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Chemistry, An Asian Journal

Maria Paula Alves Robalo, Ana Catarina Sousa, Sara Raquel Baptista, Lígia O Martins
An eco-friendly protocol for azobenzene dyes synthesis by oxidative coupling of primary aromatic amines is reported. As efficient biocatalytic systems, CotA-laccase and CotA-laccase/ABTS (2,2´-azinobis-3-ethylbenzylthiozoline-6-sulphate) enable the oxidation of various substituted anilines, in aqueous medium, ambient atmosphere and mild reaction conditions of pH and temperature. A series of azobenzene dyes were prepared in good to excellent yields in an one-pot reaction. A mechanistic proposal for the formation of the azo derivatives is presented...
November 16, 2018: Chemistry, An Asian Journal
Jinlou Gu, Pengfei Yang, Ming Gong, Yunxi Ye, Yongsheng Li, Qixin Zhuang
Simple and effective separation of isomeric organic molecules is an important but challenging task. Herein, we successfully developed a selective crystallization strategy to separate the mixtures of isomeric dicarboxylic acids (DCAs) for the first time in which, target DCAs could be preferably combined with crystallization inducer of Zr4+ ions to form a pre-designed metal-organic frameworks (MOFs) crystal structure while the entry of non-target isomeric DACs into the MOFs lattice could be exclusively inhibited...
November 16, 2018: Chemistry, An Asian Journal
Kenta Nishino, Yasuhiro Morisaki, Kazuo Tanaka, Yoshiki Chujo
To obtain solid-state emissive materials having stimuli-responsive luminescent chromic properties without phase transition, benzobithiophenes modified with two o-carborane units having various substituents in the adjacent phenyl ring in o-carborane were designed and synthesized. Their emission colors were strongly affected not only by the substituents at the para-position of the phenyl ring but also by molecular distribution in the solid state. In particular, the emission colors were changed by heating without crystal phase transition...
November 16, 2018: Chemistry, An Asian Journal
Renhua Qiu, Ting Liu, Longzhi Zhu, Shuang-Feng Yin, Chak-Tong Au, Nobuaki Kambe
A site-selective metal-free dealkylative approach to synthesize aryl alkyl and symmetrical dialkyl sulfides was developed. This procedure is convenient and has wide functional group tolerance giving rise to sulfides carrying various alkyl chains in good to excellent yields from simple alkyl sulfides and alkyl halides. This transalkylation proceeds by an ionic mechanism via sulfonium intermediates and it was proposed that DMAC may participate in part to promote the reaction.
November 15, 2018: Chemistry, An Asian Journal
Boopathy Gnanaprakasam, Moreshwar B Chaudhari
The amide is a ubiquitous functional group which found in peptides, proteins, pharmaceutical compounds, natural products, and polymers. The synthesis of amides can be done by classical approaches which consist of the reaction between carboxylic acid with an amine in the presence of an activator. Amides are known to be an inert functional group, as they are unaffected by nucleophile attacks, due to its poor electrophilic nature. The reason for this resistant behavior is obvious: the resonance stability of the amide bond...
November 14, 2018: Chemistry, An Asian Journal
Fuyuki Ito, Narumi Oka
Crystallization of organic molecules is quite complicated because the crystallization process is governed by the weak intermolecular interactions. By exploiting the aggregation-induced emission (AIE), we attempted to realize the selective detection of phase transformation during the evaporative crystallization of hexaphenylsilole (HPS), which shows different fluorescence colors in the amorphous and crystalline phases. No fluorescence emission was observed in the HPS solution immediately after dropping on the glass substrate due to the non-radiative deactivation induced by intramolecular rotational or vibrational motion, suggesting that HPS exists as a monomer in solution...
November 13, 2018: Chemistry, An Asian Journal
Shawn Sanctis, Rudolf C Hoffmann, Nico Koslowski, Sabine Foro, Michael Bruns, Jörg J Schneider
Combustion synthesis of semiconducting amorphous indium gallium zinc oxide IGZO (In:Ga:Zn, 7:1:1.5) thin films was carried out using urea nitrate precursor compounds of indium(III), gallium(III) and zinc(II). This approach provides further understanding towards the oxide formation process under a moderate temperature regime by employment of well-defined coordination compounds. All precursor compounds were fully characterized by spectroscopic techniques as well as by single crystal structure analysis. Their intrinsic thermal decomposition was studied by a combination of differential scanning calorimetry (DSC) and thermogravimetry coupled with mass spectrometry and infrared spectroscopy (TG-MS/IR)...
