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Fluorescence Enhancement of Tb 3+ in the Tb 3+ ‐Trimesic Acid‐Gd 3+ Complex: Role of Polynuclear Structures
Author(s) -
Dubey Pankaj,
Mukherjee Srijit,
Choudhury Angshuman Roy,
Viswanathan K. S.
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201900035
Subject(s) - trimesic acid , fluorescence , dynamic light scattering , chemistry , analytical chemistry (journal) , fluorescence spectroscopy , intermolecular force , materials science , crystallography , nanotechnology , nanoparticle , chromatography , molecule , physics , optics , organic chemistry
The mechanism of fluorescence enhancement of Tb 3+ in Tb 3+ ‐trimesic acid‐Gd 3+ systems has been explored using dynamic light scattering. In earlier work, the mechanism of fluorescence enhancement of Tb 3+ in these systems was proposed to be due to the formation of a polynuclear complex involving Tb 3+ , trimesic acid and Gd 3+ . However, no direct experimental evidence was presented for the mechanism in that work. In this work, we have used dynamic light scattering (DLS), to measure changes in the mean hydrodynamic diameter ( Z avg ) of the Tb 3+ ‐trimesic acid‐Gd 3+ complex, as a function of time. The Z avg was found to increase monotonically as a function of time, indicating a continuous growth in the particle size. The Eu 3+ ‐β‐diketones‐Gd 3+ system also shows enhancement of Eu 3+ fluorescence; though a different mechanism was believed to be operating in this case; namely intermolecular energy transfer. If the two systems followed different mechanisms for fluorescence enhancement, the Eu 3+ ‐β‐diketones‐Gd 3+ system, is expected to show a different time evolution of particle size. The DLS study showed that the Z avg increased rapidly to a maximum value and then remained nearly constant throughout our measurements; that is, no gradual increase in Z avg was seen as in the Tb 3+ ‐trimesic acid‐Gd 3+ system. These DLS studies of the Tb 3+ ‐trimesic acid‐Gd 3+ and Eu 3+ ‐β‐diketones‐Gd 3+ systems, therefore confirms that different mechanisms of fluorescence enhancement are operative in the two systems.