title: Configurational and constitutional information storage: multiple dynamics in systems based on pyridyl and acyl hydrazones.
abstract: The C=N group of hydrazones can undergo E/Z isomerization both photochemically and thermally, allowing the generation of a closed process that can be tuned by either of these two physical stimuli. On the other hand, hydrazine-exchange reactions enable a constitutional change in a given hydrazone. The two classes of processes: 1) configurational (physically stimulated) and 2) constitutional (chemically stimulated) give access to short-term and long-term information storage, respectively. Such transformations are reported herein for two hydrazones (bis-pyridyl hydrazone and 2-pyridinecarboxaldehyde phenylhydrazone) that undergo a closed, chemically or physically driven process, and, in addition, can be locked or unlocked at will by metal-ion coordination or removal. These features also extend to acyl hydrazones derived from 2-pyridinecarboxaldehyde. Similarly to the terpydine-like hydrazones, such acyl hydrazones can undergo both constitutional and configurational changes, as well as metal-ion coordination. All these types of hydrazones represent dynamic systems capable of acting as multiple state molecular devices, in which the presence of coordination sites furthermore allows the metal ion-controlled locking and unlocking of the interconversion of the different states.
authors.affiliation: Laboratoire de Chimie Supramoléculaire, ISIS, Université de Strasbourg, 8 Allée Gaspard Monge, 67000 Strasbourg, France.
authors.forename: Manuel N
authors.initials: MN
authors.lastname: Chaur
authors.forename: Daniel
authors.initials: D
authors.lastname: Collado
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Lehn