title: Double level selection in a constitutional dynamic library of coordination driven supramolecular polygons.
abstract: A constitutional dynamic library (CDL) of Cu(II) metallo-supramolecular polygons has been studied as a bench test to examine an interesting selection case based on molecular recognition. Sorting of the CDL polygons is achieved through a proper guest that is hosted into the triangular metallo-macrocycle constituent. Two selection mechanisms are observed, a guest induced path and a guest templated self-assembly (virtual library approach). Remarkably, the triangular host can accommodate several guests with a degree of selectivity ranging from ∼1 to ∼10(4) for all possible guest pairs. A double level selection operates: guests drive the CDL toward the triangular polygon, and, at the same time, this is able to pick a specific guest from a set of competitive molecules, according to a selectivity-affinity correlation. Association constants of the host-guest systems have been determined. Guest competition and exchange studies have been analyzed through variable temperature UV-Vis absorption spectroscopy and single crystal X-ray diffraction studies. Molecular structures and electronic properties of the triangular polygon and of the host-guest systems also have been studied by means of all electrons density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations including dispersive contributions. DFT outcomes ultimately indicate the dispersive nature of the host-guest interactions, while TDDFT results allow a thorough assignment of the host and host-guests spectral features.
authors.affiliation: Department of Chemical Sciences and INSTM , University of Padova , via Marzolo 1, 35131 Padova, Italy.
authors.forename: Marzio
authors.initials: M
authors.lastname: Rancan
authors.forename: Jacopo
authors.initials: J
authors.lastname: Tessarolo
authors.forename: Maurizio
authors.initials: M
authors.lastname: Casarin
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Zanonato
authors.forename: Silvio
authors.initials: S
authors.lastname: Quici
authors.forename: Lidia
authors.initials: L
authors.lastname: Armelao