicated that the 15% B 2 O 3 /HZSM-5 catalyst prepared by using triethyl borate as the precursor exhibited an outstanding shape-selectivity along with a high catalytic activity in alkylation of ethylbenzene with diethyl carbonate. This might be ascribed to the large molecular size of triethyl borate, which would lead to the formation of B 2 O 3 on the external surface of HZSM-5 zeolite and preserve the acid sites in the micropores of HZSM-5 zeolite. By contrast, the B 2 O 3 /HZSM-5 catalysts prepared by using trimethyl borate or boric acid led to the severe reduction in catalytic activity, which was attributed to the decrease in the amount of the total acid sites caused by the blockage of the partial pores of HZSM-5 zeolite. [ABSTRACT FROM AUTHOR]

Abstract: An organopalladium complex containing orthometalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary has been used to promote the asymmetric hydroalkoxylation reactions between weak nucleophile methanol and 1,1-bis(diphenylphosphino)ethylene or 1,1-bis(diphenylphosphino)ethylene monoxide in good regio- and stereo-selectivities in the presence of an external base. The major addition product obtained from methanol and 1,1-bis(diphenylphosphino)ethylene monoxide was subsequently isolated in a quantitative yield in its configurationally pure form and characterized by means of two-dimensional rotating-frame nuclear Overhauser enhancement (ROESY) NMR spectroscopy as well as single crystal X-ray diffraction analysis. The enantiomerically pure bis-phosphine monoxide ligand was subsequently liberated in high yield. [ABSTRACT FROM AUTHOR]

Abstract: A promising electrochemical sensor for sensitive determination of nitrite was fabricated by construction of Au nanoparticles on the surface of choline chloride (Ch) modified glassy carbon electrode (GCE). Field emission scanning electron microscope, powder X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical techniques were used for the surface characterization of the modified electrode. It was demonstrated that Ch was covalently immobilized onto the GCE surface forming a planted Ch monolayer, which could provide a suitable supporting material for the construction of Au nanoparticles. As a result, the Au nanoparticles with average size of about 110nm were assembled to form a flowerlike structure on the surface of Ch monolayer. Moreover, the uniform nano-Au/Ch film exhibited remarkable electrocatalytic activity towards the oxidation of nitrite with obvious reduction of overpotential. Under the optimum conditions, the linear range for the detection of nitrite was 4.0×10−7 to 7.5×10−4 M with a high sensitivity of 0.354μAμM−1, and a low detection limit of 1.0×10−7 M. The proposed method was successfully applied in the detection of nitrite in water samples and sausage samples, and the results were consistent with those obtained by ion chromatography and UV–visible spectrophotometric methods. [Copyright &y& Elsevier]

Abstract: Oligoaniline derivative/polyvinylpyrrolidone nanofibers containing silver nanoparticles have been successfully prepared by electrospinning technique. Silver nanoparticles were prepared through reduction of Ag+ by oligoaniline derivative, and the process of redox was monitored by UV–vis spectra. The morphology of Ag-polymer blends nanocomposites and the distribution of Ag nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical analysis of nanocomposites was checked by cyclic voltammetry (CV) in the 0.5M H2SO4. In addition, the presence of Ag nanoparticles was indicated by X-ray diffractometer (XRD). [Copyright &y& Elsevier]