New Molecular Design Concurrently Providing Superior Pure Blue, Thermally Activated Delayed Fluorescence and Optical Out-Coupling Efficiencies.

Simultaneous enhancement of out-coupling efficiency, internal quantum efficiency, and color purity in thermally activated delayed fluorescence (TADF) emitters is highly desired for the practical application of these materials. We designed and synthesized two isomeric TADF emitters, 2DPyM-mDTC and 3DPyM-pDTC, based on di(pyridinyl)methanone (DPyM) cores as the new electron-accepting units and di(tert-butyl)carbazole (DTC) as the electron-donating units. 3DPyM-pDTC, which is structurally nearly planar with a very small ΔEST, shows higher color purity, horizontal ratio, and quantum yield than 2DPyM-mDTC, which has a more flexible structure. An electroluminescence device based on 3DPyM-pDTC as the dopant emitter can reach an extremely high external quantum efficiency of 31.9% with a pure blue emission. This work also demonstrates a way to design materials with a high portion of horizontal molecular orientation to realize a highly efficient pure-blue device based on TADF emitters.

Metal induced gelation from pyridine cored poly(aryl ether) dendrons with in situ synthesis and stabilization of hybrid hydrogel composites.

Metal induced gel formation from pyridine cored poly(aryl ether) dendrons has been achieved. The gel is successfully utilized as a template for the in situ synthesis of silver nanoparticles (AgNPs) in hydrogel networks without using any external reducing or capping agents for the development of an exceptionally well-ordered AgNP-hybrid hydrogel soft composite.

Glucose-cored poly(aryl ether) dendron based low molecular weight gels: pH controlled morphology and hybrid hydrogel formation.

We designed poly(aryl ether) dendron based transparent hydrogels containing glucose moiety, which undergoes in situ transition from nanofibers to spherical aggregates, upon pH variation. The process is reversible and the assembled structures have been characterized by DLS and SEM. More importantly, efficient dispersion of graphene oxide results in lower CGC (0.08 wt%) value and higher mechanical strength, compared to the native gel.

Supramolecular design for two-component hydrogels with intrinsic emission in the visible region.

We report, for the first time, an in situ formation of two-component hydrogels from pyridine derivatives of poly(aryl ether) dendrons and tartaric acid. The two-component system (dendron + acid) undergoes J-type aggregation, leading to fibrillar type self-assembly in THF-water mixture along with blue (470 nm) and green (500 nm) intrinsic emissions.

Tunable morphology and mesophase formation by naphthalene-containing poly(aryl ether) dendron-based low-molecular-weight fluorescent gels.

Novel poly(aryl ether) dendron-based low-molecular-weight organogelaters (LMWG) containing naphthalene units at the core have been synthesized, and the self-assembly of the system has been examined in a variety of solvents and solvent mixtures. The compounds readily form gels with attractive critical gel concentration values associated with gelation-induced enhanced emission (GIEE). In addition to the remarkable properties of the previously reported anthracene and pyrene analogues (Rajamalli, P.; Prasad, E. Org. Lett.2011, 13, 3714 and Rajamalli, P.; Prasad, E. Soft Matter2012, 8, 8896), the self-assembled systems exhibit distinctly different structure-property relationships. Unlike the reported ones, the present system forms sheetlike morphology in nonpolar solvent mixtures, giant vesicles in polar solvent mixtures, and lamellar or hexagonal columnar phases in single solvents. The unique properties of the self-assembled systems, which were analyzed through electron microscopic (SEM, TEM, AFM) and spectroscopic techniques (POM, fluorescence), are attributed to the replacement of anthracene/pyrene units by naphthalene units. The present work unravels the subtle role of minute structural change in altering the properties of LMWGs based on poly(aryl ether) dendrons.

Low molecular weight fluorescent organogel for fluoride ion detection.

The design, synthesis, and the photophysical properties of a Low Molecular Weight Gel (LMWG) based on AB(3) and AB(2) type poly(aryl ether) dendrons with an anthracene chromophore attached through an acylhydrazone linkage are described. The gel is utilized for an efficient 'naked eye' detection of fluoride ions (as low as 0.1 equiv with respect to the gelator concentration), through a reversible gel-sol transition, which is associated with a color change from deep yellow to bright red.