Dual Photoswitching of a Diarylethene Ligand-Anchored Hofmann-Type Spin-Crossover Compound.

A diarylethene ligand-anchored two-dimensional Hofmann-type compound [Fe(BTEPy){Pt(CN)}](CHOH) (BTEPy = 1,2-bis[2-methyl-5-(4-pyridyl)-3-thienyl]cyclopentene) is synthesized, which undergoes a two-step spin-state transition and dual photoinduced magnetic switching.

Molecular Twist-Induced Single-Crystal Isomerization and Valence Tautomeric Transitions in a Cobalt-Dioxolene Complex.

A mononuclear valence tautomeric (VT) complex, [Co(pycz)(Sq)(Cat)] (1-trans), where pycz = 9-(pyridin-4-yl)-9H-carbazole, Sq⋅ = 3,5-di-tert-butyl-semiquinonato, and Cat = 3,5-di-tert-butyl-catecholato, is synthesized in the trans configuration, which undergoes one-step valence tautomeric transition above room temperature. Remarkably, 1-trans can transform into its isomeric structure, [Co(pycz)(Sq)(Sq)] (1-cis), at temperature above 350 K in a single-crystal-to-single-crystal way by in situ molecular twist, and the resulting 1-cis exhibits a pronounced two-step VT transition during magnetic measurements that is rare for mononuclear VT complexes. Such drastic solid-state structural transformation is reported in VT compounds for the first time, which is actuated by a crystal surface's melting-recrystallization induced phase transition process.