A newly synthesized multi-bladed benzene (2o) bearing two oxaboraanthracenyl and two N-carbazolylphenyl units undergoes highly cooperative binding with multiple methanol molecules (Hill coefficient > 3.5).
The incorporation of boron functionality into π-conjugated systems has been demonstrated to provide enhanced and intriguing emission properties due to the combined effects of pπ–π* interactions, polarization, and molecular orbital modulations.1,2 Besides, the inherent Lewis acidity of the boron centre allows coordination of Lewis bases, such as F−, amines, pyridines, and alcohols, which impairs the pπ–π* interactions, inducing substantial changes in the emission and electronic properties.3a,4 Taking advantage of such coordination properties, a variety of boron-containing colorimetric and luminescent dyes capable of sensing Lewis bases have been developed.3b,c In this context, multi-boryl units having proximal boron centres are attractive as a component of functional dyes, since they may exhibit stronger coordination ability with Lewis bases due to increased Lewis acidity as well as a chelate effect.5 For this application, a particular molecular design is required to ensure chemical stability, such as suppressing hydrolysis.
We have recently reported that 1,2-diborylacetylene (1, Fig. 1a), bearing planar 9-oxa-10-boraanthracene (OBAn) termini,6 exhibits sufficient chemical stability to allow handling in air, while retaining the typical reactivity of alkynes. For example, compound 1 undergoes the Diels–Alder reaction with tetraphenylcyclopentadienone to yield 1,2-diboryl-3,4,5,6-tetraphenylbenzene (2H, Fig. 1a), a multi-bladed benzene featuring two adjacent OBAn groups.6 Based on this finding, we newly designed 2o (Fig. 1a), in which carbazole units are introduced on the phenyl substituents at the 3,6-positions of the central benzene ring.
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