Lanthanide luminescence spectroscopy

Choppin GR and Peterman DR (1998) Applications of lanthanide luminescence spectroscopy to solution studies of coordination chemistry. Coordination Chemistry Reviews 174 283-299. 

Sinkov, S.I. Choppin, G.R. Taylor, R.J. Spectrophotometry and luminescence spectroscopy of acetohydroxamate complexes of trivalent lanthanide and actinide ions, J. Solut. Chem., 36 (2007) 815-830. 

Riehl, J. P. Muller, G. Circularly polarized luminescence spectroscopy from lanthanide systems. In Handbook on the Physics and Chemistry of Rare Earths, Gschneidner, K. A. Biinzli, J.-C. G. Eds. North-Holland Publishing Company Amsterdam, 2005 Vol. 34, pp 289-356. 

James P. Riehl and Gilles Muller, Circularly polarized luminescence spectroscopy from lanthanide systems 289... 

Interaction of the nitrate ion with lanthanide(III) in acetonitrile solution was studied by conductivity, vibrational spectroscopy and luminescence spectroscopy. Bidentate nitrate with approximate C2V local symmetry was detected. FT-IR spectral evidence for the formation of [La(N03)5]2, where La = Nd, Eu, Tb and Er with coordination number 9.9 has been obtained [128]. Two inequivalent nitrate ions bound to lanthanides were detected by vibrational spectroscopy. The inequivalent nature varied with different lanthanides. For example three equivalent nitrate groups for La and Yb, one nitrate different from the other two for Eu ion were detected. Vibrational spectral data point towards strong La-NC>3 interaction in acetonitrile [129]. Stability constants for lanthanide nitrate complexes are given in Table 4.10. 

Lanthanides substitution in proteins also provide structural and functional aspects of proteins. The techniques which provide such useful information are NMR and luminescence techniques. NMR helps assignment of peaks and also provides conformational analysis (i.e.) in identification of acid residues in the vicinity of the binding site. A useful situation arises when the lanthanum binding site is in proximity to the active site. Luminescence spectroscopy gives the number of water molecules bound and also the interionic distance in cases where two binding sites are present. 

Other examples are lanthanide(m) complexes with heptadentate ligands (derivatives of D03A) where two coordination sites are available for next ligand binding. The complexes were used for molecular recognition of some anions by means of NMR or luminescence spectroscopies <2002JA12697>. 

Keywords Nitroxide radicals Lanthanide complexes Low-temperature absorption spectroscopy Low-temperature luminescence spectroscopy Molecular magnetism... 

Lanthanide compounds play an important role in the field of luminescence spectroscopy. The excited state properties of lanthanide ions Ln + have been extensively discussed in many reviews [62-66]. Here, only a few general aspects are mentioned. 

Speghini, A., Piccinelli, F., Bettinelli, M. 2011. Synthesis, characterization and luminescence spectroscopy of oxide nanopowders activated with bivalent lanthanide ions The garnet family. Optical Materials 33 247-257. 

From analysis of lanthanide (Ln " ") tetraazatetrakis-phosphinato and phosphonato complexes (42)," self-association was observed in aqueous solution for both the [Ln(DOTP -OEt)] and [Ln(DOTP -OBu)] ester complexes through examination of their P-NMR-, EPR-, and luminescence-spectroscopy, as well as vapour-pressure osmometry data. The X-band EPR spectra were recorded for [Gd(DOTP -H)] , [Gd(DOTP -Et)] , [Gd (DOTP -OEt)], and [Gd(DOTP -OBu)] complexes in the 1-10 mmol/L concentration range at pH 7.0 and 298 K, which gave approximate Lorentzian lines with a g value around 2.0 and variable peak-to-peak line widths, (d/fpp), dependent on the concentration of the complexes. An increase in the line width was observed in all cases but was much larger for [Gd(DOTP -OEt)] increasing from 40.5 to 80.0 mT. In the phosphinato complex [Gd(DOTP -H)] , no increase was observed with A//pp around 26 mT, indicating that the... 

CIRCULARLY POLARIZED LUMINESCENCE SPECTROSCOPY FROM LANTHANIDE SYSTEMS... 

CPL investigations on Eu(III) and Tb(III) nitrate complexes with the chiral D2-symmet-ric ligand 4/, 9/, 19/ ,24/ -3,10,18,25,3l,32-hexaazapentacyclo[25.3.1.1.0.0]-dotriaconta-l-(31),2,10,12,14,16(32),17,25,27,29-decaene (7 -pydach) (Scheme 12) and its S S -pydach enantiomer have shown that the strong measured CPL, g um = —0.19 at 596 nm ( Dq Fi transition), was only due to the twisted conformation (Tsubomura et al., 1992). In the case of the complexes, [Ln(7 -pydach)] + and [Ln( S S -pydach)] +, there was no evidence of a contribution from coordinated nitrate anions on the complex chirality as previously observed. The complex structures which have been characterized by NMR and luminescence spectroscopy have suggested that the nitrate anions were not coordinated to the lanthanide (III) ion in these species and, also, that approximately three water molecules were bound to the metal center. 

This volume of the Handbook on the Physics and Chemistry of Rare Earths adds five new chapters to the science of rare earths, compiled by researchers renowned in their respective fields. Volume 34 opens with an overview of ternary intermetallic systems containing rare earths, transition metals and indium (Chapter 218) followed by an assessment of up-to-date understanding of the interplay between order, magnetism and superconductivity of intermetallic compounds formed by rare earth and actinide metals (Chapter 219). Switching from metals to complex compounds of rare earths, Chapter 220 is dedicated to molecular stmctural studies using circularly polarized luminescence spectroscopy of lanthanide systems, while Chapter 221 examines rare-earth metal-organic frameworks, also known as coordination polymers, which are expected to have many practical applications in the future. A review discussing remarkable catalytic activity of rare earths in site-selective hydrolysis of deoxyribonucleic acid (DNA) and ribonucleic acid, or RNA (Chapter 222) completes this book. 

Chapter 220. Circularly Polarized Luminescence Spectroscopy from Lanthanide Systems... 

Eu complexes were chosen as a starting point for the exploration of lanthanide PMCs for a number of reasons. The local coordination environment of Eu can be easily probed by luminescence spectroscopy due to the sensitivity of Eu emission to e structural details of its surroundings (29). In addition, many related Eu complexes have already been studied in detail (30, 31), providing compmisons to the polymeric complexes. 

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