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1.
Rod-shaped 4-methylbenzoic acid- N′-(4′- n-alkoxybenzoyl) hydrazide (series I) have been synthesized by the Schotten–Baumann reaction of 4-methylbenzhydrazide with 4- n-alkoxy benzoyl chloride using dry pyridine, as a solvent. The series I compounds have been cyclized to bent-shaped mesogenic 2-(4′-methylphenyl)-5-(4″- n-alkoxyphenyl)-1,3,4-oxadiazoles (series II) and 2-(4′-methylphenyl)-5-(4″- n-alkoxyphenyl)-1,3,4-thiadiazole (series III) using POCl 3 and Lawesson's reagent, respectively. The synthesized compounds are characterized by the combination of elemental analysis and standard spectroscopic methods. In series II, lower and middle members are non-mesogenic. n-Dodecyloxy to n-hexadecyloxy derivatives exhibit enantiotropic nematic mesophase. In series III, all the compounds synthesized exhibit enantiotropic nematic mesophase. n-Tetradecyloxy and n-hexadecyloxy derivatives also exhibit enantiotropic SmA mesophase. The mesomorphic properties of the series II and III used in this study are compared with each other and with other structurally related compound to evaluate the effect of different heterocyclic moieties as well as terminal substituents on mesomorphism. 相似文献
2.
A substantial problem in the macroscopic theory of pure superconductivity has been left forgotten for a long time since London and London in 1935. An impression survived that the Meissner effect is more substantial than the zero-resistivity. But, the London equation [ I], the Newtonian equation of motion, was abandoned, whereas the London equation [ II], derived from the Maxwell equations, was postulated. The London equation [ II] included the logical gap [ α ] in real time, whereas the London equation [ I] has been ignored without even noting the logical gap [ β ] in space. Microscopically, after the publication of F. London's book and the discovery of the isotope effect in 1950, the success of the Bardeen--Cooper--Schrieffer (BCS) theory in 1957 was likely to have finally given the definitive explanation on superconductivity by proving only the London equation [ II] that claimed the coherent condensation of Cooper pairs in the momentum space. Since then, these arguments have been regarded to be a standard among various preceding theories. Meanwhile, the London equation [ I] has faded away and has been long-forgotten. But we must not abandon the London equation [ I], and, rather, retrieve it. We later recognized also that the DC-component of a persistent current can never be determined by using the Fourier transform analysis, because of its singularity at ω?=?0 and q ?=?0 with huge differences of space-time domain. Quite recently, in 2003, we first recognized a proper and harmonious view to simultaneously account for (i) the zero-resistivity in an open system with (i- c) the resultant persistent current in a closed system, and (ii) the perfect diamagnetism at T???0?K in the space-time aspects in terms of the gauge field theory. Here, we further clarify where and how we have lost and found a properly perspective view of the superconductivity. Here, we eliminate two logical gaps [ α ] and [ β ] by using the gauge field theory for further clarifying a position of the previous and present works. We especially classify superconductors with topology which eventually leads us such as (ii-2D) magnetic flux quantization in a ring. By projecting the 3-dimensional BCS-theory with the concept of ‘coherence’ among an enormous number of Bosons like Cooper pairs onto the (1?+?3)-dimensional Minkowski space-time [β?=?( v/ c)?=?0], we clarify responses of the ground state Ψ macro at T???0?K in a set of the basic equations, for (i) the zero-resistivity, [ E K ??? qφ( R )]?=?0 at ω?=?0 and (ii) the perfect diamagnetism [ ?K ??? qA ( R )]?=?0 at q ?=?0 as an inevitable consequence at the gauge fields in the proper theory of superconductivity. 相似文献
3.
