Exciton Chirality.(A) Origins of and (B) Applications from Strongly Fluorescent Dipyrrinone Chromophores

摘要

(A) The origin of exciton interaction and examples of its application to organic stereochemistry are presented.(B) N,N'-Carbonyl-bridged dipyrrinones constitute a new class of highly fluorescent chromophores suitable for investigations of stereochemistry and absolute configuration.N,N'-Carbonylxanthobilirubic acid esters are strongly fluorescent,with a fluorescence quantum yield (psi_f) approx0.8,but produce only weak exciton CD from the trans-1,2-cyclohexanediol template.The ester of an analog with benzoic acid replacing propionic,N,N'-carbonyl-8-(4-carboxyphenyl)-3-ethyl-2,7,9-trimethyl-(10H)-dipyrrin-l-one,exhibits strong fluorescence (phi_F=0.68,lambda_(em)=493nm,lambda_(ex)=422nm in CHC1_3) and UV-Vis absorption (epsilon approx 21000 at 424 nm) in organic solvents.Its diester with (1S,2S> cyclohexanediol is fluorescent and exhibits exciton circular dichroism (DELTAepsilon=+15dm~3centre dotmol~(-1)centre dotcm~(-1),lambda=432 nm;DELTAepsilon=-4 dm~3 centre dot mol~(-1) cm~(-1),lambda=380 nm) that correlates with the Exciton Chirality Rule.