A series of acene-type conjugated molecules (1-5) containing 2-6 pyrazine units and up to 16 rectilinearly arranged fused aromatic rings were synthesized by condensation coupling of 1,2-diamines and 1,2-diketones. The energy gap of the molecules estimated from absorption edge decreases with an increase in molecular length, indicating the well-delocalized nature of the molecules. The cyclic voltammetry measurements suggest that the n-type properties of these ribbonlike pyrazine derivatives are dependent on the molecular length and the number of the pyrazine units. As the number of pyrazine units and the molecular length increase, the first reduction wave onset is shifted from -1.16 to -0.62 V (vs Ag/AgCl), corresponding to the LUMO energy levels of -3.24 and -3.78 eV, respectively. These molecules tend to aggregate in solution more readily with an increase in molecular length, as evident by (1)H NMR and UV-vis absorption spectra. Introduction of t-butyl groups in pyrene units can noticeably suppress the aggregation of these molecules in solution. High electron affinity, high environmental stability, and ease of structural modification make these compounds excellent candidates as a new class of n-type semiconductors.
We prepared dendritic perylene bisimide probes with triblock structures: perylene bisimides fluorescence cores, branched oligo(glutamic acid)s and polyethylene glycol chains. These probes showed good water solubility, low cytotoxicity and strong fluorescence in live cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.