The two-dimensional cyclic potential energy surfaces for internal rotation of the allyl substituent and its vinyl fragment
in o-allylphenol ( o-APh) depending on the OH group orientation relative to the allyl substituent were constructed by a B3LYP/6-31G method. It
is shown that o-APh exists in the gas phase as a mixture of eight non-planar rotamers ( A, B, C, D, E, F, G, and H) and their eight optical isomers ( A
1, B
1, C
1, D
1, E
1, F
1, G
1, and H
1). An intramolecular H-bond (IHB) O–H...π occurs only in four rotamers ( A, B, A
1, and B
1). The content of such rotamers in the gas phase is 47.2% (as calculated by the B3LYP/cc-pVTZ method). Taking into account
the solvation effect in the polarizable continuum model (PCM) for a solution of o-APh in cyclohexane decreases the total content of rotamers with an IHB (A and B) to 37.7%. The ratio of rotamers with OH
groups bonded by an IHB and with free OH groups that is predicted theoretically agrees with the value measured experimentally
from IR spectra of o-APH in CCl 4 solution. 相似文献
4.
Let H be a Hilbert space, A the von Neumann algebra of all bounded operators on H, B a von Neumann subalgebra of A, and w a bounded linear functional on A. The functional w is said to commute with BA if w(AB)= w(BA) for all AA. It is shown that the map Bw (BAB) is a complex measure on the orthocomplemented partially ordered set of all orthogonal projections in B for every AA if and only if w commutes with all members of B. For any AA, the conditional expectation of A with respect to B and w is defined and it is shown that this expectation exists for an Abelian separable B if w commutes with all members of B. Using Gleason's theorem it is shown that w commutes with B if and only if the density operator of w commutes with B. 相似文献
5.
Abstract The Diels–Alder adducts, 3a– e, of phencyclone, 1, have been prepared from a series of N‐ n‐alkylmaleimides, 2, with medium chain‐length n‐alkyl groups. The maleimides were obtained by cyclodehydration of the N‐ n‐alkylmaleamic acids, 4, formed from reaction of maleic anhydride with the corresponding n‐alkylamines. The five adducts prepared included derivatives from n‐heptyl, 3a; n‐octyl, 3b; n‐nonyl, 3c; n‐decyl, 3d; and n‐dodecyl, 3e. The NMR spectra of the adducts were studied in CDCl 3 at ambient temperatures at 300 MHz for proton and 75 MHz for carbon‐13, with full proton assignments achieved by high‐resolution COSY45 spectra for the aryl and the alkyl regions. Slow exchange limit (SEL) spectra were observed for both 1H and 13C spectra showing slow rotation on the NMR timescales of the unsubstituted bridgehead phenyl groups. Endo Diels–Alder adduct stereochemistry was supported by striking magnetic anisotropic shielding effects in the 1H spectra of the alkyl groups, with the NCH 2 CH 2 signal of each adduct appearing upfield of tetramethylsilane (TMS) at ca. ?0.32 ppm. Proton NMR spectra for precursor maleamic acids and maleimides are reported, with some solvent effects found (CDCl 3 vs. d 6‐acetone) for the carbon‐bound HC?CH protons of 4. Ab initio molecular modeling calculations at the Hartree‐Fock level using the 6‐31G* basis set have been performed for two key conformers of the phencyclone adduct of N‐ n‐octylmaleimide, as a representative structure for these hindered adducts, to estimate geometric parameters for the adduct. A syn conformer, with the alkyl chain directed into the adduct cavity, was found to be ca. 0.23 kcal/mol lower energy than an anti conformer (in which the alkyl chain was directed away from the phenanthrenoid moiety). 相似文献
6.
Using the convex semidefinite programming method and superoperator formalism we obtain the finite quantum tomography of some
mixed quantum states such as: truncated coherent states tomography, phase tomography and coherent spin state tomography, qudit
tomography, N-qubit tomography, where that obtained results are in agreement with those of References (Buzek et al., Chaos, Solitons and Fractals
10 (1999) 981; Schack and Caves, Separable states of N quantum bits. In: Proceedings of the X. International Symposium on Theoretical Electrical Engineering, 73. W. Mathis and T. Schindler, eds. Otto-von-Guericke University of Magdeburg, Germany (1999); Pegg and Barnett Physical Review A
39 (1989) 1665; Barnett and Pegg Journal of Modern Optics
36 (1989) 7; St. Weigert Acta Physica Slov.
