Red and Near-Infrared Photoluminescence of D‑π-A-Type Compounds Based on a 1,4-Diaryl-1-thio-1,3-butadiene Conjugated System in a Dibenzobarrelene Skeleton

1,4-Diaryl-1-thio-1,3-butadiene derivatives having a π-donor dimethylamino group and several π-acceptor substituents at both terminals of the conjugated system were synthesized by intramolecular [4 + 2] cycloaddition of 1-thio-enynes and subsequent chemical transformations. They displayed largely red-shifted absorption and emission spectra in solution, the powder state, and in polymer films. The derivatives with a 2,2-dicyanoethenyl group as the π-acceptor exhibited inverted solvatochromism in both optical absorption and fluorescence spectroscopies

Red and Near-Infrared Photoluminescence of D‑π-A-Type Compounds Based on a 1,4-Diaryl-1-thio-1,3-butadiene Conjugated System in a Dibenzobarrelene Skeleton

1,4-Diaryl-1-thio-1,3-butadiene derivatives having a π-donor dimethylamino group and several π-acceptor substituents at both terminals of the conjugated system were synthesized by intramolecular [4 + 2] cycloaddition of 1-thio-enynes and subsequent chemical transformations. They displayed largely red-shifted absorption and emission spectra in solution, the powder state, and in polymer films. The derivatives with a 2,2-dicyanoethenyl group as the π-acceptor exhibited inverted solvatochromism in both optical absorption and fluorescence spectroscopies

Fluorescent 3-Methylene-2,3-Dihydrochalcogenophenes Incorporated in a Rigid Dibenzobarrelene Skeleton

The fluorescent 3-methylene-2,3-dihydroselenophene derivative (Φ_F = 0.86 in CH₂Cl₂) incorporated in a dibenzobarrelene skeleton was synthesized by the reaction of a four-membered selenaplatinacycle with dimethyl acetylenedicarboxylate (DMAD) or reaction of bis(dibenzobarrelenyl) diselenide with DMAD in the presence of Pd(PPh₃)₄ and PPh₃. A fluorescent sulfur homologue (Φ_F = 1.0 in CH₂Cl₂) was also synthesized by the reaction of bis(dibenzobarrelenyl) disulfide with DMAD in the presence of Pd(PPh₃)₄. Selected chemical transformations of these diesters were also investigated

Synthesis of 4‑Chalcogeno-1-aza-1,3-butadiene Derivatives by Intramolecular Cyano-Diels–Alder Reaction and Borane-Coordination-Induced Fluorescence Enhancement

4-Thio-1-aza-1,3-butadiene derivatives <b>3</b> incorporating a rigid dibenzobarrelene skeleton were synthesized by the intramolecular cyano-Diels–Alder reaction of 9-anthryl cyanoethenyl sulfides <b>6</b>. The thermal reaction of <b>6</b> afforded an equilibrium mixture of <b>3</b> and <b>6</b>, but the cyclization was effectively promoted by the addition of BF₃·Et₂O or B­(C₆F₅)₃ to yield imine–borane adducts <b>8</b> and <b>9</b>. The imine–borane adducts emit intense blue fluorescence both in solution and in the crystalline state. This is in stark contrast to free imines <b>3</b>, which are weakly fluorescent. Selenium analogue <b>4</b> and <i>N</i>-oxide <b>12</b> of <b>3a</b> were synthesized, along with their B­(C₆F₅)₃ adducts

Fluorescent 3-Methylene-2,3-Dihydrochalcogenophenes Incorporated in a Rigid Dibenzobarrelene Skeleton

The fluorescent 3-methylene-2,3-dihydroselenophene derivative (Φ_F = 0.86 in CH₂Cl₂) incorporated in a dibenzobarrelene skeleton was synthesized by the reaction of a four-membered selenaplatinacycle with dimethyl acetylenedicarboxylate (DMAD) or reaction of bis(dibenzobarrelenyl) diselenide with DMAD in the presence of Pd(PPh₃)₄ and PPh₃. A fluorescent sulfur homologue (Φ_F = 1.0 in CH₂Cl₂) was also synthesized by the reaction of bis(dibenzobarrelenyl) disulfide with DMAD in the presence of Pd(PPh₃)₄. Selected chemical transformations of these diesters were also investigated

Synthesis, Structures, and Temperature-Dependent Photoluminescence of 1,4-Diphenyl-1-telluro-1,3-butadiene Incorporated in a Dibenzobarrelene Skeleton and Derivatives

1,4-Diphenyl-1-telluro-1,3-butadiene incorporated in a dibenzobarrelene skeleton was synthesized with a good yield by an intramolecular Diels–Alder reaction of the corresponding 1-(9-anthyltelluro)­enyne. Oxidation and bromination of the telluride yielded telluroxide and hypervalent <i>Te</i>,<i>Te</i>-dibromide, respectively. Their structures were determined by X-ray crystallography. Unlike its highly fluorescent sulfur and selenium congeners, the telluride is barely fluorescent in solution at room temperature due to the heavy-atom effect of tellurium. The telluride displayed temperature-dependent fluorescence; it is fluorescent with a moderate quantum yield (Φ_PL = 0.42) in the glass of 2-methyltetrahydrofuran at 77 K

