title: Terpy(Pt-salphen)2 switchable luminescent molecular tweezers.
abstract: The design and synthesis of switchable molecular tweezers based on a luminescent terpy(Pt-salphen)2 (1; terpy=terpyridine) complex is reported. Upon metal coordination, the tweezers can switch from an open "W"-shaped conformation to a closed "U"-shaped form that is adapted for selective recognition of cations. Closing of the tweezers by metal coordination (M=Zn(2+), Cu(2+), Pb(2+), Fe(2+), Hg(2+)) was monitored by (1)H NMR and/or UV/Vis titrations. During the titration, exclusive formation of the 1:1 complex [M(1)] was observed, without appearance of an intermediate 1:2 complex [M(1)2]. The crystallographic structure of the 1:1 complex was obtained with Pb(2+) and showed a distorted helical structure. Selective intercalation of Hg(2+) cations by the closed "U" form was observed. The tweezers were reopened by selective metal decoordination of the terpyridine ligand by using tris(2-aminoethyl)amine (tren) as a competitive ligand without modification of the Pt-salphen complex. Detailed photophysical studies were performed on the open and closed tweezers. Structured emission was observed in the open form from the Pt-salphen moieties, with a high quantum yield and a long lifetime. The emission is slightly modified upon closing with 1 equivalent of Zn(2+) or Hg(2+), whereas a dramatic quenching was obtained upon intercalation of additional Hg(2+).
authors.affiliation: Sorbonne Universités, UPMC Univ Paris 06, UMR 8232, Institut Parisien de Chimie Moléculaire, 4 place Jussieu, 75005, Paris (France), Fax: (+33) 1-44-27-38-41; CNRS, UMR 8232, Institut Parisien de Chimie Moléculaire, 4 place Jussieu, 75005, Paris (France).
authors.forename: Benjamin
authors.initials: B
authors.lastname: Doistau
authors.forename: Arnaud
authors.initials: A
authors.lastname: Tron
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Denisov
authors.forename: Gediminas
authors.initials: G
authors.lastname: Jonusauskas
authors.forename: Nathan D
authors.initials: ND
authors.lastname: McClenaghan
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Gontard
authors.forename: Valérie
authors.initials: V
authors.lastname: Marvaud
authors.forename: Bernold
authors.initials: B
authors.lastname: Hasenknopf
authors.forename: Guillaume
authors.initials: G
authors.lastname: Vives
keywords: cooperativity; molecular tweezers; phosphorescence; platinum; salphen