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351.
Uchiyama S Kawai N de Silva AP Iwai K 《Journal of the American Chemical Society》2004,126(10):3032-3033
We illustrate a general polymeric design of fluorescent logic gates, for example, AND, using temperature and pH as inputs. 相似文献
352.
Magri DC Callan JF de Silva AP Fox DB McClenaghan ND Sandanayake KR 《Journal of fluorescence》2005,15(5):769-775
Compound 2, which was designed to act as a fluorescent sensor for calcium according to the PET (Photoinduced Electron Transfer) principle,
shows a relatively small Ca2+-induced fluorescence enhancement factor (FE) of 1.8 whereas its close relative 1 is known to display a far higher FE value of 16. Though designed as fluorescent PET sensors for solvent polarity, compounds
5 and 6 also show negligible fluorescence enhancement as their environments are made progressively less polar even though their relatives
3 and 4 show limiting FE values of 53 and 3, respectively. Indeed, 3 and 4 are useful since they are fluorescent sensors for solvent polarity without being affected by Bronsted acidity. The poor sensory
performance of 2, 5, and 6 relative to their cousins is attributed to the presence of an oxygen proximal to the 9-position of an anthracene unit, which
opens up a CT (charge transfer) channel. Normal PET sensing service is resumed when the offending oxygen is deleted. 相似文献
353.
K.C. Kumara Swamy S. Kumaraswamy S. Raja K.S. Kumar 《Journal of chemical crystallography》2001,31(1):51-56
X-ray structures of the cyclic dithiophosphate salts [Et3NH]+[(OCH2CMe2CH2O)P(S)(S)]– (1) and [Et3NH]+[CH2{6-t-Bu-4-Me-C6H4O}2P(S)S]– (2) have been determined. Crystal data for 1: Tetragonal, P42/m, a = 13.416(7), b = 13.416(2), c = 9.153(2) Å, and Z = 4. Crystal data for 2 = Monoclinic, P21/c, a = 19.1112(17), b = 14.649(9), c = 22.7166(19) Å, = 102.883(7)°, and Z = 8. The six- and eight-membered rings in 1 and 2 have chair and boat-chair conformations respectively. Both of these compounds show weak N—H······S hydrogen bonds; interestingly, in 2 both two-center and three-center hydrogen bonds are observed in the solid state. 相似文献
354.
A series of novel pyrimido[4,5-c]isoquinolines (3a–3h) and 1,2,3-triazole-coupled pyrimido[4,5-c]isoquinolines (4a–4h) were synthesized in good to excellent yields in the one-pot method. The reaction of 6-amino-1,3-dimethyluracil with different 2-iodo benzoyl chlorides using Pd catalyst in dimethylformamide afforded corresponding pyrimido[4,5-c]isoquinolines (3a–3h). One-pot reaction of pyrimido[4,5-c]isoquinolines with propargyl bromide and benzyl azide in THF at room temperature furnished 1,2,3-triazole-coupled pyrimido[4,5-c]isoquinoline (4a–4h). In vitro antioxidant activity examination revealed that compounds 4d and 4c found to exhibit potent antioxidant activity as compared to the standard drug Trolox with IC50 values 6.02?±?0.6 and 12.18?±?0.9?µM, respectively. 相似文献
355.
Ganesh Pandey Jagadish Khamrai Akash Mishra Pulak Maity Prasanna Kumara Chikkade 《Tetrahedron》2018,74(44):6317-6327
Asymmetric total synthesis of (+)-vincadifformine and (+)-ervinceine is reported by utilizing an iminium ion triggered cascade reaction using chiral 3,3-disubstituted piperidine imine and 2,3-disubstituted indole derivatives coupling partner. In the first generation total synthesis, the pivotal imine is prepared in excellent stereoselectivity but in moderate yield involving a Birch reduction-alkylation strategy. Furthermore, to improve upon the synthesis of the decisive imine, the more practical second generation route is devised through a Johnson-Claisen rearrangement to access chiral 3,3-disubstituted piperidinone in excellent yield and stereoselectivity. Apart from synthesizing (+)-vincadifformine, this strategy is also exploited for the first asymmetric total synthesis of (+)-ervinceine employing an iminium ion mediated cascade reaction. This distinctive strategy simultaneously sets up two new rings, two new stereogenic centers, and three new sigma bonds in a single operation. 相似文献
356.
