Naphthyl-linked donor–π–acceptor fluorophores were utilized to achieve high performance and good color purity violet-blue emission in organic light-emitting devices (OLEDs).

C–H glycosylations of complex amino acids and peptides were accomplished through the assistance of triazole peptide-isosteres. The palladium-catalyzed glycosylation provided access to complex C-glycosides and fluorescent-labeled glycoamino acids.

Tremendous effort has been devoted to developing novel near-infrared (NIR) emitters and to improving the performance of NIR organic light-emitting diodes (OLEDs). Os(II) complexes are known to be an important class of NIR electroluminescent materials. However, the highest external quantum efficiency achieved so far for Os(II)-based NIR OLEDs with an emission peak wavelength exceeding 700 nm is still lower than 3%. A new series of Os(II) complexes (1-4) based on functional pyrazinyl azolate chelates and dimethyl(phenyl)phosphane ancillaries is presented. The reduced metal-to-ligand charge transfer (MLCT) transition energy gap of pyrazinyl units in the excited states results in efficient NIR emission for this class of metal complexes. Consequently, NIR OLEDs based on 1-4 show excellent device performance, among which complex 4 with a triazolate fragment gives superior performance with maximum external quantum efficiency of 11.5% at peak wavelength of 710 nm, which represent the best Os(II)-based NIR-emitting OLEDs with peak maxima exceeding 700 nm.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201906738. zation because of the strong spin-orbit coupling exerted by the thrid-row transition metal elements. [3,18,19] Among these, Pt(II)-based NIR OLEDs represent the state-of-the-art results in the range of 700-900 nm. [18,[20][21][22][23] In particular, in 2017, our group achieved a milestone in NIR OLEDs research, and realized NIR OLEDs with EQE up to 24 ± 1% at 740 nm by using the pyrazinyl pyrazolate Pt(II)-based emitter. [22] Although the efficiencies of these Pt(II)-based NIR OLEDs are remarkable, which also demonstrated a promising way to reduce the efficiency roll-off of the Pt(II)-based NIR OLEDs by using the metal-metal-to-ligand charge transfer (MMLCT) transition. [22][23][24] But in general, NIR OLEDs based on squareplanar Pt(II) emitters, particularly for porphyrin-based Pt(II) phosphors, typically suffer from serious efficiency roll-off at high current density, due to the long-lived triplet exciton generated and corresponding self-quenching. [18,21,25] In comparison Adv. Funct.

Organic materials containing arylamines have been widely used as hole-transporting materials as well as emitters in organic light-emitting devices (OLEDs). However, it has been pointed out that the C-N bonds in these arylamines can easily suffer from degradation in excited states, especially in deep-blue OLEDs. In this work, phenanthro[9,10-d]imidazole (PI) is proposed as a potential donor with higher stability than those of arylamines. Using PI as the donor, a donor-acceptor type deep-blue fluorophore 1-phenyl-2-(4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1,1':4',1″-terphenyl]-4-yl)-1H-phenanthro[9,10-d]imidazole (BITPI) is designed and synthesized. Results from UV-aging test on neat films of BITPI and other three arylamine compounds demonstrate that PI is indeed a more stable donor comparing to common arylamines. An OLED using BITPI as an emitter exhibits good device performances (EQE over 7%) with stable deep-blue emission (color index: (0.15, 0.13)) and longer operation lifetime than the similarly structured device using arylamine-based emitter. Single-organic layer device based on BITPI also shows superior performances, which are comparable to the best results from the arylamine-based donor-acceptor emitters, suggesting that PI is a stable donor with good hole transport/injection capability.