Quinonoid Metal Complexes:  Toward Molecular Switches

Abstract

The peculiar redox-active character of quinonoid metal complexes makes them extremely appealing to design materials of potential technological interest. We show here how the tuning of the properties of these systems can be pursued by using appropriate molecular synthetic techniques. In particular, we focus our attention on metal polyoxolene complexes exhibiting intramolecular electron transfer processes involving either the ligand and the metal ion or the two dioxolene moieties of a properly designed ligand thus inducing electronic bistability. The transition between the two metastable electronic states can be induced by different external stimuli such as temperature, pressure, light, or pH suggesting the use of these systems for molecular switches.

Valence‐Tautomeric Metal–Organic Nanoparticles

“…[9,10] Inspired by this last approach, here we show how using the appropriate multitopic organic ligand makes it possible to structure well-known functional building blocks in the form of spherical particles. Polymerization of electroactive {Co(3,5-dbsq)(3,5-dbcat)} units, [14] where 3,5-dbsq À and 3,5-dbcat 2À are respectively the semiquinonate radical and catecholate forms of 3,5-di-tert-butyl-1,2-benzoquinone (dbq), with the ligand 1,4-bis(imidazol-1-ylmethyl)benzene (bix) [15,16] Since each electronic isomer has a different magnetic moment and optical properties, these complexes are candidates for use in future molecular electronic devices and switches, [17,18] and therefore serve as an excellent model system to create the first functional NMOPs that exhibit valence tautomerism.In a typical experiment, an aqueous solution of Co(CH 3 COO) 2 ·4 H 2 O was added to an ethanolic solution of 3,5-di-tert-butyl-1,2-catechol and bix with vigorous stirring at room temperature, and a very intense blue color developed. Blue nanoparticles were precipitated by fast addition of water to the mixture.…”

Molekulare Nanomagnete als Testobjekte für die Quantenmechanik

“…[13] Die am häu-figsten untersuchten schaltbaren Magnete sind Spincrossover-, [57][58][59][60] Polycyanometallat- [61][62][63] und Metalldioxolenkomplexe, welche Redoxisomerie zeigen. [64][65][66][67][68] Zu den attraktiven Besonderheiten dieser Systeme zählen die Mçglichkeit einer optisch induzierten Umwandlung zwischen verschiedenen magnetischen Zuständen unterschiedlicher Leitfähigkeiten sowie die Mçglichkeit zur Untersuchung des Stark-Effekts. [17] Cobaltdioxolenkomplexe unterliegen Redoxisomerisierung durch einen intermolekularen Elektronentransfer zwischen dem Liganden und dem Metallion (Abbildung 3 …”

Crystal Structure and Magnetic Properties of a novel Fe(II) complex with 2,2′:6′2′′-Terpyridine Ligand

“…In order to control SCO behavior, external stimuli such as thermal stimulus, irradiation, pressure, or guest molecules are normally used. [1][2][3][4][5][6][7][8][9] SCO compounds have attracted much attention, not only from the viewpoint of basic science, but also for their practical applications, because such bistable compounds may be used for future memory and switching devices. Because of this, a large number of SCO complexes have been developed since the first spin transition phenomenon was observed by Cambi and Szego in 1931.…”