Junki Ochi

o-Carborane, a cluster compound containing boron and adjacent carbon atoms, displays intriguing luminescent properties. Recently, compounds containing o-carborane units were found to show suppressed aggregation-induced quenching and intense solid-state emission; they also show potential for the development of stimuli-responsive luminochromic materials. In this Minireview, we introduce three kinds of fundamental photochemical properties: aggregation-induced emission, twisted intramolecular charge

An ultrapure deep-blue multi-resonance-induced thermally activated delayed fluorescence material (DOB2-DABNA-A) is designed and synthesized. Benefiting from a fully resonating extended helical π-conjugated system, this compound has a small ΔE_ST value of 3.6 meV and sufficient spin-orbit coupling to exhibit a high-rate constant for reverse intersystem crossing (k_RISC = 1.1 × 10⁶s^-1). Furthermore, an organic light-emitting diode employing DOB2-DABNA-A a

Because of their unique luminescence properties, such as aggregation-induced emission (AIE), intense solid-state luminescence and stimuli-responsive luminochromism, aryl-substituted o-carboranes have attracted attention as a platform for developing functional optoelectronic materials. However, there still remains one fundamental issue with the detailed mechanism of solution quenching in AIE behaviors. Aryl-modified o-carboranes with AIE properties exhibit intense emission not in solution but in

Although excimer emission is a useful luminescent phenomenon for fabricating optical sensors and probes, it is difficult to apply excimer emission for film sensors due to critical concentration quenching in the solid state. Therefore, robust molecular designs for solid-state excimer emission are still being explored. One of the key examples is the previously reported acridine-ethynyl-<i>o</i>-carborane <b>AcE1</b>, which showed a bright solid-state excimer emission assisted by characteristic C<s

Abstract o ‐Carborane, a cluster compound containing boron and adjacent carbon atoms, displays intriguing luminescent properties. Recently, compounds containing o ‐carborane units were found to show suppressed aggregation‐induced quenching and intense solid‐state emission; they also show potential for the development of stimuli‐responsive luminochromic materials. In this Minireview, we introduce three kinds of fundamental photochemical properties: aggregation‐induced emission, twisted intramolec

We report highly‐efficient and solid‐state excimer emission based on the acridine– o ‐carborane dyad possessing the ethynyl spacer. The previous pyrene‐modified o ‐carborane showed excimer emission only at 77 K in the crystalline state, meanwhile, the current acridine‐modified molecule presented excimer emission with high efficiency ( Φ PL = 0.23) in the crystalline state at room temperature. From single‐crystal X‐ray crystallography, it was indicated that two acridine moieties were stacked and

Herein, we report the unique solid-state excimer emission of three types of acridine-tethered o-carboranes with variable degrees of methylation at the o-carborane unit. They all showed columnar packing structures based on dimer formation, and two types of π-overlapping motifs were alternately stacked. From the photoluminescence (PL) measurements on the crystalline samples, it was found that three types of luminescence bands can simultaneously appear: monomer emission, excimer emission from the m

It is still challenging to realize a dual-emission system, in which two luminescent bands simultaneously appear by photoexcitation, in solid with organic dyes due to the difficulty in regulation of electronic properties in the excited state and concentration quenching. o-Carborane is known to be a versatile platform for constructing solid-state emitters since the sphere boron cluster is favorable for suppressing intermolecular interactions and subsequently concentration quenching. Here, we show

Invited for the cover of this issue is the group of Kazuo Tanaka at Kyoto University. The image depicts the control of solid-state dual-emissive properties by modulating the intramolecular hydrogen bonding in boron clusters. Read the full text of the article at 10.1002/chem.202200155.

We synthesized two types of the regioisomers fused by a phenylnaphthalene ring with variable connection points to the <i>o</i>-carborane scaffold. In this paper, we describe their photoluminescence (PL) properties and detailed photochemical mechanisms. According to the series of optical measurements, interestingly, they showed different PL characters in terms of wavelength and the dual-emission character despite that they have the common aromatic unit. Variable-temperature PL measurements and qu

Abstract o-Carborane-based emitters have been greatly developed over the last ten years. From the viewpoint of molecular symmetry, o-carborane has one type of equivalent carbon and four types of equivalent boron atoms. However, in contrast to the vast research of aryl-modified o-carboranes on the carbon atom of o-carborane, substitution on the boron atom is less investigated. Herein, we introduced an anthracene unit on the B(3) position of o-carborane and explored the substitution position effec

Abstract An ultrapure deep‐blue multi‐resonance‐induced thermally activated delayed fluorescence (MR‐TADF) material ( DOB2‐DABNA‐C‐NP ) is synthesized as a promising emitter for organic light‐emitting diodes (OLEDs). The emission color is precisely tuned by adopting the asymmetric structure, which is modified from the previously reported symmetric compounds. Notably, the compound exhibits narrowband pure blue emission at 458 nm with a small full width at half maximum (FWHM) of 27 nm. In addition

Abstract Four monocarborane anion-based compounds connected to a pyrene moiety were synthesized by combining two monocarborane anion scaffolds and two counter cations. The effects of the cage structure and the counter cation on the optical properties were investigated from UV‒vis absorption and photoluminescence (PL) measurements. The PL spectra in the solid state were unique for each compound, derived from the different shapes of the carborane cage and counter cation. These results suggest grea

An oxygen-sulfur replacement for improving thermally activated delayed fluorescence (TADF) materials based on a multiple-resonance (MR) effect is reported. A comprehensive computational analysis of four possible isomers revealed that the precise placement of the sulfur atom is crucial to suppress undesired spectral red-shifts. Among them, a promising deep-blue emitter, DOB2-DABNA-C-NP-S-1, exhibits emission at 458 nm with a narrow full width at half maximum (FWHM) of 20 nm. Moreover, its reverse

Abstract Herein, we report the unique solid‐state excimer emission of three types of acridine‐tethered o ‐carboranes with variable degrees of methylation at the o ‐carborane unit. They all showed columnar packing structures based on dimer formation, and two types of π‐overlapping motifs were alternately stacked. From the photoluminescence (PL) measurements on the crystalline samples, it was found that three types of luminescence bands can simultaneously appear: monomer emission, excimer emission