Commutator perturbation method in the study of vibrational–rotational spectra of diatomic molecules

The commutator perturbation method, an algebraic version of the Van Vleck–Primas perturbation method, expressed in terms of ladder operators, has been applied to solving the eigenvalue problem of the Hamiltonian describing the vibrational–rotational motion of a diatomic molecule. The physical model used in this work is based on Dunham's approach. The method facilitates obtaining both energies and eigenvectors in an algebraic way. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 721–726, 2000     

Exact solutions of the rigid rotor in the electric field

We first present a new constraint condition on the confluent Heun function H_C(α, β, γ, δ, η;z) (β, γ ≥ 0, z ∈ [0, 1]) and then illustrate how to solve the rigid rotor in the electric field. We find its exact solutions unsolved previously through solving the Wronskian determinant. The present results compared with those by the perturbation methods are found to have a big difference for a large parameter a. We also present 2D and 3D probability density distributions by choosing different angular momentum quantum numbers l. We observe that the original eigenvalues with degeneracy (2 l + 1) are split into the (l + 1) state with approximate eigenvalues l(l + 1) for small a but large l.     

Algebraic expressions of Clebsch–Gordon coefficients for the group chain O† ⊃ C

Using the algebraic expressions of the projection operators for the group chain O ? C, concise algebraic expressions of the Clebsch–Gordon (CG) coefficients are derived in the group chain O ? C for both single‐valued and double‐valued representations. The simplicity of the expressions is that they are merely functions of the quantum numbers of the group chain O ? C. The symmetry of the CG coefficients is also derived. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

A dimethylzinc/diphenylphosphinoylimine approach to the asymmetric synthesis of the calcimimetic agent NPS R‐568

An asymmetric synthesis of the calcimimetic agent NPS R‐568 using a (1R,2S)‐N‐benzylephedrine‐promoted addition of dimethylzinc to a diphenylphosphinoylimine derived from 3‐methoxybenzaldehyde is described. The enantiomeric ratio of the key amine fragment was determined to be 93:7 (86% ee), favoring the (R)‐enantiomer by derivatization and chiral stationary phase HPLC analysis. Copyright © 2010 John Wiley & Sons, Ltd.     

Highly Enantioselective Carbonyl–Ene Reactions of 2,3‐Diketoesters: Efficient and Atom‐Economical Process to Functionalized Chiral α‐Hydroxy‐β‐Ketoesters

Carbonyl–ene reactions of 2,3‐diketoesters catalyzed by [Cu{(S,S)‐tBu‐box}](SbF₆)₂ [box=bis(oxazoline)] generate chiral α‐functionalized α‐hydroxy‐β‐ketoesters in up to 94 % yield and 97 % ee. The 2,3‐diketoesters are conveniently accessed from the corresponding α‐diazo‐β‐ketoester, and a catalyst loading as low as 1.0 mol % can be achieved.     

Application of the Lie algebraic approach to diffractionally and rotationally inelastic molecule–surface scattering

The Lie algebraic approach of Alhassid and Levine [Phys. Rev. A 18 , 89 (1978)] is applied to the molecule–surface scattering. Specially, the diffractionally and rotationally inelastic scattering of a diatomic molecule from a solid surface is dealt with. Within the framework of the close-coupling method, we construct a Hamiltonian for the scattering system and use it to generate a dynamical algebra h₆. By solving equations of motion for the group parameters, the scattering wave functions near the surface are obtained. Computed transition probabilities of diffractively and rotationally inelastic scattering of H₂ from LiF(001) surface with the use of Lie algebraic method are seen to agree well with the coupled-channel calculations. The Lie algebraic method thus appears to have a wide range of validity for describing the dynamics of gas–surface scattering. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 981–989, 1997     

Expeditious asymmetric synthesis of a stereoheptad corresponding to the C(19)-C(27)-ansa chain of rifamycins: formal total synthesis of Rifamycin S

In the presence of sulfur dioxide and an acid promoter, (-)-(1E,3Z)-2-methyl-1-((1S)-1-phenylethoxy)penta-1,3-dien-3-yl isobutyrate reacts with (Z)-3-(trimethylsilyloxy)pent-2-ene giving a silyl sulfinate intermediate that undergoes, in the presence of palladium catalyst, a desilylation and retro-ene elimination of SO(2) with formation of (-)-(1Z,2S,3R,4S)-1-ethylidene-2,4-dimethyl-5-oxo-3-((1S)-1-phenylethoxy)-heptyl isobutyrate as major product. This ethyl ketone undergoes cross-aldol reaction with (2S)-2-methyl-3-[(tert-butyldimethylsilyl)oxy]propanal giving an aldol that is reduced into a stereoheptad corresponding to the C(19)-C(27)-segment of Rifamycins with high diastereoselectivity and enantiomeric excess.     