Neutral Methyl and Cationic Aluminum Complexes Supported by a <i>trans</i>-1,2-Cyclooctanediyl-Bridged [OSSO]-Type Bis(phenolato) Ligand: Synthesis, Structures, and Use in Catalysis for Propylene Oxide Polymerization

Treatment of <i>trans</i>-1,2-cyclooctanediyl-bridged [OSSO]-type bis­(phenolate) <b>1</b> with Me₃Al in hexane led to the formation of methylaluminum <b>4</b> as colorless crystals. X-ray diffraction analysis of <b>4</b> revealed that the aluminum center adopts a distorted-trigonal-bipyramidal geometry which occupies the axial positions with one phenoxide oxygen and one sulfur atoms. The dealkylation reaction of <b>4</b> with 1 equiv of B­(C₆F₅)₃ in C₆D₆ afforded the novel cationic aluminum species <b>5</b>²⁺ as a dimeric structure, which was isolated in the form of a [MeB­(C₆F₅)₃]⁻ salt. In the crystal structure of <b>5</b>²⁺, one aluminum atom has a distorted-trigonal-bipyramidal environment, in which phenoxide and μ-bridging oxygen atoms are located at two axial positions, whereas the other aluminum atom has a distorted-square-pyramidal geometry, which occupies the axial position with a nonbridged oxygen atom. The cationic species <b>5</b>²⁺ promoted the ring-opening polymerization (ROP) of propylene oxide to give an atactic polymer in 44% yield with a low molecular weight (<i>M</i>_n = 2500) and a very narrow molecular weight distribution (PDI = 1.04)

Fluorescent 3-Methylene-2,3-Dihydrochalcogenophenes Incorporated in a Rigid Dibenzobarrelene Skeleton

The fluorescent 3-methylene-2,3-dihydroselenophene derivative (Φ_F = 0.86 in CH₂Cl₂) incorporated in a dibenzobarrelene skeleton was synthesized by the reaction of a four-membered selenaplatinacycle with dimethyl acetylenedicarboxylate (DMAD) or reaction of bis(dibenzobarrelenyl) diselenide with DMAD in the presence of Pd(PPh₃)₄ and PPh₃. A fluorescent sulfur homologue (Φ_F = 1.0 in CH₂Cl₂) was also synthesized by the reaction of bis(dibenzobarrelenyl) disulfide with DMAD in the presence of Pd(PPh₃)₄. Selected chemical transformations of these diesters were also investigated

Synthesis of 4‑Chalcogeno-1-aza-1,3-butadiene Derivatives by Intramolecular Cyano-Diels–Alder Reaction and Borane-Coordination-Induced Fluorescence Enhancement

4-Thio-1-aza-1,3-butadiene derivatives <b>3</b> incorporating a rigid dibenzobarrelene skeleton were synthesized by the intramolecular cyano-Diels–Alder reaction of 9-anthryl cyanoethenyl sulfides <b>6</b>. The thermal reaction of <b>6</b> afforded an equilibrium mixture of <b>3</b> and <b>6</b>, but the cyclization was effectively promoted by the addition of BF₃·Et₂O or B­(C₆F₅)₃ to yield imine–borane adducts <b>8</b> and <b>9</b>. The imine–borane adducts emit intense blue fluorescence both in solution and in the crystalline state. This is in stark contrast to free imines <b>3</b>, which are weakly fluorescent. Selenium analogue <b>4</b> and <i>N</i>-oxide <b>12</b> of <b>3a</b> were synthesized, along with their B­(C₆F₅)₃ adducts

Synthesis, Structures, and Temperature-Dependent Photoluminescence of 1,4-Diphenyl-1-telluro-1,3-butadiene Incorporated in a Dibenzobarrelene Skeleton and Derivatives

1,4-Diphenyl-1-telluro-1,3-butadiene incorporated in a dibenzobarrelene skeleton was synthesized with a good yield by an intramolecular Diels–Alder reaction of the corresponding 1-(9-anthyltelluro)­enyne. Oxidation and bromination of the telluride yielded telluroxide and hypervalent <i>Te</i>,<i>Te</i>-dibromide, respectively. Their structures were determined by X-ray crystallography. Unlike its highly fluorescent sulfur and selenium congeners, the telluride is barely fluorescent in solution at room temperature due to the heavy-atom effect of tellurium. The telluride displayed temperature-dependent fluorescence; it is fluorescent with a moderate quantum yield (Φ_PL = 0.42) in the glass of 2-methyltetrahydrofuran at 77 K