Quantum chemical studies on antimalarial of artemisinin (qinghaosu) derivatives

In this paper theoretical studies were performed on artemisinin (qinghaosu) derivatives with semiempirical quantum chemical methods AMI and PM3. The antimalarial activity -logC has an obvious correlation with the net charge of C(16) and bond orders of bonds O(1)-C(10), O(2)-C(6), O(1)-O(2) and O(5)-C(16). According to the calculation results, we derived structure-activity relationship, presented the probable pharmacophore of qinghaosu derivatives and the interaction fashion between the drugs and the plasmodium receptor.     

微波诱导低级醇的等离子体化学反应

微波诱导低级醇的等离子体化学反应王真，洪品杰，张承聪，戴树珊（云南大学化学系，昆明，６５００９１）关键词微波，等离子体化学，低级醇等离子体能产生大量的活性自由基、亚稳态粒子和激发态离子，它所包含的能量传递过程和反应过程不仅与反应碰撞理论有关，而且还涉...     

Parallel internally contracted multireference configuration interaction

A parallel implementation of the internally contracted (IC) multireference configuration (MRCI) module of the MOLPRO quantum chemistry program is described. The global array (GA) toolkit has been used in order to map an existing disk-paging small-memory algorithm onto a massively parallel supercomputer, where disk storage is replaced by the combined memory of all processors. This model has enabled a rather complicated code to be ported to the parallel environment without the need for the wholesale redesign of algorithms and data structures. Examples show that the parallel ICMRCI program can deliver results in a fraction of the time needed for equivalent uncontracted MRCI computations. Further examples demonstrate that ICMRCI computations with up to 10⁷ variational parameters, and equivalent to uncontracted MRCI with 10⁹ configurations, are feasible. The largest calculation demonstrates a parallel efficiency of about 80% on 128 nodes of a Cray T3E-300. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1215–1228, 1998     

Binding of hexacyanoferrate(II) by aliphatic amines in aqueous solution

The stability of hexacyanoferrate(II)-amine(methylamine, ethylenediamine, diethylenetriamine and tetraethylenepentamine) was determined potentiometrically. Species Fe(CN)₆(A)H _j ^(j–4) (A=amine) are formed in all the systems investigated, with j=1...n+2 (n=number of aminogroups). Some other complexes Fe(CN)₆(A)_iH_j (with i>1) were also found. The stability of these complexes is fairly high: the full protonated amine species, show for the reaction Fe(CN)₆ ^4- + H_nAⁿ⁺ = Fe(CN)₆(A)H_n ^(n-4) an equilibrium constant given by logK=0.686+2.10n. Factors affecting the stability are discussed in comparison with similar systems, together with the importance of interferences.     

液晶态分子在分析化学中的应用进展

评述了液晶态分子在分析化学中的应用进展，包括其超分子的分子识别作用，液晶在色谱，光谱探针，核磁共振谱等分析化学领域中的应用。     

卤化银乳剂的热增感效应研究

温度对卤化银胶片感光度的影响很早就有人进行过研究．在１９３４年,Ｗｅｂｂ［１］研究了不同温度下卤化银乳剂的互易率曲线,并发现温度对感光度的影响与照度有关．当照度很低时,在一定温度范围内感光度会随温度的降低而升高;在高照度下,随温度的升高感光度也增高．...     

Iodoplumbate mit vier‐ und fünffach koordinierten Pb2+‐Ionen

Iodoplumbates with Tetra‐ and Penta‐coordinated Pb²⁺ Ions In contrast to all known iodoplumbates with octahedrally coordinated Pb²⁺ ions, square pyramidal geometry is observed in the iodoplumbate chains of (Pr₄N)[PbI₃] ( 1 ) and [Mg(dmf)₆][PbI₃]₂ ( 2 ), whereas the isolated anions in (Ph₄P)₂[Pb₂I₆] ( 3 ) and [Bu₃N–(CH₂)₃–NBu₃][PbI₄] ( 4 ) contain tetra‐coordinated lead atoms. (Pr₄N)[PbI₃] ( 1 ): a = 910.86(6), b = 1221.46(7), c = 1907.7(1) pm, V = 2122.5(2) · 10⁶ pm³, space group P2₁2₁2₁; [Mg(dmf)₆][PbI₃]₂ ( 2 ): a = 891.24(9), b = 1025.34(7), c = 1234.82(9) pm, α = 92.938(8), β = 106.457(8), γ = 98.100(7)°, V = 1066.4(2) · 10⁶ pm³, space group P1; (Ph₄P)₂[Pb₂I₆] ( 3 ): a = 1174.5(1), b = 722.29(7), c = 3104.8(4) pm, β = 100.50(1)°, V = 2589.8(5) · 10⁶ pm³, space group P2₁/n; [Bu₃N–(CH₂)₃–NBu₃][PbI₄] ( 4 ): a = 2178.3(1), b = 1008.63(5), c = 1888.3(1) pm, β = 110.003(5)°, V = 3898.6(4) · 10⁶ pm³, space group P2/c.     

FTIR study of hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide,and acetonitrile in supercritical CO_2

FTIR spectroscopy was used to study the hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide (DMSO),and acetonitrile in supercritical CO_2 at 318.15 K, and 12.5 and 16.5 MPa. The concentrations of the cosolvents range from 0—0.6 mol·L~(-1). The area percentage of absorption bands for hydrogen-bonded and nonhydrogen-bonded species was obtained from the IR spectra. The acid and the cosolvents can form hydrogen bond even when their concentrations are very low. At fixed solute concentration, the extent of hydrogenbonding increases with cosolvent concentration. At higher ethanol concentrations, it seems that one stearic acid molecule can hydrogen bond with more than one ethanol molecules simultaneously. It is seen that the strength of the hydrogen bond formed by the acid and the cosolvents is in the order: DMSO>ethanol>acetonitrile.     

Solubility of stearic acid in supercritical CO_2-acetonitrile mixtures

The solubility of stearic acid in supercritical CO2 with acetonitrile (CH3CN) cosolvent was measured at 318.15 K in the pressure range from 9.5 to 16.5 MPa, and the cosolvent concentration ranges from 0. 0 to 5.5 mol% . The solubility increases with acetonitrile concentration and pressure, and it also increases with the apparent density of CO2 d1(moles of CO2 in per liter of fluid) at higher cosolvent concentrations. At lower d1, however, the solubility of the acid at lower acetonitrile concentrations is lower than that in pure CO2 provided that d1 is fixed, which is discussed qualitatively based on the clustering of the components in the system.