Energy transfer and photoluminescence properties of lanthanide-containing polyoxotitanate cages coordinated by salicylate ligands.
Subramanian, Gomathy Sandhya
Dalton transactions (Cambridge, England : 2003)
Royal Society of Chemistry
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Li, N., Subramanian, G. S., Matthews, P. D., Xiao, J., Chellappan, V., Rosser, T. E., Reisner, E., et al. (2018). Energy transfer and photoluminescence properties of lanthanide-containing polyoxotitanate cages coordinated by salicylate ligands.. Dalton transactions (Cambridge, England : 2003), 47 (16), 5679-5686. https://doi.org/10.1039/c8dt00825f
Polyoxotitanate (POT) cages have attracted considerable attention recently, much of this from the fact that they can be considered to be structural models for the technologically important semiconductor TiO2. Among the reported POT cages, lanthanide-containing (Ln-POT) cages are of particular interest owing to the fascinating luminescence properties of Ln3+ ions and the versatile coordination environments that they can adopt. In the present study, we report the energy transfer mechanism and photoluminescence properties of a series of isostructural Ln-POT cages coordinated by salicylate ligands, of general formula [LnTi6O3(OiPr)9(salicylate)6] (Ln-1, Ln = La to Er excluding Pm). Both visible (for Pr-1, Sm-1, Eu-1, Ho-1 and Er-1) and near-infrared (for Nd-1 and Er-1) Ln3+-centred photoluminescence can be sensitised in solution, and most importantly, their excitation bands all extend well into the visible region up to 475 nm. With the assistance of steady-state and time-resolved photoluminescence spectroscopy, an energy-transfer mechanism involving the salicylate-to-Ti4+ charge-transfer state is proposed to account for the largely red-shifted excitation wavelengths of these Ln-1 cages. The photoluminescence quantum yield of Nd-1 upon excitation via the charge-transfer state reaches 0.30 ± 0.01 % in solution, making it among the highest reported values for Nd3+-complexes in the literature.
External DOI: https://doi.org/10.1039/c8dt00825f
This record's URL: https://www.repository.cam.ac.uk/handle/1810/277368