title: Vernier-templated synthesis, crystal structure, and supramolecular chemistry of a 12-porphyrin nanoring.
abstract: Vernier templating exploits a mismatch between the number of binding sites in a template and a reactant to direct the formation of a product that is large enough to bind several template units. Here, we present a detailed study of the Vernier-templated synthesis of a 12-porphyrin nanoring. NMR and small-angle X-ray scattering (SAXS) analyses show that Vernier complexes are formed as intermediates in the cyclo-oligomerization reaction. UV/Vis/NIR titrations show that the three-component assembly of the 12-porphyrin nanoring figure-of-eight template complex displays high allosteric cooperativity and chelate cooperativity. This nanoring-template 1:2 complex is among the largest synthetic molecules to have been characterized by single-crystal analysis. It crystallizes as a racemate, with an angle of 27° between the planes of the two template units. The crystal structure reveals many unexpected intramolecular C-H⋅⋅⋅N contacts involving the tert-butyl side chains. Scanning tunneling microscopy (STM) experiments show that molecules of the 12-porphyrin template complex can remain intact on the gold surface, although the majority of the material unfolds into the free nanoring during electrospray deposition.
authors.affiliation: Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, OX1 3TA (UK).
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Kondratuk
authors.forename: Johannes K
authors.initials: JK
authors.lastname: Sprafke
authors.forename: Melanie C
authors.initials: MC
authors.lastname: O'Sullivan
authors.forename: Luis M A
authors.initials: LM
authors.lastname: Perdigao
authors.forename: Alex
authors.initials: A
authors.lastname: Saywell
authors.forename: Marc
authors.initials: M
authors.lastname: Malfois
authors.forename: James N
authors.initials: JN
authors.lastname: O'Shea
authors.forename: Peter H
authors.initials: PH
authors.lastname: Beton
authors.forename: Amber L
authors.initials: AL
authors.lastname: Thompson
authors.forename: Harry L
authors.initials: HL
authors.lastname: Anderson
keywords: conjugation; macrocycles; porphyrinoids; supramolecular chemistry; template synthesis