Benchmarking of Density Functionals for the Description of Optical Properties of Newly Synthesized π-Conjugated TADF Blue Emitters

Computational modeling of the optical characteristics of organic molecules with potential for thermally activated delayed fluorescence (TADF) may assist markedly the development of more efficient emitting materials for organic light-emitting diodes. Recent theoretical studies in this area employ mostly methods from density functional theory (DFT). In order to obtain accurate predictions within this approach, the choice of a proper functional is crucial. In the current study, we focus on testing the performance of a set of DFT functionals for estimation of the excitation and emission energy and the excited singlet-triplet energy gap of three newly synthesized compounds with capacity for TADF. The emitters are designed specifically to enable charge transfer by π-electron conjugation, at the same time possessing high-energy excited triplet states. The functionals chosen for testing are from various groups ranging from gradient-corrected through global hybrids to range-separated ones. The results show that the monitored optical properties are especially sensitive to how the long-range part of the exchange energy is treated within the functional. The accurate functional should also be able to provide well balanced distribution of the π-electrons among the molecular fragments. Global hybrids with moderate (less than 0.4) share of exact exchange (B3LYP, PBE0) and the meta-GGA HSE06 are outlined as the best performing methods for the systems under study. They can predict all important optical parameters correctly, both qualitatively and quantitatively.     

Estrone derived 2-naphthol analogue in the diastereoselective one-pot Betti-condensation

Molecular Diversity - The utility of deoxy-isoequilenine synthesized from estrone as valuable 2-naphthol analogue is demonstrated in the three components Betti-condensation. A simple, efficient and...     

1,7,9,10-Tetrasubstituted PMIs Accessible through Decarboxylative Bromination: Synthesis,Characterization, Photophysical Studies,and Hydrogen Evolution Catalysis

In this work, we present a new synthetic strategy for fourfold-substituted perylene monoimides via tetrabrominated perylene monoanhydrides. X-ray diffraction analysis unveiled the intramolecular stacking orientation between the substituents and semicircular packing behavior. We observed the remarkable influence of the substituent on the longevity and nature of the excited state upon visible light excitation. In the presence of poly(dehydroalanine)-graft-poly(ethylene glycol) graft copolymers as solubilizing template, the chromophores are capable of sensitizing [Mo₃S₁₃]²⁻ clusters in aqueous solution for stable visible light driven hydrogen evolution over three days.     

High-Performance Near-Infrared Chlorinated Rylenecarboximide Fluorophores via Consecutive C−N and C−C Bond Formation

A new class of near-infrared (NIR) fluorophores, PAI , is obtained by consecutive C−N/C−C bond formation between diphenylamines and 9,10-dibromoperylenecarboximide. Owing to the rigid structure, extended π-conjugation and pronounced push-pull substitution, these fluorophores show emission maxima up to 804 nm and large Stokes shifts. The extraordinarily high fluorescence quantum yields from 47 % to 70 % are attributed to chloro substitution in the bay positions of the perylene core. These characteristics, together with high photostability, qualify them as useful NIR emitters for applications as biomarkers and security inks.