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

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

Impact of a Picolinate Ancillary Ligand on Phosphorescence and Fluoride Sensing Properties of BMes₂‑Functionalized Platinum(II) Compounds

Two new dimesitylboron (BMes₂)-functionalized 2-phenylpyridine cyclometalated Pt­(II) complexes (<b>2</b> and <b>3</b>) with a picolinate or a methyl-picolinate as the ancillary ligand have been synthesized via a one-pot procedure at ambient conditions with high yields (>70%). The crystal structures of these Pt­(II) complexes were determined by single-crystal X-ray diffraction analysis, which revealed the presence of extended π-stacking interactions in the crystal lattice of <b>2</b> and discrete dimer formation in the lattice of <b>3</b>. Both complexes exhibit dual phosphorescence emission in solution at room temperature under N₂ atmosphere. These unusual photophysical properties have been systematically investigated by spectroscopic and computational studies, which established that the phosphorescent dual emission originates from admixture of ³LLCT and ³ILCT/³MLCT transitions. Fluoride titration experiments were conducted to further confirm the origin of phosphorescence in these compounds. The phosphorescent properties and the phosphorescent response toward fluoride ions by compounds <b>2</b> and <b>3</b> are distinctly different from the previously known BMes₂-functionalized N^∧C-chelate Pt­(II) compounds, which are attributed to the introduction of the low-lying π* orbital by the picolinate ancillary ligand in the Pt­(II) compounds

A Dual-Emissive Phosphine–Borane Lewis Pair with a U‑Shaped Linker: Impact of Methylation and Complexation on Fluoride Binding Affinity

To investigate phosphine to borane through-space charge transfer and its utility in anion sensing and the formation of metal complexes, a phosphine–borane Lewis pair (<b>1</b>) connected by a U-shaped linker has been synthesized. <b>1</b> could be readily converted to a phosphonium salt (<b>2</b>) and two 2:1 complexes with Au­(I) (<b>1-Au</b>) and Pt­(II) (<b>1-Pt</b>). The photophysical properties of the new compounds were examined and compared. Compound <b>1</b> displayed an intense P → B CT transition and a bright solvent-dependent dual emission that is switchable by fluoride ions. <b>2</b> and <b>1-Pt</b> showed a turn-off and a turn-on fluorescent response, respectively, toward fluoride ions. The binding constant of <b>2</b> with F^– was found to be 2 orders of magnitude greater than that of <b>1</b>. The mechanism that is responsible for the distinct fluorescence response of <b>1</b>, <b>2</b>, and <b>1-Pt</b> toward fluoride ions is proposed

Highly Efficient Dual-Color Electrochemiluminescence from BODIPY-Capped PbS Nanocrystals

Electrochemiluminescence (ECL) of a hybrid system consisting of PbS nanocrystals (NCs) and a BODIPY dye (BDY) capping ligand was discovered to produce highly efficient dual emissions with tri-<i>n</i>-propylamine as a coreactant. By means of spooling ECL spectroscopy, the strong dual ECL emission peaks of 984 and 680 nm were attributed to the PbS and BDY moieties, respectively, and found to be simultaneous during the light evolution and devolution. The ECL of the PbS was enhanced via NC collisions with the electrode and reached an efficiency of 96% relative to that of Ru­(bpy)₃²⁺, which is the highest among the semiconductor NCs

Effective Alkoxylation of Phosphorescent Heteroleptic Iridium(III) Compounds Bearing Fluorinated Bipyridine Ligands

Facile one-pot synthetic methods for new alkoxo-functionalized heteroleptic cyclometalated Ir­(III) compounds have been developed. Nucleophilic substitution of fluorine atoms in [(dfpypy)₂Ir­(μ-Cl)]₂ (dfpypy = 2′,6′-difluoro-2,3′-bipyridine) by a methoxyethanol in the presence of an ancillary ligand led to the formation of the new alkoxo-functionalized heteroleptic Ir­(III) compounds Ir­[(RO)₂pypy]₂(N^∧O) in good yields. These compounds have a distorted octahedral geometry around the Ir­(III) center with an <i>N,N-trans-meridional</i> configuration. They exhibit intense blue to yellow phosphorescence (λ_max = 453–558 nm) with moderate to excellent quautum efficiencies (0.22 to 0.96). Comparative studies on the fluoro analogues, Ir­(dfpypy)₂(N^∧O), were also carried out. Our investigation established that the substitution of a fluorine atom by an alkoxy chain can greatly improve the solubility of the compounds in common organic solvents without significantly altering the emission color and efficiencies, making alkoxy-functionalized Ir­(III) compounds potential candidates for use in solution-processable phosphorescence OLEDs