4 (1999) 613).
PACs index: 03.65.Ud 相似文献
7.
Quantum mechanical operators and quantum fields are interpreted as realizations of timespace manifolds. Such causal manifolds
are parametrized by the classes of the positive unitary operations in all complex operations, i.e., by the homogenous spaces D( n)= GL(C
R
n
)/ U( n) with n=1 for mechanics and n=2 for relativistic fields. The rank n gives the number of both the discrete and continuous invariants used in the harmonic analysis, i.e., two characteristic masses
in the relativistic case. ‘Canonical’ field theories with the familiar divergencies are inappropriate realizations of the
real 4-dimensional causal manifold D(2). Faithful timespace realizations do not lead to divergencies. In general they are reducible, but nondecomposable—in addition
to representations with eigenvectors (states, particle), they incorporate principal vectors without a particle (eigenvector)
basis as exemplified by the Coulomb field.
In the orthogonal and unitary groups O( N
+, N
−), respectively, the positive orthogonal and unitary ones are O( N) and U( N), respectively. 相似文献
8.
We present a new ab initio approach to describe the statistical behavior of long ideal polymer chains near a plane hard wall. Forbidding the solid half-space
to the polymer explicitly (by the use of Mayer functions) without any other requirement, we derive and solve an exact integral
equation for the partition function G
D( r, r′, N) of the ideal chain consisting of N bonds with the ends fixed at the points r and r′ . The expression for G( r, r′, s) is found to be the sum of the commonly accepted Dirichlet result G
D( r, r′, N) = G
0( r, r′, N) - G
0( r, r”, N) , where r” is the mirror image of r′ , and a correction. Even though the correction is small for long chains, it provides a non-zero value of the monomer density
at the very wall for finite chains, which is consistent with the pressure balance through the depletion layer (so-called wall
or contact theorem). A significant correction to the density profile (of magnitude 1/is obtained away from the wall within one coil radius. Implications of the presented approach for other polymer-colloid problems
are discussed. 相似文献
9.
In an effort to discover potential cytotoxic agents, a series of novel (Z)-5-((1,3-diphenyl-1H-pyrazol-4-yl)methylene)-3-((1-substituted phenyl-1H-1,2,3-triazol-4-yl)methyl)thiazolidine-2,4-dione derivatives (8a–n) were designed and synthesized in various steps with acceptable reaction procedures with quantitative yields and characterized by 1H NMR, 13C NMR, IR, HRMS and ESI–MS spectra. These newly synthesized novel derivatives were screened for their in vitro cell viability/cytotoxic studies against human breast cancer cell line (MCF-7) with various concentrations of 0.625 µM, 1.25 µM, 2.5 µM, 5 µM and 10 µM, respectively. The biological interpretation assay outcome was demonstrated in terms of cell viability percentage reduction and IC50 values against standard reference drug cisplatin. Based on these results, most of the derivatives exhibited promising cytotoxic activity. Among them, particularly compounds 8j (R1?=?OMe and R3?=?NO2) and 8e (R3?=?CF3) demonstrate remarkable cytotoxic activity with IC50 values 0.426 µM?±?0.455 and 0.608 µM?±?0.408, which are even better than the standard drug cisplatin 0.636 µM?±?0.458 and compounds 8m (R2?=?OMe and R3?=?OMe) and 8c (R3?=?OMe) exhibited closely equivalent IC50 values to the standard drug with IC50 values 0.95 µM?±?0.32 and 0.976 µM?±?0.313 and rest of the compounds exhibits moderate cytotoxic activity. Moreover, molecular modeling studies and ADME calculations of the novel synthesized derivatives are in adequate consent with the pharmacological screening results. 相似文献
10.