In this review, we summarize advances in [4+3] and a few other annulation/cycloaddition reactions for the construction of seven membered rings, with an emphasis on the literature subsequent to the year 2010. The type of products include the following: azepines, diazepines, benzazepinones, 1,2‐diazepinones, oxazepinones, benzothiazepines, benzodiazepinones, benzoxopinones, cyclohepta[b]indoles, benzoxazepines, azepino‐indoles, oxepines/oxazepanes, triazepines oxepinoindolones/azepinoindolones, oxadiazepines, azabicyclooctanes. Emphasis is also given to cover diverse types of annulations; possible intermediates are displayed in the illustrated schemes to aid future work. 相似文献
357.
S. Prasanna S.P. Venkateshan 《Experimental Thermal and Fluid Science》2011,35(6):1019-1029
Schlieren and its variants such as differential interferometry and schlieren microscopy, have been used extensively for flow visualization where first derivative fields are captured. The derivative fields obtained from the schlieren like methods can be further processed to estimate the temperature field when the first derivative fields relate to those of temperature. Temperature construction from first derivative field is an ill-posed problem owing to the experimental noise and a few discrete points where measured temperatures may be available. A new approach has been proposed where the domain is discretized into a large number of triangular elements and least-squares based finite-element analysis is performed over the discretized domain. The domain and boundaries are identified manually based on prior knowledge. Temperature fields have been constructed for experimentally obtained first derivative fields from a Differential Interferometer (DI) for different cases. The performance of the new methodology is found to be good. 相似文献
358.
Simson Prasanna Kumar Revanasiddappa Manjunatha Thimmappa Venkatarangaiah Venkatesha Gurukar Shivappa Suresh 《Russian Journal of Electrochemistry》2013,49(4):299-306
Graphite electrode is modified by casting multi-walled carbon nanotubes (MWCNTs) wrapped with polystyrene sulphonate (PSS) onto the surface of the bare graphite electrode. The modified electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The behavior of the modified electrode towards the oxidation of ascorbic acid (AA), dopamine (DA) and uric acid (UA) has been determined by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CA). The modified electrode showed better electrocatalytic activity towards AA, DA and UA compared to bare graphite electrode. The electrochemical oxidation signals of AA, DA and UA are well separated into three distinct peaks with peak potential difference of 222, 128 and 350 mV between AA-DA, DA-UA and AA-UA respectively in CV studies and corresponding peak potential separation in DPV are 228, 120 and 348 mV. This modified electrode was successfully used for simultaneous determination of AA, DA and UA in ternary mixture. 相似文献
359.
Nalivela Kumara Swamy 《合成通讯》2013,43(16):2435-2445
The synthesis of two new trihydroxylated pyrrolidines, in a highly diastereoselective manner, has been developed using the Meyer–Schuster rearrangement as a key step.
360.
Munazza Tamkeen Fatima Zeyaul Islam Prasanna R. Kolatkar Ammira Sarah Al-Shabeeb Akil 《Molecules (Basel, Switzerland)》2022,27(13)
Obesity is a chronic disease with increasing cases among children and adolescents. Melanocortin 4 receptor (MC4R) is a G protein-coupled transporter involved in solute transport, enabling it to maintain cellular homeostasis. MC4R mutations are associated with early-onset severe obesity, and the identification of potential pathological variants is crucial for the clinical management of patients with obesity. A number of mutations have been reported in MC4R that are responsible for causing obesity and related complications. Delineating these mutations and analyzing their effect on MC4R’s structure will help in the clinical intervention of the disease condition as well as designing potential drugs against it. Sequence-based pathogenicity and structure-based protein stability analyses were conducted on naturally occurring variants. We used computational tools to analyze the conservation of these mutations on MC4R’s structure to map the structural variations. Detailed structural analyses were carried out for the active site mutations (i.e., D122N, D126Y, and S188L) and their influence on the binding of calcium and the agonist or antagonist. We performed molecular dynamics (MD) simulations of the wild-type and selected mutations to delineate the conformational changes, which provided us with possible reasons for MC4R’s instability in these mutations. This study provides insight into the potential direction toward understanding the molecular basis of MC4R dysfunction in disease progression and obesity. 相似文献