Search

The elaboration of multichromophoric system which can undergo a reversible transformation over more than two different states can be easily performed by the covalent assembly of several identical switching subunits around a central node. However, the selective addressability of each of them still represents a challenging task. This study reports on the elaboration of multichromophoric systems incorporating three identical indolino-oxazolidine (BOX) moieties as multimodal addressable units. Depending of the open/closed oxazolidine ring status of each of them, these systems can be interconverted between four different states in stepwise manner by using indifferently acid addition or electrochemical stimulation. More important, we have demonstrated by using a dissymmetric triarylamine node that the classical statistical BOX opening is broken then reaching a regioselective addressability. The switching of the three identical BOX units differentiated by their π conjugated junction to the central core follows a preferential order leading to the preponderant and successive formation of only four forms over the eight theoretically and equally expected. To provide limitations and outlooks for such strategy, their switching capacities have been rationalized by DFT calculations.

The development of molecular switches such as photochromic and electrochromic systems still represents a major concern in numerous application fields. If numerous pure organic switch families have been explored so far, concerning the coordination compounds, the choice seems more limited. In this context, we are exploring the possibility to elaborate a new addressable ligand family based on benzazolo-oxazolidine (BOX) moiety, a poorly investigated switch family, known for its acido-, electro- and photochromism properties. As proof of concept, two ligands bearing a BOX moiety were prepared using a pyridine as metal binding site after what corresponding Zn(II) complexes were synthesized and characterized. The acido-, electro- and photochemical behaviors of the free ligand as well as complexes were studied. This study reveals a subtle and interesting tautomeric equilibrium between oxazolidine ring opening and pyridine protonation whatever the nature of the stimulation. More interestingly, it conducts to observe the possibility to catch and release zinc ion on demand by using two external and orthogonal stimulations.