The spectroscopy of trivalent lanthanoid ions in organic hosts

This thesis deals with the synthesis of trivalent lanthanoid complexes, their crystallographic structures and their absorption and emission spectroscopy. The trivalent lanthanoid ions (Ce(III) - Lu(III), with the exception of radioactive Pm(III)) were complexed with the heptadentate ligand 2,2'2"- tris(salicylideneimino)triethylamine [H₃L¹]. Structural characterisation by X-ray crystallography revealed that the complexes were isomorphous and isostructural crystallising in the trigonal P -3 c 1 space group. 

X-ray photoelectron spectroscopy has been used to examine the core electron binding energies of all the trivalent lanthanoids (La(III)- Lu(III)) in the [LnL¹] series. The spin-orbit coupling of trivalent lanthanoids in an organic host is examined and the presence of satellites is explained. 

The spectral and geometric trends of the [LnL¹] series of complexes were analysed. Low temperature polarised absorption and luminescence spectra were reported for the nine complexes with transitions that are suitable for analysis. The assigned energy levels were fitted to a parameterised electronic Hamiltonian. Both the angular and radial geometry changes that occur as a function of the change of lanthanoid ion were studied. The structural parameters relate to changes in the ligand field. The ligand field was calculated from the analysis of the f- f transitions and was fitted globally across the whole series accoimting for contraction of the f-orbitals as a function of atomic number. 

[CrL¹] was synthesised to examine the possibility of doping transition metals into the [LnL¹] series of complexes. Consequently, the doped complexes [Gd_0.9Cr_0.1L¹] and [Gd_0.9Cr_0.1Er_0.05L¹] were synthesised, characterised crystallographically and their absorption and luminescence spectra were studied.  

The mono and dinuclear Yb(III) complexes and the dinuclear Er(III) complexes of 2,2’2”-tris(3-methoxysalicylideneimino)triethylamine ([YbL³], [Yb₂L³]²⁺ and [Er₂L³]²⁺) were synthesised and characterised structurally by X-ray crystallography. The [Yb₂L³]²⁺ and [Er₂L³]²⁺ complexes are isomorphous and their low temperature absorption spectra have been studied. 

N,N’-Bis(salicylideneiminoethyl)ethylenediaminenittatoerbium(III) methanol solvate, [ErL⁴(N0₃)].(CH₃0H) has been synthesised, characterised structurally and studied at low temperature using absorption and luminescence spectroscopy. 

The cage complexes (nitrato-,κO,κO’)(8,22,35-trimethyl-l,4,12,15,18,26,31, 39-octaazapentacyclo-[13.13.16.10.120,24.133,37]tetraconta-4,6,8,10(44),l 1,18,20, 22(43),2,5,31,33,35,37(42),38-pentadecane-42,43,44-triolato-κNl ,κN4,κN26,κN31, κO42,κO43,κO44)erbium(III)diperchlorate, [H₃ErL⁶(NO₃)](ClO₄)₂ and aqua(8,22,35 -trichloro-l,4,12,15,18,26,31,39-octaazapentacyclo-[13.13.16.10.120,24.133,37]- tefraconta-4,6,8,10(44), 11,18,20,22(43),2,5,31,33,35,37(42),38-pentadecane-42,43,44 -triolato-κNl,κN4,κN26,κN31,κO42,κO43,κO44) erbium(III) triperchlorate dihydrate, [H₃ErL⁷](ClO₄)₃.2H₂O have been synthesised and characterised structurally using X-ray crystallography.