Takehiko Yamato

Blue-emitting butterfly-shaped 1,3,5,9-tetraarylpyrenes: synthesis, crystal structures, and photophysical properties.

The first example of aryl-functionalized, butterfly-shaped, highly fluorescent and stable blue-emitting monomers, namely, 7-tert-butyl-1,3,5,9-tetrakis(p-R-phenyl)pyrenes, were synthesized by the Suzuki-Miyaura cross-coupling reaction from a novel bromide precursor of 1,3,5,9-tetrabromo-7-tert-butylpyrene. The crystal structures and optical and electronic properties have been investigated.

Pyrene-based Y-shaped solid-state blue emitters: synthesis, characterization, and photoluminescence.

A series of pyrene-based Y-shaped blue emitters, namely, 7-tert-butyl-1,3-diarylpyrenes 4 were synthesized by the Suzuki cross-coupling reaction of 7-tert-butyl-1,3-dibromopyrene with a variety of p-substituted phenylboronic acids in good to excellent yields. These compounds were fully characterized by X-ray crystallography, UV/Vis absorption and fluorescence spectroscopy, DFT calculations, thermogravimetric analysis, and differential scanning calorimetry. Single-crystal X-ray analysis revealed that the Y-shaped arylpyrenes exhibited a low degree of π stacking owing to the steric effect of the bulky tert-butyl group in the pyrene ring at the 7-position, and thus, the intermolecular π-π interactions were effectively suppressed in the solid state. Despite the significantly twisted nonplanar structures, these molecules still displayed efficient intramolecular charge-transfer emissions with clear solvatochromic shifts on increasing solvent polarity. An intriguing fact is that all of these molecules show highly blue emissions with excellent quantum yields in the solid state. Additionally, the two compounds containing the strongest electron-accepting groups, CN (4 d) and CHO (4 f), possess high thermal stability, which, together with their excellent solid-state fluorescence efficiency, makes them promising potential blue emitters in organic light-emitting device applications.

Pyrene-cored blue-light emitting [4]helicenes: synthesis, crystal structures, and photophysical properties.

The synthesis, crystal structures and photophysical properties of two types of pyrene-cored blue-light emitting [4]helicenes (7 and 9) are reported. The chemical structures of all synthesized compounds were fully confirmed by 1H and 13C NMR spectra, mass spectroscopy as well as elemental analysis. Single-crystal X-ray analysis of these [4]helicenes revealed that there are two types of laterally naphthalene annulated helical architectures, which are clearly influenced by different R substituents. The photophysical properties of the [4]helicenes (7 and 9) were fully investigated in both solutions and films, along with the pre-cyclization products, 4,9- and 4,10-bis(phenylethenyl)pyrenes (6 and 8). Notable optical features were obtained in these compounds, which make them promising candidates for several important applications in modern electronic and optoelectronic devices, such as blue emitters in organic light-emitting devices (OLEDs), or as models for further exploring the development of a new generation of organic materials based on pyrene.

Synthesis, crystal structure and complexation behaviour of a thiacalix[4]arene bearing 1,2,3-triazole groups

The structure and complexation behaviour of 1,3-alternate-1,2,3-triazole based on thiacalix[4]arene,1,3-alternate-1 and 2 have been determined by means of X-ray analysis, fluorescence and 1H NMR spectroscopy. The X-ray results suggested that the nitrogen atom N3 on triazole ring can act as hydrogen bond acceptors in the self-assembly of a supramolecular structure. The fluorescence spectra changes indicated that the thiacalix[4]arene bearing 1,2,3-triazole groups were highly selective for Ag+ in comparison with other tested metal ions by enhancement of the monomer emission of pyrene. The 1H NMR results suggested that Ag+ can be strongly bonded by the triazole groups with the cooperation of the ionophoric cavity formed by the two inverted benzene rings and the sulfur atoms of the thiacalix[4]arene.

Synthesis and inclusion properties of C3-symmetric triazole derivatives based on hexahomotrioxacalix[3]arene

A series of metal ion receptors cone-7,15,23-tri-tert-butyl-25,26,27-tris{[1H-(1-arylmethyl)(1,2,3-triazolyl)]-4-methoxy}hexahomotrioxacalix[3]arenes, cone-3–cone-5, have been synthesized from 7,15,23-tri-tert-butyl-25,26,27-tris(propargyloxy)hexahomotrioxacalix[3]arene 2via click chemistry. The complexation properties of the receptors cone-3–cone-5 toward the selected binding of heavy metal and transition metal ions have been evaluated. The structure of cone-3 was elucidated by single-crystal X-ray crystallography.

Synthesis and Structure of 2,3-Bis(5-tert-butyl-2-methoxyphenyl)buta-1,3-diene by Bromine Elimination of (Z)-1,4-Dibromo-2,3-bis(5-tert-butyl-2-methoxyphenyl)-2-butene

Abstract 2,3-Bis(5-tert-butyl-2-methoxyphenyl)buta-1,3-diene was prepared by bromination of (Z)- and (E)-2,3-bis(5-tert-butyl-2-methoxyphenyl)-2-butene followed by treatment with zinc powder in a mixture of CH2Cl2 and acetic acid, which was converted to the corresponding o-terphenyl skeleton by the condensation with dimethyl acetylenedicarboxylate followed by oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone. GRAPHICAL ABSTRACT