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361.
Hasan Karabıyık Hande Petek Nazan Ocak İskeleli Çiğdem Albayrak 《Structural chemistry》2009,20(5):903-910
The molecular and crystal structure of (E)-2-Acetyl-4-(2-bromophenyldiazenyl)phenol (1) and (E)-2-Methyl-4-(o-tolyldiazenyl)phenol (2) were characterized and determined by single crystal X-ray diffraction method besides spectroscopic means. The periodic organization
of 1 is stabilized by C–H···O type weak H-bond and Br···O type weak halogen bonding and thus, a two dimensional puckered network
is established almost parallel to () the plane. Molecules of 2 are linked into C(7) chains generated by translation along the [1 0 1] direction with the aid of O–H···N type H-bonds, and these chains are
strengthened by C–H···π interactions involving o-tolylphenol ring. Quantum chemical studies at B3LYP/6-311 ++G(d,p) level reveal that potential barrier of the compounds around
Ar–N torsions is of double minimum character unless it is defected by the presence of o-substituent groups in the vicinity of the azo bridge. The results from crystallographic and quantum chemical studies suggest
that azo benzene compounds may adapt non-planar geometry apart from the most stable planar conformation, which is located
on the secondary minima of double potential barrier regarding rotational motion around Ar–N bonds. 相似文献
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A recent study on the Taylor series method of second order and the trapezoidal rule for dynamic equations on time scales has been continued by introducing a derivation of the Taylor series method of arbitrary order on time scales. The error and convergence analysis of the method is also obtained. The 2-step Adams–Bashforth method for dynamic equations on time scales is concluded and applied to examples of initial value problems for nonlinear dynamic equations. Numerical results are presented and discussed. 相似文献
365.
For the computation of the macroscopic tangent that is required in multiscale volumetric homogenization techniques, two methods are summarized. First, a condensation approach is followed where the linearity of variational terms associated with the penalty enforcement of boundary conditions is explored in order to extract a macroscopic tangent at any stage of the Newton–Raphson iterations of a microstructural testing procedure. As an alternative approach, a second method is explored that requires only the knowledge of infinitesimally close macroscopic deformation states. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献