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Synthesis 2002(9): 1185-1190
DOI: 10.1055/s-2002-32537
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis and Properties of Photoluminescent 1,4-Bis-(α-cyano-4-methoxystyryl)benzenes

Christiane Löwea,b, Christoph Weder*b
a On leave from the Swiss Federal Laboratories for Materials Testing and Research (EMPA), Ueberlandstrasse 129, 8600 Dübendorf, Switzerland
b Department of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland Ohio 44106-7202, USA
Fax: +1(216)3684202; e-Mail: chw6@po.cwru.edu;
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Publication History

Received 11 April 2002
Publication Date:
28 June 2002 (online)

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Abstract

1,4-Bis-(α-cyano-4-methoxystyryl)benzene (1a) and 1,4-bis-(α-cyano-4-methoxystyryl)-2,5-dimethoxybenzene (1b) were synthesized by the Knoevenagel reaction of (4-methoxyphenyl)acetonitrile with terephthaldicarboxyaldehyde and 2,5-dimethoxy terephthaldicarboxyaldehyde, respectively. Both phenylene vinylene oligomers are highly photoluminescent, and the comparison of the emission spectra of the crystalline solids with the ones of the corresponding low-viscosity molecular solutions reveals, particularly in case of 1b, an extremely large bathochromic shift. This effect is consistent with the formation of excimers that are characterized by low-bandgap emission. With the objective to control the emission characteristics of these dyes beyond the limiting states of molecular solution and crystalline solid, the investigation of their photophysical characteristics was extended to the liquid crystalline state and the isotropic melt, as well as to blends with isotactic polypropylene.

Key words

phenylene vinylene oligomer - photoluminescence - liquid crystal - excimer luminescence - Knoevenagel reaction - colour tuning