Photophysical and anion sensing properties of a triphenylamine-dioxaborinine trimeric compound

Herein, we report the synthesis and photophysical characterization of the novel tris(4-(2,2-difluoro-6-methyl-2H-1 lambda(3),3,2 lambda(4)-dioxaborinin-4-yl)phenyl)amine trimeric probe (A2) via the reaction between triphenylamine (1), acetic anhydride, and BF3 & BULL;OEt2 implying the twelve new bond formation in a one-pot manner. This highly fluorescent compound in solution (phi up to 0.91 at 572 nm) and solid state (phi = 0.24 at 571 nm) showed a better solvatofluorochromism than its analog monomeric A1 due to symmetry-broken charge transfer, which is consistent with high solvent dipolarity (SdP) response in Catalan's multiparametric regression. Notably, A2 had a high sensibility and selectivity for CN- or F- in solution (LODCN-/F- = 0.18/0.70 mu M), and CN- can be discriminated from F- by the reaction of A2 with 3.0 equiv. of CN-. In addition, A2 was impregnated on filter paper to prepare test strips that were applied to naked-eye qualitative sensing of CN- or F-. Finally, the octupolar system in A2 allows for better action of two-photon excitation cross-section values when compared with that of the dipolar structure in A1. These findings provide further information for the design of new efficient two-photon absorption dyes.

Automated summary

In this study, a novel tris(4-(2,2-difluoro-6-methyl-2H-1 lambda(3),3,2 lambda(4)-dioxaborinin-4-yl)phenyl)amine trimeric probe (A2) was synthesized via a one-pot reaction, demonstrating twelve new bond formations. A2 exhibited high fluorescence in solution (phi up to 0.91 at 572 nm) and solid state (phi = 0.24 at 571 nm), with better solvatofluorochromism compared to its analog monomeric A1. Additionally, A2 showed high sensitivity and selectivity for CN- or F- in solution and could differentiate between CN- and F- through a reaction with CN-. Moreover, A2 was utilized in test strips for naked-eye qualitative sensing of CN- or F-, and its octupolar structure allowed for better two-photon excitation cross-section values compared to the dipolar structure of A1. These findings contribute to the design of efficient two-photon absorption dyes.