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Terpy(Pt–salphen) 2 Switchable Luminescent Molecular Tweezers
Author(s) -
Doistau Benjamin,
Tron Arnaud,
Denisov Sergey A.,
Jonusauskas Gediminas,
McClenaghan Nathan D.,
Gontard Geoffrey,
Marvaud Valérie,
Hasenknopf Bernold,
Vives Guillaume
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201404064
Subject(s) - terpyridine , molecular tweezers , tweezers , intercalation (chemistry) , chemistry , crystallography , ligand (biochemistry) , metal , luminescence , heteronuclear molecule , supramolecular chemistry , quenching (fluorescence) , stereochemistry , crystal structure , materials science , nuclear magnetic resonance spectroscopy , fluorescence , inorganic chemistry , organic chemistry , biochemistry , receptor , optoelectronics , quantum mechanics , physics
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+ .