title: 3- and 4-(α-diazobenzyl)pyridine-N-oxides as photoresponsive magnetic couplers for 2p-4f heterospin systems: formation of carbene-Tb(III) and carbene-Dy(III) single-molecule magnets.
abstract: 3- and 4-(α-diazophenyl)pyridine-N-oxides, and , were prepared as new photoresponsive magnetic couplers in heterospin systems. Lanthanide dinuclear complexes, [Ln(III)(tta)3()]2; Ln(III) = Gd (), Tb (), and Dy () and tta = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate, bridged with in μ2 coordination mode were obtained. The obtained , , and were isostructures. The isomeric complex, [Tb(III)(tta)3()]2 was also prepared. In the carbene-Ln(III) complexes [Ln(III)(tta)3( and )]2 generated by photolysis, regioselectively interacted with the Ln(III) ions through pyridine-N-oxide, in which the magnetic coupling of was weakly ferromagnetic, while that of was insignificant. Before and after irradiation of , no SMM behavior was observed. In contrast, the Tb(III) and Dy(III) complexes being anisotropic functioned as heterospin SMMs. Before irradiation, showed no SMM behavior. After irradiation, two species showing slow magnetic relaxations were produced and one of them exhibited SMM behavior with the thermal activation barrier, Ueff/kB = 30 K, and τ0 = 5.8 × 10(-8) s. In , SMM behaviors were observed before and after irradiation, and the Ueff/kB value of 102 K (τ0 = 3.6 × 10(-7) s) before irradiation was reduced to 39 K (τ0 = 1.5 × 10(-8) s) after irradiation.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan. koga@fc.phar.kyushu-u.ac.jp karasawa@fc.phar.kyushu-u.ac.jp.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Murashima
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan. koga@fc.phar.kyushu-u.ac.jp karasawa@fc.phar.kyushu-u.ac.jp and PRESTO, Japan Science and Technology Agency, Kawaguchi, 332-0012, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Karasawa
authors.affiliation: Bruker AXS K.K., Moriyacho, Kanagawa-ku, Yokohama, 221-0022, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Yoza
authors.affiliation: Department of Applied Quantum Physics, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 812-0395, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Inagaki
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan. koga@fc.phar.kyushu-u.ac.jp karasawa@fc.phar.kyushu-u.ac.jp.
authors.forename: Noboru
authors.initials: N
authors.lastname: Koga