Hydroxyl-containing mesogens. Synthesis and liquid-crystalline properties of 2-o-hydroxyarylpyrimidines

We have synthesized 5-alkyl(alkoxy)-2-(o-lzydroxy-p-alkoxyphenyl)pyrimidines and considered the effect of the OH group on the inesomorphism. We have found that in binuclear o-hydroxyarylpyrimidines, an ortho OH group forming an intramolecular hydrogen bond increases T_mp, inhibits the appearance of nematic properties, and promotes the appearance of a smectic A.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 30, No. 1, pp. 90–92, January, 1994.     

Accuracy analysis of airborne gravimeter calibration using repeated flight paths

Some possible errors in determining the gravity anomalies are discussed. Such errors may be caused by an inaccurate calibration of the gravimeter used in an airborne survey system. An approach based on wavelet decompositions is proposed for its additional calibration with the use of flight data obtained during repeated flights.     

Transient-field strength measurements for52Cr traversing Fe hosts at high velocity and polarization transfer mechanisms

Transient-field strengths were measured for⁵²Cr ions traversing polarized Fe hosts at velocities up to 12υ₀ (12υ₀ =c/137 = Bohr velocity). The results are compared with predictions of various transient-field parametrizations and discussed in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving Cr ions. Theg-factor of the first 2⁺ state of⁵²Cr was also measured by the transient-field technique and found to be in accord with shell model calculations.     

Iteration scheme for accelerometer unit calibration by a guaranteeing approach

Methods for accelerometer unit calibration are usually based on sufficiently strict requirements on the knowledge of the gravity orientation with respect to the unit (of the order of fractions of an arc minute). But it is not always possible to know the orientation with such high accuracy. In the present paper, we consider an approach to accelerometer unit calibration for whose implementation it suffices to have rough angular information (of the order of tens of arc minutes). We use a guaranteeing approach to calculate optimal schemes calibration experiments and propose an iterative scheme of calibration.     

Crystal and molecular structure of 2-(2′-methylaminophenyl)-4H-3,1-benzoxazine-4-one

A planar structure for molecules of 2-(2-methylaminophenyl)-4H-3,1-benzoxazine-4-one was found by x-ray structural analysis. Shortening of the N-Ph bond and lengthening of the distance between amino- and azine-N atoms in comparison to the tosyl analog was demonstrated to lead to a bathochromic shift of the absorption spectrum and a hypsochromic displacement of the luminescence spectrum. As a result, the Stokes shift of 2-(2-methylaminophenyl)-4H-3,1-benzoxazine-4-one is smaller than that of 2-(2-tosylaminophenyl)-4H-3,1-benzoxazine-4-one. In the crystal, molecules of 2-(2-methylaminophenyl)-4H-3,1-benzoxazine-4-one are stacked with intermolecular interaction energy between molecules in the stack of –12.5 and –14.2 kcal/mole. The stacks are joined into layers parallel to (010).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1781–1785, August, 1989.     

Molecular and crystal structure of N,N′-di-(p-tosyl)-2,8-dimethoxyphengomazine-6,12-dione

Branch of the Institute of Chemical Physics, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 5, pp. 109–115, September–October, 1988.     

Initiation of the internal-conversion process in the phenyl benzoate molecule

The INDO and CNDO/S methods were used to calculate changes in the energy of the ground state and the energy of the first singlet-singlet transition of phenyl benzoate permitted with respect to its multiplet nature with consistent rotation of phenyl groups of the molecule in the cis conformation. It was found that in the lowest excited singlet state of the phenyl benzoate molecule an adiabatic photoreaction can occur, as a result of which the energy of the S₀-S₁ electron transition decreases to values of 2 eV. With motion of the molecular system along the coordinate of the photoreaction, an internal-conversion process is initiated, which leads to the experimentally observed absence of luminescence of phenyl benzoate solutions.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 21, No. 3, pp. 365–367, May–June, 1985.     

Complexation of Cu(II) with <Emphasis Type="SmallCaps">L</Emphasis>- and <Emphasis Type="SmallCaps">DL</Emphasis>-threonine: An ESR study

Complexation of Cu(II) ions with L- and DL-threonine in aqueous solution was studied. Treatment of the ESR spectra of solutions containing Cu(II) and threonine in various ratios and having various pH, involving total line shape analysis, revealed formation of geometric isomers of the complex ions [Cu(thrH_–1)₂]^2– differing in the mutual arrangement of the N and O atoms in the equatorial plane; the complexation and isomerization equilibrium constants were determined.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1388–1391.Original Russian Text Copyright © 2004 by Statsenko, Bolotin, Panyushkin.This revised version was published online in April 2005 with a corrected cover date.     

Gyromagnetic ratios of excited states in186W

The gyromagnetic ratios of the 4 ₁ ⁺ , 6 ₁ ⁺ , and 2 ₂ ⁺ states in¹⁸⁶W were measured relative to that of the 2 ₁ ⁺ level by means of the transient field implantation perturbedγ-ray angular distribution technique. The nuclei in the states of interest were Coulomb excited using a beam of 220-MeV⁶³Cu projectiles and recoiled swiftly through a thin, polarized Fe foil. The present measurements yielded ratiosg(4 ₁ ⁺ )/g(2 ₁ ⁺ )=1.04±0.07,g(6 ₁ ⁺ )/g(2 ₁ ⁺ )=1.03 ±0.20 andg(2 ₂ ⁺ )/g(2 ₁ ⁺ )=0.63±0.13. The sizable disparity between the measuredg-factors of the ground- and excited-band is examined within the context of the interacting boson approximation model.     

Disparity of measured gyromagnetic ratios of ground- and excited-band states in184W

Gyromagnetic ratios of levels in the ground-band and of the 2 ₂ ⁺ state in¹⁸⁴W were measured by means of the transient magnetic field perturbedγ-ray angular distribution technique. The levels of interest were Coulomb excited by beams of 220-MeV⁵⁸Ni and⁶³Cu ions. The results show theg-factor of the 2 ₂ ⁺ state to be approximately half the effectively constant value found for the ground-band levels. This disparity is compared with those previously obtained for the corresponding states in^188–192Os and¹⁸⁶W; these are discussed in the context of the interacting boson model.