Through-Space Charge-Transfer Emitting Biphenyls Containing a Boryl and an Amino Group at the o,o′-Positions

Abstract

A new class of organoboron compounds containing a boryl and an amino group at the o,o'-positions of biphenyls display bright through-space intramolecular charge transfer fluorescence owing to the close contact between the boryl and the amino groups. Binding of the fluoride ions results in the remarkable blue shift and color change of the fluorescence, enabling colorimetric and ratiometric fluoride ion sensing.

Triarylboranes with a 2‐Dimesitylboryl‐2’‐(N,N‐dimethylamino)biphenyl Core Unit: Structure–Property Correlations and Sensing Abilities to Discriminate Between F− and CN− Ions

“…The two benzene rings attached to the nitrogen and boron atoms are labeled as P1 and P2 and the benzene ring of one mesityl group is labeled as P3. With regard to the X‐ray crystal structure of 1 , the following three features are noted:15a 1) the biphenyl moiety is significantly twisted with a P1‐P2 torsion angle up to 70.7° due to the remarkable steric hindrance between the boryl and amino groups; 2) the boryl and amino groups are arranged on the same side of the biphenyl axis with a very close B⋅⋅⋅N distance (3.59 Å), despite the large steric congestion between them; 3) possible intramolecular π–π stacking interaction exists between benzene rings P1 and P3 (dihedral angle=27.4°, centroid–centroid distance=3.87 Å).…”

Recent developments in and perspectives on three-coordinate boron materials: a bright future

“…More recently, Zhao and co-workers reported a simpler compound exhibiting through-space ICT, with a dimesitylborane and a dimethylamine incorporated at the o , o ′-positions of a biphenyl framework 4 . 37 The Lambert group reported a hexaarylbenzene with three triarylamine donors and three triarylborane acceptors with weak donor–acceptor interactions due to through-space charge transfer. 38 Additionally, the excitation energy can be redistributed between the aryl substituents within the fluorescence lifetime.…”

Borylated Arylisoquinolines: Photophysical Properties and Switching Behavior of Promising Tunable Fluorophores

“…Alternatively, excited-state electron transfer from the fluoroboronateÀaryl residue to the isoquinoline part could be responsible for the quenching mechanism. [7,[21][22][23][24][25][26][27][28] DFT calculations (see the Supporting Information) of compound 9 showed that the HOMO was located on the anthryl moiety and that the LUMO involved the anthryl À Bpin part. [64] By taking a closer look at compound 2, it was obvious that the LUMO did not involve the isoquinoline group (as for the other naphthalene-derived compounds), but instead involved the vacant boron p p orbital.…”

“…This process is often accompanied by an "on-off" fluorescence switching. [16,17] Indeed, systems in which "off-on" fluorescence switching [18][19][20] or a ratiometric emission response [7,[21][22][23][24][25][26][27][28] are observed are of great interest for sensing purposes. Other designs have used the classical photoinduced electron-transfer approach, [29][30][31] by integrating electron-donating fluorophores with electron-accepting triarylboranes.…”