November 13, 2018: Chemistry, An Asian Journal
Tao He, Weixin Ou, Ben Zhong Tang, Jianguang Qin, Youhong Tang
This paper employs a specially designed aggregation-induced emission fluorogen (AIEgen) to in vivo visualize the process of Hg2+ bioaccumulation in a common species of freshwater zooplankton Daphnia carinata (D. carinata) by two methods, direct Hg2+ absorption and ingestion of Hg2+ contaminated food. We analysed the relevance between photoluminescence (PL, I595/I480) ratios and Hg2+ (CHg2+) and developed the master curve for Hg2+ determination based on measuring the PL intensity of the solution. Meanwhile, fluorescent image analysis showed that the major recipient organs of Hg2+ in D...
November 13, 2018: Chemistry, An Asian Journal
Sheshanath V Bhosale, Santosh P Goskulwad, Mohammad Al Kobaisi, Duong Duc La, Rajesh S Bhosale, Malavath Ratanlal, Sidhanath V Bhosale
Naphthalenediimide-tetraphenylethylene with alanine spacer (coded as: NDI-(Ala-TPE)2) were synthesized to study the influence of the chirality of amino acid spacer on its self-assemblies. Here we particularly show that NDI-Ala-TPE bearing L-alanine gives left-handed (M-type) helical superstructure, while D-alanine produces right-handed (P-type) helical ribbons in THF:H2O at 40:60% v/v ratios. However, particular aggregates were observed at higher 20:80% v/v ratios. Circular dichroism is used to characterise induction of chirality and the handedness of the helical superstructures, and the microstruture of the self-assembled materials was visualised using scanning electron microscopy and DLS confirm formation of particular aggregates in solution...
November 12, 2018: Chemistry, An Asian Journal
Bing Shi Li, Hongkun Li, Ben Zhong Tang
Aggregation-induced emission luminogens (AIEgens) are a new class of luminophors, which are non-emissive in solutions, but emit intensively upon aggregation. By properly designing the chemical structures of the AIEgens, their aggregation process can be tuned towards desired direction to give the diverse novel luminescent architectures of micelles, rods and helical fibers. The AIEgens represent a kind of promising building blocks for the fabrication of luminescent micro/nanostructures with controllable morphologies...
November 11, 2018: Chemistry, An Asian Journal
Hai Dong, Ying Zhang, Fu-Long Zhao, Tao Luo, Zhichao Pei
A concise approach to Neu5Ac-α-2,3-LacNPhth trisaccharide derivative was developed. Firstly, the regio/stereoselective glycosylation between glycoside donors and glucoNPhth diol acceptors was investigated. It was found that the regioselectivity depends not only on the steric hindrance of the C2-NPhth group and the C6-OH protecting group of the glucosamine acceptors, but also on the leaving group and protecting group of the glycoside donors. Under optimized conditions, LacNPhth derivatives were synthesized up to a 92% yield through the regio/stereoselective glycosylation between peracetylated-α-galactopyranosyl trichloroacetimidate and p-​methoxyphenyl 6-O-tert-butyldiphenylsilyl-2-deoxy-2-phthalimido-β-D-glucopyranoside, avoiding the formation of glycosylated orthoesters and anomeric aglycon transfer...
November 9, 2018: Chemistry, An Asian Journal
Akira Matsumoto, Keisuke Asano, Seijiro Matsubara
An asymmetric cyanation of acylsilanes involving the in situ formation of chiral acylsilane cyanohydrins followed by their kinetic resolution via organocatalytic cycloetherification is described. The highly enantio- and diastereoselective cycloetherification was crucial for achieving a high efficiency in the kinetic resolution. Consequently, acylsilane cyanohydrins containing a tetrasubstituted chiral carbon atom bearing silyl, cyano, and hydroxy groups were obtained in an enantioenriched form. This protocol therefore offers an efficient catalytic approach to optically active acylsilane cyanohydrins, which exhibit potential as chiral building blocks for the synthesis of pharmaceutically relevant chiral organosilanes...
November 8, 2018: Chemistry, An Asian Journal
Cheng Tian, Hui Zhao, Jian Mei, Shijian Yang
In this study, the photocatalytic activity of g-C3N4 synthesized via different precursor (urea, thiourea and dicyandiamide, respectively) is investigated in the degradation process of tetracycline. Owing to the efficient charge separation and transfer, prolonged radiative lifetime of charge, large surface area and nanosheet morphology, the urea-derived g-C3N4 exhibits the superior photocatalytic activity for tetracycline degradation under visible light irradiation. This performance can compare with that of most reported g-C3N4 based composite photocatalysts...