The utilization of an ionic liquid, [bmim][BF 4] as both reaction medium and promoter for a multi-component reaction of aldehyde ( 1) and 5-amino-3-methyl-1-phenylpyrazole ( 2) with Meldrum acid ( 3) or dimedone ( 5) is studied. From this reaction, pyrazolo[3,4- b]pyridinone ( 4) and pyrazolo[3,4- b]quinolinone ( 6) derivatives were prepared in high yields. This novel procedure showed such advantages as environmentally benign nature,
enhanced efficiency, simple operation process, and mild reaction conditions. As an application, the procedure was successfully
used in the preparation of a set of pyrimidine nucleoside–pyrazolo[3,4- b]pyridine and pyrazolo[3,4- b]quinolinone hybrids with potential biological activities. 相似文献
11.
Giant positive or negative magnetoresistance is calculated in a band model. The spectra of the band electrons in a two-sublattice
antiferromagnetic intermetallic compound depend on the antiferromagnetism vector L( T, H). The metamagnetic transition to the ferromagnetic phase is accompanied by splitting with respect to the spin σ, displacement of the energy bands, and a decrease in the effective masses of the band electrons. This mechanism of giant
negative magnetoresistance is also accompanied by an increase in the relaxation time τ jσ. Scattering by chemical-bond fluctuations is considered as the main relaxation mechanism. Giant positive magnetoresistance
results from a four-subband model of 4 f and 5 f intermetallic compounds. The electron effective masses m
jσ( J
jT
) of the ( j, σ) bands increase with the mean angular momentum J
1T
( T, H) of an ion in the jth sublattice of 4(5) f ions. The thermodynamics of such a four-sublattice model, the nonlinear magnetization and magnetoresistance curves, and the
nonmonotonic dependence of the specific heat C
m( T, H) on the field H are calculated.
Fiz. Tverd. Tela (St. Petersburg) 39, 1806–1814 (October 1997) 相似文献
12.
A comprehensive review of structure work on high- T
c
oxides as reported during the years 1987 and 1988 is given. Thirteen structures are refined from X-ray single-crystal and/or neutron powder diffraction data: I. (Ba 1–x
,K
x
)BiO 3 ( T
c
=30 K), II. (La 2–x
, Sr
x
)CuO 4 ( T
c
=40 K), III. (Nd, Ce, Sr) 2CuO 4 ( T
c
=28 K), IV. (Nd 2–x
, Ce
x
)CuO 4 ( T
c
=24 K), V. YBa 2Cu 3O 7 ( T
c
=90 K), VI. YBa 2Cu 4O 8 ( T
c
=80 K), VII. Y 2Ba 4Cu 7O 14 ( T
c
=40 K), VIII. Pb 2Sr 2NdCu 3O 8 ( T
c
=70 K), IX. TlBa 2CaCu 2O 7 ( T
c
=103 K), X. TlBa 2Ca 2Cu 3O 9 ( T
c
=120 K), XI. Tl 2Ba 2CuO 6 ( T
c
=90 K), XII. Tl 2Ba 2CaCu 2O 8 ( T
c
=112 K), XIII. Tl 2Ba 2Ca 2Cu 3O 10 ( T
c
=125 K). Except for I (perovskite type), II (K 2NiF 4 type) and IV (Nd 2CuO 4 type) they represent new structure types. Structure data, bond distances, structure drawings and calculated X-ray powder diffraction patterns are given for each compound. Structural features and correlations with superconductivity are discussed. The review contains 301 citations. 相似文献
13.
The concept of bond valence (BV) is widely used in crystal chemical considerations, e.g. to assess equilibrium positions of
atoms in crystal structures from an empirical relationship between bond length R
M−X
and bond valence S
A−X
=exp [(R
0
−R
M−X
) / b] as sites where the BV sum V(A)=∑ s
M−X
equals the formal valence V
id
of the cation M
+
. Our modified BV approach that systematically accounts for the softness of the bond may then be effectively used to study
the interplay between structure and properties of solid electrolytes. This is exemplified for correlations to experimental
data from IR, NMR, and impedance spectroscopy. Combining the bond valence approach with reverse Monte Carlo (RMC) modeling
or molecular dynamics (MD) simulations provides a deeper understanding of ion transport mechanisms, especially in highly disordered
or amorphous solids.
