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Xingcheng Zhang, Hualin Xiong, Hongwei Yang, Guangbin Cheng
5-Amino-4,6-dinitro-1,3-dihydroxy-benzene (6) was synthesized through the ring-opening reaction of macrocyclic compound 4 with the aid of VNS (vicarious nucleophilic substitution of hydrogen) reaction conditions. The mechanism of ring opening of macrocyclic compound 4 was studied. 5-Amino-2,4,6-trinitro-1,3-dihydroxy-benzene (8) was obtained after the nitration of 6 in KNO3 and concentrated sulfuric acid. The thermal stability, sensitivity, and other detonation performances of 6 or 8 were compared to commercially used 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) or 1,3,5-trinitrotriazacyclohexane (RDX), respectively...
June 2017: ChemistryOpen
Virginia Wycisk, Katharina Achazi, Ole Hirsch, Christian Kuehne, Jens Dernedde, Rainer Haag, Kai Licha
Herein, we present a new synthetic route to cyanine-based heterobifunctional dyes and their application as fluorescent linkers between polymers and biomolecules. The synthesized compounds, designed in the visible spectral range, are equipped with two different reactive groups for highly selective conjugation under physiological conditions. By applying indolenine precursors with functionalized benzenes, we achieved water-soluble asymmetric cyanine dyes bearing maleimido and N-hydroxysuccinimidyl functionalities in a three-step synthesis...
June 2017: ChemistryOpen
Michaela Serpi, Roberto De Biasi, Fabrizio Pertusati, Magdalena Slusarczyk, Christopher McGuigan
A synthetic procedure for the preparation of phosphoramidate prodrugs of C-nucleosides is reported. Different phosphorochloridates were reacted with 3'-O-protected N-acetyl-2'-deoxypseudoisocytidine or 3'-O-protected 2'-deoxypseudoisocytidine, followed by acidic hydrolysis of the protecting group. In the presence of the N-acetyl moiety, the enolisable keto group of the nucleobase was able to react (like the 5'-OH) with the phosphorochloridates to give bisphosphorylated derivatives. Epimerisation (β to α) occurred if the amino group of the nucleobase was unprotected...
June 2017: ChemistryOpen
Rakesh Puttreddy, Ngong Kodiah Beyeh, Robin H A Ras, Kari Rissanen
The C-ethyl-2-methylresorcinarene (1) forms 1:1 in-cavity complexes with aromatic N,N'-dioxides, only if each of the aromatic rings has an N-O group. The structurally different C-shaped 2,2'-bipyridine N,N'-dioxide (2,2'-BiPyNO) and the linear rod-shaped 4,4'-bipyridine N,N'-dioxide (4,4'-BiPyNO) both form 1:1 in-cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host-guest interactions between the 1,3-bis(4-pyridyl)propane N,N'-dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti-gauche conformation...
June 2017: ChemistryOpen
Renato P Orenha, Marcus V J Rocha, Jordi Poater, Sérgio E Galembeck, F Matthias Bickelhaupt
We have analyzed structure, stability, and Ru-NO bonding of the trans-[RuCl(NO)(NH3)4](2+) complex by using relativistic density functional theory. First, we focus on the bond dissociation energies associated with the three canonical dissociation modes leading to [RuCl(NH3)4](+)+NO(+), [RuCl(NH3)4](2+)+NO, and [RuCl(NH3)4](3+)+NO(-). The main objective is to understand the Ru-NO(+) bonding mechanism in the conceptual framework of Kohn-Sham molecular orbital theory in combination with a quantitative energy decomposition analysis...
June 2017: ChemistryOpen
Kolle E Thomas, Christine M Beavers, Kevin J Gagnon, Abhik Ghosh
Presented herein is a study of the acid-induced demetalation of two sterically hindered copper corroles, Cu β-octabromo-meso-triphenylcorrole (Cu[Br8TPC]) and β-octakis(trifluoromethyl)-meso-tris(p-methoxyphenyl)corrole (Cu[(CF3)8TpOMePC]). Unlike reductive demetalation, which affords the free-base β-octabromocorrole, demetalation of Cu[Br8TPC] under non- reductive conditions (CHCl3/H2SO4) resulted in moderate yields of free-base 5- and 10-hydroxy isocorroles. The isomeric free bases could be complexed to Co(II) and Ni(II), affording stable complexes...
June 2017: ChemistryOpen
Luciana Vieira, Jennifer Burt, Peter W Richardson, Daniel Schloffer, David Fuchs, Alwin Moser, Philip N Bartlett, Gillian Reid, Bernhard Gollas
The electrodeposition of tin, bismuth, and tin-bismuth alloys from Sn(II) and Bi(III) chlorometalate salts in the choline chloride/ethylene glycol (1:2 molar ratio) deep eutectic solvent was studied on glassy carbon and gold by cyclic voltammetry, rotating disc voltammetry, and chronoamperometry. The Sn(II)-containing electrolyte showed one voltammetric redox process corresponding to Sn(II)/Sn(0). The diffusion coefficient of [SnCl3](-), detected as the dominating species by Raman spectroscopy, was determined from Levich and Cottrell analyses...
June 2017: ChemistryOpen
Barry Moore, Robert L Schrader, Karol Kowalski, Jochen Autschbach
The longest-wavelength π-to-π* electronic excitations of rhodamine-like dyes (RDs) with different group 16 heteroatoms (O, S, Se, Te) have been investigated. Time-dependent Kohn-Sham theory (TDKST) calculations were compared with coupled-cluster (CC) and equations-of-motion (EOM) CC results for π-to-π* singlet and triplet excitations. The RDs exhibit characteristics in the TDKST calculations that are very similar to previously investigated cyanine dyes, in the sense that the singlet energies obtained with nonhybrid functionals are too high compared with the CC results at the SD(T) level...
June 2017: ChemistryOpen
Albert Gandioso, Marta Palau, Alba Nin-Hill, Ivanna Melnyk, Carme Rovira, Santi Nonell, Dolores Velasco, Jaume García-Amorós, Vicente Marchán
We report the synthesis and photochemical properties of a series of dicyanocoumarinylmethyl (DEAdcCM)- and dicyanocoumarinylethyl (DEAdcCE)-based photocages of carboxylic acids and amines with absorption maximum around 500 nm. Photolysis studies with green light have demonstrated that the structure of the coumarin chromophore as well as the nature of the leaving group and the type of bond to be photocleaved (ester or carbamate) have a strong influence on the rate and efficiency of the uncaging process. These experimental observations were also supported by DFT calculations...
June 2017: ChemistryOpen
Christina M Bock, Gangajji Parameshwarappa, Simon Bönisch, Walter Bauer, Corina Hutterer, Maria Leidenberger, Oliver Friedrich, Manfred Marschall, Barbara Kappes, Andreas Görling, Svetlana B Tsogoeva
The straightforward and efficient synthesis of complex aza- and carbobicyclic compounds, which are of importance for medicinal chemistry, is a challenge for modern chemical methodology. An unprecedented metal-free six-step domino reaction of aldehydes with malononitrile was presented in our previous study to provide, in a single operation, these bicyclic nitrogen-containing molecules. Presented here is a deeper investigation of this atom-economical domino process by extending the scope of aldehydes, performing post-modifications of domino products, applying bifunctional organocatalysts and comprehensive NMR studies of selected domino products...
June 2017: ChemistryOpen
Ezequiel F V Leitão, Elizete Ventura, Miguel A F de Souza, José M Riveros, Silmar A do Monte
The mechanism of the O2(⋅-) and H2O2 reaction (Haber-Weiss) under solvent-free conditions has been characterized at the DFT and CCSD(T) level of theory to account for the ease of this reaction in the gas phase and the formation of two different set of products (Blanksby et al., Angew. Chem. Int. Ed. 2007, 46, 4948). The reaction is shown to proceed through an electron-transfer process from the superoxide anion to hydrogen peroxide, along two pathways. While the O3(⋅-) + H2O products are formed from a spin-allowed reaction (on the doublet surface), the preferred products, O(⋅-)(H2O)+(3)O2, are formed through a spin-forbidden reaction as a result of a favorable crossing point between the doublet and quartet surface...
June 2017: ChemistryOpen
Suru V John, Christian C De Filippo, Simone Silvestrini, Michele Maggini, Emmanuel Iwuoha
Through a cycloaddition reaction, fullerene (C60) was derivatized with a novel organic compound 5-(benzo[b]thiophen-3-yl)pyridine-3-carbaldehyde to form the processable and stable 3-(benzo[b]thiophene-3yl)-5-fullero-1-methylpyrrolidinepyridine (BTFP) compound. BTFP exhibits close similarities to phenyl-C61-butyric-acid-methyl-ester (PCBM) in terms of first reduction potential values (-0.62 and -0.61 V vs. Ag/AgCl, for BTFP and PCBM, respectively) and lowest occupied molecular orbital (LUMO) energy level values (3...
June 2017: ChemistryOpen
Jaap E Borger, Maarten K Jongkind, Andreas W Ehlers, Martin Lutz, J Chris Slootweg, Koop Lammertsma
The development of selective functionalization strategies of white phosphorus (P4) is important to avoid the current chlorinated intermediates. The use of transition metals (TMs) could lead to catalytic procedures, but these are severely hampered by the high reactivity and unpredictable nature of the tetrahedron. Herein, we report selective first steps by reacting P4 with a metal anion [Cp*Fe(CO)2](-) (Cp*=C5(CH3)5), which, in the presence of bulky Lewis acids (LA; B(C6F5)3 or BPh3), leads to unique TM-substituted LA-stabilized bicyclo[1...
