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Eric V Anslyn

Publications and source records attributed to Eric V Anslyn.

44 records · Page 3Linked to original sources
PubMed2003

Preorganized bis-zinc phosphodiester cleavage catalysts possessing natural ligands: a lesson pertinent to bimetallic artificial enzymes.

Two preorganized bis-zinc receptors (2 and 3) were synthesized wherein the metals were ligated with ligands present in natural phosphodiesterases: imidazoles and carboxylates. The intrametallic distance is near 4.5 A, that found in natural nucleases and other successful artificial nucleases. With only two imidazoles (2), the zinc binding affinities were not high enough to achieve cooperativity. Yet, with a third ligand, a carboxylate (3), cooperativity was found in the cleavage of HPNPP. The preorganization of 3 was achieved using a "steric gearing" strategy. The enhancement was 80-fold for cooperation between the two metals relative to a mono-metallic analogue (5). However, there was no observable enhancement in the hydrolysis of RNA using 3 relative to 5. Therefore, we conclude that placing two zinc atoms that are ligated with natural ligands at the appropriate distance for catalysis is not sufficient to enhance the cleavage of RNA, but is successful for activated RNA substrate mimics.

Biomimetic Materials↗
PubMed2003

A fluorescent sensor for 2,3-bisphosphoglycerate using a europium tetra-N-oxide bis-bipyridine complex for both binding and signaling purposes.

Host 1 was designed and synthesized as a fluorescent sensor for 2,3-bisphosphoglycerate (BPG, 3). The design features a tris-functionalized triethylbenzene core to preorganize binding groups. The three cationic moieties, a tetra-N-oxide bipyridine-europium complex and two ammonium groups, were included to complement the three anionic functionalities on the guest. Beyond acting as a binding site, the europium complex was used to signal binding of the guest through modification of the charge transfer emission. A 1:1 complex with BPG was determined in 50 % methanol/acetonitrile with a K(a) of 6.7 x 10(5) mol(-1) by monitoring the reduction of the fluorescence signal upon guest addition. In the titration of related glycolytic intermediates lacking a second phosphate (4-6) into host 1, 2:1 host to guest binding was observed. Similarly, control compound 2, which lacks the ammonium groups, binds BPG and 4-6 in a 2:1 fashion. Also, phenylphosphate 7 binds to host 1 in a 1:1 stoichiometry with a K(a) over three times less than 3.

2,2'-Dipyridyl↗
PubMed2002

A colorimetric sensing ensemble for heparin.

A receptor possessing ammoniums and a novel amino acid with a boronic acid side chain was designed and synthesized. The receptor shows good affinity and selectivity for heparin over similar polysaccharides possessing lower anionic charge density. The affinity for heparin is similar to that for a heparin disaccharide, indicating that disaccharidic units are the likely sites for binding to the receptor. The receptor has a potential use for creating a colorimetric assay for heparin.

Anticoagulants↗
PubMed2002

1,3,5-2,4,6-functionalized, facially segregated benzenes-exploitation of sterically predisposed systems in supramolecular chemistry.

In the present article, we introduce the unique steric features of 1,3,5-substituted triethylbenzenes as a design principle for host molecules and supramolecular systems. Due to steric gearing, all three functional substituents are disposed on the same side of the phenyl plane. The use of this benzene scaffold has lead to the synthesis of various receptor molecules for a wide range of different guest species. Furthermore, the facially segregated systems can be used as building blocks with a controlled conformation in the synthesis of macrocycles or self-assembled supramolecular systems.

Anions↗
PubMed2002

Novel C3-symmetric molecular scaffolds with potential facial differentiation.

The conversion of 1,3,5-substituted benzene and mesitylene by electrophilic aromatic substitution and Sonogashira cross-coupling, respectively, furnished the C3-symmetric, hexasubstituted benzene derivatives 1 and 2 with an alternating substitution pattern. Based on the molecular scaffolds obtained, the two systems serve as model compounds for novel receptor molecules with distinct geometric features. X-ray structures have been obtained for 1 and 2, which are discussed in regard to their aptitude as receptor platforms or supramolecular building blocks. By looking at the rotational barriers for the functional groups placed around the molecular scaffolds by variable temperature 1H NMR spectroscopy, 1 and 2 turn out to exist in rapidly interconverting conformations. The alignment of these potential binding groups around the molecular scaffolds should be strongly biased by specific interactions with suitable guest molecules.

Journal Article↗
PubMed2002

Toward a stable hydroxyphosphorane.

[reaction: see text] Hydroxy-pentaoxy-phosphoranes are transient intermediates formed during the hydrolysis of various phosphoesters. Kinetic analyses support the existence of such compounds, although they are not isolated. In an attempt to create a stable example, 2 equiv of a ligand possessing a very high effective molarity were attached to a central phosphorus. Instead of obtaining a hydroxyphosphorane, analysis by (31)P and (19)F NMR spectroscopy and X-ray crystallography showed the product to be a phosphotriester. The reason for this is discussed.

Crystallography, X-Ray↗
PubMed2002

Stochastic sensing of IP(3) has far-reaching consequences.

Hagan Bayley's group at Texas A&M University has devised a stochastic sensing methodology for the quantitation of the second messenger inositol 1,4,5-trisphosphate. The unique sensing scheme is very selective and has the potential to measure cytosolic concentrations of IP(3).

Biological Transport↗