Local structure models for crystalline electrolytes are derived by combining crystallographic structure information with simulations.
A method for the prediction of the activation energy of the ionic conductivity from the bond valence analysis of the crystal
structure is proposed. Taking into account the mass dependence of the conversion factor from bond valence mismatch into an
activation energy scale, we could establish a correlation that holds for different types of mobile ions. The strong coupling
of the H + transfer to the anion motion in proton conductors requires a special treatment. For glassy solid electrolytes RMC structure
models are BV-analyzed to assess the total number of equilibrium sites and to identify transport pathways for the mobile ions.
Recently, we have reported a correlation between the pathway volume fraction and the transport properties that permits to
predict both absolute value and activation energy of the dc ionic conductivities of disordered solids (including mixed alkali
glasses) directly from their structural models. Here we discuss a corresponding BV analysis of molecular dynamics simulation
trajectories that allows quantifying the evolution of pathways in time and the influence of temperature on the transport pathways.
Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14 — 18, 2004. 相似文献
14.
Pyrazolo[3,4- b]pyridines having 4-chloro-5-chloroethyl side chain are synthesized by the reaction of 5-aminopyrazole and cyclic β-formylester
gave aminopyrazolodihydrofuranone intermediate, which on cyclization in phosphorous oxychloride exclusively converted in to
4-chloro-5-chloroethyl pyrazolo[3,4- b]pyridines 4(a-b) in major amount. The side chain with acetic acid, thiourea and aromatic amines are used to form angular ring leads to formation
of tricyclic Furo[2,3- d]pyrazolo[2,3- b]pyridines 5(a-b), pyrazolo[3,4- b]thieno[2,3- d]pyridines 6(a-b) and pyrazolo[3,4- b]pyrrolo[2,3- d]pyridines 7(a-n) respectively. The substituents effect at C 4 position on fluorescence properties of pyrazolopyridines has been studied. Moreover the effect of electron donor and halogen
substituents on fluorescence properties of pyrazolopyrrolopyridines 7(a-n) has been investigated along with their fluorescent quantum yield. 相似文献
15.
In this paper the procedure of large-scale averaging of the magnetic-field diffusion equation with the α-term curl α( r, t) B( r, t) is used to show that a nonuniform distribution of the turbulent helicity fluctuations (more precisely, the fluctuations
of the coefficient α) with a zero average value gives rise to large-scale amplification of the initial magnetic field. A detailed study is carried
out of the dependence of the resulting large-scale α effect on the characteristics of the correlator 〈〈 α( r, t) α( r″, t″)〉〉 in a rotating medium with a nonuniform distribution of the angular velocity ω= ω( ρ,z) ( ρ is the distance for the rotation axis z). The effect of helicity fluctuations and the diffusion coefficient on the turbulent diffusion process is also investigated.
Zh. éksp. Teor. Fiz. 116, 85–104 (July 1999) 相似文献
16.
In this paper are presented absorption and fluorescence emission properties of 3-styrylindoles viz. 3-(2-phenylethenyl- E)-NH-indole ( 1), 3-[2-(4-nitrophenyl)ethenyl- E)-NH-indole ( 2), 3-[2-(4-cyanophenyl)ethenyl- E]-N-ethylindole ( 3) and 3-[2-(4-cyanophenyl)ethenyl- E]-NH-indole ( 4) in organic solvents, 1,4-dioxane-water binary mixtures and micelles (SDS, CTAB and Triton-X-100). The fluorescence properties
of 2- 4 have been utilized to probe the microenvironment (binding constant, CMC, micropolarity and solubilization site) of the micelles. 相似文献
17.
