Related Experiment Video
Updated: May 15, 2025
14:22
Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation
Published on: April 11, 2014
15.0K
Uranyl fluorescence in acidic solution: quenching effects by tetramethylammonium (TMA+)
Thomas D Persinger1, Michael C Heaven2, Richard E Wilson1
1Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA. tpersinger@anl.gov.
Physical Chemistry Chemical Physics : PCCP
|April 30, 2025
Summary
Tetra-methylammonium (TMA+) ions significantly quench uranyl luminescence in aqueous solutions, reducing fluorescence lifetime more than other cations. This suggests TMA+ enhances uranyl-nitrate complex formation, impacting uranyl photophysics.
Area of Science:
- Photochemistry
- Inorganic Chemistry
- Solution Chemistry
Background:
- Uranyl luminescence is sensitive to its chemical environment.
- Understanding cation interactions is crucial for controlling uranyl photophysical properties.
Purpose of the Study:
- To investigate the quenching effects of various cations on uranyl luminescence in aqueous media.
- To elucidate the mechanism of uranyl luminescence quenching by alkali metal and quaternary ammonium cations.
Main Methods:
- Studied uranyl luminescence in solutions with varying nitrate salts at low pH.
- Measured fluorescence decay lifetimes and emission spectra.
- Analyzed decay rate versus concentration data (Stern-Volmer plots).
Main Results:
- Tetra-methylammonium (TMA+) significantly reduced uranyl fluorescence lifetime (to 0.6 μs from 1.4-1.9 μs).
- TMA+ enhanced uranyl-nitrate complex formation.
- Dynamic quenching was observed for Li+, TMA+, and TEA+ at higher concentrations.
Conclusions:
- TMA+ is a potent quencher of uranyl luminescence, likely via enhanced complexation.
- Cation identity plays a critical role in modulating uranyl photophysics.
- Further studies on temperature and isotopic effects (D2O) provide kinetic insights.
Related Concept Videos
01:26Variables Affecting Phosphorescence and Fluorescence
396
Fluorescence and phosphorescence are essential phenomena in fields like analytical chemistry, biological imaging, and materials science, where they detect molecular properties and visualize cellular structures. Understanding the variables that influence these luminescent behaviors is crucial for maximizing accuracy and efficiency in their applications. These variables can broadly be grouped into chemical structure, solvent properties, and external conditions, each playing a distinct role in...
396
01:25Basicity of Heterocyclic Aromatic Amines
5.4K
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
5.4K
01:18Basicity of Aromatic Amines
7.0K
The basicity of aromatic amines is much weaker than that of aliphatic amines due to the involvement of the lone pair of electrons over the N atom in resonance with the aryl rings. Generally, the electron-donating ability of any substituents on the aryl ring of aromatic amines increases the basicity of the amine by increasing electron density, and hence the availability of lone pair on the nitrogen. On the other hand, electron-withdrawing functional groups on the aryl ring of amines decrease the...
7.0K
01:14Photoluminescence: Applications
343
Photoluminescence offers a wide range of applications due to its inherent sensitivity and selectivity. This technique allows for both direct and indirect analyses of the analyte. Direct quantitative analysis is possible when the analyte exhibits a favorable quantum yield for fluorescence or phosphorescence. However, an indirect analysis may be feasible if the analyte is not fluorescent or phosphorescent, or if the quantum yield is unfavorable. Indirect methods include reacting the analyte with...
343
01:21Basicity of Aliphatic Amines
5.6K
Amines can behave as Brønsted–Lowry bases by accepting a proton from the acid to form corresponding conjugate acids. Due to a lone pair of nonbonding electrons, aliphatic amines can also act as Lewis bases by forming a covalent bond with an electrophile.
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates...
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates...
5.6K
01:26EDTA: Auxiliary Complexing Reagents
514
EDTA titrations are usually carried out in highly basic conditions, where the fully deprotonated form of EDTA, Y4−, actively complexes with the free metal ions in the solution. Several metal ions precipitate as hydrous oxide (hydroxides, oxides, or oxyhydroxides) under these conditions, lowering the concentration of free metal ions in the solution. For this reason, auxiliary complexing agents or ligands such as ammonia, tartrate, citrate, or triethanolamine are used in EDTA titrations to...
514