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21.
Analysis of a TE011 mode composite sapphire-rutile dielectric resonator has been carried out to study the temperature variation of resonance
frequency, close to the Cs atomic clock hyperfine frequency of 9.192 GHz. The complementary behavior of dielectric permittivity
with temperature of the composite has been exploited to obtain the desired turning point in the resonant frequency. The frequency
of the composite structure is found to be independent of the shield diameter beyond four times the puck diameter. 相似文献
22.
J. Shashidhara Prasad 《Optics Communications》1975,14(2):267-270
An attempt has been made to understand the rotatory dispersion data of Scarabaeid bettle exocuticles in the light of two different approaches adopted to describe the form optical rotation in liquid crystals. It is shown that the approach based on the difference equations for wave propagation in a periodic structure has an edge over the one based on Oseen's dielectric continuum model. 相似文献
23.
H. R. Manjunath S. Naveen C. S. Ananda Kumar S. B. Benaka Prasad M. A. Sridhar J. Shashidhara Prasad K. S. Rangappa 《Journal of chemical crystallography》2012,42(5):504-507
Abstract
The title compound, C23H23FN3O2 has been synthesized and the structure was investigated by X-ray diffraction studies. The compound crystallizes in the triclinic crystal class in the space group P[`1]P\overline{1} with cell parameters a = 9.345(2) ?, b = 10.940(3) ?, c = 11.986(4) ?, α = 72.349(6)°, β = 68.106(18)°, γ = 66.867(5)°, Z = 2 and V = 1027.8(5) ?3. The hydantoin ring adopts a planar conformation and is affected by the π conjugation. The pyrrolidine and piperidine rings in the bicyclo octane moiety adopt envelope and chair conformations respectively. The structure exhibits both inter and intramolecular hydrogen bonds of the type N–H···O, C–H···O and C–H···N. One of the oxygen atoms attached to the hydantoin ring simultaneously accepts two hydrogen bonds to form a three centered hydrogen bonding pattern. 相似文献24.
The title compound, 4-(cholestroxycarbonyl)pentyloxy-4'-heptyloxycarbonylbiphenyl (C53H78O5), is a novel dimesogen comprising two mesogenic units dissimilar in nature. It crystallizes in the orthorhombic space group P212121 with cell parameters a = 6.241(3), b = 17.943(5), c = 43.13(5), Z = 4. The structure was solved using SHELXS (Sheldrick, 1997) and refined using SHELXL (Sheldrick, 1997). The final residual was R = 0.0803 for 1769 reflections with I < 2 σ(I). In the crystal phase the molecule is linear and the terminal groups show stretching with higher bond distances. The packing of the molecules shows imbrication, herringbone and stacking along the a, b, and c axes, respectively. The structure also exhibits an intermolecular hydrogen bond of the type CH…O. The space group suggests the possibility of a chiral mesophase. 相似文献
25.
N. C. Shivaprakash P. K. Rajalakshmi J. Shashidhara Prasad 《Molecular Crystals and Liquid Crystals》2013,570(3-4):317-322
The properties of cholesterol derivatives are important owing to the involvement of these compounds in a myriad of industrial and biological research areas such as thermography, display devices and the formation in atherosclerosis of arterial deposits containing cholesteryl esters. Molecular structural studies of mesogens in the crystalline state have been carried out in search of a better understanding of the physical properties which lead to mesophase formation. It has been demonstrated previously for a homologous series of nematogens1 how the molecular packing coefficients of the solid phase vary with increasing chain length and how this throws light upon the variation of other physical properties. Here, we extend this treatment to the cholesteryl alkanoates. Detailed crystal structure analysis is available for only one member of this series: cholesteryl tetradecanoate, which was studied by Craven and de Titta.2 Prior to this, unit cell dimensions and space groups has been obtained for 13 members by Barnard and Lydon.3 They found the crystallography of these compounds to be complex. No overall homology of crystal structure was apparent and at least eight different types of crystal structure occur. 相似文献
26.
Priti Adlakha S. Naveen S. Lakshmi Atul Manvar Denish Karia Anamik Shah M. A. Sridhar J. Shashidhara Prasad 《Journal of chemical crystallography》2009,39(6):389-394
Abstract A novel unsymmetrical dihydropyridine, possessing carboxymethyl and carbomethoxy groups at C(3) and C(5), respectively, has
been produced using a modified Hantzsch synthesis, under solvent free conditions, in a domestic microwave oven. The product
obtained was characterized by spectroscopic techniques and finally confirmed by X-ray diffraction studies. The title compound
C17H18N2O5 crystallizes in the monoclinic system in the space group P21/c with cell parameters a = 12.860(2) ?, b = 7.4950(6) ?, c = 16.734(3) ?, β = 94.436(3)°, Z = 4 and V = 1608.1(4) ?3. The 1,4-dihydropyridine ring in the structure is in a flattened boat conformation. The molecule possesses a chiral center
at C4. The 3-nitrophenyl ring is nearly orthogonal to the 1,4-dihydropyridine ring. The carbonyl groups at C3 and C5 are oriented
in −antiperiplanar and +synperiplanar conformations, respectively. The structure exhibits both inter and intramolecular hydrogen bonds of the type N–H···O and
C–H···O.
