Catalyst- and Template-Free Ultrafast Visible-Light-Triggered Dimerization of Vinylpyridine-Functionalized Tetraarylaminoborane: Intriguing Deep-Blue Delayed Fluorescence.

A photoredox-catalyst- and template-free sunlight-induced molecular dimerization of a vinylpyridine-functionalized tetraarylaminoborane (TAAB) has been accomplished for the first time. The reaction is quantitative, highly regioselective, and thermally irreversible. The presence of the propeller-shaped TAAB framework allows selective photodimerization of one of the two vinyl pyridine units. Monomer 1 and photodimer 2 exhibit distinct photophysical properties with delayed fluorescence (DF) both in solution and the solid state, which was confirmed by steady-state and time-resolved luminescence studies. Quantum mechanical calculations were performed to support the experimental observations. Our new approach using [2+2] cycloaddition chemistry paves the way for the development of highly sought-after deep-blue DF materials.

Borylated perylenediimide: self-assembly, photophysics and sensing application.

Triarylboryl appended perylenediimide (PDI-TAB) is designed and synthesized. The incorporation of triarylboranes (TABs) decreases self-aggregation and increases the solubility of PDI-TAB in common organic solvents. Fluorescence emission colors ranging from red, yellow and green are realized by judiciously modulating the concentration of PDI-TAB in solution. The morphology and dimensions of the self-assemblies formed by PDI-TAB can be controlled by changing the experimental conditions. For example, PDI-TAB forms fibers of finite length when bulk powder is dispersed in methanol; it shows flexible lengthy 1D fibers when dichloromethane solution of PDI-TAB is injected into methanol solvent. PXRD analysis indicates that the molecular organization remains the same in both cases. PDI-TAB functions as a selective fluorogenic sensor for toxic fluoride anions; the sensing mechanism is explained by using theoretical calculations.

Diarylboryl-phenothiazine based multifunctional molecular siblings.

Herein we report the multifunctional characteristics such as aggregation induced emission (AIE), triboluminescence (TL), mechanofluorochromism and temperature sensing of molecular siblings 1 (10-(dimesitylboryl)phenothiazine) and 2 (10-(bis(2,6-dimethylphenyl)boryl)phenothiazine).

Conformational Restrictions in meso-(2-Thiazolyl)-BODIPYs: Large Stokes Shift and pH-Dependent Optical Properties.

The design, synthesis, and characterization of a series of thiazole-appended boron-dipyrromethene (BODIPY) derivatives 1-4 is reported. The fluorescence emission colors of 1-4 were fine-tuned by modulating the dihedral angle between BODIPY and thiazole by judiciously varying the number of methyl substituents on both the BODIPY and thiazole moieties. Compounds 1 and 2 with fewer methyl substituents on the BODIPY core showed a large Stokes shift (≈110 nm) relative to derivatives 3 and 4 with more methyl substituents. In addition, the optical properties of 1 and 2 are sensitive to the pH of the medium. The experimentally observed results were corroborated with theoretical calculations.