Arsenal for providing 1,3,5,7-tetrakis(chlorocarhonyl)cubane and 1,3,5,7-adamantanetetra-carboxylic acid chloride for the synthesis of compounds V, V1, and VII.
A theory was formulated for the description of circularly polarized¯uorescence (CPF) from a chiral nematic ® lm in the spectral region outside the selective re¯ection band. The CPF theory incorporates: (1 ) the ability of a chiral nematic ® lm to accomplish both circular dichroism and circular polarization and ( 2) linearly polarized¯uorescence from chromophores unaxially aligned in the nematic sublayers comprising the ® lm. Chiral nematic¯uid ® lms consisting of a nematic¯uid, BDH 18523, and a chiral dopant, cholesteryl oleate, were prepared for hosting 1,6-diphenylhexatriene as a¯uorescent dye. The experimentally determined dissymmetry factor using both left-and right-handed circularly polarized excitations was found to be in good agreement with the theoretical prediction with all the system parameters determined a priori. The theory was also employed to furnish insight into the e ects of the concentration of the¯uorescent dye and chiral nematic ® lm thickness on the dissymmetry factor.
Thermotropic nematic and chiral-nematic conjugated polymers consisting of polythiophene
and poly(p-phenylene) backbones carrying cyanobiphenyl and (−)-cholesterol as pendant groups were
synthesized and characterized as a new class of optical polymers. Spontaneous assembly of the conjugated
backbone was promoted by liquid crystalline mesomorphism on the part of the pendants, thereby allowing
uniaxially and helically aligned glassy films to be prepared for polarized photoluminescence (PL) studies.
In the thiophene series, the conjugated backbone was found to yield an absorption peak red-shifted from
those of the monomers and pendant groups. This permitted selective photoexcitation of the polythiophene
backbone to be accomplished. In the p-phenylene series, the conjugated backbone did not give rise to a
unique absorption peak. However, with excitation at the long wavelength edge of the absorption peak,
PL of the poly(p-phenylene) backbone was found to be 1 order of magnitude stronger than that of the
pendant cyanobiphenyl group. These ordered solid films produced significant degrees of linearly and
circularly polarized PL. Existing theories were found to be capable of representing the experimental
results with independently measured absorption coefficient, average refractive index, and optical
birefringence.
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