title: Factors Affecting the Formation of 2:1 Host:Guest Inclusion Complexes of 2-[(R-Phenyl)amine]-1,4-naphthalenediones (PAN) in β- and γ-Cyclodextrins.
abstract: The molecular hosts cyclodextrins form inclusion complexes with a wide variety of guests, resulting in complexes with various host:guest stoichiometries. In the case of a series of 19 1,4-naphthoquinolines as guests with either β- or γ-cyclodextrin studied using electrospray mass spectroscopy, in most cases only 1:1 complexes were observed, with 2:1 host:guest complexes observed in just 6 out of 38 host:guest combinations. It is shown that these higher-order complexes were observed only in the case of small (or no) electronically withdrawing substituents, and were much less likely in the case of the larger γ-cyclodextrin host. The size and electronic properties of the substituents involved shows that both steric and electronic factors must be taken into account in predicting which cyclodextrin host:guest stoichiometries will be stable enough to form (or once formed, be robust enough to be observed in the ESI-MS experiments). It is clear that the prediction of host-guest stoichiometry for a specific host-guest pair is complicated, and involves a subtle interplay of both electronic and steric factors. However, there are definite trends, which can be used to help predict host:guest stoichiometry for a given host-guest pair.
authors.affiliation: Département de Chimie et Biochimie, Université de Moncton, Moncton, NB E1A 3E9, Canada. krzysztof.jankowski@umoncton.ca.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Jankowski
authors.affiliation: Département de Chimie et Biochimie, Université de Moncton, Moncton, NB E1A 3E9, Canada. christine.lamouroux@areva.com.
authors.forename: Christine
authors.initials: C
authors.lastname: Lamouroux
authors.affiliation: Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, México D.F. 04510, Mexico. manueljemex@gmail.com.
authors.forename: Manuel
authors.initials: M
authors.lastname: Jiménez-Estrada
authors.affiliation: Département de Chimie et Biochimie, Université de Moncton, Moncton, NB E1A 3E9, Canada. sebastien.arseneau@hotmail.com.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Arseneau
authors.affiliation: Department of Chemistry, University of Prince Edward Island, Charlottetown, PEI C1A 4P3, Canada. bwagner@upei.ca.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Wagner
mesh_terms: D008958:Models, Molecular; D015394:Molecular Structure; D009285:Naphthoquinones / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D047392:beta-Cyclodextrins / Q000737:chemistry*; D047408:gamma-Cyclodextrins / Q000737:chemistry*
chemical_list: D009285:Naphthoquinones; D047392:beta-Cyclodextrins; D047408:gamma-Cyclodextrins
keywords: ESI-MS; cyclodextrin inclusion complexes; cyclodextrins; host-guest inclusion; host-guest stoichiometry; molecular modeling