Β-substituted Sulfones Research Articles

Synthesis and spectroscopic study of phenylene–(poly)ethynylenes substituted by amino or amino/cyano groups at terminal(s): electronic effect of cyano group on charge-transfer excitation of acetylenic π-systems

To gain insight into substituent electronic effect on charge-transfer excitation of acetylenic π-systems, phenylene–(poly)ethynylenes substituted by Ph 2N or Ph 2N/cyano groups were synthesized by combination of Sonogashira coupling and double elimination protocol of β-substituted sulfones. These substituted phenyleneethynylenes showed large molar absorption coefficients ɛ, and emitted strong fluorescence upon UV light irradiation. Phenylene–(poly)ethynylenes, which involve butadiyne or hexatriyne motifs, emitted fluorescence in remarkably lower fluorescence quantum yields Φ F as their polyethynylene motifs –(C C) n – expanded. The drastic decrease of fluorescence quantum yields Φ F were explained in terms of increasing nonradiative reaction rate constants k nr, which had been determined by the corresponding fluorescence quantum yields Φ F and lifetime values τ. The emission underwent a large bathochromic shift in polar solvents because the charge-separated excited state is more stabilized than the ground state. Comparison of slope values ρ in Lippert/Mataga plot for the Ph 2N and Ph 2N/cyano-substituted phenylene–(poly)ethynylenes revealed that the latter underwent large change of dipole moments upon photo-excitation although highly expanded acetylenic π-systems with cyano group did little.

Synthesis and spectroscopic study of diphenylamino-substituted phenylene-(poly)ethynylenes: remarkable effect of acetylenic conjugation modes

A series of diphenylamino-substituted phenylene-(poly)ethynylenes were successfully synthesized by a combination of Sonogashira coupling and double elimination protocol of β-substituted sulfones. When UV-light was irradiated, the amino-substituted phenylene-(poly)ethynylene emitted strong luminescence. The emission underwent a large bathochromic shift in polar solvent because of stabilization of their charge-separated excited states. Analyses of fluorescence life times of aminoacetylenes revealed that radiationless process was suppressed in the polar solvent CH 2Cl 2, resulting in high quantum yields.

Blue emitting fluorophores of phenyleneethynylenes substituted by diphenylethenyl terminal groups for organic light-emitting diodes

Phenyleneethynylene motifs substituted by diphenylethenyl groups at both ends were prepared successfully by use of double elimination protocol of β-substituted sulfones for introducing phenyleneethynylene arrays followed by Wittig–Horner reaction for introducing diphenylethenyl moiety. The hybrid blue fluorophores exhibited strong emission even in the solid-state films ( Φ F ≧ 0.60) while, in CHCl 3 solution, incorporation of substituents on the central phenylene unit significantly enhanced emission efficiency up to Φ F = 0.57. The OLED devices with use of these blue fluorophores as an emitting material provided maximum external quantum efficiency of η ext = 2.4%.

Double Elimination Protocol for the Synthesis of Arylene Ethynylenes Containing Heteroaromatic Rings.

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Double elimination protocol for aryleneethynylenes

A variety of aryleneethynylenes are synthesized by double elimination reaction of β-substituted sulfones. The acetylenic bond is formed from readily available aromatic aldehydes and benzylic sulfones. A sequence of aldol reaction, trapping of the aldolates with a leaving group, and eliminations proceeds in one pot. The utility of this protocol is exemplified by synthesis of dihalo diphenylacetylenes, 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene, and double-helical aromatic acetylenes.

Double elimination protocol for the synthesis of arylene ethynylenes containing heteroaromatic rings

The double elimination reaction of β-substituted sulfones offers a versatile strategy for synthesis of arylene ethynylene kits containing heteroaromatic rings. A sequence of aldol reaction between α-sulfonyl carbanion and aldehyde, trapping the resulting aldolate to give β-substituted sulfone, and double elimination of this intermediate can be integrated in one pot. This protocol allows thiophene, pyridine, and ferrocene units to be accommodated in phenylene ethynylene arrays.Key words: arylene–ethynylenes, heteroaromatic rings, ferrocene, double elimination, sulfones.

Double Elimination Protocol for Access to Pyridine‐Containing Arylene‐Ethynylenes.

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Double Elimination Protocol for Access to Pyridine-Containing Arylene–Ethynylenes

Abstract The arylene–ethynylene arrays involving pyridine were constructed successfully by taking advantage of double elimination reaction of β-substituted sulfones (sulfoximines) which are easily accessible from arylmethyl sulfones (sulfoximines) and aromatic aldehydes. This protocol was utilized for synthesis of an enantiopure arylene–ethynylene framework bearing a binaphthyl stereogenic core.

Double Elimination Protocol for Convenient Synthesis of Dihalodiphenylacetylenes: Versatile Building Blocks for Tailor‐Made Phenylene‐Ethynylenes

AbstractDihalodiphenylacetylenes are conveniently synthesized by a double elimination reaction of β‐substituted sulfones which are readily obtained from halogen‐substituted benzyl sulfone and benzaldehyde derivatives. Halogens can be incorporated at any desired positions in the diphenylacetylene skeleton simply by choosing the substitution position of the halogen on the aromatic rings of the starting compounds. The diphenylacetylenes with different halogen substituents thus obtained undergo sequential carbon‐carbon bond formations due to the different reactivities of the halogens. Thus, various moieties can be incorporated on the diphenylacetylene skeleton at whichever positions so that a variety of tailor‐made phenylene‐ethynylenes with regulated structure and composition could be designed.

High Birefringent Bisdiynes and Hexatriynes Based on Double Elimination of β-Substituted Sulfones

Abstract In order to realize high birefringence, acetylenes with long molecular size such as bis(phenyldiynyl)benzenes 1 and diphenylhexatriynes 4 are synthesized successfully on the basis of double elimination of the β-substituted sulfones which can be prepared easily by reaction of benzyl or propargyl sulfones with propynal derivatives.