ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe osmium-catalyzed asymmetric dihydroxylation: a new ligand class and process improvementK. Barry Sharpless, Willi Amberg, Youssef L. Bennani, Gerard A. Crispino, Jens Hartung, Kyu Sung Jeong, Hoi Lun Kwong, Kouhei Morikawa, Zhi Min Wang, Cite this: J. Org. Chem. 1992, 57, 10, 2768–2771Publication Date (Print):May 1, 1992Publication History Published online1 May 2002Published inissue 1...

Shift work: The identity of an anion complexed to indole-based macrocycles can be determined by the NMR chemical shift NH protons (see picture). difference in shifts arises from a strength hydrogen-bonding interactions between and anions.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTImproved enantioselectivity in asymmetric dihydroxylations of terminal olefins using pyrimidine ligandsGerard A. Crispino, Kyu Sung Jeong, Hartmuth C. Kolb, Zhi Min Wang, Daqiang Xu, and K. Barry SharplessCite this: J. Org. Chem. 1993, 58, 15, 3785–3786Publication Date (Print):July 1, 1993Publication History Published online1 May 2002Published inissue 1 July...

As a new type of foldamers, oligoindoles containing 4, 6, and 8 indole rings were synthesized, their folding properties characterized by combination 1H NMR techniques UV/visible titration experiments. When chloride was added, the NH signals downfield shifted as result hydrogen-bond formation, aromatic upfield stacking between two indoles. Moreover, ROESY experiment provided definitive NOE evidence for helical in presence chloride. Finally, experiments demonstrated that formed 1:1 complexes...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular recognition with convergent functional groups. VI. Synthetic and structural studies a model receptor for nucleic acid componentsBen Askew, Pablo Ballester, Chris Buhr, Kyu Sung Jeong, Sharon Jones, Kevin Parris, Williams, Julius Rebek Jr.Cite this: J. Am. Chem. Soc. 1989, 111, 3, 1082–1090Publication Date (Print):February 1, 1989Publication History Published online1 May 2002Published inissue 1 February...

Chiral indolocarbazole dimers fold into a helical conformation by virtue of intramolecular hydrogen bonds, as demonstrated (1)H NMR and CD spectra optical rotations. In particular, the properties were found to be extremely sensitive nature solvent, depending on whether they are folded or not. The sense can reversibly switched binding sulfate ion, which gives rise complete inversion spectra. mode absolute stereochemistry complexes was unequivocally determined single-crystal X-ray structures,...

A series of indolocarbazole-based foldamers have been prepared which can fold into a helical array with an internal cavity encircled by multiple indole NHs, thus allowing for binding anions hydrogen bonds. The folding has confirmed computer modeling, 1H NMR spectroscopy, 2D ROESY experiments, and studies. water-soluble derivative binds small, hydrophilic in the order Cl− > F− Br− but negligibly large, diffuse such as I− ClO4−. Interestingly, relative affinities fluoride chloride ions water...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConvergent functional groups. X. Molecular recognition of neutral substratesK. S. Jeong, T. Tjivikua, A. Muehldorf, G. Deslongchamps, M. Famulok, and J. Rebek Jr.Cite this: Am. Chem. Soc. 1991, 113, 1, 201–209Publication Date (Print):January 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.org/doi/10.1021/ja00001a029https://doi.org/10.1021/ja00001a029research-articleACS PublicationsRequest reuse...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSyntheses and crystal structures of the cinchona alkaloid derivatives used as ligands in osmium-catalyzed asymmetric dihydroxylation olefinsWilli Amberg, Youssef L. Bennani, Raj K. Chadha, Gerard A. Crispino, William D. Davis, Jens Hartung, Kyu Sung Jeong, Yasukazu Ogino, Tomoyuki Shibata, Barry SharplessCite this: J. Org. Chem. 1993, 58, 4, 844–849Publication Date (Print):February 1, 1993Publication History Published online1 May 2002Published...

Azobenzene-based chloride transporters exhibit photoresponsive transport activities across lipid and plasma membranes.

Abstract The development of synthetic receptors capable selectively binding guests with diverse structures and multiple functional groups poses a significant challenge. Here, we present the efficient assembly foldamer-based for monosaccharides, utilising principles complexation-induced equilibrium shifting adaptive folding. Diimine 4 can be quantitatively assembled from smaller components when d -galactose is added as guest among monosaccharides examined. During this assembly, dual shifts...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular recognition with convergent functional groups. VII. Energetics of adenine binding model receptorsKevin Williams, Ben Askew, Pablo Ballester, Chris Buhr, Kyu Sung Jeong, Sharon Jones, and Julius Rebek Jr.Cite this: J. Am. Chem. Soc. 1989, 111, 3, 1090–1094Publication Date (Print):February 1, 1989Publication History Published online1 May 2002Published inissue 1 February...

Hydrogen bonding to anions drives the helical folding of an indolocarbazole oligomer, thus resulting in internal cavity with six NHs and two OHs for binding sulfate high selectivity.

Abstract A series of oligoindole foldamers 1 a – d that are highly fluorescent were prepared by using biindole derivative as the repeating unit, and their folding anion‐binding properties revealed H NMR fluorescence spectroscopy. The oligoindoles exist in an extended conformation, but adopt compact helical structure presence anion. anion is entrapped inside tubular cavity strand, comprising four aryl units per turn, multiple hydrogen bonds with indole NHs. These structural features confirmed...

A series of indolocarbazole-pyridine (IP) oligomers were prepared that fold into helical conformations, and their folding features in solution the solid state revealed. Helical these IP foldamers is induced by dipolar interactions through ethynyl bond π-stacking between two repeating units. Upon folding, (1)H NMR signals aromatic protons significantly shifted upfield Δδ = 0.5-2.2 ppm. In addition, hypochromic shifts fluorescence quenching observed absorption emission spectra. X-ray crystal...

Adopting the concept of procarrier for first time, we demonstrated controlled transport chloride ions across lipid and cellular membranes. Procarriers containing highly hydrophilic appendages were initially inactive due to lack their partitioning into lipophilic membranes but activated in presence specific enzymes that able hydrolyze off generate an active carrier under conditions. Namely, with ester-bond-linked appendage was most by esterase (PLE) at pH = 7.4, whereas a glycosyl-bond-linked...

Electronic and structural properties of energetically low-lying isomers isolated TixOy (x = 1-6, y 1-12) molecular systems have been investigated by density functional theoretical methods. A variety stationary points are thoroughly characterized. We report total cluster energies, equilibrium geometries harmonic vibrational wavenumbers.

Oligoindole-based chiral foldamers have been synthesized by incorporating (S)- or (R)-1-phenylethylamine to both ends of the tetraindole scaffold. The oligoindoles fold into a helical conformation upon binding an anion hydrogen bonds, which gives rise induced circular dichroism (CD) signal large amplitude, implying preferential formation one isomer over another. Theoretical calculations suggest that (P)-helix (S,S)-oligoindole 8a be more energetically stable than corresponding (M)-helix.

A colorimetric anion receptor based on an indole scaffold has been synthesized by incorporating azobenzene chromophore to the 5-position of indole. The binds anions hydrogen bonds which are effectively transmitted through resonance give rise color changes. cyanide ion induced a pronounced change from light yellow reddish orange, but less intense or negligible changes were observed with other examined here.