Over the rainbow: Three highly luminescent compounds use hydrogen‐bonding interactions to spontaneously generate hollow nanospheres when dropcast from anhydrous solvents (see picture). Together, they cover more than 75 % of the gamut of a conventional liquid crystalline display.

The unusual spontaneous formation of submicrometer-sized vesicles from a small, nonamphiphilic bis-biuret difluorene derivative upon dissolution of the solid in an anhydrous organic solvent was investigated using multiple scattering techniques. Time-resolved light scattering (TLS) measurements confirm that the self-assembly process is driven by hydrogen-bonding interactions, leading to the formation of vesicles at a critical concentration ∼1 × 10–4 M in tetrahydrofuran as determined by absorbance and surface tension measurements. Results from cryogenic-scanning electron microscopy (cryo-SEM), dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS) experiments are consistent with the existence of vesicle-like aggregates in solution. DLS studies indicate a broad distribution of aggregates with a mean hydrodynamic radius ⟨R H ⟩ = 303 nm (polydispersity =0.49). SAXS profiles show two decay regimes (low-Q decay, very large aggregates; large-Q decay, smaller species). The analysis models the large aggregates as vesicles (hollow spheres) with a mean external radius R o = 750 nm and an internal radius R i = 720 nm while the smaller aggregates have a mean radius R = 2.2 nm. The results obtained by cryo-SEM show spherical aggregates of vesicles size in the range ca. 100 nm to 1 μm. Transmission electron microscopy (TEM) micrographs evidence the presence of aggregates whose morphology is compatible with budding and pearling processes as possible mechanisms for the formation of vesicles.

Self-assembled aggregates offer great potential for tuning the morphology of organic semiconductors, thereby controlling their size and shape. This is particularly interesting for applications in electroluminescent (EL) devices, but there has been, to date, no reports of a functional EL device in which the size and color of the emissive domains could be controlled using self-assembly. We now report a series of molecules that spontaneously self-organize into small EL domains of sub-micrometer dimensions. By tailoring the emissive chromophores in solution, spherical aggregates that have an average size of 300 nm in diameter and emit any one color, including CIE D65 white, are spontaneously formed in solution. We show that the individual aggregates can be used in EL devices built either using small patterned electrodes or using a sandwich architecture to produce devices emitting in the blue, green, red, and white. Furthermore, sequential deposition of the three primary colors yields an RGB device in which single aggregates of each color are present in close proximity.

The morphology of aggregates formed by an E-azobenzene derivative possessing terminal phenylenebiuret hydrogen-bonding groups can be manipulated by the solvent composition and UV irradiation.

A new synthesis of 5,10,15-hexaaryltruxene derivatives has been developed. Experimental observations and theoretical calculations confirmed that the presence of aryl substituents on the sp(3)-hybridized bridge carbon atoms had an effect on the photophysical properties of the truxene core. Interestingly, the cage compound 11 possessing a distorted truxene core was verified by X-ray diffraction analysis; the influence of the peripheral aryl substituents on the photophysical properties of the truxene core was diminished because of its molecular rigidity.