Probing electrochemical properties of pi-conjugated thienylenevinylenes/fullerene C(60) adducts by ESI/MS: evidence for dimerized cation-radicals

Oligothienylenevinylenes/C(60) dyads n-C and triads n-C(2) are studied by electrospray mass spectrometry. A clear correlation is observed between the nature of the charged species detected by mass spectrometry, i.e. protonated molecule [M + H], (+) cation radical M(+.) and dication M(++), and the oxidation potentials of the molecules. Moreover, under defined solubility conditions, mass spectrometry provides conclusive evidences for the reversible dimerization of cation-radicals of n-C(2) compounds.     

Quasi‐random integration in quantum chemistry: Efficiency,stability, and application to the study of small atoms and molecules constrained in spherical boxes

This project consists of two parts. In the first part, a series of test calculations is performed to verify that the integrals involved in the determination of atomic and molecular properties by standard self‐consistent field (SCF) methods can be obtained through Halton, Korobov, or Hammersley quasi‐random integration procedures. Through these calculations, we confirm that all three methods lead to results that meet the levels of precision required for their use in the calculation of properties of small atoms or molecules at least at a Hartree–Fock level. Moreover, we have ensured that the efficiency of quasi‐random integration methods that we have tested is Halton=Korobov>Hammersley?pseudo‐random. We also find that these results are comparable to those yielded by ordinary Monte Carlo (pseudo‐random) integration, with a calculation effort of two orders of smaller magnitude. The second part, which would not have been possible without the integration method previously analyzed, contains a first study of atoms constrained in spherical boxes through SCF calculations with basis functions adapted to the features of the problem: Slater‐type orbitals (STOs) trimmed by multiplying them by a function that yields 1 for 0 < r < (R‐δ), polynomial values for (R‐δ) < r < R and null for r > R, R being the radius of the box and δ a variationally determined interval. As a result, we obtain a equation of state for electrons of small systems, valid just in the limit of low temperatures, but fairly simple. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Nanotechnology with soft materials.

Nature exploits self-organization of soft materials in many ways, to produce cell membranes, biopolymer fibers and viruses, to name just three. Mankind is now able to design materials at the nanoscale, whether through atom-by-atom or molecule-by-molecule methods (top-down) or through self-organization (bottom-up). The latter method encompasses soft nanotechnology. Self-organization of soft materials can be exploited to create a panoply of nanostructures for diverse applications. The richness of structures results from the weak ordering because of noncovalent interactions. Thus, thermal energy is important as it enables transitions between phases with differing degrees of order. The power of self-organization may be harnessed most usefully in a number of nanotechnology applications, which include the preparation of nanoparticles, the templating of nanostructures, nanomotor design, the exploitation of biomineralization, and the development of functionalized delivery vectors.     

SDS/n－C5H11OH/n－C7H16/H2O体系中W/O－BI微乳液界面电性质

In the system of SDS/n-C5H11OH/n-C7H16/H2O with the weight ratio of SDS/n-C5H11OH/H2O system at5.0/47.5/47.5, the upper phase of the system was W/O microemulsion, and the lower phase was the bicontinuous microemulsion. When the n-heptane content was less than 1%, with the increase of the n-heptane content, the capacitance (Co, Cod) in the upper phase (W/O) dropped, the capacitance (CB1, CBld) in the lower phase (BI) raised. At the same time, the W/O-BI inteffacial potential (ΔE), capacitance (Ci), and charge-transfer current (ict) decreased.After the n-heptane content reached 1%, with the increase of the n-heptane content, ΔE, Ci and ict demonstrated no significant change.     

Molecular mechanics and dynamics of biomolecules using a solvent continuum model

An easy implementation of molecular mechanics and molecular dynamics simulation using a continuum solvent model is presented that is particularly suitable for biomolecular simulations. The computation of solvation forces is made using the linear Poisson-Boltzmann equation (polar contribution) and the solvent-accessible surface area approach (nonpolar contribution). The feasibility of the methodology is demonstrated on a small protein and a small DNA hairpin. Although the parameters employed in this model must be refined to gain reliability, the performance of the method, with a standard choice of parameters, is comparable with results obtained by explicit water simulations. Copyright 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1830-1842, 2001     

氢甲酰化反应溶剂效应的量子化学研究

在B3LYP/6-31G(d, p)(Rh和P采用LANL2DZ + Polar)水平下,利用自洽反应场（SCRF）的Onsager模型,系统研究了C6H12、C6H6、THF、CH2Cl2、CH3OH和H2O（相对介电常数ε分别为2.02、2.25、7.58、8.93、32.63和78.39）六种溶剂对乙烯氢甲酰化反应中各驻点的结构和反应机理的影响.分别在上述溶剂中优化了反应物、产物、中间体和过渡态的结构,并计算了自由能和活化自由能.计算结果表明,不同溶剂对反应势能面上各驻点的结构和能量均有一定的影响,而且随着相对介电常数ε的增加,反应的活化自由能下降.水是以上六种溶剂中最佳的溶剂,这与大量的实验研究结果一致.     

Study on Electrochemiluminesce of Ru(bpy3)2+ Immobilized in a Titania Sol‐Gel Membrane

The immobilization of tris(2,2′‐bipyridyl)ruthenium(II), Ru(bpy)₃²⁺, at a glassy carbon electrode was achieved by entrapping the Ru(bpy)₃²⁺ in a vapor deposited titania sol‐gel membrane. The electrogenerated chemiluminescence (ECL) of the immobilized Ru(bpy)₃²⁺ was studied. The Ru(bpy)₃²⁺ modified electrode showed a fast ECL response to both oxalate and proline. The ECL intensity was linearly related to concentrations of oxalate and proline over the ranges from 20 to 700 μmol L^?1 and 20 to 600 μmol L^?1, respectively. The detection limits for oxalate and proline at 3σ were 5.0 μmol L^?1 and 4.0 μmol L^?1, respectively. This electrode possessed good precision and stability for oxalate and proline determinations. The electrogenerated chemiluminescence mechanism of proline system was discussed. This work provided a new way for the immobilization of Ru(bpy)₃²⁺ and the application of titania sol‐gel membrane in electrogenerated chemiluminescence.     

1,2‐Dithioquadratato‐ und 1,2‐Dithiooxalatoindate(III)

Indium(III) chloride forms in water with potassium 1,2‐dithiooxalate (dto) and potassium 1,2‐dithiosquarate (dtsq) stable coordination compounds. Due to the higher bridging ability of the 1,2‐dithiooxalate ligand in all cases only thiooxalate bridged binuclear complexes were found. From 1,2‐dithioquadratate with an identical donor atom set mononuclear trischelates could be isolated. Five crystalline complexes, (BzlMe₃N)₄[(dto)₂In(dto)In(dto)₂] ( 1 ), (BzlPh₃P)₄[(dto)₂In(dto)In(dto)₂] ( 2 ), (BzlMe₃N)₃[In(dtsq)₃] ( 3 ), (Bu₄N)₃[In(dtsq)₃] ( 4 ) and (Ph₄P)[In(dtsq)₂(DMF)₂] ( 5 ), have been isolated and characterized by X‐ray analyses. Due to the type of the complex and the cations involved these compounds crystallize in different space groups with the following parameters: 1 , monoclinic in P2₁/c with a = 14.4035(5) Å, b = 10.8141(5) Å, c = 23.3698(9) Å, β = 124.664(2)°, and Z = 2; 2 , triclinic in P with a = 11.3872(7) Å, b = 13.6669(9) Å, c = 17.4296(10) Å, α = 88.883(5)°, β = 96.763(1)°, γ = 74.587(5)°, and Z = 1; 3 , hexagonal in R3 with a = 20.6501(16) Å, b = 20.6501(16) Å, c = 19.0706(13) Å and Z = 6; 4 , monoclinic in P2₁/c with a = 22.7650(15) Å, b = 20.4656(10) Å, c = 14.4770(9) Å, β = 101.095(5)°, and Z = 4; 5 , triclinic in P with a = 9.2227(6) Å, b = 15.3876(9) Å, c = 15.5298(9) Å, α = 110.526(1)°, β = 100.138(1)°, γ = 101.003(1)°, and Z = 2.     

Real‐time lock‐in energy loss imaging with a novel high‐speed image processing CCD video camera

We have developed a high‐speed image processing CCD video camera for real‐time energy‐loss imaging using a conventional electron microscope with an energy‐loss imaging facility. As an initial demonstration of real‐time lock‐in energy‐loss imaging, a background‐subtracted energy‐loss image was observed by attaching the high‐speed image processing CCD video camera to an analytical electron microscope equipped with a floating‐type energy‐loss imaging analyser. Copyright © 2003 John Wiley & Sons, Ltd.     

A case study in conformation design: learning by doing

Efforts are described to design simple, fully flexible but conformationally preorganised omega-hydroxy-nonanoic acids that could serve as the conformation controlling unit in analogues of the potent protein-kinase C activator aplysiatoxin. Such analogues are macrodilactones incorporating the designed omega-hydroxy-nonanoic acid and 3,4-dihydroxy-pentanoic acid, which contains the pharmacophoric groups. The design process (replacement of CH(2) groups by an oxygen atom, annelation of a six-membered ring and placement of alkyl substituents) of the omega-hydroxy-nonanoic acids was monitored by force-field calculations. In the end of this process simple analogues of aplysiatoxin are proposed in which the proper disposition of the pharmacophoric groups is secured by a conformationally flexible but preorganised template structure as part of the macrodilactone ring.