中村 一希

Circularly polarized luminescence (CPL) has significantly increased the interest in biological fields. In this research, a water-soluble Eu(iii) complex with a helical complex structure, EuLCOOH, was incorporated in chiral DNA in aqueous solutions. The photoluminescence performance of this DNA/EuLCOOH hybrid system was investigated. Compared to EuLCOOH alone, emission intensity and emission lifetime were effectively improved in the presence of DNA. The major binding between EuLCOOH and DNA was proven to be the electrostatic interaction. Owing to this interaction, the chiral environment provided by DNA successfully induced CPL from EuLCOOH

This study investigates the electrochemical modulation of luminescence color, i.e., electrofluorochromism, of an Eu complex in a polyether solvent. The electrofluorochromic (EFC) reaction of the Eu complex occurred via a reversible redox reaction between Eu3+ and Eu2+. Initially, the intrinsically stable Eu3+ complex showed intense red photoluminescence (PL) induced by f-f transitions. After the electrochemical reduction of Eu3+ to Eu2+, broad blue PL was observed attributed to the d-f transitions in the Eu2+ complex. This distinct blue luminescence from the Eu2+ complex was attributed to the effective stabilization of the Eu2+ state by the polyether solvent. The dynamic EFC reaction that changes the valence state of the Eu ion can be potentially applied to novel chemical sensors, security devices, and display devices.

We report the circularly polarized luminescence (CPL) for [Ru(bpy)3]I2 (1) and [Ru(bpy)3][M2(ox)3] (M = Zn (2), Mn (3)). Whereas compound 1 is a simple salt of [Ru(bpy)3]2+, 2 and 3 are MOFs in which the chiral [Ru(bpy)3]2+ ions are encapsulated in a homochiral gyroidal skeleton of [M2(ox)3]2-. Whereas the solution of 1 exhibited weak CPL with a luminescence dissymmetry factor of |glum| ∼ 10-4, the CPL was significantly enhanced in solid-state 1-3 with |glum| = 2 × 10-2 for 1, 4 × 10-2 for 2, and 1 × 10-1 for 3. The enhanced CPL in 3 was attributable to an energy transfer between the homochiral guest and host in 3.