title: The Rich Tautomeric Behavior of Campestarenes.
abstract: Campestarenes are a new family of Schiff-base macrocycles that form selectively in a one-step synthesis. These macrocycles with five-fold symmetry show solvent-dependent tautomerization and dimerization or aggregation. In this paper, we have prepared new soluble campestarenes that do not aggregate. The initial single-crystal X-ray diffraction study of a campestarene reveals that these macrocycles are nearly flat. The tautomeric behavior of the campestarenes has been extensively studied by variable-temperature, multinuclear NMR spectroscopy, UV/Vis spectroscopy, and IR spectroscopy. In polar solvents, such as DMF, the molecules exist predominantly in their keto-enamine form, but the enol-imine tautomer is dominant in non-polar solvents. A detailed computational study of the tautomeric forms of campestarenes provides a theoretical basis for their behavior and corroborates the experimental data. The results of this study give the first comprehensive understanding of the electronic and spectroscopic properties of these pentagonal macrocycles.
authors: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
authors: Zhengyu
authors: Z
authors: Chen
authors: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
authors: Samuel
authors: http://orcid.org/0000-0002-7439-209X
authors: S
authors: Guieu
authors: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
authors: Nicholas G
authors: NG
authors: White
authors: La. M.I. and LaSSCAM INSTM Sezione Basilicata, Dipartimento di Chimica, Università della Basilicata, Via dell'Ateneo Lucano 10, 85100, Potenza, Italy.
authors: Francesco
authors: F
authors: Lelj
authors: Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
authors: Mark J
authors: http://orcid.org/0000-0002-3546-7132
authors: MJ
authors: MacLachlan
keywords: campestarenes; permittivity; solvent-dependent; tautomerization