Asymmetric N,C-chelate organoboron compounds bearing two different aryl groups at the boron center undergo photoisomerization reactions that involve exclusively the less bulky aryl group, generating various strongly colored "dark isomers". These species thermally isomerize to 4bH-azaborepin molecules by direct hydrogen atom transfer from a borirane cycle to the pyridyl moiety and ring expansion. Mechanistic insight into these highly regioselective transformations was obtained from kinetic data and through computational studies.

A new class of highly efficient and stable, blue-phosphorescent Pt complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching-from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi-response phenomenon. Highly efficient singlet-oxygen sensitization by the Pt compounds yields UV-light-induced phosphorescence enhancement and color switching.

With the aid of borylation and oxidative coupling reactions, six new polycyclic aromatic hydrocarbons (PAHs) doped by nitrogen−boron−nitrogen (NBN) units were achieved. The structure−optoelectronic property relationship for this group of compounds was examined. All six compounds are fluorescent with contrasting emission colors and quantum yields.

considerable attention as promising emitters in highly efficient organic light-emitting diodes (OLEDs), [1] because they can realize high internal quantum efficiencies of nearly 100% for electroluminescence (EL) through favorable upconversion of triplet excitons to singlet excitons via reverse intersystem crossing (RISC). To design efficient TADF emitters, a sufficiently small singlet-triplet energy splitting (ΔE ST ) is required to ensure an effective RISC process which is usually facilitated by a large spatial separation of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). [2] Many efficient TADF emitters with small or even vanishing ΔE ST usually adopt a twisted charge-transfer (CT) configuration composed of an electron-donor (D) and an electron-acceptor (A) moiety. [3] However, a large twist angle generally weakens the oscillator strength and thus decreases the photoluminescence (PL) quantum yield (Φ PL ), and limiting OLED efficiency. [4] Hence, the appropriate choice of the number of D and A units and their linkers are of vital importance to achieve excellent TADF emitters with small ΔE ST and high emission efficiency. [1a,5] Like phosphorescent materials, most TADF emitters are in general dispersed into suitable host matrices to suppress concentration or aggregation-caused emission quenching and/or exciton annihilation in OLEDs. In particular, the exciton quenching originated from the long excited state lifetime of the TADF emitters during upconversion process of triplet excitons can lead to the efficiency roll-off. [6] Doped OLEDs require complicated configurations and precisely controlled fabrication procedures to ensure reproducibility of emission color and quantum efficiency. Hence, using neat (nondoped) emitting layers for TADF-based devices are highly desired for the purpose of simplified device structures and reduced efficiency roll-off. Nonetheless, to date, efficient OLEDs using neat TADF emitting layers remain rare and in high demand. [1c,i,7] To develop such devices, further understanding on the relationship between the TADF molecular structures and optoelectronic properties is necessary. [1h,5a,8] Recently, boron-containing polycyclic aromatic hydrocarbons have emerged to be very promising for optoelectronics Three isomeric boron-containing thermally activated delayed fluorescent (TADF) emitters, namely m-AC-DBNA, p-AC-DBNA, and m′-AC-DBNA, are constructed by incorporating an electron-donor acridine (AC) moiety into meta-, para-, or meta′-positions of an electron-accepting boron-embedded rigid framework. The substitutional positions are found to dramatically affect thermal, photophysical, and electroluminescent (EL) properties. The experimental results show that the para-substituted compound (p-AC-DBNA) exhibits higher decomposition temperature, higher photoluminescence (PL) quantum efficiencies, smaller singlet-triplet energy splitting, shorter delayed fluorescence lifetimes as well as a fast reverse intersystem crossing rate of over 1...

An aldehyde functionalized amino-borane has been found to respond to multiple external stimuli such as temperature, pressure and solvents, producing distinct patterns and colours.