Akio Yoneda

Synthesis and Crystallochromy of 1,4,7,10‐Tetraalkyltetracenes: Tuning of Solid‐State Optical Properties of Tetracenes by Alkyl Side‐Chain Length

We synthesized a series of 1,4,7,10-tetraalkyltetracenes using a new 2,6-naphthodiyne precursor and 2,5-dialkylfurans as starting materials (alkyl=methyl to hexyl). Surprisingly, the solid-state color of the tetracenes ranges through yellow, orange, and red. Both yellow and red solids are obtained for the butyl derivative. Optical properties in solution show no marked differences; however, those in the solid state show characteristics that vary with alkyl side-chain length: methyl, propyl, and pentyl derivatives are orange; ethyl and butyl derivatives are yellow; and another butyl and hexyl derivative are red. X-ray analyses reveal that the molecular structures are planar, semi-chair, or chair forms; the chair form takes a herringbone-like arrangement and the other forms take slipped parallel arrangements. The mechanism of crystallochromy is discussed in terms of molecular structure, crystal packing, and calculations that take account of exciton coupling.

Conformational polymorphism and optical properties in the solid state of 1,4,7,10-tetra(n-butyl)tetracene

Two conformational polymorphs of 1,4,7,10-tetra(n-butyl)tetracene showed different characteristics of molecular structure, packing arrangement and optical properties in the solid state.

Influence of Alkyl Chain Length on the Solid-State Packing and Fluorescence of 1,4,5,8-Tetra(alkyl)anthracenes

1,4,5,8-Tetra(alkyl)anthracenes (alkyl = methyl, ethyl, n-propyl, and n-hexyl) were prepared by a sequence of reactions of 1,2,4,5-tetrabromobenzene and 2,5-dialkylfurans in the presence of n-BuLi, hydrogenation, and treatment with acid. The influence of alkyl chain length on the packing patterns in the crystals and the fluorescent properties in the solid state was investigated. X-ray analysis revealed that the molecular structures can be classified into plane, semi-chair, and chair forms and that the packing patterns can be categorized into two-dimensional (herringbone) and one-dimensional (slipped-parallel) arrangements, in both of which there is no π–π stacking. In the case of the methyl, ethyl, and n-propyl derivatives, the wave shapes of the fluorescence spectra in the solid state resemble each other; on the other hand, the n-hexyl derivative displayed a slightly red-shifted and broader spectrum. The absolute quantum yield depended on the transition dipole moments because of the packing patterns and crystal rigidity. The n-propyl derivative demonstrated the highest quantum yield of Φf = 0.85 among the tetra(alkyl)anthracenes.

Silver and thallium(I) complexation with dibenzo-16-crown-4

Dibenzo-16-crown-4 (1) indicates high silver and thallium(I) ion selectivity over sodium, potassium, and rubidium ion evaluated from the solvent extraction of metal picrates, while its cation-binding ability is lower than those of dibenzo-18-crown-6 (2) and dibenzo-22-crown-6 (3). Taking account of the highest thallium(I) ion selectivity for 1 obtained from extraction experiments, PVC membrane thallium(I)-selective electrodes based on 1 are prepared. The electrode shows the best potentiometric selectivity coefficients for thallium(I) over potassium and rubidium than those of 2 and 3, and commercially available bis(crown ether)s (4).

Synthesis and properties of a new ethyne-linked donor/acceptor pentamer

Abstract A new alternating π-donor/π-acceptor pentamer with ethyne linkage was synthesized by a bi-directional method using Sonogashira reactions. The pentamer showed small HOMO–LUMO gap compared with other π-conjugated oligomers.

Synthesis and Photoinduced Alignment of Photo-Cross-Linkable Copolymer Liquid Crystals Containing Tolane Side Groups

ABSTRACT Methacrylate copolymer liquid crystals (CPLCs) comprising photo-cross-linkable 4-(4′-methoxycinnamoyloxy)biphenyl (4MCB) side groups and 4-cyano- or 4-methyltolane side groups were synthesized. Thermally enhanced molecular reorientation behavior of CPLC films was investigated by irradiating with linearly polarized ultraviolet (LPUV) light and subsequent annealing. The exposure to LPUV light generated an axis-selective photoreaction of the 4MCB groups for all CPLC films. Thermally enhanced cooperative in-plane reorientation was observed for CPLC copolymerized with a 4-methoxytolane side groups and the generated birefringence was 0.25. However, out-of-plane reorientation was predominant when a comonomer with a 4-cyanotolane group was copolymerized.

Synthesis of 2-(substituted methyl)quinolin-8-ols and their complexation with Sn(II)

A new method for the synthesis of 2-(substituted methyl)quinolin-8-ol is described. 2-Methyl-8-methoxyquinoline 3 was prepared as a key building block; lithiation of 3 with LDA and subsequent addition of alkyl halides followed by reaction in 48% HBr afforded the 2-alkylquinolin-8-ols 6a,b. On the other hand, the use of alkanediyl dihalides as the electrophile gave bis(quinolin-8-ol) derivatives containing an alkyl bridge 12. The complexation of 2-alkyl-8-hydroxyquinolines with SnCl2 in alkaline methanol produced the bis(quinolin-8-ol) complexes 13a,b, whereas in the case of the bis(quinolin-8-ol) derivatives, intractable solids were obtained. The molecular structure of 13b was elucidated by X-ray analysis.

Synthesis and crystal structure of 4,7-bis (2-thienylethynyl)-2,1,3-benzothiadiazole

4,7-Bis(2-thienylethynyl)-2,1,3-benzothiadiazole was prepared by Sonogashira coupling. The crystal structure showed that one thiophene ring is coplanar and the other is perpendicular to the benzothiadiazole ring.

Synthesis and crystal structure of 2,2'-dimethyl-8,8'- biquinolyl

2,2′-Dimethyl-8,8′-biquinolyl was prepared by homo-coupling and its structure was first elucidated by X-ray analysis.

2,3-Dimeth­oxy-5,12-tetra­cenequinone

The molecule of the title compound, C20H14O4, is approximately planar [maximum deviation 0.168 (2) Å]. The two methoxy groups are slightly twisted relative to the plane of the 5,12-tetracenequinone system, with twist angles of 3.3 (3) and 5.6 (2)°. All O atoms are involved in intermolecular C—H⋯O interactions and the molecules are arranged into slipped face-to-face stacks along the b axis via π–π interactions with an interplanar distance of 3.407 (2) Å.