Related Experiment Video
Updated: May 15, 2026
09:38
Fabrication Procedures and Birefringence Measurements for Designing Magnetically Responsive Lanthanide Ion Chelating Phospholipid Assemblies
Published on: January 3, 2018
Periodic behavior of lanthanide coordination within reverse micelles.
Ross J Ellis1, Yannick Meridiano, Renato Chiarizia
1Chemical Sciences & Engineering Division, Argonne National Laboratory, Argonne, IL 60439, USA. rellis@anl.gov
Chemistry (Weinheim an Der Bergstrasse, Germany)
|January 9, 2013
Summary
Lanthanide coordination in nanoconfined reverse micelles differs from bulk solutions, influenced by micelle size and acidity. This study reveals trends in lanthanide coordination numbers and nitrate binding modes within these unique environments.
Area of Science:
- Coordination Chemistry
- Nanomaterials Science
- Spectroscopy
Background:
- Lanthanide(III) coordination behavior is crucial for applications in nanosynthesis and separations.
- Understanding lanthanide coordination in confined environments is less explored compared to bulk solutions.
- Reverse micelles (RMs) offer tunable nanoconfined environments for studying chemical phenomena.
Purpose of the Study:
- To investigate the coordination trends of lanthanide(III) ions within nanoconfined solvation environments.
- To elucidate the influence of RM morphology (size, hydration) and solution acidity on lanthanide coordination.
- To compare lanthanide coordination in RMs with their behavior in bulk solutions and solid states.
Main Methods:
- Formation of reverse micelles (RMs) using malonamide amphiphiles (DMDOHEMA) in n-heptane.
- Incorporation of lanthanide(III) and nitrate ions into RM cores under acidic and neutral conditions.
- Characterization using X-ray absorption spectroscopy (XAS), including L3-edge XANES and EXAFS, for structural insights.
- Small-angle X-ray scattering (SAXS) for RM morphology analysis.
- Time-resolved laser-induced fluorescence spectroscopy (TRLIFS) for Eu species hydration number determination.
Main Results:
- Lanthanide coordination number decreases from 9 oxygen atoms for early lanthanides (Nd, Eu) to 8 for late lanthanides (Tb, Yb), consistent with lanthanide contraction.
- RM acidity significantly impacts nitrate coordination: acidic, larger RMs favor monodentate binding, while neutral, smaller RMs favor bidentate binding.
- Hydration numbers of Eu species were quantified, showing influence of RM environment.
- Metrical insights into Ln-O interatomic distances and coordination environments were obtained across the lanthanide series.
Conclusions:
- Lanthanide coordination chemistry within nanoconfined RMs is distinct from solid-state or bulk solution behavior.
- The nanoconfined environment, modulated by RM size and acidity, dictates lanthanide coordination modes and hydration.
- These findings provide fundamental insights into lanthanide periodic behavior at the atomic and mesoscale within RMs, relevant for advanced applications.
More Related Videos
Related Concept Videos
01:30Micelles
Micelle formation is an intricate process that hinges on the properties of amphiphilic or amphipathic molecules and the conditions of the system in which they are found. Amphiphilic molecules, which have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts, play a critical role in this process.In aqueous environments, these molecules arrange themselves such that their hydrophilic heads are turned towards the water phase, while their hydrophobic tails are oriented away...
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:57Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.