Mesogenic behaviour of two series of orthopalladated polar inline derivatives and their organic ligands (II)

One series of 4-n-octyl-N-(4-X-benzylidene)anilines and two series of polar orthopalladated complexes derived from these of type Pd₂(μ-Y)₂ p-X-C₆H₃-CH = N-C₆H₄-C₈H₁₇₂; X: -H, -F, -Cl, -Br, -NO₂, -CN, -CH₃, -OCH₃, -CF₃, -COOCH₃, -OCOCH₃ and -OCOQH₅; Y: -OAc and -Cl; have been synthesized and their mesogenic properties studied. In the polar Schiff bases used as organic ligands, the polar end group determines both the presence of the mesophase and the type of mesophase exhibited. In the complexes, however, it is the central structure of the molecule that practically always determines mesogenic behaviour. No acetato-bridged complex is mesogenic. All the chloro-bridged complexes, however, show mesogenic behaviour. All these compounds show smectic A mesophases with the exception of the CN compound, which only exhibits a nematic mesophase.     

Boundary element solution of the two-dimensional groundwater flow equation with stochastic free surface boundary condition

An innovative approach to the approximate solution of stochastic partial differential equations in groundwater flow is presented. The method uses a formulation of the Ito's lemma in Hilbert spaces to derive partial differential equations satisfying the moments of the solution process. Since the moments equations are deterministic, they could be solved by any analytical or numerical method existing in the literature. This permits the analysis and solution of stochastic partial differential equations occurring in two-dimensional or three-dimensional domains of any geometrical shape. The method is tested for the first time in the present paper through a practical application in a sandy phreatic aquifer at the Chalk River Nuclear Laboratories, Ontario, Canada. The equation solved is the two-dimensional LaPlace equation with a dynamic, randomly perturbed, free surface boundary condition. The moments equations are derived and solved by using the boundary integral equation method. A comparison is made with a previous analytical solution obtained by applying the randomly forced one-dimensional Boussinesq equation, and some observations on modeling procedures are given.     

UV-spectrophotometric determination of beclomethasone dipropionate and phenylethyl alcohol in a nasal spray by inverse least-squares regression

Inverse least-squares (ILS) regression was used for the simultaneous UV spectrophotometric determination of the active principle (beclomethasone dipropionate) and a solvent (phenylethyl alcohol) in a pharmaceutical preparation commercially available in nasal spray form. A factorial design was used to establish the calibration equations, which enables the construction of calibration models using a minimum number of samples. The operating wavelengths were chosen by first choosing that coinciding with the absorption maximum for the analyte to be determined and then adding terms, one at a time, following the stepwise-forward procedure until no significantly improved S.E. is obtained. Single calibration equations were found for both constituents that provide satisfactory results in absorbance mode. The ILS procedure was applied to five industrial preparations with highly satisfactory results. In all, coefficients of variation values were less than 2%.     

Palladium(II) iminophosphine complexes

New complexes of general formula [PdCl₂(NP)] (NP = o-Ph₂PC₆H₄-CH=N-R; R = Me, ⁱ Pr, ^t Bu, NH-Me) and [Pd(NP)₂](ClO₄)₂ (NP = o-Ph₂PC₆H₄-CH=N-R; R = Me, ⁱ Pr) have been prepared by directly reacting the precursor PdCl₂(PhCN)₂ with iminophosphines (NP) in 1:1 and 1:2 molar ratios respectively. When the chloro-complex [PdCl₂(o-Ph₂PC₆H₄-CH=N ⁱ -Pr)] was treated with CF₃SO₃Ag in MeCN, the labile complex [Pd(o-Ph₂PC₆H₄-CH=N ⁱ -Pr)(MeCN)₂](CF₃SO₃)₂ was obtained in good yield. The reactivity of the new precursor towards a variety of neutral N- and P-donor ligands (py, PMe₂Ph, PMePh₂, PEt₃, bipy, dppe, 2-thpy) has been studied. The new complexes were characterized by partial elemental analyses and by spectroscopy (i.r., ¹H- and ³¹P-n.m.r.). The molecular structure of the aquo-complex [Pd(NP)(2-thpy)(H₂O)](CF₃SO₃)₂ has been determined by a single-crystal diffraction study, showing that the iminophosphine acts as a chelating ligand with coordination around the palladium atom slightly distorted from square-planar geometry.     

Influence of hydrolysis, purification, and calibration method on furosine determination using Ion-pair reversed-phase high-performance liquid chromatography

The influence of HCI concentration (6M, 8M, and 10M) and the ratio of sample protein to acid (1 or 5 mg of protein per mL of acid) on furosine formation during sample hydrolysis is studied. The conditions that maximize furosine formation are 10M HCI in the ratio of 1 mg of protein to 1 mL of acid. Purification of the hydrolysate by solid-phase extraction is also considered by examining the effect of hydrolysate volume and volume of 3M HCI used to elute the furosine. Furosine quantitation is carried out using the standard additions and external standard methods. The results indicate that there is no interference by the sample matrix and that external calibration is adequate.     

Bis(tetra‐n‐butylammonium) di‐μ‐chloro‐bis[(tetramethyl buta‐1,3‐diene‐1,2,3,4‐tetracarboxylato‐κ2C1,C4)palladium]

The anionic complex in the title compound, (C₁₆H₃₆N)₂[Pd₂(C₁₂H₁₂O₈)₂Cl₂], lies on a centre of inversion, so that the {Pd₂(μ‐Cl)₂} core is planar, which is the most frequent conformation found for complexes containing this moiety in the Cambridge Structural Database [October 2001 Release; Allen & Kennard (1993). Chem. Des. Autom. News, 8 , 1, 31–37]. This dinuclear complex has a Pd?Pd distance of 3.5119 (4) Å. The bite angle of the chelating ligand [79.79 (8)°] distorts the square‐planar coordination around the metal atom.