Ring Structure and Aromatic Substituent Effects on the pK a of the Benzoxaborole Pharmacophore

In this work, we present an investigation into the physical properties of a unique class of aromatic boronic acids, the benzoxaboroles. Using spectrophotometric methods, the ionization constants of a family of substituted benzoxaboroles are determined. Heterocyclic ring modifications are examined to determine their effects on the ionization of the boronic acid moiety. It is also shown that the substituent effects about the aromatic ring follow a Hammett relationship with the compounds' measured pK a values. Finally, these substituent effects are also shown to extend to the sugar binding properties of these compounds under physiologically relevant conditions. Combined, these data will inform medicinal chemists wishing to tailor the ionization and/or ability of this class of compound to bind diol-containing biomolecules.

Bis- and tris-naphthoimidazolium derivatives for the fluorescent recognition of ATP and GTP in 100% aqueous solution

Naphthoimidazolium groups can form unique ionic hydrogen bonds with anions as imidazolium moieties, and in addition, they are fluorescent, so no further elaborative synthesis is needed to introduce a fluorescent group. In this paper, three naphthoimidazolium derivatives were synthesized and studied for the recognition of nucleotides. Compound 1 composed of a single naphthoimidazolium group and quaternary ammonium group did not show any significant fluorescent changes with various anions and nucleotides, such as ATP, GTP, CTP, TTP, UTP, ADP and AMP. A tripodal compound 3 bearing three naphthoimidazolium groups and three quaternary ammonium groups, respectively, showed large fluorescence enhancements with UTP, CTP and TTP and moderate fluorescence enhancements with ATP and pyrophosphate and a fluorescence quenching effect with GTP. On the other hand, compound 2 bearing two naphthoimidazolium groups and two quaternary ammonium groups displayed a selective fluorescence enhancement with ATP and a selective fluorescence quenching effect with GTP in 100% aqueous solution.

Ratiometric fluorescent sensor for silver ion and its resultant complex for iodide anion in aqueous solution

In aqueous solution, sensor DQAg can selectively detect Ag(+) based on inhibition of the resonance, demonstrating a large hypsochromic shift of 84 nm and remarkable changes in the ratio (F(481 nm)/F(565 nm)) of the emission intensity (R/R(0) up to 26-fold). Furthermore, the resultant Ag-DQAg also displays a ratiometric and highly selective response to iodide anion over other anions due to the liberation of DQAg from the complex by precipitating AgI.

Zn(II)-cyclam based chromogenic sensors for recognition of ATP in aqueous solution under physiological conditions and their application as viable staining agents for microorganism

Two chromogenic complexes, L.Zn (where L is (E)-4-((4-(1,4,8,11-tetraazacyclotetradecan-1-ylsulfonyl)phenyl)diazenyl)-N,N-dimethylaniline) and its [2]pseudorotaxane form (α-CD.L.Zn), were found to bind preferentially to adenosine triphosphate (ATP), among all other common anions and biologically important phosphate (AMP, ADP, pyrophosphate, and phosphate) ions in aqueous HEPES buffer medium of pH 7.2. Studies with live cell cultures of prokaryotic microbes revealed that binding of these two reagents to intercellular ATP, produced in situ, could be used in delineating the gram-positive and the gram-negative bacteria. More importantly, these dyes were found to be nontoxic to living microbes (eukaryotes and prokaryotes) and could be used for studying the cell growth dynamics. Binding to these two viable staining agents to intercellular ATP was also confirmed by spectroscopic studies on cell growth in the presence of different respiratory inhibitors that influence the intercellular ATP generation.

Amide- and urea-functionalized pyrroles and benzopyrroles as synthetic, neutral anion receptors

This critical review is dedicated to the anion complexation chemistry of amide- and urea-functionalized (benzo)pyrroles, such as pyrroles, indoles, carbazoles, isoindoles, naphthalenodipyrroles and benzodipyrroles. It provides a comprehensive overview of these simple and neutral anion sensors from the first examples up to very recent studies. There is a discussion of a gradual progress made over time, often based on careful analysis of the properties of former generations that have subsequently led to obtaining excellent effectivities and selectivities. The influence of these species on other fields of chemistry and their applications there are also discussed (57 references).

Anion receptor chemistry: highlights from 2008 and 2009

This critical review covers advances in anion complexation in the year 2008 and 2009. The review discusses anion receptors that employ hydrogen bond donors (both NH and CH), electrostatic interactions, Lewis acidic centres and combinations of these three types of binding interaction to complex anions. Additionally nanotechnological approaches to anion sensing in aqueous solution, lipid bilayer transporters and recent work on the use of anions to drive conformational change are highlighted (130 references).