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.

The mechanism of supramolecular polymerization has been elucidated for an archetype organogelator molecule composed of a perylene bisimide aromatic scaffold and two amide substituents. This molecule self-assembles into elongated one-dimensional nanofibers through a cooperative nucleation-growth process. Thermodynamic and kinetic analyses have been applied to discover conditions (temperature, solvent, concentration) where the spontaneous nucleation can be retarded by trapping of the monomers in an inactive conformation, leading to lag times up to more than 1 h. The unique kinetics in the nucleation process was confirmed as a thermal hysteresis in a cycle of assembly and disassembly processes. Under appropriate conditions within the hysteresis loop, addition of preassembled nanofiber seeds leads to seeded polymerization from the termini of the seeds in a living supramolecular polymerization process. These results demonstrate that seeded polymerizations are not limited to special situations where off-pathway aggregates sequester the monomeric reactant species but may be applicable to a large number of known and to be developed molecules from the large family of molecules that self-assemble into one-dimensional nanofibrous structures. Generalizing from the mechanistic insight into our seeded polymerization, we assert that a cooperative nucleation-growth supramolecular polymerization accompanied by thermal hysteresis can be controlled in a living manner.

The synthesis, self-assembly, and gelation ability of a series of organogelators based on perylene bisimide (PBI) dyes containing amide groups at imide positions are reported. The synergetic effect of intermolecular hydrogen bonding among the amide functionalities and pi-pi stacking between the PBI units directs the formation of the self-assembled structure in solution, which beyond a certain concentration results in gelation. Effects of different peripheral alkyl substituents on the self-assembly were studied by solvent- and temperature-dependent UV-visible and circular dichroism (CD) spectroscopy. PBI derivatives containing linear alkyl side chains in the periphery formed H-type pi stacks and red gels, whereas by introducing branched alkyl chains the formation of J-type pi stacks and green gels could be achieved. Sterically demanding substituents, in particular, the 2-ethylhexyl group completely suppressed the pi stacking. Coaggregation studies with H- and J-aggregating chromophores revealed the formation of solely H-type pi stacks containing both precursor molecules at a lower mole fraction of J-aggregating chromophore. Beyond a critical composition of the two chromophores, mixed H-aggregate and J-aggregate were formed simultaneously, which points to a self-sorting process. The versatility of the gelators is strongly dependent on the length and nature of the peripheral alkyl substituents. CD spectroscopic studies revealed a preferential helicity of the aggregates of PBI building blocks bearing chiral side chains. Even for achiral PBI derivatives, the utilization of chiral solvents such as (R)- or (S)-limonene was effective in preferential population of one-handed helical fibers. AFM studies revealed the formation of helical fibers from all the present PBI gelators, irrespective of the presence of chiral or achiral side chains. Furthermore, vortex flow was found to be effective in macroscopic orientation of the aggregates as evidenced from the origin of CD signals from aggregates of achiral PBI molecules.

Luminous nanorods: The self‐assembly of core‐twisted perylene bisimide fluorophores (see structures) in nonpolar organic solvents is directed by hydrogen‐bonding interactions. This supermolecular concept resulted in one‐dimensional J‐aggregates with a fluorescence quantum yield of near unity.

A series of highly soluble and fluorescent, at core tetraaryloxy-substituted and in imide positions hydrogen atom containing perylene bisimide (PBI) dyes 1a-e with varying peripheral side chains have been synthesized and thoroughly characterized. The self-assembly of these PBIs has been studied in detail by UV/vis, linear dichroism (LD) and circular dichroism (CD) spectroscopy, and scanning probe microscopy (AFM, STM). These studies revealed that the present PBIs self-assemble into extended double string cables, which consist of two hydrogen-bonded supramolecular polymeric chains of densely packed and strongly excitonically coupled PBI chromophores, providing highly fluorescent J-aggregates. The aggregation strength ("melting" temperature) and the fluorescence properties of these J-aggregates are dependent on the number and chain length of the peripheral alkoxy substituents, thus revealing a structure-property relationship. In contrast to previously reported assemblies of PBIs, for which the aggregation process is described by the isodesmic (or equal K) model, a cooperative nucleation-elongation mechanism applies for the aggregation of the present assemblies as revealed by concentration-dependent UV/vis absorption studies with the chiral PBI 1e, providing equilibrium constants for dimerization (= nucleation) of K(2) = 13 +/- 11 L mol(-1) and for elongation of K = 2.3 +/- 0.1 x 10(6) L mol(-1) in methylcyclohexane (MCH). LD spectroscopic measurements have been performed to analyze the orientation of the monomers within the aggregates. The nonlinearity of chiral amplification in PBI aggregates directed by sergeants-and-soldiers principle has been elucidated by coaggregation experiments of different PBI dyes using CD spectroscopy. The dimensions as well as the molecular arrangement of the monomeric units in assemblies have been explored by atomic force microscopy (AFM) and scanning tunneling microscopy (STM).