title: Twisted baskets.
abstract: A preparative procedure for obtaining a pair of twisted molecular baskets, each comprising a chiral framework with either right ((P)-1syn) or left ((M)-1syn) sense of twist and six ester groups at the rim has been developed and optimized. The racemic (P/M)-1syn can be obtained in three synthetic steps from accessible starting materials. The resolution of (P/M)-1syn is accomplished by its transesterification with (1R,2S,5R)-(-)-menthol in the presence of a Ti(IV) catalyst to give diastereomeric 8(P) and 8(M). It was found that dendritic-like cavitands 8(P) and 8(M), in CD2Cl2, undergo self-inclusion ((1)H NMR spectroscopy) with a menthol moiety occupying the cavity of each host. Importantly, the degree of inclusion of the menthol group was ((1)H NMR spectroscopy) found to be greater in the case of 8(P) than 8(M). Accordingly, it is suggested that different folding characteristic of 8(P) and 8(M) ought to affect the physicochemical characteristics of the hosts to permit their effective separation by column chromatography. The absolute configuration of 8(P)/8(M), encompassing right- and left-handed "cups", was determined with the exciton chirality method and also verified in silico (DFT: B3LYP/TZVP). Finally, the twisted baskets are strongly fluorescent due to three naphthalene chromophores, having a high fluorescence quantum yield within the rigid framework of 8(P)/8(M).
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue (USA).
authors.forename: Keith
authors.initials: K
authors.lastname: Hermann
authors.forename: Yaowalak
authors.initials: Y
authors.lastname: Pratumyot
authors.forename: Shane
authors.initials: S
authors.lastname: Polen
authors.forename: Alex M
authors.initials: AM
authors.lastname: Hardin
authors.forename: Erdin
authors.initials: E
authors.lastname: Dalkilic
authors.forename: Arif
authors.initials: A
authors.lastname: Dastan
authors.forename: Jovica D
authors.initials: JD
authors.lastname: Badjić
mesh_terms: D002384:Catalysis; D005453:Fluorescence; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry
chemical_list: D009281:Naphthalenes; D014025:Titanium
keywords: cavitands; encapsulation; host-guest systems; stereoselective recognition; supramolecular chirality