The self-assembly of a new, highly fluorescent perylene bisimide dye 2 into pi stacks, both in solution and condensed phase, has been studied in detail by NMR spectroscopy, vapor pressure osmometry (VPO), UV/Vis and fluorescence spectroscopy, differential scanning calorimetry (DSC), optical polarizing microscopy (OPM) and X-ray diffraction. The NMR and VPO measurements revealed the formation of extended pi-pi stacks of the dye molecules in solution. The aggregate size determined from VPO and DOSY NMR measurements agree well with that obtained from the concentration and temperature-dependent UV/Vis spectral data by employing the isodesmic model (equal K model). In the condensed state, dye 2 possesses a hexagonal columnar liquid crystalline (LC) phase as confirmed by X-ray diffraction analysis. The columnar stacking of this dye has been further explored by atomic force microscopy (AFM). Well-resolved columnar nanostructures of the compound are observed on graphite surface. A color-tunable luminescence from green to red has been observed upon aggregation which is accompanied by an increase of the fluorescence lifetime and depolarization. The observed absorption properties can be explained in terms of molecular exciton theory. The charge transport properties of dye 2 have been investigated by pulse radiolysis-time resolved microwave conductivity measurements and a 1D charge carrier mobility up to 0.42 cm(2) V(-1) s(-1) is obtained. Considering the promising self-assembly, semiconducting, and luminescence properties of this dye, it might serve as a useful functional material for nano(opto)electronics.
EDGE ARTICLEAndrew J. deMello, Joshua B. Edel et al. Rapid cell extraction in aqueous twophase microdroplet systems PERSPECTIVE Barry M. Trost et al. Catalytic asymmetric allylic alkylation employing heteroatom nucleophiles: a powerful method for C-X bond formation
A new perylene bisimide dye has been synthesized which self-assembles into columnar nanoaggregates and liquid crystalline mesophases with striking photoluminescent properties.
A perylene bisimide derivative bearing two phenyl substituents with chiral solubilizing alkyl chains at the imide N atoms has been synthesized, and its self-assembly properties in solution and condensed phase have been investigated. Temperature-dependent CD spectra revealed the coexistence of two different kinds of chiral aggregates, differing in size and handedness. The chiral side chains effect a higher order within the self-assemblies, resulting in an increased charge-carrier mobility in the columnar liquid crystalline mesophase. [structure: see text]
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