Index Abstract A novel unsymmetrical dihydropyridine, possessing carboxymethyl and carbomethoxy groups at C(3) and C(5) respectively, has
been produced using a modified Hantzsch synthesis, under solvent free conditions, in a domestic microwave oven. The product
obtained was characterized by spectroscipic techniques and finally confirmed by X-ray diffraction studies. The title compound
C17H18N2O5 crystallizes in the monoclinic system in the space group P21/c with cell parameters a = 12.860(2) ?, b = 7.4950(6) ?, c = 16.734(3) ?, β = 94.436(3)°, Z = 4 and V = 1608.1(4) ?3. The 1,4-dihydropyridine ring in the structure is in a flattened boat conformation. The molecule possesses a chiral center
at C(4). The 3-nitrophenyl ring is nearly orthogonal to the 1,4-dihydropyridine ring. The carbonyl groups at C(3) and C(5)
are oriented in −antiperiplanar and +synperiplanar conformations respectively. The structure exhibits both inter and intramolecular hydrogen bonds of the type N–H···O and C–H···O.
相似文献
M. A. SridharEmail: |
27.
J.Shashidhara Prasad 《Optics Communications》1974,12(4):389-391
The interpretation of the reflection spectrum from the measurements of Fergason and Adams et al. by Subramanyam envisaging absorption of light by the material is shown to be incorrect. Some refined measurements of circular dichroism on the mixtures of the cholesteric substances as used by the above authors are reported which conclusively invalidate the explanation of Subramanyam. 相似文献
28.
K. S. Rangappa H. Mallesha N. V. Anilkumar H. S. Yathirajan M. A. Sridhar N. K. Lokanath J. Shashidhara Prasad 《Journal of chemical crystallography》2000,30(4):255-258
The structures of the title compounds, tris(2-hydroxy-3-t-butyl-5-methylbenzene)-methane)C34H46O3.3H2O, 3) and N-benzyl-N-phenylbenzamide (C20H17NO, 6), have been investigated by X-ray crystallography. Compound 3 crystallizes in the trigonal space group
with cell parameters a = 14.090(5) Å, b = 14.090(5)Å, c = 10.485(5)Å, Z = 2. Compound 6 crystallizes in the monoclinic space group C2/c with cell parameters a = 24.533(4)Å, b = 9.176(4)Å, c = 16.711(5)Å, = 125.88(2)°, Z = 8. Compound 3 has both intra-and intermolecular hydrogen bonds. It also exhibits a helical columnar arrangement of the molecules and goes into mesophase before melting into an isotropic liquid. 相似文献
29.
B.?H.?Doreswamy M.?Mahendra K.?Abiraj D.?Channe?Gowda M.?A.?Sridhar J.?Shashidhara?PrasadEmail author 《Journal of chemical crystallography》2005,35(10):829-833
Boc-Gly-Val-Pro-OBzl, a protected tripeptide fragment of repeating sequences of mammalian elastic protein elastin was synthesized and characterized by X-ray diffraction method. The sequence C24 H35 N3 O6 crystallizes in the orthorhombic space group P212121 with the parameters a = 9.4700(11) Å, b = 9.8980(8) Å, c = 26.721(3) Å, V = 2504.7(4) Å3 and Z = 4. The final residual factor is 0.0670. The structure exhibits intra and intermolecular hydrogen bonds. 相似文献
30.
C. S. Ananda Kumar S. Naveen S. B. Benaka Prasad N. R. Thimme Gowda N. S. Linge Gowda M. A. Sridhar J. Shashidhara Prasad K. S. Rangappa 《Journal of chemical crystallography》2007,37(11):727-731
1-Benzhydryl-4-phenylmethane sulfonyl piperazine was synthesized from 1-benzhydryl piperazine with phenylmethane sulfonyl chloride. The product obtained was characterized by 1H NMR, MS and IR techniques and finally confirmed by X-ray crystallography. The title compound C24H26N2O2S, M r = 406.53, crystallizes in the orthorhombic crystal class in the space group Pbca with unit cell parameters a = 11.1240(10)Å, b = 9.4940(15)Å, c = 40.239(4)Å, Z = 8 and V = 4249.7(9)Å3. The structure was solved by direct methods and refined to R 1=0.0561 for 2,445 reflections with [I > 2 σ(I)]. The piperazine ring adopts a chair conformation. The sulfonyl moiety is in a distorted tetrahedral configuration. 相似文献