June 2017: ChemistryOpen
Xinxin Qi, Li-Bing Jiang, Chao Zhou, Jin-Bao Peng, Xiao-Feng Wu
A convenient and general zinc-catalyzed borylation of aryl diazonium salts and aryltriazenes has been developed. With bis- (pinacolato)diboron as the borylation reagent, aryldiazonium tetrafluoroborate salts and aryltriazenes were transformed into the corresponding arylboronates in moderate to excellent yields under mild conditions. As a convenient and practical methodology, no additional ligands, base, or any other additives are required here.
June 2017: ChemistryOpen
Wannisa Sukjee, Chompoonuch Tancharoen, Pa-Thai Yenchitsomanus, M Paul Gleeson, Chak Sangma
Polymers can be synthesized to recognize small molecules. This is achieved by introducing the target molecule during monomer self-assembly, where they can be incorporated during cross-linking polymerization. Following additional pre-processing, the material obtained can then be applied as a sensing layer for these molecules in many applications. The sensitivity of the polymers depends on the "active sites" imprinted on the surface. Increasing the number of active sites on the polymers surface can be achieved by using nanoparticles as a platform to support and concentrate the molecules for imprinting...
June 2017: ChemistryOpen
Anna Vallverdú-Queralt, Emmanuelle Meudec, Matthias Eder, Rosa M Lamuela-Raventos, Nicolas Sommerer, Véronique Cheynier
Polyphenols, including tannins and red anthocyanin pigments, are responsible for the color, taste, and beneficial health properties of plant-derived foods and beverages, especially in red wines. Known compounds represent only the emerged part of the "wine polyphenol iceberg". It is believed that the immersed part results from complex cascades of reactions involving grape polyphenols and yeast metabolites. We used a non-targeted strategy based on high-resolution mass spectrometry and Kendrick mass defect plots to explore this hypothesis...
June 2017: ChemistryOpen
Jih Ru Hwu, D Balaji Chandrasekhar, Kuo Chu Hwang, Chun-Cheng Lin, Jia-Cherng Horng, Fa-Kuen Shieh
Benzyne was developed as a reducing agent in the key step of converting amino sugars and ketoses into deoxy sugars, which occur widely in natural products. Many deoxy sugars exhibit antibiotic and anticancer activities, and furthermore, they play essential biological roles. By treatment with CS2 and then Ac2O, amino sugars and ketoses were converted into the corresponding 1,3-thiazolidine-2-thiones. In the key step, these intermediates were treated with 2-trimethylsilylphenyl triflate (2.0 equiv.) and CsF (3...
June 2017: ChemistryOpen
Shan Hu, Bo He, Ke-Jie Du, Xiao-Juan Wang, Shu-Qin Gao, Ying-Wu Lin
The design of artificial metalloenzymes has achieved tremendous progress, although few designs can achieve catalytic performances comparable to that of native enzymes. Moreover, the structure and function of artificial metalloenzymes in non-native states has rarely been explored. Herein, we found that a c-type cytochrome b5 (Cyt b5), N57C/S71C Cyt b5, with heme covalently attached to the protein matrix through two Cys-heme linkages, adopts a non-native state with an open heme site after guanidine hydrochloride (Gdn⋅HCl)-induced unfolding, which facilitates H2O2 activation and substrate binding...
June 2017: ChemistryOpen
Bin Zhang, Yan Zhang, Zheming Wang, Zengqiang Gao, Deliang Yang, Dongwei Wang, Yanjun Guo, Daoben Zhu
A dual-functional organic-inorganic hybrid (BEDT-TTF)2Cu2(HCOO)5 (1) (BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene) was obtained through the electrochemical oxidation of neutral BEDT-TTF in the presence of an ammonium salt of the one-dimensional copper-formate framework [(C2H5)3NH]2Cu2(HCOO)5 in a C6H5Cl-C2H5OH solution. Compound 1 was composed of organic donor BEDT-TTF(+0)⋅(5) in a θ-phase arrangement and Jahn-Teller distorted (4,4) grid anion sheets [Cu2(HCOO)5(-)] n with S=1/2. We identified the material as a semiconductor with values of σ300K=10(-1) S cm(-1)...
June 2017: ChemistryOpen
Sari Deketelaere, Tuyen Van Nguyen, Christian V Stevens, Matthias D'hooghe
Due to the emerging resistance against classical β-lactam-based antibiotics, a growing number of bacterial infections has become harder to treat. This alarming tendency necessitates continued research on novel antibacterial agents. Many classes of β-lactam antibiotics are characterized by the presence of the 3-aminoazetidin-2-one core, which resembles the natural substrate of the target penicillin-binding proteins. In that respect, this Review summarizes the different synthetic pathways toward this key structure for the development of new antibacterial agents...
June 2017: ChemistryOpen
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