title: A monomer-dimer nanoswitch that mimics the working principle of the SARS-CoV 3CLpro enzyme controls copper-catalysed cyclopropanation.
abstract: A triangular framework with a terpyridine and shielded phenanthroline at its termini constitutes an open/close nanoswitch that is toggled by chemical inputs. In the presence of copper(I) ions, the open triangular framework (OPEN-I) firmly closes to a catalytically inactive heteroleptic [Cu(phen)(terpy)](+) complex (CLOSE). Reversible switching between CLOSE and OPEN-I states was demonstrated by successive addition and removal of Cu(+). In contrast, after addition of iron(II) ions to the CLOSE state a bishomoleptic dimeric [Fe(terpy)2](2+) complex is formed with the copper(I) ions placed in the phenanthroline cavities (OPEN-II). Due to its coordinatively unsaturated [Cu(Phen)](+) sites the dimeric iron complex is able to serve as a catalyst in the cyclopropanation of Z-cyclooctene using ethyl diazoacetate.
authors.affiliation: Center of Micro and Nanochemistry and Engineering, Organische Chemie I, Universität Siegen, Adolf-Reichwein-Str. 2, D-57068 Siegen, Germany. schmittel@chemie.uni-siegen.de.
authors.forename: Soumen
authors.initials: S
authors.lastname: De
authors.forename: Susnata
authors.initials: S
authors.lastname: Pramanik
authors.forename: Michael
authors.initials: M
authors.lastname: Schmittel
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D000086782:Coronavirus 3C Proteases; D003521:Cyclopropanes / Q000737:chemistry*; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D010618:Phenanthrolines / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: D003521:Cyclopropanes; D010618:Phenanthrolines; D011725:Pyridines; D003300:Copper; C030797:cyclopropane; D007501:Iron; D003546:Cysteine Endopeptidases; D000086782:Coronavirus 3C Proteases