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Vernier‐Templated Synthesis, Crystal Structure, and Supramolecular Chemistry of a 12‐Porphyrin Nanoring
Author(s) -
Kondratuk Dmitry V.,
Sprafke Johannes K.,
O'Sullivan Melanie C.,
Perdigao Luis M. A.,
Saywell Alex,
Malfois Marc,
O'Shea James N.,
Beton Peter H.,
Thompson Amber L.,
Anderson Harry L.
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.201403714
Subject(s) - nanoring , porphyrin , supramolecular chemistry , chemistry , crystallography , cooperativity , molecule , small angle x ray scattering , crystal structure , stereochemistry , materials science , nanotechnology , photochemistry , scattering , organic chemistry , biochemistry , physics , optics
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 CH⋅⋅⋅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.