Stimuli-Responsive -Conjugated Polymers Showing Solid-State Emission Based on Boron-Fused Azomethine Complexes with NNO-Tridentate Ligands

We report stimuli-responsive luminescent -conjugated polymers involving the boron-fused azomethine (BAm) structure with the NNO-tridentate ligands and demonstrate their application to film-type sensors. The acid-responsive properties of the polymers are provided by the free lone-pair electrons of the nitrogen atom on the BAm unit. The polymer films showed red shifts in emission wavelengths under acid vapor, and the responses were reversible and corresponded to deprotonation. Furthermore, owing to environmental sensitivity in the film state, unique luminescent color changes were observed. The bilayer films of the BAm polymer coated by poly(n-butyl methacrylate) exhibited vapochromic luminescence with gradual blue shifts (orange → yellow → green) by vapor annealing with chloroform depending on the exposure time. We demonstrated that these changes were applicable for evaluating solvent-vapor permeability of target membranes. This study shows that nitrogen substitution into existing organic compounds is effective for creating stimuli-responsive materials

Facile Preparation of Near Infrared-Luminescent Protein Complexes with Conjugated Polymers Consisting of Boron Azobenzene Units

We report herein facile preparation of near infrared (NIR)-luminescent protein complexes with conjugated polymers. We have discovered that solid-state luminescence in the NIR region can be obtained from the series of conjugated polymers consisting of boron azobenzene complexes. We demonstrate in this paper that protein molecules can be modified through adsorption with the boron azobenzene-containing conjugated polymers simply by mixing in an aqueous buffer and subsequently purification with filtration followed by freeze drying. The modified protein complexes can exhibit NIR emission in the buffer and high dispersibility. In particular, comparing to the complex with indocyanine green (ICG), which is a conventional NIR-luminescent dye, polymer-modified protein complexes showed higher resistance to photobleaching. Finally, by using lipase as a scaffold, we confirmed that enzymatic activity can be detected after polymer modification

Selective modulation of energy levels of frontier orbitals in solid-state luminescent boron-fused azomethine polymers with orthogonal orientations to the main chains

The development of polymers with film luminescence and property tuning is still a relevant topic due to concentration quenching which most of the organic luminophores suffer from. Based on boron-fused azomethine (BAm) complexes which can show aggregation-induced emission (AIE) and crystallization-induced emission (CIE), we previously obtained solid-state luminescent polymers. In this study, we synthesized π-conjugated polymers involving BAms orthogonally oriented to the main chains. In particular, the synthesized polymers have quite different properties from parallell-oriented BAm-consisting π-conjugated polymers that have been previously reported. The synthesized polymers can show intense luminescence in solutions and films. Moreover, we found that the energy levels of one of the frontier molecular orbitals (FMOs) can be selectively perturbed depending on the ligand structure. Furthermore, by selecting condensed reagents in the azomethine bond formation reaction, the monomer structure followed by the perturbed FMO can be determined. Finally, we observed that the synthesized polymers exhibit steady emission in both solutions and films in the near-infrared (NIR) region (λPL = 686 nm, ΦPL = 4% in solution, λPL = 709 nm, and ΦPL = 3% in film). Computer calculations support these experimental data. In this study, a new series of solid-state luminescent π-conjugated polymers with tunable energy levels is demonstrated

Stimuli-Responsive -Conjugated Polymers Showing Solid-State Emission Based on Boron-Fused Azomethine Complexes with NNO-Tridentate Ligands

We report stimuli-responsive luminescent -conjugated polymers involving the boron-fused azomethine (BAm) structure with the NNO-tridentate ligands and demonstrate their application to film-type sensors. The acid-responsive properties of the polymers are provided by the free lone-pair electrons of the nitrogen atom on the BAm unit. The polymer films showed red shifts in emission wavelengths under acid vapor, and the responses were reversible and corresponded to deprotonation. Furthermore, owing to environmental sensitivity in the film state, unique luminescent color changes were observed. The bilayer films of the BAm polymer coated by poly(n-butyl methacrylate) exhibited vapochromic luminescence with gradual blue shifts (orange → yellow → green) by vapor annealing with chloroform depending on the exposure time. We demonstrated that these changes were applicable for evaluating solvent-vapor permeability of target membranes. This study shows that nitrogen substitution into existing organic compounds is effective for creating stimuli-responsive materials

Facile Preparation of Near Infrared-Luminescent Protein Complexes with Conjugated Polymers Consisting of Boron Azobenzene Units

We report herein facile preparation of near infrared (NIR)-luminescent protein complexes with conjugated polymers. We have discovered that solid-state luminescence in the NIR region can be obtained from the series of conjugated polymers consisting of boron azobenzene complexes. We demonstrate in this paper that protein molecules can be modified through adsorption with the boron azobenzene-containing conjugated polymers simply by mixing in an aqueous buffer and subsequently purification with filtration followed by freeze drying. The modified protein complexes can exhibit NIR emission in the buffer and high dispersibility. In particular, comparing to the complex with indocyanine green (ICG), which is a conventional NIR-luminescent dye, polymer-modified protein complexes showed higher resistance to photobleaching. Finally, by using lipase as a scaffold, we confirmed that enzymatic activity can be detected after polymer modification