半花菁衍生物分子非线性光学性质的理论研究

采用有限场(FF)/PM3方法对半花菁衍生物的第一超极化率和分子前线轨道性质进行了计算.结果表明,半花菁衍生物分子的第一超极化率主要与D-π-A结构有关,σ-烷基链对分子第一超极化率的影响很小,并且分子第一超极化率与分子前线轨道HOMO和LUMO能级差ΔEHL呈较好的线性关系.     

2，4-二羟甲基四氢吡咯衍生物的合成及对烯烃环氧化反应的诱导

用手性的丙烯酸薄荷醇酯与原位生成的1，3-偶极试剂发生Diels-Alder反应， 得到一系列新的手性2，4-二酯基四氢吡咯衍生物，经氢化铝锂还原得到纯的手性 2，4-二羟甲基吡咯衍生物。并首次发现，在用Oxone氧化烯时，2，4-二羟甲基四 氢吡咯衍生物能有效地诱导烯烃发生环氧化反应，转化率达到定量。     

Use of fluorinated diphenylolmethane derivatives for preparing heat-resistant elastic polyurethanes

Fluorinated diphenylolmethane derivatives were used for the first time as chain extenders in urethane formation reactions in preparation of elastic materials. Fluorinated diphenylolmethane derivatives exhibit positive surface activity. Owing to this fact and to the presence of reactive hydroxy groups, these derivatives allow preparation of fluorinated polyurethane materials with enhanced resistance to heat and aggressive media.     

苝四羧酸二酰亚胺系有机光导材料的光敏性与结构的关系研究

用AM1和CNDO方法优化得PTCAs可能存在的稳定结构.对比晶体结构发现化合物3-5晶体中以成键能较高的共面结构存在,该结构有利于形成分子的紧密堆积.最小二乘法拟合结果表明单取代化合物的光敏性与分子激发跃迁能(△E_L-H)存在定量构效关系(QSPR),r＞0.95;双取代化合物的光敏性与从CGL到CTL的空穴注入效率(△E_T-G)存在QSPR,r＞0.97.表明光电转换两个过程在不同类型PTCAs的光敏性产生过程中占据的作用不同:分子激发难易是影响单取代化合物光敏性的主要因素;而空穴注入效率是影响双取代化合物光敏性的主要因素.     

Cu-catalyzed oxidation of indoles to isatins

The first example of Cu-catalyzed oxidation of indoles to isatin derivatives by the use of cheap aqueous tert-butyl peroxide as an oxidant was developed. This methodology is practically convenient and highly functional group tolerant, allowing a variety of indole derivatives to transform into the corresponding isatin derivatives in good yields.     

Binding studies between tetrathiafulvalene derivatives and cyclobis(paraquat-p-phenylene)

The complexation between a number of different pi-electron donating TTF derivatives and the pi-electron accepting tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT(4+)) has been studied by (1)H NMR and UV-vis spectroscopy. The results demonstrate that the strength of association between the donors (TTF derivatives) and acceptor (CBPQT(4+)) is strongly dependent on the pi-electron donating properties (measured by the first redox potential ) of the TTF derivatives. However, the first redox potential () is not the only factor of importance. The extended pi-surface of the TTF derivatives also exerts a stabilizing influence upon complexation. The kinetics for the complexation-decomplexation were studied using (1)H NMR spectroscopy and are related to the bulkiness of the TTF derivatives. These effects may serve to improve the design of interlocked molecular systems, especially (bistable) molecular switches, in which CBPQT(4+) and a derivatized TTF unit are incorporated.     

