Synthesis and Crystal Structure of Two-dimensional Network Supramolecular Complex [Cu(dafo)_2(H_2O)_2](ClO_4)_2

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｕｐｒａｍｏｌｅｃｕｌａｒｃｏｍｐｌｅｘｅｆｏｒｍｅｄｂｙｔｈｅｗｅａｋｉｎｔｅｒａｃｔｉｏｎｓ (ｅｌｅｃｔｒｏｓｔａｔｉｃｉｎｔｅｒａｃｔｉｏｎ ,ｈｙｄｒｏｇｅｎｂｏｎｄｓ ,ｖａｎｄｅｒＷａａｌｓｆｏｒｃｅ ,ｓｈｏｒｔ ｒａｎｇｅｅｘｃｌｕｓｉｏｎｆｏｒｃｅ ,ｅｔｃ .)ｏｆｍｏｒｅｔｈａｎｔｗｏｓｏｒｔｓｏｆｓｐｅｃｉｅｓｉｓａｎｏｒｇａｎｉｚｉｎｇｅｎｔｉｔｙｔｈａｔｕｓｕａｌｌｙｐｏｓｓｅｓｓｅｓｓｐｅｃｉａｌｓｔｒｕｃｔｕｒｅａｎｄｆｕｎｃｔｉｏｎ .1Ｓｕｐ…     

A Mild and Efficient Procedure for the Preparation of Chromone-2-carboxylates

Chromone-2-carboxylates are widely used for the pharmacological activity of several of its derivatives1. The general synthesis of such chromone derivates includes two steps (Scheme 1): a Claison condensation of dialkyl oxalate with 2-hydroxyacetophenones to achieve alkyl 3-(2-hydroxyphenyl)-3-oxopropanoates in the presence of NaH, NaOEt, or NaOMe; cyclodehydration of the alkyl 3-(2-hydroxyaryl)-3-oxopropanoates to obtain chromones under acid condition. The total yield of the two steps is q…     

Rapid method for the determination of amino acids in serum by capillary electrophoresis

Ion-pair and hydrophilic interaction chromatographies are considered to be complementary methods of choice for analyzing intact glucosinolates from broccoli. Ion-pair chromatography resolves non-polar glucosinolates, such as those containing indole moieties, while hydrophilic interaction chromatography is superior for separating polar glucosinolates, such as glucoraphanin and glucoiberin. Reversed-phase separations using hydrophilic endcapped C18-bonded silica and a 50 mM ammonium acetate-methanol gradient mobile phase resolve both polar and non-polar glucosinolates negating the need for switching columns.     

pH-dependent electron transfer from re-bipyridyl complexes to metal oxide nanocrystalline thin films

Photoinduced interfacial electron transfer (ET) from molecular adsorbates to semiconductor nanoparticles has been a subject of intense recent interest. Unlike intramolecular ET, the existence of a quasicontinuum of electronic states in the solid leads to a dependence of ET rate on the density of accepting states in the semiconductor, which varies with the position of the adsorbate excited-state oxidation potential relative to the conduction band edge. For metal oxide semiconductors, their conduction band edge position varies with the pH of the solution, leading to pH-dependent interfacial ET rates in these materials. In this work we examine this dependence in Re(L(P))(CO)3Cl (or ReC1P) [L(P) = 2,2'-bipyridine-4,4'-bis-CH2PO(OH)2] and Re(L(A))(CO)3Cl (or ReC1A) [L(A) = 2,2'-bipyridine-4,4'-bis-CH2COOH] sensitized TiO2 and ReC1P sensitized SnO2 nanocrystalline thin films using femtosecond transient IR spectroscopy. ET rates are measured as a function of pH by monitoring the CO stretching modes of the adsorbates and mid-IR absorption of the injected electrons. The injection rate to TiO2 was found to decrease by 1000-fold from pH 0-9, while it reduced by only a factor of a few to SnO2 over a similar pH range. Comparison with the theoretical predictions based on Marcus' theory of nonadiabatic interfacial ET suggests that the observed pH-dependent ET rate can be qualitatively accounted for by considering the change of density of electron-accepting states caused by the pH-dependent conduction band edge position.     

The inviscid Burgers equation with initial data of Brownian type

The solutions to Burgers equation, in the limit of vanishing viscosity, are investigated when the initial velocity is a Brownian motion (or fractional Brownian motion) function, i.e. a Gaussian process with scaling exponent 0<h<1 (typeA) or the derivative thereof, with scaling exponent –1<h<0 (typeB). Largesize numerical experiments are performed, helped by the fact that the solution is essentially obtained by performing a Legendre transform. The main result is obtained for typeA and concerns the Lagrangian functionx(a) which gives the location at timet=1 of the fluid particle which started at the locationa. It is found to be a complete Devil's staircase. The cumulative probability of Lagrangian shock intervals a (also the distribution of shock amplitudes) follows a (a)^–h law for small a. The remaining (regular) Lagrangian locations form a Cantor set of dimensionh. In Eulerian coordinates, the shock locations are everywhere dense. The scaling properties of various statistical quantities are also found. Heuristic interpretations are provided for some of these results. Rigorous results for the case of Brownian motion are established in a companion paper by Ya. Sinai. For typeB initial velocities (e.g. white noise), there are very few small shocks and shock locations appear to be isolated. Finally, it is shown that there are universality classes of random but smooth (non-scaling) initial velocities such that the long-time large-scale behavior is, after rescaling, the same as for typeA orB.     

Carbolithiation of substituted stilbenes and styrenes with dithianyllithiums

Carbolithiation of a range of substituted stilbenes and styrenes with dithianyllithiums is described, leading to the rapid, efficient and stereocontrolled assembly of highly functionalized dithiane intermediates for acyl-equivalents synthesis.     

投篮球、推铅球和掷手榴弹的力学--物理与体育系列专题之九

投篮球入篮、推铅球和掷手榴弹这三种常见的运动，可以用比较简单的抛射体运动的计算方法和公式来统一处理．这是因为，篮球、铅球和手榴弹在空中运动的速度不大，我们主要关心重心位置的变化，空气阻力影响可以忽略不计(参看下面所给的参考数据)．本文将分别讨论有关这三种运动的一些有实际意义的有趣味的问题．