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101.
The synthesis and structure-activity-relationship (SAR) for a series of N-substituted piperazinyl carbamoyl 7-15 and piperazinyl acetyl 18-26 derivatives of tetrahydropapaverine have been carried out. The general synthetic methods of carbamoyl tetrahydropapaverine analogues involve N-substituted piperazines and carbamoyl imidazole tetrahydropapaverine as starting materials. Another route for synthesizing these compounds, involving the formation of carbamoyl imidazole piperazine has also been explored. Acylation of tetrahydropapaverine followed by substitution with various piperazinyl moities afforded the acetyl tetrahydropapaverine derivatives. Variously substituted piperazines have been used to monitor the effect of electron releasing and electron withdrawing substituents upon the antispasmodic activity of the molecules. Effect of varying electron densities on the antispasmodic activity, by altering the position of these groups on the benzene ring has also been monitored. Pharmacological methods involve the in vitro antispasmodic activity studies on a freshly removed guinea pig ileum using a force displacement transducer amplifier connected to a physiograph. Among the analogues synthesized in the present study, a promising compound 7, a potent muscle relaxant as compared to papaverine has been obtained. 相似文献
102.
103.
Kundu S Pal A Ghosh SK Nath S Panigrahi S Praharaj S Pal T 《Inorganic chemistry》2004,43(18):5489-5491
Ligands with a beta-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized gold nanoparticles of different shapes from aqueous HAuCl(4) solution. Evolution of stable gold nanoparticles follows first order (k approximately equal to 10(-2) min(-1)) kinetics with respect to Au(0) concentration. Growth of particles of different shapes (spherical or triangular or hexagonal) goes hand in hand under the influence of different beta-diketones, which have excellent capping and reducing properties. Chlorine insertion was observed to take place in the beta-diketone skeleton. 相似文献
104.
J Mondal A Modak A Dutta S Basu SN Jha D Bhattacharyya A Bhaumik 《Chemical communications (Cambridge, England)》2012,48(64):8000-8002
Surface functionalization of SBA-15 followed by its reaction with Cu(OAc)(2) has been carried out to develop a new Cu-grafted functionalized mesoporous material, which catalyzes one-pot three component coupling of different aryl halides with thiourea and benzyl bromide in aqueous medium to produce aryl thioethers in very good yields (80-88%). 相似文献
105.
Rabindra N. Roy Lakshmi N. Roy Kathleen A. Allen Casey J. Mehrhoff Isaac B. Henson Jessica M. Stegner Alexis L. Jenkins Ankita A. Shah Stephen D. Rocchio 《Journal of solution chemistry》2012,41(6):1044-1053
In this study, we report the pH values of two buffer solutions without chloride ion and eight buffer solutions with NaCl with an ionic strength I=0.16 mol?kg?1. Electromotive force (emf) techniques have been used to get the cell potentials at 12 temperatures from 5 to 55?°C, including 37?°C. An extended form of the Bates-Guggenheim convention is used in the entire ionic strength range, 0.04 to 0.16?mol?kg?1. The residual liquid junction potentials (??E j ) of the buffer solutions of MOBS have been estimated from previous measurements with a flowing junction cell. These values of ??E j have been used for correction in order to ascertain the operational pH values of four buffer solutions of MOBS at 25 and 37?°C. These solutions are recommended as pH standards for physiological application in the pH range 7.4 to 7.7. 相似文献
106.
Dhananjaya Patra Mohan Ramesh Duryodhan Sahu Harihara Padhy Chih‐Wei Chu Kung‐Hwa Wei Hong‐Cheu Lin 《Journal of polymer science. Part A, Polymer chemistry》2012,50(5):967-975
A conjugated main‐chain copolymer ( PBT ) consisting of bithiazole, dithieno[3,2‐b:2′,3′‐d]pyrroles (DTP), and pendent melamine units was synthesized by Stille polymerization, which can be hydrogen‐bonded (H‐bonded) with proper molar amounts of bi‐functional π‐conjugated crosslinker F (i.e., two uracil motifs covalently attached to a fluorene core through triple bonds symmetrically) to develop a novel supramolecular polymer network ( PBT/F ). The effects of multiple H‐bonds on light harvesting capabilities, HOMO levels, and photovoltaic properties of polymer PBT and H‐bonded polymer network PBT/F are investigated. The formation of supramolecular polymer network ( PBT/F ) between PBT and F was confirmed by FTIR and XRD measurements. Because of the stronger light absorption, lower HOMO level, and higher crystallinity of H‐bonded polymer network PBT/F , the solar cell device containing PBT/F showed better photovoltaic properties than that containing polymer PBT . The preliminary results show that the solar cell device containing 1:1 weight ratio of PBT/F and [6,6]‐phenyl C71 butyric acid methyl ester (PC71BM) offers the best power conversion efficiency (PCE) value of 0.86% with a short‐circuit current density (Jsc) of 4.97 mA/cm2, an open circuit voltage (Voc) of 0.55 V, and a fill factor (FF) of 31.5%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
107.
