Fluorescence porphyrin complexes

For the photodiagnostic use of these compounds, a high quantum yield of fluorescence, r, is desirable. The metal complexes of the common first-row transition metals are not suitable, because they show very low 4>f values. On the other hand, porphyrin complexes of d° and d10 elements show appreciable fluorescence, although generally less than that of the metal-free compounds, presumably because of the heavy-atom effect (e.g., TPP ZnTPP, Table 5). The further operation of the heavy-atom effect, which increases the rate of intersystem crossing (/cisc) by... 

Stelmakh and Tsvirko have also proposed the mechanism [b] for the production of S2 state fluorescence in Mg, Zn, and lanthanide-porphyrins complexes (15), and showed the possibility of another mechanism of pumping by triplet-triplet annihilation (16)(mechanism [a]). The latter process was considered to predominate at relatively low values of the excitation densities. However, the contribution of the mecahnism [C] was not determined experimentally. The experimental results in the present work are summarized as follows ... 

The overall oxygen sensitivity exhibited by an optical sensor is basically predefined by the Stern-Volmer constant Ksv. The sensitivity of the final optical oxygen sensor increases with Ksv [65]. Generally, high Ksv values are provided by the Pd- and Pt-porphyrin complexes, by Ru(dpp)3, and by pyrene. Fluorescence quenching by oxygen not only affects the fluorescence intensity of the dye, but also has an influence on its lifetime r (Fig. 6) ... 

Macrotetracyclic cryptate 87 containing a Zn-porphyrin complex as a photoactive subunit and two lateral [18]-N204 macrocyclic receptors was developed by Lehn and co-workers.146 In a CHC13/ CH3OH (9 1) solution, the two receptors were able to complex Ag+ to form a polymetallic cryptate, 87-Ag+. The Ag+ ion in the polymetallic cryptate quenches the typical Zn- porphyrin fluorescence by a 10-fold factor via a PET process and by forming a long-lived charge-separated state. 

Ito, A.S., Azzellini, G.C., Silva, S.C., Serra, O., and Szabo, A.G. (1992) Optical absorption and fluorescence spectroscopy studies of ground state melanin-cationic porphyrin complexes, Biophys. Chem., 45 79-89. 

Ligand localized 7r r ES are common to complexes having large aromatic ligands. Absorption and emission bands attributed to nn states shift to the red with increasing P [6]. For example, fluorescence maxima from the ligand centered states of the tetraphenyl porphyrin complexes Mg(TPP) and Zn(TPP) display shifts ranging from —34 cm VlOO MPa in methanol to —94 cm /fOO MPa in chloroform with... 

The steady state and time-resolved fluorescence measurements unequivocally showed that efficient singlet-singlet excited state energy transfer from the Zn-porphyrin complex to the freebase porphyrin takes place in these assemblies. Indeed, the observed energy transfer rates in both types of assemblies are much faster than those which the Fbrster mechanism would suggest. 

The C5 position of dU has been used to attach a variety of labels or reporter groups, in particular fluorophores ° (see section 3.5). The pyrene-modified analogue (39) has been used to detect RNA bulge conformations in the HIV-TAR RNA sequence where the fluorescence is greatly enhanced,and as a donor for the red emitter nile red (40) when the two dyes are adjacent in duplex DNA the result is white light that is emitted upon excitation of (39). A zinc-porphyrin complex has been added to C5 of dU for use in electron transfer. Norbornene has been attached via an alkyne linker for post-synthetic modification with nitrile oxides in a copper-free Click reaction, " and various dienes have been attached for Diels-Alder tagging of DNA. The photoaffinity tag (41) has been incorporated into DNA adjacent to a damaged DNA base (8-oxo-dG or thymine dimer) such that when exposed to repair systems, the repair enzyme is trapped by the diazirine for mass spectroscopic characterisation. ... 

Fig. 7 Fluorescence microscopy of an organometallic ruthenium porphyrin complex (right) in Mc300 cells, where blue, green and red correspond to a DAPI stained nucleus, lysotracker green and the ruthenium complex. ...

Realization of TL detection under a microscope allows ultrasensitive detection of non-fluorescence molecules. An example of dye solution detection in a microchannel is illustrated in Fig. 8 [3]. The microchannel was 150 p,m wide and 100 p,m deep. The solvent used was benzene and the molar absorption coefficient of the porphyrine complex was 3.2x10 M cm . The expected value was cal-... 

Deaggregation of the porphyrin-diboronic acid 6 occurred when it complexed with a sugar, particularly D-fhictose, due to increased hydrophilicity. This resulted in a marked increase in absorbance at 400 nm or fluorescence intensity." Complexation of the diphenylboronic acid derivative 7 with mono- and di-saccharides was studied by c.d., resulting in a method for predicting the absolute configuration of saccharides." ... 

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