Issue 39, 2021, Issue in Progress

Alteration of intramolecular electronic transition via deboronation of carbazole-based o-carboranyl compound and intriguing ‘turn-on’ emissive variation

Abstract

The conversion of closo-o-carborane–containing compounds to the nido-o-species via deboronation causes photophysical changes that could be used for sensing applications. 9-Methyl-9H-carbazole–based closo- (closo-Cz) and nido-o-carboranyl (nido-Cz) compounds were prepared and fully characterised by multinuclear NMR spectroscopy and elemental analysis, and the solid-state molecular structure of closo-Cz was analysed by X-ray crystallography. Although the closo-compound exhibited an emissive pattern centred at λem = ca. 530 nm in the rigid state only (in THF at 77 K and as a film), nido-Cz demonstrated intense emission in the near-UV region (λem = ca. 380 nm) in both solution and film states at 298 K. The positive solvatochromic effect of nido-Cz and the results of theoretical calculations for both the o-carboranyl compounds supported that these emissive features originate from intramolecular charge transfer (ICT) corresponding to the o-carborane. Furthermore, the calculations verified that the electronic role of the o-carboranyl unit changed from acceptor to donor upon deboronation from closo-Cz to nido-Cz. Investigations of the radiative decay mechanisms of closo-Cz and nido-Cz according to their quantum efficiencies (Φem) and decay lifetimes (τobs) suggested that the ICT-based radiative decays of closo-Cz and nido-Cz readily occur in the film (solid) and solution state, respectively. These observations implied that the emission of closo-Cz in the solution state could be drastically enhanced by deboronation to nido-Cz upon exposure to an increasing concentration of fluoride anions. Indeed, turn-on emissive features in an aqueous solution were observed upon deboronation, strongly suggesting the potential of closo-Cz as a turn-on and visually detectable chemodosimeter for fluoride ion sensing.

Graphical abstract: Alteration of intramolecular electronic transition via deboronation of carbazole-based o-carboranyl compound and intriguing ‘turn-on’ emissive variation

Supplementary files

Article information

Article type
Paper
Submitted
12 May 2021
Accepted
05 Jul 2021
First published
07 Jul 2021
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2021,11, 24057-24064

Alteration of intramolecular electronic transition via deboronation of carbazole-based o-carboranyl compound and intriguing ‘turn-on’ emissive variation

S. H. Lee, M. S. Mun, M. Kim, J. H. Lee, H. Hwang, W. Lee and K. M. Lee, RSC Adv., 2021, 11, 24057 DOI: 10.1039/D1RA03716A

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements