Synthesis and Photoluminescence of Tetracyanidonitridorhenium(V) Complexes with Five-Membered N-Heteroaromatic Ligands and Photoluminescence-Intensity Change

Moe Seike; Kojiro Nagata; Hayato Ikeda; Akitaka Ito; Eri Sakuda; Noboru Kitamura; Atsushi Shinohara; Takashi Yoshimura

doi:10.1021/acsomega.9b02749

Synthesis and Photoluminescence of Tetracyanidonitridorhenium(V) Complexes with Five-Membered N-Heteroaromatic Ligands and Photoluminescence-Intensity Change

ACS Omega. 2019 Nov 4;4(25):21251-21259. doi: 10.1021/acsomega.9b02749. eCollection 2019 Dec 17.

Authors

Moe Seike¹, Kojiro Nagata², Hayato Ikeda¹, Akitaka Ito³, Eri Sakuda⁴, Noboru Kitamura⁵, Atsushi Shinohara^{1

6}, Takashi Yoshimura^{2

6}

Affiliations

¹ Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan.
² Radioisotope Research Center, Institute for Radiation Sciences, Osaka University, Suita 565-0871, Japan.
³ Major of Molecular Design, School of Environmental Science and Engineering, Kochi University of Technology, Kochi 782-8502, Japan.
⁴ Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan.
⁵ Department of Chemical Sciences and Engineering, Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan.
⁶ Project Research Center for Fundamental Sciences, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan.

Abstract

Novel tetracyanidonitridorhenium(V) complexes with five-membered N-heteroaromatic ligands, (PPh₄)₂[ReN(CN)₄L] [L = imidazole (Him) (2), 1-methylimidazole (Mim) (3), and pyrazole (pyz) (4)] and (PPh₄)₂[ReN(CN)₄L]·L [L = Him (5) and Mim (6)], were synthesized by the reactions of (PPh₄)₂[ReN(CN)₄] (1) with Him, Mim, and pyz, and their structures were determined by single-crystal X-ray analysis. The complexes 2, 3, 4, and 6 showed intense photoluminescence, with the emission quantum yields (Φ_em) being 0.65-0.75 in the solid state at 296 K. In contrast, the Φ_em and τ_em values of 5 are significantly smaller and shorter, respectively, than the relevant values of 2. The interconversion reactions among 1, 2, and 5 accompanied by large photoluminescence-intensity changes were accomplished by solvent-free reactions and exposure of water. The mechanochemical reaction of 2 with 1 mol equiv of Him in the solid state gave 5. Complex 5 was also obtained by the mechanochemical reaction of 1 with 2 mol equivalents of Him in the solid state. By placing solid of 5 in water, the solid showed intense photoluminescence to give 2. Complex 1 was produced under vacuum at 185 °C from 2 or 5.