UNSPECIFIED. (2002) Supramolecular organization of alpha,alpha '-disubstituted sexithiophenes. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 124 (7). pp. 1269-1275. ISSN 0002-7863

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Abstract

The self-assembly of alpha,alpha'-linked sexithiophenes with chiral and achiral penta(ethylene glycol) chains attached at the alpha- positions of the terminal rings, that is, 2,2':5',2":5",2'''',2'''':5'''',2'''''- sexithiophene-5,5'''''-dicarboxylic acid- (2S)-2-methyl-3,6,9,12,15-pentaoxahexadecyl ester (1) and 2,2':5',2":5",2''':5"',2'''':5''''m2'''''-sexithiophene-5,5'''''-dicarboxylic acid-3,6,9,1 2,15-pentaoxahexadecyl ester (2), respectively is described. Analysis of the UV/vis, fluorescence, circular dichroism, and circular polarization of luminescence spectroscopic data shows that these compounds form chiral aggregates in polar solvents and in the solid state. In n-butanol aggregation occurs at temperatures below 30 degreesC, while above this threshold temperature the aggregates break up without an intermediate disordered state of aggregation, and the compounds are molecularly dissolved. The "melting temperature" of the aggregates depends on the concentration of sexithiophene, indicating that the optical changes observed are a result of intermolecular processes. Mass spectrometric measurements reveal that 1 and 2 can form mixed aggregates. Analysis of the optical spectra reveals that in these mixed aggregates, chiral 1 molecules act as "sergeants" to direct the packing of the "soldiers" 2, illustrating cooperativity within the columns. In water, the same type of chiral aggregates are formed as in n-butanol below 30 degreesC; however, these aggregates are still present, but the chirality is lost above 30 degreesC. In spin-coated films of 1 chiral aggregates are present. AFM studies show that 1 self-organizes into chiral fiberlike structures in the solid state. Furthermore both 1 and 2 display thermotropic liquid crystalline behavior between 180 and 200 degreesC.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Journal or Publication Title:	JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Publisher:	AMER CHEMICAL SOC
ISSN:	0002-7863
Date:	20 February 2002
Volume:	124
Number:	7
Number of Pages:	7
Page Range:	pp. 1269-1275
Identification Number:	10.1021/ja0113403
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/11218

Data sourced from Thomson Reuters' Web of Knowledge

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