X-ray Difraction and Polymorphism of Smectic Liqid Crsystals. II. D and E Modifications

Diele, Siegmar; Brand, P.; Sackmann, H.

doi:10.1080/15421407208083838

Cited by 120 publications

(33 citation statements)

References 3 publications

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“…That means with respect to the smectic layers that a layer structure without order (S,, S,) within the layers can pass over with decreasing temperature by phase transitions into layer structures with order in the layers Whereas the smectic phases of S, and S, types have been extensively studied the structure investigations of the highly ordered SE phase are restricted to a few classes of substances (SE9 S"). (DIELE et al 1972(DIELE et al , 1974(DIELE et al , 1982DOUCET et al;LEADBETTER et al 1979LEADBETTER et al , 1979. In.the present paper the structure investigations in two further series The series I1 exhibits besides the SE phase the S , phase, too.…”

Section: Introductionmentioning

confidence: 92%

Structure and Packing in Smectic E and Smectic A Phases in the Series of 4‐n‐Alkyloxy‐4′‐alkanoylbiphenyls

Diele

Tosch

Mahnke

et al. 1991

Cryst. Res. Technol.

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By means of X-ray investigations the structure of the SE and S,-phases of the title compounds has been studied. The lattice parameters of the orthorhombic S , structure are given. The thickness of the smectic layers is nearly the same in the SE and S, phases and agrees well with the length of the molecules in their most stretched form. That suggests a similar conformation of the alkyl chains in both phases. A model of the packing in the SA phase is discussed which IS based on a dense packing with antiparallel orientation of molecules with a non-symmetrical shape.Mit Hilfe von rontgenographischen Verfahren wurde die Struktur der SE und S , Phasen der genannten Verbindungen untersucht. Die Gitterparameter der orthorhombischen Struktur in der SE Phase werden angegeben. Die Dicke der smektischen Schichten in der SE und S, Phase ist nahezu gleich und stimmt gut mit der Lange der Molekule in ihrer gestreckten Form iiberein. Dieses Ergebnis legt eine ahnliche Konformation der Alkylketten in beiden Phasen nahe. Es wird ein Packungsmodell fur die SA Phase diskutiert, das auf einer dichten Packung antiparallel orientierter Molekiile von nichtsymmetrischer Form basiert.

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Section: Introductionmentioning

confidence: 92%

Structure and Packing in Smectic E and Smectic A Phases in the Series of 4‐n‐Alkyloxy‐4′‐alkanoylbiphenyls

Diele

Tosch

Mahnke

et al. 1991

Cryst. Res. Technol.

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“…The structure of the D phase has been strongly suggests the existence of a three-dimensional investigated by X-ray di raction ( XRD) and several network structure. structural models have been proposed: the spherical This current work is undertaken to probe the structure micelle model by Diele et al [ 5], the linked spherical and dynamic nature of the D phase of ANBC by the micelle model and unconnected in® nite rod model by use of 14 N NMR spectroscopy. In 1 H NMR spectroEtherington et al [ 6 ], and the interpenetrating jointed scopy, the spin relaxation process is, in general, closely rod ( IPJR) model by Tardieu and Billard [7] and connected with both inter-and intra-molecular dipole Levelut and Fang [ 8].…”

Section: Introductionmentioning

confidence: 99%

14N NMR studies on an optically isotropic liquid crystalline D phase of 4'-n-alkoxy-3'-nitrobiphenyl-4-carboxylic acids (ANBC)

Tansho¹,

Onoda²,

Kutsumizu³

et al. 1998

Liquid Crystals

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14 N nuclear magnetic resonance ( NMR) measurements have been carried out for three members of 4¾ -n-alkoxy-3¾ -nitrobiphenyl-4-carboxylic acids (ANBC-n, where the number of carbon atoms in the alkoxy group, n, is 14, 16, and 22) in the temperature range 400± 500 K. ANBC-16 and -22 show an optically isotropic D phase. The 14 N NMR spectrum of the D phase showed a single peak, which may result from isotropically averaged quadrupole interactions around the 14 N nucleus. Relaxation time measurements indicate the existence of two relaxational processes, faster anisotropic and slower isotropic motions, and suggest that in both cases ANBC molecules act as a dimer. The present 14 N NMR results may be interpreted in the framework of the IPJR model, indicating that the structure of the D phase is a three-dimensional network continuous over the unit lattice.

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“…The results presented reveal that the eOE ect of nitro substitution in achiral calamitic liquid crystals on their has been studied in [254][255][256][257][258][259][260][261][262][263][264][265][266][267][268]. The mesomorphic [27,178,[195][196][197][198][199][200][201][202] inter-…”

Section: L Ateral Nitro Substitutionmentioning

confidence: 88%

Nitro substitution in achiral calamitic liquid crystals

Petrov¹,

Shimizu

2001

Liquid Crystals

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X-ray Difraction and Polymorphism of Smectic Liqid Crsystals. II. D and E Modifications

Cited by 120 publications

References 3 publications

Structure and Packing in Smectic E and Smectic A Phases in the Series of 4‐n‐Alkyloxy‐4′‐alkanoylbiphenyls

Structure and Packing in Smectic E and Smectic A Phases in the Series of 4‐n‐Alkyloxy‐4′‐alkanoylbiphenyls

14N NMR studies on an optically isotropic liquid crystalline D phase of 4'-n-alkoxy-3'-nitrobiphenyl-4-carboxylic acids (ANBC)

Nitro substitution in achiral calamitic liquid crystals

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