Structure-property relationships of donor/acceptor-functionalized tetrakis(phenylethynyl)benzenes and bis(dehydrobenzoannuleno)benzenes

A series of tetrakis(phenylethynyl)benzenes and bis(dehydrobenzoannuleno)benzenes have been synthesized containing tetra-substitutions of neutral, donor, and mixed donor/acceptor groups. To ascertain the importance of substitutional and structural differences of the phenylacetylenes, the optical absorption and emission properties of each series were examined. Conjugation effectiveness, electron density, planarity, and geometry of charge-transfer pathways were found to have a pronounced effect on the overall optical and material properties. Considerable self-association behavior due to face-to-face stacking in solution was observed for donor/acceptor-functionalized macrocycles and was quantified by concentration-dependent H-1 NMR measurements. A solvent-dependent polymerization of one macrocycle regioisomer was observed and characterized. To provide further insight into the energy levels and electronic transitions present, computational studies of each system were performed.