Molecular recognition of organic ammonium ions in solution using synthetic receptors

Abstract

SummaryAmmonium ions are ubiquitous in chemistry and molecular biology. Considerable efforts have been undertaken to develop synthetic receptors for their selective molecular recognition. The type of host compounds for organic ammonium ion binding span a wide range from crown ethers to calixarenes to metal complexes. Typical intermolecular interactions are hydrogen bonds, electrostatic and cation–π interactions, hydrophobic interactions or reversible covalent bond formation. In this review we discuss the different classes of synthetic receptors for organic ammonium ion recognition and illustrate the scope and limitations of each class with selected examples from the recent literature. The molecular recognition of ammonium ions in amino acids is included and the enantioselective binding of chiral ammonium ions by synthetic receptors is also covered. In our conclusion we compare the strengths and weaknesses of the different types of ammonium ion receptors which may help to select the best approach for specific applications.

A Review of Biochar and Soil Nitrogen Dynamics

“…Although the exact mechanism for NH 4 + retention was not identified it was suggested that physical entrapment of NH 4 + in biochar pore structures may have been responsible [28]. Given that the NH 4 + ion has a diameter of 286 pm [29] and there is wide range of pore sizes in biochar materials [30] this is entirely possible. Prost et al [31] also found surface areas of biochars decreased during composting due to compost-derived materials clogging biochar pores with the biochar also absorbing leachate and nutrients.…”

Encapsulation of alkyl and aryl derivatives of quaternary ammonium cations within cucurbit[n]uril (n = 6,7) and their inverted diastereomers: density functional investigations

“…Developing synthetic receptor for selective molecular recognition of ammonium cation is crucial in chemistry and molecular biology [51]. It is known that the size-complementarities of the host cavity and the guest govern the host-guest binding.…”

“…The interaction of these hosts and quaternary ammonium cations stem from hydrogen bonding. In addition, electrostatic and cation-π interactions [51] contribute toward such binding. The present work analyzes how complexation of CB [n] or iCB[n] with 1,6-hexyldiammonium (HDA) or xylyldiammonium (XYL) cationic guests, prototype representatives of aliphatic and aromatic molecular systems, respectively, influences 1 H NMR of the isolated host or the guest.…”

Using Molecular Modelling to Study Interactions Between Molecules with Biological Activity

“…Both binding and selectivity in binding can be understood through the combined efforts of several non-covalent interactions, such as hydrogen bonding, electrostatic interactions, hydrophobic interactions, cation-π interactions, π-π stacking interactions and steric complementarity [Späth & König, 2010]. Formation of complexes is also possible in the case of neutral ligands.…”