title: Supramolecular aggregates with distinct optical properties from PDI oligomers of similar structures.
abstract: The self-assembly behaviors of two series of monodispersed oligomers consisting of perylenediimide (PDI) linked by ethynylene and butadiynylene spacers are investigated in solutions. In spite of the very similar chemical structures, the two sets of oligomers manifest completely different optical properties upon self-aggregation, implying differed aggregate structures. While the oligomers containing butadiynylene spacers form H-aggregates, those featuring ethynylene linkers display J-aggregation characteristics. Thermodynamic analysis revealed that the self-association constants of both series of oligomers increase with the number of PDI units in the backbones. Oligomers containing the same number of PDI units but different spacers display nearly identical enthalpy changes. According to the molecular exciton theory, the observed H- and J-aggregates are suggested to comprise similar packing motifs with slightly varied slipping angles, giving rise to greatly disparate optical properties.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Department of Applied Chemistry, Centre for Soft Matter Science and Engineering, Key Lab of Polymer Chemistry & Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China. dhzhao@pku.edu.cn.
authors.forename: Qifan
authors.initials: Q
authors.lastname: Yan
authors.forename: Kang
authors.initials: K
authors.lastname: Cai
authors.forename: Dahui
authors.initials: D
authors.lastname: Zhao