Description of the optical and molecular properties in lanthanide macrocyclic complexes using quantum chemical relativistic methods
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Fecha
2015
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Profesor/a Guía
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en
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
The lanthanides or most commonly known as .. rare earths" have attracted the interest
of thc scic11tific comrnunity i11 thc last 30 ycars, duc to their uniquc and appealing
characteristics. Probably, one of the most interesting is their f-f inherent spectroscopic
properties in thc nea.r infra-red rcgion of the spectra prescnting charactcristic narrow
"line-like" emission bands. Additionally, these f-f transitions are parity (and sornetimes
also spin) forbidclen, rcsulting in vcry long livcd excited states. Unfortunately,
as another consequence of the parity (Laporte) forbidden nature of the 4f transitions,
the direct absorption of Ln(III) cations is quite poor, and they hence have very low
molar absorption coefficients which limits their practical usage. For that reason, the
use of molecular antennas, which absorbed highly effi.ciently the light and then promete
a charge/energy transfer to the lanthanide center (populating their excited states), was
proposed as a simple and useful way to sensitize and enhance the lanthanide luminescence.
In this way, this doctoral dissertation entitled: "Description of the Optical and
Molecular Properties in Lanthanide ::Ylacrocyclic Complexes Using Quantum Chemical
Relativistic Methods", is a study based on the relativistic density functional and
the wave-function theory of a series of poly-aza and poly-oxo lanthanide macrocyclic
complexes, whose purpose is to characterize: i) the ground and excited states, ii) the
lanthanide-macrocycle interaction, and iii) the nature of the main electronic transitions
involved in optical applications. During the development of this work, we found interesting
results on the characterization of the bond interaction, energetics and optical
properties, that show the potential use of 1r-conjugated macrocyclic systems as molecular
antennas which could sensitize the lanthanide luminescence throughout a charge
transfer phcnomena, which is favoured by a dativc covalcnt intcraction betwccn thc
macrocyclic ligand and the lanthanide center. Moreover, it was achieved an extensivc
knowledge of thc clectronic structurc, cspecially the multi-coufigurational naturc
of the ground and excited states, as a consequence of the low-lying character of the
lanthanidc 4f-shcll ancl thc strong statc rnixiug possibility due to the low sy111rnetry
and the spin-orbit coupling effect.
Notas
Tesis (Doctorado de Filosofía en Fisicoquímica Molecular)
Palabras clave
Complejos Lantánidos