<i>trans</i>-Aminoboration across Internal Alkynes Catalyzed by B(C₆F₅)₃ for the Synthesis of Borylated Indoles

We report here a facile B­(C₆F₅)₃ catalyzed <i>trans</i>-aminoboration of internal alkynes, furnishing 3-position borylated indoles at ambient temperature. This reaction proceeds with the breaking of a B–N bond and the formation of N–C and B–C bonds to produce indole and derivatives in one step. It works well for various boron reagents and alkynyl-anilines. The borylated indoles can be further derivatized to give column stable organoboron compounds that can be used for future functionalization

Benzothiaoline Three-Coordinated Organoboron Compounds with a BN Bond: Dual Emission and Temperature-Dependent Excimer Fluorescence

A series of 2,2-disubstituted benzothiazoline-BMes₂ (Mes = mesityl) compounds containing a BN bond have been prepared and fully characterized. Their photophysical properties were investigated by UV–vis and fluorescence spectroscopy, which revealed the presence of solvent- and concentration-dependent dual emission. On the basis of the spectroscopic data, the dual emission was assigned to monomer and excimer fluorescence of the molecule, respectively. Experimental and TD-DFT computational data indicated that the purple-blue monomer emission of these compounds is mainly from an intramolecular charge transfer (CT) transition between the benzo-sulfur moiety and the boron center. The yellow-green excimer emission is attributed to intermolecular interactions involving the benzo-sulfur unit. Furthermore, the excimer emission maxima of all compounds were found to be sensitive to temperature, shifting to lower energy with decreasing temperature, which illustrates the potential for this class of compounds to be used as luminescent thermometers

Cascade Dehydrogenative Hydroboration for the Synthesis of Azaborabenzofulvenes

Tandem dehydrogenative hydroboration has been established to be highly effective in the synthesis of BN isosteres of benzofulvene and derivatives. The scope of this synthetic method is applicable to a variety of substrates. Spectroscopic and computational studies indicate that the new azaborabenzofulvenes have similar electronic properties as their carbonaceous analogues

Copper(I) Complexes Bearing 1,2-Phenyl-Bridged P^∧N, P^∧N^∧P, and N^∧P^∧N Chelate Ligands: Structures and Phosphorescence

With the aim to obtain new phosphorescent Cu­(I) compounds, several new 1,2-phenyl-bridged P^∧N, P^∧N^∧P, and N^∧P^∧N chelate ligands were designed and synthesized. These ligands were found to form complexes with Cu­(I) ion readily via either solution reactions or solid-state grinding process. The new Cu­(I) compounds based on this class of ligands display phosphorescence with emission color ranging from blue to red. The structure of the ligand and the nature of the N-heterocycle in the chelate ligands were found to have a significant impact on the phosphorescent properties of the Cu­(I) compounds

Chelation-Assisted Photoelimination of B,N-Heterocycles

Metal-chelation and internal H bonds have been found to greatly enhance the photoelimination quantum efficiency of B,N-heterocycles by 2 orders of magnitude. Green phosphorescent Pt­(II)-functionalized 1,2-azaborines have been achieved via photoelimination. A mechanistic pathway for the PE reaction has been established

Efficient and High Yield One-Pot Synthesis of Cyclometalated Platinum(II) β-Diketonates at Ambient Temperature

Cyclometalated Pt(II) β-diketonates are widely used as efficient luminescent materials but are typically prepared at high temperatures in low yields using excess reagents. A one-pot synthesis of these complexes is described employing stoichiometric reagents and short reaction times at ambient temperature, giving yields of up to 94%. The method is applicable to a broad range of substrates including N^∧C, P^∧C, and C^∧C chelate Pt(II) complexes and different β-diketonate ligands

Chelation-Assisted Photoelimination of B,N-Heterocycles

Metal-chelation and internal H bonds have been found to greatly enhance the photoelimination quantum efficiency of B,N-heterocycles by 2 orders of magnitude. Green phosphorescent Pt­(II)-functionalized 1,2-azaborines have been achieved via photoelimination. A mechanistic pathway for the PE reaction has been established

Influence of Extended Conjugation on Photophysical/Electronic Properties and Photoelimination of BN-Heterocycles

A 1,1-hydroboration reaction was used successfully to create brominated BN-heterocyclic compounds, which are amenable to Stille coupling reactions for the construction of new BN-heterocyclic compounds, including a new polymeric BN-heterocycle that has an extended π-conjugated backbone. The conjugated backbone of the new BN-heterocycles was found to have a great influence on the photophysical and electronic properties of this class of compounds. In addition, the photoelimination reactivity of the new BN-heterocycles was also found to be greatly dependent on the extent of the conjugated backbone. Several new 1,2,4-triazole-fused boranaphthalenes have been obtained successfully via photoelimination

Tuning the Colors of the Dark Isomers of Photochromic Boron Compounds with Fluoride Ions: Four-State Color Switching

Combining a three-coordinated boron (BMes₂) moiety with a four-coordinated photochromic organoboron unit leads to a series of new diboron compounds that undergo four-state reversible color switching in response to stimuli of light, heat, and fluoride ions. Thus, these hybrid diboron systems allow both convenient color tuning/switching of such photochromic systems, as well as visual fluoride sensing by color or fluorescent emission color change

Modulating the Photoisomerization of N,C-Chelate Organoboranes with Triplet Acceptors

Triplet acceptors such as naphthalene, pyrene, and anthracene have been found to be highly effective in controlling the photoisomerization efficiency of N,C-chelate boryl chromophores, establishing the involvement of a photoactive triplet state in the isomerization of this class of photochromic compounds