Application of dansyl derivatization to the high pressure liquid chromatographic identification of equine estrogens

The HPLC qualitative analysis of conjugated estrogens is accomplished by a two-step procedure involving the formation of the corresponding dansyl derivatives. The first step involves the acid hydrolysis of the conjugated estrogens, followed by dansyl derivatization and HPLC separation of these derivatives on a liChrosorb Si-60 column with 50% (v/v) chloroform-n-heptane as the mobile phase. All of the dansyl estrogens are well separated except for the 17-keto estrogens, estrone, equilin, and equilenin. The second step, designed to detect the three 17-keto estrogens, begins with the selective sodium borohydride reduction of the conjugated 17-keto estrogens to the corresponding 17-hydroxyl compounds (the beta-epimer being formed in vast predominance over the alpha-epimer), followed by acid hydrolysis, dansyl derivatization, and HPLC separation of the derivatives as in the first step. Detection of the 17-keto estrogens is possible by determining differences in peak heights between the chromatograms of the first and second analyses. The The proposed method is sensitive, the dansyl derivatives stable, and nine different estrogens can be readily identified.     

Analytical first derivatives of molecular surfaces with respect to nuclear coordinates

We present analytical expressions for the first derivatives of area and other geometrical quantities of polygonal tesserae defined on molecular surfaces. This is a necessary step in the calculation of free energy derivatives with respect to nuclear coordinates for molecular solutes, in the framework of the polarizable continuum method. An application to solute-solvent dispersion energy derivatives is presented. © 1996 by John Wiley & Sons, Inc.     

Organosilicon compounds III. Silicon-substituted thiophene derivatives of mercaptoethylamine as possible radioprotective agents

The preparation of the first organosilicon containing derivatives of mercaptoethylamine as possible radioprotective agents is described. The synthesis of these compounds via the thiazolidine intermediate was chosen due to the known radioprotective action of certain thiazolidines. We have prepared seventeen previously unreported organosilicon derivatives of which eleven contain the thiazolidine moiety and six are derivatives of mercaptoethylamine. The ability of these derivatives to protect against ionizing radiation will be determined.     

Slope estimations at terminal values of three equidistant data

A new method is presented for estimating derivatives at the end points of three curvilinear data points. For first derivatives, the accuracy of the method is similar to that of the standard method, but it has the advantage that second derivatives are not necessarily all equal and can be more accurate than those predicted by conventional methods.     

Synthesis and spectroscopic properties of nickel complexes of benzo-, 1,2-naphtho-, or 2,3-naphthoannulated β-oxatetraazachlorins

The first β-oxatetraazachlorin derivatives have been synthesized starting from phthalonitrile derivatives and 5,5-dimethyl-1,3-oxazolidine-2,4-dione instead of the previously employed tetramethylsuccinonitrile. Absorption and magnetic circular dichroism (MCD) spectral properties are similar to those obtained for the corresponding tetramethyl-substituted TAC derivatives, confirming the presence of the low-symmetry aromatic structures.     

Kinetic resolution of N-acyl-β-lactams via benzotetramisole-catalyzed enantioselective alcoholysis

The first nonenzymatic kinetic resolution of β-lactams has been achieved. Alcoholysis of their N-aroyl derivatives in the presence of a simple chiral acyl transfer catalyst, benzotetramisole, produces β-amino acid derivatives with excellent enantioselectivity.     

Use of polyanions for alkylation of hydrazine derivatives

Alkylation of hydrazine and its derivatives still remains a quite complicated task. The novel method utilizing the polyanion strategy is reported. Formation and use of trianion for alkylation of hydrazine derivatives is first reported. Described method provides fast and convenient access to multialkylated derivatives. Scope and limitations of new method are also investigated.     

RI-MP2: first derivatives and global consistency

The evaluation of RI-MP2 first derivatives with respect to nuclear coordinates or with respect to an external electric field is described. The prefix RI indicates the use of an approximate resolution of identity in the Hilbert space of interacting charge distributions (Coulomb metric), i.e., the use of an auxiliary basis set to approximate charge distributions. The RI technique is applied to first derivatives of the MP2 correlation energy expression while the (restricted) Hartree-Fock reference is treated in the usual way. Computational savings by a factor of 10 over conventional approaches are demonstrated in an application to porphyrin. It is shown that the RI approximation to MP2 derivatives does not entail any significant loss in accuracy. Finally, the relative energetic stabilities of a representative sample of closed-shell molecules built from first and second row elements have been investigated by the RI-MP2 approach, and thus it is tested whether such properties that refer to potential energy hypersurfaces in a more global way can be described with similar consistency to the more locally defined derivatives. Received: 17 December 1996 / Accepted: 27 March 1997     

Beta-replacement reaction of serine-O-carbonate derivatives with thiols catalyzed by a pyridoxal model having an ionophore side-chain

Serine-O-carbonate derivatives, including peptides having a serine-O-carbonate residue at the N-terminal position, are catalytically transformed into S-substituted cysteine derivatives employing the pyridoxal model having an ionophore function in the presence of Li+; this is the first artificial model mimicking cystathionine Beta-synthase.     

Oxydation des olefines par les sels mercuriques—X: Bicyclisation stéréosélectivé du chloro-2 méthyl-7 undécatriène-2,6E,10 en dérivés trans hydrindaniques

The reaction of the title triene with mercuric acetate leads first to mercurated cyclohexanols and then to trans-hydrindane derivatives. The analogous non-mercurated compound leads to a mixture of cis- and trans-hydrindane derivatives.     

Adaptive biasing force method for scalar and vector free energy calculations

In free energy calculations based on thermodynamic integration, it is necessary to compute the derivatives of the free energy as a function of one (scalar case) or several (vector case) order parameters. We derive in a compact way a general formulation for evaluating these derivatives as the average of a mean force acting on the order parameters, which involves first derivatives with respect to both Cartesian coordinates and time. This is in contrast with the previously derived formulas, which require first and second derivatives of the order parameter with respect to Cartesian coordinates. As illustrated in a concrete example, the main advantage of this new formulation is the simplicity of its use, especially for complicated order parameters. It is also straightforward to implement in a molecular dynamics code, as can be seen from the pseudocode given at the end. We further discuss how the approach based on time derivatives can be combined with the adaptive biasing force method, an enhanced sampling technique that rapidly yields uniform sampling of the order parameters, and by doing so greatly improves the efficiency of free energy calculations. Using the backbone dihedral angles Phi and Psi in N-acetylalanyl-N'-methylamide as a numerical example, we present a technique to reconstruct the free energy from its derivatives, a calculation that presents some difficulties in the vector case because of the statistical errors affecting the derivatives.     

Density functional theory study on the first hyperpolarizabilities of organoimido derivatives of hexamolybdates

The first hyperpolarizabilities and origin of nonlinear optical (NLO) properties of arylimido molybdate derivatives have been investigated by density functional theory (DFT). The molecular orbital character analysis reveals that organoimido-to-polyanion charge transfer may be responsible for the NLO properties of this kind of molybdate derivatives. The NLO study shows intra-ion charge transfer is helpful to increase the first hyperpolarizability of arylimido molybdate derivatives. The lengthening of organoimido pi-conjugation enhances the betavec value. System 4 has the largest betavec value at the static electronic field, 1.238 x 10(-27)esu. Orbital analysis shows that the degree of charge transfer between polyanion cluster and organic segment was increased when the second organoimido polyanion was introduced. The present investigation provides important insight into NLO origin and properties of polyanion arylimido molybdate derivatives.     

A new family of two stage symmetric two-step methods with vanished phase-lag and its derivatives for the numerical integration of the Schrödinger equation

A family of two stage low computational cost symmetric two-step methods with vanished phase-lag and its derivatives is developed in this paper. More specifically we produce:

• a two-stage symmetric two-step eighth algebraic order method which has the phase-lag and its first, second and third derivatives vanished and
• a two-stage symmetric two-step sixth algebraic order method, which is P-stable and has the phase-lag and its first and second derivatives vanished.

The local truncation error, the interval of periodicity and the effect of the vanishing of the phase-lag and its derivatives on the efficiency of the obtained method are also studied in this paper.

     

Syntheses of 1-Azaazulan-2-One Analogs of Adrenergic Agents

The Friedel-Crafts reaction of 1-azaazulan-2-ones with α-haloacid chloride in the presence of aluminum trichloride gives the corresponding α-haloacyl derivatives. Treatment of these reaction products first with various secondary amines and then with sodium borohydride gives new adrenergic active amine derivatives.