Corrigendum: Triazole‐Tailored Guanosine Dinucleosides as Biomimetic Ion Channels to Modulate Transmembrane Potential 下载免费PDF全文
108.
New fluorescent peptide-based sensors (1–3) for monitoring heparin in serum sample were synthesized using short peptides (1∼3mer) as a receptor. The peptide-based sensors (2 and 3) showed a sensitive ratiometric response to heparin both in aqueous buffered solution (10 mM HEPES, pH 7.4) and in 2% human serum sample by increase of excimer emission of pyrene at 480 nm and concomitant decrease of monomer emission of pyrene at 376 nm, whereas the peptide-based sensor 1 showed a turn off response only by decrease of monomer emission at 376 nm. 2 and 3 exhibited excellent selectivity toward heparin among various anions and competitors of heparin including chondroitin 4-sulfate (ChS) and hyaluronic acid (HA). Peptide-based sensor 3 showed a more sensitive response to heparin than 2. The detection limit of 3 was determined as 36 pM (R2 = 0.998) for heparin in aqueous solution and 204 pM (R2 = 0.999) for heparin in aqueous solutions containing 2% human serum. The peptide-based sensors, 2 and 3 provided a practical and potential tool for the detection and quantification of heparin in real biological samples. 相似文献
109.
Single‐Crystal‐to‐Single‐Crystal Transition in an Enantiopure [7]Helquat Salt: The First Observation of a Reversible Phase Transition in a Helicene‐Like Compound 下载免费PDF全文
Dr. Naba K. Nath Lukáš Severa Dr. Roman A. Kunetskiy Prof. Ivana Císařová Prof. Michal Fulem Prof. Květoslav Růžička Dr. Dušan Koval Dr. Václav Kašička Dr. Filip Teplý Prof. Panče Naumov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13508-13512
Here it is reported that crystals of an enantiopure [7]helquat salt undergo reversible thermal solid–solid phase transition at 404 K. Differential scanning calorimetry (DSC), capillary electrophoresis (CE), and X‐ray diffraction analysis were used to unravel the mechanistic details of this process. The single‐crystal‐to‐single‐crystal course enabled direct monitoring of the structural changes by in situ variable‐temperature X‐ray diffraction, thus providing the first direct evidence of a solid phase transition in a helicene‐like compound. 相似文献
110.
Gold/Palladium Alloy for Carbon–Halogen Bond Activation: An Unprecedented Halide Dependence 下载免费PDF全文
Dr. Raghu Nath Dhital Dr. Karan Bobuatong Prof. Dr. Masahiro Ehara Prof. Dr. Hidehiro Sakurai 《化学:亚洲杂志》2015,10(12):2669-2676
New catalytic activity of gold/palladium alloy nanoclusters (NCs) for carbon–halogen bond activation is demonstrated. In the case of an aryl chloride, the inclusion of gold in a bimetallic catalyst is indispensable to achieve the coupling reactions. Gold has the unique effect of stabilizing palladium, such that Pd2+ leached from clusters by means of spillover of chloride during oxidative addition. The thus‐formed spillover intermediate further reacts heterogeneously in both Ullmann and Suzuki‐type coupling reactions through a new type of mechanism. In the case of an aryl bromide, Ullmann coupling occurs through the spillover of bromide, similar to that of aryl chloride. However, a significant fraction of palladium also leached, which diminished the Ullmann coupling activity of the aryl bromide and, as a result, the order of reactivity was ArCl>ArBr. With regard to the activation of the C?Br bond towards a Suzuki‐type reaction, the inclusion of a higher gold content in gold/palladium clusters stabilized palladium to prevent the leaching of Pd2+ from the clusters by means of spillover of bromide. The spillover intermediate reacts heterogeneously with PhB(OH)2, palladium‐rich gold/palladium, or pure palladium clusters; the oxidative addition of ArBr favors the extraction of palladium from the clusters, yielding Pd2+ intermediates. The extracted intermediates react homogenously (Pd2+/Pd0 catalysis) with PhB(OH)2, which results in the higher selectivity of the cross‐coupling product. An initial step to observe such unprecedented halide dependency, together with the dynamic behavior of palladium on the surface of gold is the oxidative addition of Ar?X. A detailed insight into the first oxidative addition process was also examined by quantum chemical calculations. 相似文献