November 8, 2018: Chemistry, An Asian Journal
Xianglong Li, Zexiu Liu, Kai Luo, Xiuhui Yin, Xucong Lin, Chunling Zhu
Ag2Se quantum dots (QDs) with near-infrared (NIR) fluorescence have been widely utilized in NIR fluorescence imaging in vivo because of their narrow bulk band gap and excellent biocompatibility. However, most of synthesis methods for Ag2Se QDs were expensive and the reactants were too toxic. In this paper, a new protein-templated biomimetic synthesis approach was proposed for Ag2Se QDs preparation by employing bovine serum albumin (BSA) as template and dispersant. The BSA-templated Ag2Se QDs (Ag2Se@BSA QDs) showed NIR fluorescence with high fluorescence quantum yield (≈21...
November 6, 2018: Chemistry, An Asian Journal
Xia Cao, Bao-Gui Cai, Guo-Yong Xu, Jun Xuan
Cascade radical addition/cyclization reaction of 2-vinylanilines with alkynes for the synthesis of biologically important naphthalene derivatives is reported. In this transformation, the in situ formed diazonium salts from 2-vinylanilines served as efficient aryl radical precursors and the reaction was run under metal-free conditions.
November 6, 2018: Chemistry, An Asian Journal
Panzhe Qiao, Bojing Sun, Haoze Li, Kai Pan, Guohui Tian, Lei Wang, Wei Zhou
Ag/mesoporous black TiO2 nanotubes heterojunctions (Ag-MBTHs) are fabricated through surface hydrogenation, wet-impregnation and photoreduction strategy. The as-prepared Ag-MBTHs possess a relatively high specific surface area of ~85 m2 g-1 and an average pore size of ~13.2 nm. The Ag-MBTHs with narrow bandgap of ~2.63 eV extend the photoresponse from UV to visible light and near-infrared (NIR) region, which exhibit excellent visible-NIR-driven photothermal catalytic and photocatalytic performance for complete conversion nitro aromatic compounds (100%) and mineralization of high-toxic phenol (100%)...
November 6, 2018: Chemistry, An Asian Journal
Yuta Shimasaki, Masaki Kitahara, Miho Shoji, Atsushi Shimojima, Hiroaki Wada, Kazuyuki Kuroda
Ordered mesoporous Au was prepared using double gyroid (cubic Ia-3d) mesoporous silica KIT-6 as a template. The Au frameworks were formed within the template via a seed-mediated growth process. Au nanoparticles were initially prepared as seeds within the mesopores, and subsequently, they were grown under mild and controlled reducing conditions. The transmission electron micrographs and scanning electron micrographs of mesoporous Au after the removal of the template revealed the formation of mesoporous Au replicas...
November 6, 2018: Chemistry, An Asian Journal
Yukio Hitotsuyanagi, Masahito Hirai, Masumi Odagiri, Miho Komine, Tomoyo Hasuda, Haruhiko Fukaya, Koichi Takeya
Two new RA-series bicyclic hexapeptides, RA-XXV (4) and RA-XXVI (5), which have no N-methyl group at Tyr-5, were isolated from the roots of Rubia cordifolia L. Their amino acid compositions and sequences were determined by interpretation of MS and 1D and 2D NMR data and their relative structures were elucidated by X-ray crystallography of 4 and RA-XXVI acetate (6). The absolute stereochemistry of 4 was established by the total synthesis of 4, and that of 5, by the chemical correlation with 4. Peptides 4 and 5 exhibited cytotoxicity toward human promyelocytic leukemia HL-60 (IC50=0...
November 4, 2018: Chemistry, An Asian Journal
Akitsu Hirono, Hayato Sakai, Taku Hasobe
A series of terrylene derivatives such as monoazaterrylene (MATerry), 1,6-diazaterrylene (DiATerry) and pristine terrylene (Terry) were synthesized by changing number of nitrogen atoms at the bay region (1 and 6 positions of the Terry core). The electrochemical measurements suggested the first one-electron reduction and oxidation potentials became positively shifted with increasing number of nitrogen atoms, which agrees with the energies of the corresponding highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) states estimated by DFT method...
October 31, 2018: Chemistry, An Asian Journal
Shota Ooi, Takayuki Tanaka, Takahisa Ikeue, Kazuhisa Yamasumi, Kento Ueta, Daiki Shimizu, Masatoshi Ishida, Hiroyuki Furuta, Atsuhiro Osuka
Copper complexes of corroles have recently been a subject of keen interest due to their ligand non-innocent character and unique redox properties. Here we investigated bis-copper complex of a triply-linked corrole dimer that serves as a pair of divalent metal ligands but can be reduced to a pair of trivalent metal ligands. Reaction of triply-linked corrole dimer 2 with Cu(acac)2 (acac = acetylacetonate) gave bis-copper(II) complex 2Cu as a highly planar molecule with a mean-plane deviation value of 0.020 Å, where the two copper ions were revealed to be divalent by ESR, SQUID, and XPS methods...
October 30, 2018: Chemistry, An Asian Journal
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