Recent Progress in the Development of Solid‐State Luminescent o‐Carboranes with Stimuli Responsivity

• Published in: Angewandte Chemie International Edition Vol. 59; no. 25; pp. 9841 - 9855
• Main Authors: Ochi, Junki, Tanaka, Kazuo, Chujo, Yoshiki
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 15.06.2020
• Edition: International ed. in English
• Subjects: Agglomeration; Boron; Boron compounds; Carborane; carboranes; Charge transfer; chromism; Crystals; Emission; Excimers; luminescence; Optical properties; Photochemicals; Stimuli; stimuli responsivity; emission; luminescence; chromism; stimuli responsivity; carboranes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201916666

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 transfer in crystals, and environment‐sensitive excimer formation in solids. Based on these properties, several types of luminochromism, such as thermos‐, vapo‐, and mechanochromism, have been discovered. Based mainly on results from recent studies, we illustrate these mechanisms as well as unique luminescent behaviors of o‐carborane derivatives. Shine on you crazy diamond! In this Minireview a series of arene‐modifiedo‐carboranes are described that display solid‐state emission as well as stimuli‐responsive optical properties. The unique photochemistry of these o‐carboranes, such as aggregation‐induced emission (AIE), twist‐induced charge‐transfer (TICT) emission, and solid‐state excimer emission, is explored.