Luminescence Spectra Of Complexes Research Articles

Electronic structures of organometallic complexes of f elements LXXIII: Parametric analysis of the crystal field splitting pattern of tris(η 5-pentamethylcyclopentadienyl)cerium(III)

By comparing the far infrared (polyethylene pellets, room temperature) and mid-infrared spectra (KBr pellets, room temperature and ca. 90 K) of pseudo trigonal planar Ce(η 5-C 5Me 5) 3 ( 1) with the corresponding ones of La(η 5-C 5Me 5) 3 ( 2) and considering the low temperature paramagnetic susceptibility data of 1 the crystal field (CF) splitting pattern of 1 could be derived. The free parameters of a phenomenological Hamiltonian were fitted to this pattern achieving an r.m.s. deviation of 8.9 cm −1 for seven assignments. The fact that the difference of the experimental energies of the barycenters of CF levels of the multiplets 2F 7/2 and 2F 5/2 is larger than in the gaseous free Ce 3+ ion (experimental “anti”-relativistic nephelauxetic effect) could be explained by coupling effects of these multiplets via the CF, resulting in a lower spin–orbit coupling parameter than in the case of the free gaseous Ce 3+ ion. The experimental CF splitting pattern of 1 is compared to the results of a relativistic DV-Xα calculation on the pseudo trigonal planar model compound Ce(η 5-C 5H 5) 3. In addition, the prediction of the energies of f → d and charge transfer transitions of Ce(η 5-C 5H 5) 3 are compared to the absorption and luminescence spectra of complex 1.

Spectral, luminescent, and electrochemical properties of cyclometalated complexes of Rh(III) based on 1-phenylpyrazole with ethylenediamine and heterocyclic diimines

A series of [Rh(ppz)2(N^N)]+ complexes (ppz− is the deprotonated form of 1-phenylpyrazole and (N^N) is ethylenediamine, 2,2′-bipyridyl, 1,10-phenanthroline, 4,7-diphenyl-1,10-phenanthroline, and 2,2′-biquinoline) is obtained and characterized by 1H NMR spectroscopy, electronic absorption and emission spectroscopy, and cyclic voltamperometry. A 0.75-V anodic shift of the ligand-centered reduction potentials of complexes compared to free heterocyclic (N^N) ligands is observed. The vibrationally structured luminescence spectra of complexes are attributed to intraligand spin-forbidden optical transitions localized on the {Rh(N^N)} metal-complex fragments.

Deactivation pathways of the electronic excitation of ions of lanthanide complexes in polymers with functional groups

Complexes Eu(TTA)3phen and Eu(MBTA)3phen, as well as complexes Tb(MBTA)3phen and Tb(TTA)3phen, which do not luminesce in solutions, are shown to luminesce in polymer films (TTA is thenoyltrifluoroacetone, MBTA is n-methoxybenzoyltrifluoroacetone, and phen is o-phenanthroline). Luminescence of complexes of Eu and Tb in films of a polymer, poly(methylene-bis-anthranilamide) 1,6-hexamethylenedicarboxylic acid (PAA-5), having a high concentration of functional anthranilate groups, is studied. From the behavior of the luminescence intensity (I lum), the luminescence decay time, and the luminescence spectra of complexes of these lanthanides in polymer films, the following regular features were revealed. (i) During the film preparation at 90°C, Ln complexes are attached to PAA-5 via anthranilate groups. (ii) Irradiation of these films in the range of the absorption band of ligands (TTA or MBTA) leads to deactivation of the electronic excitation of ions according to the diketone detachment mechanism and to further binding of complexes to polymers. In this case, I lum(Eu(III)) decreases because the introduction of anthranilate groups of the polymer into the first coordination sphere of Eu(III) complexes enhances the nonradiative deactivation of these ions, whereas I lum(Tb(III)) increases since the introduction of these groups suppresses the nonradiative deactivation of Tb complexes through triplet states of ligands (TTA and MBTA). (iii) Upon storage of films in the dark (20°C), complexes detach themselves from the polymer and return to their initial structure. In PAA-5 films into which Eu and Tb complexes were simultaneously introduced, the color of the emission from the irradiation spot changes from red to green.

Luminescence spectra of complexes of europium with NN?-bis(salicylaldehyde)ethylenediamine and its derivatives

Luminescence spectra of complexes of europium with NN?-bis(salicylaldehyde)ethylenediamine and its derivatives

Luminescence spectra in tetrahalomanganate complexes

Experimental data on the luminescence spectra of complexes made with manganese halides and ammonium salts are reported at several temperatures. Using these experimental determinations, we have computed and drawn the configurational coordinate diagrams.

The low temperature luminescence of complexes of acridine orange with polyelectrolytes

The low temperature luminescence spectra of complexes of acridine orange with a series of polyelectrolytes can be interpreted semiquantitatively in terms of nearest neighbor interactions of the bound species, using an Ising type model. Nearest neighbor interactions induce a spectral shift of fluorescence to longer wavelengths and quench phosphorescence.

Luminescence spectra of complexes of uranyl nitrate with heterocyclic amines

Luminescence spectra of complexes of uranyl nitrate with heterocyclic amines