Ytterbium complexes porphyrins

The luminescence of ytterbium-porphyrin complexes has also been investigated and found to be associated with intramolecular energy transfer, (Kachura et al., 1974). Small shifts in the positions as well as some broadening of the emission lines were observed when the potentially coordinating molecules pyridine and quinoline were used as solvents. Spectral sensitivity to axial coordination is an important feature that may allow the use of these complexes as probes of molecular structure in heme proteins. 

Porphyrin complexes of yttrium, lanthanum, cerium, praesodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and thorium can be synthesized using this method. 

Most of the lanthanide porphyrin complexes are paramagnetic, except those of lanthanum and lutetium which are diamagnetic. They all show paramagnetic behaviors in the NMR spectra similar to those of the lanthanide 0-diketonate complexes, except that the shift capabilities are less.4 Some of these paramagnetic lanthanide complexes (i.e., that of ytterbium) show Curie behavior at low temperature. Diamagnetic lutetium shows some ring current phenomena.4... 

Porphyrin molecules form stable complexes with lanthanide ions, these complexes have intensive absorption in a visible range of spectrum. Erbium, ytterbium and neodymium complexes are characterized by a 4f-luminescence in near IR-range of spectrum [1]. The most studied complexes with porphyrins are ytterbium complexes since Yb has smaller ionic radius in comparison with lanthanum (radius of Yb ion is 1.01 A), which determines higher stability of these metallocomplexes. Distinctive feature of Yb porphyrin complexes is a characteristic narrow and rather intensive luminescence band located in the IR-range at 975-985 nm, in so-called therapeutic window of tissue transparency. ... 

Molybdenum catalysts, Ruthenium porphyrins, Ruthenium(lll) complexes, Iron catalysts, Titanium catalysts. Sharpless epoxidation, Tungsten catalysts, Methyltrioxorhenium, Cobalt, Nickel, Platinum, Aerobic epoxidation, Lanthanum, Ytterbium, Calcium, BINOL-complexes. 2008 Elsevier B.v. 

The detection of DNA strands by NIR luminescent lanthanide complexes is possible through the modulation of Yb luminescence in Pd-porphyrin-containing complexes upon nucleic acid binding [48] or by the sensitivity of the intramolecular energy transfer towards the presence of DNA sensing in coumarin-rhodamine-modified ytterbium complexes [95]. 

The photophysical properties of 20 are particularly interesting, in that the triplet energy of the porphyrin chromophore is comparable to the emissive state of and can be thermally repopulated at room temperature [52], This leads to a dependence of the emission intensity and lifetimes upon the degree of sample aeration. In most cases, energy transfer from the chromophore to the lanthanide occurs via the MLCT state of the chromophore, and normal behaviour is observed. However, the broad nature of the emission from luminescent MLCT states means that the tail of this emission is often superimposed upon the relatively weak luminescence from the lanthanide ion. In such situations the two signals can be resolved readily provided that their lifetimes differ significantly. This is not the case with many complexes related to [Rulbpyls] ", which have luminescence lifetimes comparable with those of neodymium and ytterbium complexes. 

Seven-coordinate lanthanide complexes with p-diketones are lacking, such an example is [Yb(TFPP)(L ) (H2O)] (see Figiue 10) where H2TFPP = 5,10,15,20-tetia(4-fluorophenyl)porphyrin. Water that binds to ytterbium(ni) ion quenches the NIR emission of Yb +, resulting a shorter lifetime of 2.4ps. 

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