Systematic color tuning of a family of luminescent azole-based organoboron compounds suitable for OLED applications

Abstract

A new tunable luminescent family of heterocyclic aromatic compounds containing boron has been prepared and characterized through NMR spectroscopy, mass spectrometry, absorption and fluorescence spectroscopy as well as structural study using single crystal X-ray crystallography. Spectroscopic properties of the new compounds were also studied using DFT and TDDFT computational models that showed very good agreement of the theoretical data with experimental results. Through introduction of auxochromic atoms such as sulfur and extension of the π system of the ligands it is possible to cover a large range of the visible spectrum. Activation and enhancement of the luminescence is achieved by condensation reactions that introduce the boron fragment forming stable, sublimable compounds suitable for OLED applications.

Correlation among Singlet-Oxygen Quenching, Free-Radical Scavenging, and Excited-State Intramolecular-Proton-Transfer Activities in Hydroxyflavones, Anthocyanidins, and 1-Hydroxyanthraquinones

“…Nagaoka and co-workers have explained ESIPTs of various molecules, including the above-mentioned anthraquinone derivatives, in terms of the nodal-plane model, which is a simple but informative tool for prediction of ESIPT properties . Many chemists have cited the nodal-plane model and recognized usefulness of the explanation even in recent years. − The nodal-plane model is applicable not only to ESIPT but also to photorearrangement of o -vinyl diaryl ether, photoisomerization of bacteriorhodopsin, boron coordination, and so on …”

“…4 Many chemists have cited the nodal-plane model and recognized usefulness of the explanation even in recent years. 2−4 The nodal-plane model is applicable not only to ESIPT but also to photorearrangement of o-vinyl diaryl ether, 15 photoisomerization of bacteriorhodopsin, 16 boron coordination, 17 and so on. 18 In the present work, to answer the above-mentioned questions, we studied the 1 O 2 quenching, free-radical scavenging, and ESIPT activities of hydroxyflavones (HFs), anthocyanidins (ACs), and 1-hydroxyanthraquinones (1HAQs) by means of laser, stopped-flow, and steady-state spectroscopies.…”

Combining the Bethe–Salpeter Formalism with Time-Dependent DFT Excited-State Forces to Describe Optical Signatures: NBO Fluoroborates as Working Examples

“…In the present work, we tackle the 10 NBO dyes shown in Scheme . These molecules have been recently synthesized, − and no theoretical investigations were performed beyond some calculations of molecular orbitals and purely vertical TD-DFT transition energies . Of course, from the above analysis of literature data, it seems that we have reached a deadlock: the highly correlated wave function models are computationally nontractable for the considered compounds (some have more than 20 conjugated π-electrons), whereas TD-DFT will probably be inaccurate.…”

Efficient Blue Phosphorescent OLEDs with Improved Stability and Color Purity through Judicious Triplet Exciton Management

“…fac-Ir(ppy) 3 as a reference, the HOMO and LUMO energy levels of emitters can be modified accordingly to achieve a blue shifted emission by: 1) lowering the HOMO energy level with the addition of electron withdrawing groups to the phenyl ring or the employment of electron withdrawing ancillary ligands, [15][16][17] 2) increasing the LUMO energy level and triplet energy gap by cyclometalating with phenyl azole based ligands including phenyl imidazole, pyrazole, oxazole and thiazole. [18][19][20][21] Recently a third route was introduced to exhibit an efficient blue phosphorescent emission by breaking the conjugation between the donor and acceptor portions of the phenylpyridine ligand and forming a 6-membered metal chelation ring. [22] A symmetric Pt complex with carbazolyl-pyridine cyclometalating ligands, i.e.…”