A high-throughput screening approach for simultaneous analysis and quantification of the percent conversion of up to 48 reactions has been developed using a thin-layer chromatography (TLC) imaging method. As a test-bed reaction, we monitored 48 thiol conjugate additions to a Meldrum's acid derivative () in parallel using TLC. The TLC elutions were imaged using a cell phone and a LEGO brick-constructed UV/vis light box.
View Article and Find Full Text PDFThree water-soluble N-alkyl ammonium resorcinarene chlorides decorated with terminal hydroxyl groups at the lower rims were synthesized and characterized. The receptors were decorated at the upper rim with either terminal hydroxyl, rigid cyclohexyl, or flexible benzyl groups. The binding affinities of these receptors toward three viologen derivatives, two of which possess an acetylmethyl group attached to one of the pyridine nitrogens, in water were investigated via H NMR spectroscopy, fluorescence spectroscopy, and isothermal titration calorimetry (ITC).
View Article and Find Full Text PDFN-Alkyl ammonium resorcinarene chlorides, stabilized by an intricate array of hydrogen bonds leading to a cavitand-like structure, bind amides. The molecular recognition occurs through intermolecular hydrogen bonds between the carbonyl oxygen and the amide hydrogen of the guests and the cation-anion circular hydrogen-bonded seam of the hosts, as well as through CH⋅⋅⋅π interactions. The N-alkyl ammonium resorcinarene chlorides cooperatively bind a series of di-acetamides of varying spacer lengths ranging from three to seven carbons.
View Article and Find Full Text PDFThe use of reversible covalent-bonding in a four-component assembly incorporating chiral alcohols was recently reported to give a method for determining the enantiomeric excess of the alcohols via CD spectroscopy. Experiments that probe the mechanism of this assembly, which consists of 2-formylpyridine (), dipicolylamine (), Zn(II), and alcohols, to yield zinc-complexes of tren-like ligands, are presented. The studies focus upon the mechanism of conversion of a hemi-aminal () to a hemi-aminal ether (), thereby incorporating the fourth component.
View Article and Find Full Text PDFCONSPECTUS: The advent of high-throughput screening (HTS) for chiral catalysts has encouraged the development of fast methods for determining enantiomeric excess (ee). Traditionally, chromatographic methods such as chiral HPLC have been used for ee determination in HTS. These methods, however, are not optimal because of high duty cycle.
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