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Most Requested Journal Articles 1Q04-Chemistry and Related

Following is one of the journal articles most requested by researchers using CAS online services.

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CAS indexed 82 chemical substances from this document. CAS subject entries for this document include: Fluorescence; NMR (nuclear magnetic resonance); UV and visible spectra; and 1 additional concept.

CAPLUS COPYRIGHT 2004 ACS on STN

TITLE:	Diarylamino groups as photostable auxofluors in 2-benzoxazolylfluorene, 2,5-diphenyloxazoles, 1,3,5-hexatrienes, 1,4-distyrylbenzenes, and 2,7-distyrylfluorenes
AUTHOR(S):	Kauffman, Joel M.; Moyna, Guillermo
CORPORATE SOURCE:	Department of Chemistry Biochemistry, University of the Sciences in Philadelphia, Philadelphia, PA, 19104, USA
SOURCE:	Journal of Organic Chemistry (2003), 68(3), 839-853 CODEN: JOCEAH; ISSN: 0022-3263
PUBLISHER:	American Chemical Society
LANGUAGE:	English

ABSTRACT:
The relationship of structure to optical spectral properties was detd. for five types of fluors in a search for an optimum-wavelength shifter to be used as part of the detection systems for high-energy particles from accelerators. In a search for photostable fluors to serve as wave-shifters in plastic fibers it was found that the wavelengths of interest, absorption max 410 .+-. 10 nm and fluorescence emission max 480 .+-. 20 nm, along with other properties, such as high soly. and short fluorescence decay time, could be obtained from fluorophors composed of arom. rings and vinyl groups only by using amino groups as auxochromes to give bathochromic shifts of wavelengths. Since primary, monoalkyl, and dialkylamino groups were not sufficiently photostable, a no. of fluorophores bearing diarylamino groups were investigated. Syntheses of the fluors made use of the Buchwald amination, an improved version of the Emmons-Horner reaction, and other common reactions. The fluor types were the following: a 2-benzoxazolyl-7-(4-diarylamino)fluorene (I), 2-(4-cyanophenyl)-5-(4-aminophenyl)oxazoles, 1,3,5-hexatrienes, 1,4-distyrylbenzenes, and 2,7-distyrylfluorenes. The unsym. fluors I and the 2-(4-cyanophenyl)-5-(4-aminophenyl)oxazoles were not as bright as the best hexatrienes, distyrylbenzenes, and distyrylfluorenes, which were all sym. Where the 1,6-diaryl-1,3,5-hexatrienes had high fluorescence quantum yield (.PHI.f), the 1,1,6,6-tetraaryl-1,3,5-hexatrienes had both lower .epsilon. and .PHI.f. Where the 1,4-distyrylbenzenes had high .PHI.f, the 1,4-bis(2-phenylstyryl)benzenes had .PHI.f = 0. Diarylamino groups as auxofluors conferred higher photochem. stability than dialkylamino groups on similar fluorophores. The 1,4-distyrylbenzenes and the 2,7-distyrylfluorenes had the most desirable properties overall, which included fast decay times of 2 ns. Computer simulations predicted absorption and emission wavelengths fairly well, but were of little help for the prediction of brightness, stability, .PHI.f, or decay time.  

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