Extension of the PS-GVB electronic structure code to transition metal complexes

We have developed a parameterization enabling ab initio electronic structure calculation via the PS-GVB program on transition-metal-containing systems using two standard effective core potential basis sets. Results are compared with Gaussian-92 for a wide range of complexes, and superior performance is demonstrated with regard to computational efficiency for single-point energies and geometry optimization. Additionally, the initial guess strategy in PS-GVB is shown to provide considerably more reliable convergence to the ground state. © 1997 John Wiley & Sons, Inc. J Comput Chem 18 : 1863–1874, 1997     

Application of combined approach to analyze the constituents of essential oil from Dong quai

A combined approach of sub-window factor analysis and spectral correlative chromatography has been employed to analyze the constituents of essential oils of Dong quai. Essential oils are the main pharmacological active individuals of Dong quai. Some constituents in the main root of Dong quai have been identified by GC-MS with the help of sub-window factor analysis resolving two-dimensional original data into mass spectra and chromatograms. Correlative constituents in another part of the root fiber have been recognized by spectral correlative chromatography. Seventy six of 97 separated constituents in the essential oil of main root were identified and quantified, accounting for about 91.36% of the total content. Sixty seven correlative components in the essential oil of root fiber were recognized. The result proves that the combined approach is powerful enough for the analysis of complex herbal samples.     

A self‐contrast approach to evaluate the inhibitory effect of chrysosplenetin,in the absence and presence of artemisinin,on the in vivo P‐glycoprotein‐mediated digoxin transport activity

In this study, we used a self‐contrast method, which excluded the individual difference, to evaluate the inhibitory effect of chrysosplentin (CHR) in the presence or absence of artemisinin (ART) on the P‐glycoprotein (P‐gp) transport activity. A sensitive and rapid UHPLC–MS/MS method was applied for quantification of digoxin, a P‐gp‐specific substrate, in rat plasma. A pharmacokinetic study was carried out: first after an oral administration of digoxin at a dose of 0.09 mg/kg (first period), followed by a 20‐day wash‐out, then after another administration of digoxin (second period). During the second period, test compounds were orally given three times per day for seven consecutive days. Results showed that the t_1/2 of digoxin in all the groups had no significant difference between the first and second periods. The AUC_0–24, C_max, t_max, and Cl_z/F of the negative control and ART alone groups showed no difference. However, the AUC_0–24 and C_max in the CHR alone, CHR–ART (1:2) and verapamil (positive control) groups showed 2.34‐, 3.04‐, 1.79‐, and 1.81‐, 1.99‐, 2.06‐fold increases along with 3.50‐, 3.84‐ and 4.76‐fold decreases for CL_z/F, respectively. The t_max in the CHR–ART (1:2) group increased 3.73‐fold. In conclusion, our self‐contrast study suggested that CHR, especially when combined with ART in a ratio of 1:2, inhibited P‐gp activity while ART alone has no effect. Copyright © 2016 John Wiley & Sons, Ltd.     

An extrapolation procedure to obtain the total fringe number from Gouy fringe pattern data

A rapid new procedure is described for getting the total number of fringes J from Gouy fringe pattern data. This PQ method is exact and the results excellent (within 0.01–0.03 fringe) for ideal systems (_j=0 for all j, Q₀=0). Such systems include most binaries; for these, the diffusion coefficient is either constant or a polynomial function of concentration with small concentration differences. For multicomponent systems and some binaries, Q₀ can be significantly different from 0. In these cases, the PQ method unambiguously gives the integer number of fringes. If in addition Q₀/Q₁ is larger than 2.0, then J obtained from a second extrapolation procedure is also good.