Synthesis of Benzofuro- and Indolo[3,2‑<i>b</i>]indoles via Palladium-Catalyzed Double <i>N</i>‑Arylation and Their Physical Properties

Two kinds of ladder-type π-conjugated compounds, benzofuro­[3,2-<i>b</i>]­indoles (BFIs) and indolo­[3,2-<i>b</i>]­indoles (IIs), were successfully synthesized using palladium-catalyzed double <i>N</i>-arylation of anilines with the corresponding dihalobiaryls. Photophysical properties were evaluated by UV–vis and photoluminescence spectroscopies and theoretical calculations. BFI derivatives showed higher quantum yields (33–39%) than the II derivative (29%). The absorption bands of the II derivative were more red-shifted compared to BFI derivatives

Circularly Polarized Luminescence from Chiral Spiro Molecules: Synthesis and Optical Properties of 10,10′-Spirobi(indeno[1,2‑<i>b</i>][1]benzothiophene) Derivatives

Chiral spiro polycyclic aromatic compounds with thiophene and/or thiophene <i>S</i>,<i>S</i>-dioxide units were synthesized as a new family of circularly polarized luminescence (CPL) materials. Oxidation of the thiophene unit to its <i>S</i>,<i>S</i>-dioxide provided significant changes in photophysical properties such as much higher fluorescence quantum yield and positive solvatochromism in photoluminescence spectra. Density functional theory calculations qualitatively demonstrated the observed absorption properties. The prepared chiral spiro compounds exhibit intense CPL signals with a relatively large dissymmetry factor for small organic molecules

Circularly Polarized Luminescence from Chiral Spiro Molecules: Synthesis and Optical Properties of 10,10′-Spirobi(indeno[1,2‑<i>b</i>][1]benzothiophene) Derivatives

Chiral spiro polycyclic aromatic compounds with thiophene and/or thiophene <i>S</i>,<i>S</i>-dioxide units were synthesized as a new family of circularly polarized luminescence (CPL) materials. Oxidation of the thiophene unit to its <i>S</i>,<i>S</i>-dioxide provided significant changes in photophysical properties such as much higher fluorescence quantum yield and positive solvatochromism in photoluminescence spectra. Density functional theory calculations qualitatively demonstrated the observed absorption properties. The prepared chiral spiro compounds exhibit intense CPL signals with a relatively large dissymmetry factor for small organic molecules

Synthesis and Properties of Benzophospholo[3,2‑<i>b</i>]benzofuran Derivatives

Benzophospholo­[3,2-<i>b</i>]­benzofuran (BPBF) derivatives were studied as a new family of phosphole-containing π-conjugated organic materials. The versatile reactivity of the trivalent phosphorus center of the parent BPBF offered access to a variety of derivatives by simple chemical modifications. The diversity-oriented synthetic route was also developed to allow facile access to BPBFs with a different substituent on the phosphorus center. Photophysical properties were revealed based on UV–vis and photoluminescence spectroscopies and theoretical calculation. The characteristic property of BPBF derivatives is highly efficient photoluminescence. In particular, phosphole oxide derivatives demonstrated intense blue fluorescence with high quantum yield over 85% even in the solid state

Copolymerization of Epoxides with Carbon Dioxide Catalyzed by Iron–Corrole Complexes: Synthesis of a Crystalline Copolymer

Iron–corrole complexes were found to copolymerize epoxides with CO₂. The first iron-catalyzed propylene oxide/CO₂ copolymerization has been accomplished. Moreover, the glycidyl phenyl ether (GPE)/CO₂ copolymerization with this catalyst provided a crystalline material as a result of the isotactic poly­(GPE) moiety

Facile Estimation of Catalytic Activity and Selectivities in Copolymerization of Propylene Oxide with Carbon Dioxide Mediated by Metal Complexes with Planar Tetradentate Ligand

Mechanistic studies were conducted to estimate (1) catalytic activity for PPC, (2) PPC/CPC selectivity, and (3) PPC/PPO selectivity for the metal-catalyzed copolymerization of propylene oxide with carbon dioxide [PPC: poly­(propylene carbonate); CPC = cyclic propylene carbonate; PPO: poly­(propylene oxide)]. Density functional theory (DFT) studies demonstrated that the Δ<i>G</i>_crb – Δ<i>G</i>_epx value should be an effective indicator for the catalytic activities [Δ<i>G</i>_epx: dissociation energy of ethylene oxide from the epoxide-coordinating metal complex; Δ<i>G</i>_crb: dissociation energy of methyl carbonate from the metal–carbonate complex]. In addition, metal complexes with a subthreshold Δ<i>G</i>_epx value were found to show low PPC/CPC selectivity. The PPC/PPO selectivity was related to the Δ<i>G</i>_alk – Δ<i>G</i>_epx value and steric environment around the metal center (Δ<i>G</i>_alk: dissociation energy of alkoxide ligand from the metal center). Based on the mechanistic studies, two metal complexes were designed and applied to the copolymerization to support validity of these indicators. The results presented here should be useful for brand-new catalyst candidates since these indicators can be easily calculated by DFT method without computing transition states

Synthesis and Properties of [7]Helicene-like Compounds Fused with a Fluorene Unit

[7]­Helicene-like compounds with a fluorene unit were successfully synthesized using a platinum-catalyzed double cyclization reaction. Crystal structures and photophysical properties of these compounds were also studied. In particular, they were found to exhibit a high fluorescence quantum yield and a relatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminescence (CPL) for small molecules

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Facile Synthetic Route to Highly Luminescent Sila[7]helicene

A facile synthetic route to dimethylsila[7]helicene by using a Lewis acid catalyzed double-cyclization reaction for construction of the twisted two phenanthrene moieties is described. Sila[7]helicene exhibited a high fluorescence quantum yield and a realatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminencence (CPL) for small molecules

Facile Synthetic Route to Highly Luminescent Sila[7]helicene

A facile synthetic route to dimethylsila[7]helicene by using a Lewis acid catalyzed double-cyclization reaction for construction of the twisted two phenanthrene moieties is described. Sila[7]helicene exhibited a high fluorescence quantum yield and a realatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminencence (CPL) for small molecules