Unipolar 1-phenylimidazo[1,5-a]pyridine: A new class of ultra-bright sky blue emitters for solution-processed organic light emitting diodes

Three fluorophores based on Imidazo[1,5-a]pyridine (ImPy) decorated with aromatic π-system (C3 position of ImPy is decorated with naphthalene, methoxy-naphthalene and pyrene) were designed and synthesized by one-pot synthesis method. The...

Preferential solvation of p-nitroaniline in a binary mixture of chloroform and hydrogen bond acceptor solvents: the role of specific solute-solvent hydrogen bonding

Preferential solvation of solvatochromic probe p-nitroaniline (PNA) has been studied in binary mixtures of chloroform with different hydrogen bond acceptor (HBA) solvents using the spectroscopic transition energy (E_T). Analyses of the solvatochromic shifts of the absorption spectra of PNA in different neat solvents as a function of the solvent polarity parameters reveal the major contribution from the solvent dipolarity/polarizability and HBA basicity in the solvation of PNA. The event of preferential solvation in the chloroform-HBA binary mixtures and the preference of one solvent above the other in the solvation shell have been attributed to the hydrogen bond donor and acceptor ability of the solvent mixtures. HBA solvents form a strong hydrogen bond with the amino group while chloroform forms a hydrogen bond with the nitro group of PNA. This specific functional group recognition increases the local concentration at specific sites resulting in location specific preferential solvation and synergistic preferential solvation. Solvents with comparable polarity have been found to show significant synergistic behavior as a result of the formation of stronger solvent-solvent hydrogen bonded S₁-S₂ species. These propositions were found to be supported by theoretical solvation models, calculated HOMO-LUMO energy gaps, the effect of deuterated solvent on the extent of PS, and ¹H NMR spectral analyses.

Triphenylamine based yellowish-orange light emitting organic dyes (donor–π–acceptor) for hybrid WLEDs and OLEDs: synthesis, characterization and theoretical study

Six novel yellowish-orange light emitting dye molecules consisting of an electron deficient phenone (acceptor) linked to triphenylamine (donor), were designed and synthesized.

Structural Mimics of Phenyl Pyridine (ppy) - Substituted, Phosphorescent Cyclometalated Homo and Heteroleptic Iridium(III) Complexes for Organic Light Emitting Diodes - An Overview

Today organic light emitting diodes are a topic of significant academic and industrial research interest. OLED technology is used in commercially available displays, and efforts have been directed to improve this technology. Design and synthesis of phosphorescent based transition metals are capable of harvesting both singlet and triplet excitons and achieve 100 % internal quantum efficiency is an active area of research. Among all the transition metals, iridium is considered a prime candidate for OLEDs due to its prominent photophysical characteristics. In the present review, we have concentrated on the Iridium based homo and heteroleptic complexes that have dissimilar substitutions on phenylpyridine ligands, different ancillary ligands and the effect of substitution on HOMO/LUMO energies and a brief discussion and correlation on the photophysical, electrochemical and device performances of the different complexes have been reviewed for organic light emitting diodes.