Optically actuating ultra-stable radicals in a large π-conjugated ligand constructed photochromic complex

• Published in: Science China. Chemistry Vol. 64; no. 3; pp. 432 - 438
• Main Authors: Hu, Ji-Xiang, Jiang, Xiao-Fan, Ma, Yu-Juan, Liu, Xue-Ru, Ge, Bang-Di, Wang, A-Ni, Wei, Qi, Wang, Guo-Ming
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.03.2021; Springer Nature B.V
• Subjects: Antiferromagnetism; Bisphosphonates; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Couplings; Electron transfer; Electrons; Free radicals; Functional materials; Information storage; Ligands; Light; Light irradiation; Photochromism; Room temperature; π-conjugated ligands; photochromic; electron transfer; ultra-stable radicals; gigantic photodemagnetization
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-020-9891-4

Producing ultra-stabilized radicals via light irradiation has raised considerable concern but remains a tremendous challenge in functional materials. Herein, optically actuating ultra-stable radicals are discovered in a sterically encumbered and large π-conjugated tri(4-pyridyl)-1,3,5-triazine (TPT) ligands constructed photochromic compound Cu 3 (H-HEDP) 2 TPT 2 -2H 2 O ( QDU-12 ; HEDP=hydroxyethylidene diphosphonate). The photogeneration of TPT • radicals is the photoactive behavior of electron transfer from HEDP motifs to TPT units. The ultra-long-lived radicals are contributed from strong interchain π-π interactions between the large π-conjugated TPT components, with the radical lifetime maintained for about 18 months under ambient conditions. Moreover, the antiferromagnetic couplings between TPT • radicals and Cu 2+ ions plummeted the demagnetization to 35% of its original state after light irradiation, showing the largest room temperature photodemagnetization in the current radical-based photochromic materials.