π-Conjugated molecules with electron-donating (D) and –accepting (A) groups such as D-π-A compounds have been focused on strong photo/electro-luminescent materials by means of intermolecular charge transfer (ICT). However, π-conjugated molecules cause concentration quenching due to π-π stacking in the aggregated state, and these compounds display the low solubility in organic solvents. On the other hand, the dissymmetric emission of right and left circularly polarized light from chiral luminophores, circular polarized luminescence (CPL), also received much attention because they have a potential use of 3D display devices. But well-known CPL materials such as lanthanide complexes often face several problems such as high cost, synthetic difficulty, and low solubility. Thus simple organic molecules displaying OLED and/or CPL with easy synthesis, emission as solid phase, high solubility, and low cost, are desired. To develop functional organic luminophores, we focused on the disilane-modified cyclophane skeleton, named tetrasila[2.2]paracyclophane. This molecule has planar-chirality from cyclophane-typed structure, and displays emissive properties from σ-π conjugation and high solubility derived from the suppression of intermolecular interaction by large SiMe2 moieties. Here we designed and synthesized a new class of symmetrical and unsymmetrical tetrasila[2.2]thiophenophanes. Conformational studies on the kinetics of the interconversion was investigated by X-ray diffraction and variable-temperature NMR experiments. Flipping motion could be controlled by the modification of aryls, the condition as solid phase, and the capture by host molecules. And unsymmetrical silathiophenophanes displayed blue-green ICT emission with higher quantum yield (Φ=49%). We also achieved optical resolution to prepare chiral compound, showing CPL properties with the acceptable dissymmetry factor for small organic molecules (|glum| = 1.7 × 10-3). Moreover, a green-emitting organic light-emitting diode (OLED) was fabricated, which showed an external quantum efficiency of 0.6%.

Synthesis and physical properties of tetrasila[2.2]thiophenophane derivatives for the luminescent and chiroptical materials

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.