A protocol for the synthesis of N-substituted 2-hydro-4-amino-pyrido[2,3- d]pyrimidin-7(8 H)-ones ( 11) is described. Thus, the formylation of a 2-aminopyridone 12 in 85% formic acid/Ac 2O, proceeding via in situ cyclization to the intermediate formamide 13, affords the corresponding 2-hydro-4-oxo-pyridopyrimidine 14, which is converted to a 4-chloro-pyridopyrimidine 15 upon treatment with POCl 3. The subsequent transformation to the title compounds is carried by treatment with the corresponding amine in MeOH under
microwave irradiation conditions. 相似文献
18.
Tetrakis‐(4‐chlorophenylthio)‐butatriene ( 3a) and tetrakis‐( tert‐butylthio)‐butatriene ( 3b) were synthesized, and their crystal structures were determined. The compound 3a is monoclinic, space group P2 1/c, a=6.9785(8), b=8.6803(9), c=22.884(2) Å, β=93.887(6) o, V=1383.0(3) Å 3, Z=2. The compound 3b is monoclinic, space group P2 1/n, a=11.0615(6), b=10.8507(4), c=11.2717(6) Å, β =116.427(2) o, V=1211.5(1) Å 3, Z=4. The title compounds 3a and 3b reside on an inversion center so that only half of the molecule is crystallographically unique. Both compounds are not planar. The crystal structures of 3a and 3b have cumulated double bonds. The C7–C8–C8 i and C5–C6–C6 i angles that show the linearity in both structures, respectively, are 176.4(3)° in 3a and 175.6(2)° in 3b. 相似文献
19.
Electron paramagnetic resonance study of the single crystals of two PROXYLs, trans-2,5-bis(4-methylphenyl)-2,5-dimethylpyrrolidine-1-oxy [(±)- 1] and trans-2-(4-methylphenyl)-2,5-dimethyl-5-phenylpyrrolidine-1-oxy [(±)- 2] was conducted. The obtained spectra were always fitted well by a single Lorentzian. The principal g-values ( g
x
, g
y
, g
z
) of (±)- 1 and (±)- 2 were determined as (2.00990, 2.00639, 2.00266) and (2.01106, 2.00742, 2.00389), respectively. The profiles of half width
at half maximum (HWHM) depending on two polar angles, θ and ϕ, were measured in all directions. The angular profiles of the
exchange interaction (| J
0|) were attempted to be estimated by dividing the experimental HWHM by the calculated total second moment ( M
2
tot) with the crystallographic data. For (±)- 1, | J
0| along the c-axis was estimated to be much larger than that along the a- or b-axis. This suggests that (±)- 1 is a one-dimensional magnet along the c-axis.
Authors' address: Yohei Noda, Electron Spin Chemistry Laboratory, Department of Chemistry, Graduate School of Science, Kyoto
University, 606-8502 Kyoto, Japan 相似文献
20.
The phase transition in neodymium crystal from the paramagnetic to the magnetically ordered phase at the temperature T N = 19.9 K is discussed in the terms of Landau's theory. It is shown that the calculated six-dimensional active representations at the point q = vb 1, with—0.5 < v < 0.5, v ≠ 0, induce transitions to “single- q”, “double- q” and “triple- q” spin structures. A general formula for the spin vector S(r) for T < T N is derived, from which a variety of spin structures can be obtained depending on the choice of the free parameters. The spin structure calculated by Bak and Lebech (1978) is obtained from that formula as a particular solution which is compatible with Landau's theory. An antiferromagnetic spin structure which represents a modification of that given by Bak and Lebech (1978) is calculated. The corresponding cross-section for neutron elastic magnetic scattering fulfils the experimental conditions listed by Lebech (1981). It is shown that the magnetic satellites of the type ( h ± v, 0, 0) cannot appear for any type of structure following from our general formula for S(r). These satellites therefore can be connected only with representations at the point q = μ 1 b 1 + μ 2 b 2,—0.5 < μ 1, μ 2 < 0.5, μ 1, μ 2 ≠ 0, μ 1 ≠ μ 2. 相似文献
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