摘要:

In the present study we investigate the effect of hydrogen bonding secondary interactions on the crystalline and liquid crystalline phases of quaternary ammonium salts functionalized by a hydroxyl or a carboxylic group attached at the polar head through an appropriate spacer. The observed liquid crystalline phases have resulted from the interplay of the effects of the long aliphatic chain,n=12, 14, 16, 18, the length of the spacerm=1, 3, 4, 5, 6 and certainly of hydrogen bonding interactions. The smectic liquid character of these quaternaries was established by optical microscopy, differential scanning calorimetry and X-ray diffraction studies.

ISSN:1058-725X    

DOI:10.1080/10587259808045531

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Three novel unsymmetrically substituted DBTTF derivatives, (MeO)2(MDO) DBTTF, (EDO) (MDO) DBTTF, and (MeO)2(EDO) DBTTF, have been synthesized and their physicochemical properties are elucidated. Here, MeO, MDO, and EDO mean methoxy, methylenedioxy, and ethylenedioxy groups, respectively. Trimethylaluminum is found to be suitable for the syntheses of the above DBTTF derivatives using the non-coupling method. MDO is rather an effective substituent in reducing the difference between the first and the second redox potentials. The crystal structures of (MeO)2(MDO) DBTTF and (MeO)2(EDO) DBTTF were analyzed by an X-ray crystal structure analysis. In the crystal of (MeO)2(MDO) DBTTF, two molecules form a face-to-face pair, in which two molecules arrange so as to cancel their dipole moments to each other. The molecules of (MeO)2(EDO) DBTTF form a herringbone column structure in the crystal. Intermolecular short S··S atomic contacts are not found in the crystals of (MeO)2(MDO) DBTTF and (MeO)2(EDO) DBTTF. However, intermolecular interactions through C··C and C··O atomic contacts, and hydrogen bondings are recognized.

ISSN:1058-725X    

DOI:10.1080/10587259808045532

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The ternary phase diagram of the mixturesn-C22H46:n-C23H48:n-C24H50has been established at 293 K by X-ray diffraction experiments on forty one samples. This study indicates the existence of limited terminal solid solutions in the neighbourhood of three puren-alkanes and three domains of intermediate phases, identical to those observed in the binary systems and denoted β‘1, β“1, β’2:on the basis of powder X-ray diffraction photographs, the patterns of the phases β‘1and β’2 are indistinguishable and these two intermediate solid solutions on both sides of the middle intermediate phase β”1are isostructural as in the binary systems.

ISSN:1058-725X    

DOI:10.1080/10587259808045533

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The thermal and liquid crystalline properties of the new binary systems, consisting of a polycarbonate type of a main-chain liquid crystal polymer (PC) and a twin liquid crystal (TN-n:n= number of central methylene units) with a nitro terminal unit, were examined. The binary systems having PC and TN-nwith even-numbered central methylene units (n= 6, 8) showed an induced smectic A phase with batonnets and a fan texture. However, the binary systems consisting of PC and TN-nwith odd-numbered central methylene units (n= 5, 7) formed an induced smectic C phase in addition to an induced smectic A phase. In the induced smectic C phase, the schlieren with two and four brushes was observed.

ISSN:1058-725X    

DOI:10.1080/10587259808045534

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Nitration of hexaalkoxytriphenylene has very recently been reported to produce exclusively the 1-nitro-hexaalkoxytriphenylene. We have found that nitration of such discotics is not restricted to only one ring of triphenylene; all the three rings can be nitrated successively to produce mononitro-, dinitro- and trinitro-hexaalkoxytriphenylenes. These nitro-triphenylenes are valuable precursors to several other triphenylene derivatives. Mononitration of monohydroxy-penta-alkoxytriphenylene gives the monohydroxy-mononitro derivative, an extremely important precursor to functionalized triphenylene polymers.

ISSN:1058-725X    

DOI:10.1080/10587259808045535

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

“Solid State Physics: Problems and Solutions” by Laszlo Mihaly and Michael C. Martin, John Wiley and Sons, New York, 1996; ISBNO-471-15287-0; xiv + 261 pages (paper); $29.95.

ISSN:1058-725X    

DOI:10.1080/10587259808045536

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:1058-725X    

DOI:10.1080/10587259808045510

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor