Hg(II)-coordination by sugar-acids: role of the hydroxy groups.
E Ferrari1, R Grandi, S Lazzari
1Department of Chemistry, University of Modena and Reggio Emilia, via Campi 183, 41100 Modena, Italy.
Journal of Inorganic Biochemistry
|November 4, 2005
Summary
This study reveals how derivatized sugars like glucuronic acid, galacturonic acid, and glucosaminic acid bind to mercury ions. Glucuronic acid forms the most stable mercury complexes by coordinating through specific oxygen and hydroxyl groups.
Area of Science:
- Coordination chemistry
- Carbohydrate chemistry
- Environmental chemistry
Background:
- Mercury (Hg(II)) is a toxic heavy metal pollutant.
- Derivatized sugars can potentially chelate metal ions.
- Understanding metal-ligand interactions is crucial for remediation strategies.
Purpose of the Study:
- To investigate the complexation of mercury (Hg(II)) by derivatized sugars: glucuronic acid (GluA), galacturonic acid (GalA), and glucosaminic acid (GlNA).
- To determine the stability constants and coordination sites of the resulting metal-sugar complexes.
- To explore ternary complexes involving 2,2'-bipyridine.
Main Methods:
- Potentiometric titrations to determine stability constants.
- (1)H Nuclear Magnetic Resonance (NMR) spectroscopy to identify coordination sites.
- Isolation and characterization of solid-state complexes using Infrared (IR) spectroscopy.
Main Results:
- Glucuronic acid (GluA) forms stable Hg(II) complexes by coordinating through its carboxylic oxygen and O-4 hydroxyl group.
- Galacturonic acid (GalA) forms less stable complexes, with metal ligation involving the carboxylic oxygen and O-5 ring oxygen.
- Glucosaminic acid (GlNA) chelates Hg(II) effectively via its carboxylic oxygen and alpha-amino group.
- Ternary complexes with 2,2'-bipyridine were also studied.
Conclusions:
- Derivatized sugars exhibit varying affinities and coordination modes for Hg(II) complexation.
- Glucuronic acid demonstrates superior stability in Hg(II) complexation among the studied sugars.
- These findings contribute to understanding mercury's environmental fate and potential chelation therapies.
Related Concept Videos
02:54Coordination Compounds and Nomenclature
In most main group element compounds, the valence electrons of the isolated atoms combine to form chemical bonds that satisfy the octet rule. For instance, the four valence electrons of carbon overlap with electrons from four hydrogen atoms to form CH4. The one valence electron leaves sodium and adds to the seven valence electrons of chlorine to form the ionic formula unit NaCl (Figure 1a). Transition metals do not normally bond in this fashion. They primarily form coordinate covalent bonds, a...
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
01:19Aldehydes and Ketones with Alcohols: Hemiacetal Formation
Similar to water, alcohols can add to the carbonyl carbon of the aldehydes and ketones. The addition of one molecule of alcohol to the carbonyl compound forms the hemiacetal or half acetal. As depicted below, in a hemiacetal, the carbon is directly linked to an OH and OR group.
01:19Reactions of Acid Anhydrides
The reactions of acid anhydrides are analogous to the reactions of acid chlorides and proceed via a nucleophilic acyl substitution. They only differ in the identity of the leaving group. During an acid chloride reaction, the leaving group is a chloride ion, and the by-product is hydrochloric acid. However, in an acid anhydride reaction, the leaving group is a carboxylate ion, and the by-product is a carboxylic acid.
01:10Aldehydes and Ketones with HCN: Cyanohydrin Formation Mechanism
Cyanohydrins are formed when cyanide nucleophiles and carbonyl compounds like aldehydes and ketones react. A strong base, the cyanide ion, catalyzes cyanohydrin formation. The ions are generated from HCN under aqueous conditions. Once the cyanide ions are generated, the first step involves the nucleophilic attack of the cyanide ions on the electrophilic carbonyl carbon. This attack shifts the π electrons from the C=O to the oxygen atom forming the alkoxide ion intermediate. The alkoxide anion...
01:19Overview of Functional Groups
Functional groups are a group of atoms with characteristic properties, which when linked to the carbon skeleton of a molecule, alter the properties of that molecule. For example, certain functional groups will make a molecule hydrophilic, whereas others will make them hydrophobic. These functional groups are an indispensable part of organic chemistry and important components of biological molecules, such as carbohydrates, proteins, lipids, and nucleic acids. Each functional group is a unique...