Intraligand Fluorescence Research Articles

Coexisting intraligand fluorescence and phosphorescence of hafnium(IV) and thorium(IV) porphyrin complexes in solution

The closed-shell metalloporphyrins Hf(TPP)(OAc) 2 and Th(TPP)(acac) 2 (TPP=dianion of tetraphenylporphyrin, OAc=acetate, acac=acetylacetonate) display intraligand fluorescence and additional heavy-atom-induced intraligand phosphorescence, which is observed at room temperature in fluid solution and very efficiently quenched by O 2 with potential significance for the sensing of trace amounts of dioxygen.

Synthesis and spectroscopic properties of (oxytetracycline)tricarbonylrhenium(I) chloride

The complex (OTC)Re I(CO) 3Cl, with OTC=oxytetracycline, has been prepared and characterized by elemental analysis, ESI–MS, IR and UV–Vis spectroscopy. The complex, which contains OTC as a bidentate ligand, shows an OTC intraligand fluorescence at λ max=570 nm with Φ=2×10 −3 at λ exc=390 nm.

Reductive fluorescence quenching of the photoexcited dihydroxy antimony(V) tetraphenylporphine cation in acetonitrile solution

At 298 K in acetonitrile solution, the dihydroxy antimony(V) tetraphenylporphine cation [Sb V(TPP)(OH) 2] + shows an intraligand fluorescence at λ max=598 nm with τ F=1.46 ns and a quantum yield of φ F = 0.028. While the presence of dioxygen has no significant effect on the value of φ F, the fluorescence is very efficiently quenched by Cl −, Br −, I − and SCN − ions. At quencher concentrations below 10 −2 M the reaction follows Stern–Volmer kinetics with high rate constants close to the diffusion-controlled limit. Based on the observation of the reduced complex [Sb III(TPP)] + as a permanent photoredox product, the quenching mechanism can be characterized as a bimolecular electron transfer process involving the lowest excited singlet (ππ *) state of the [Sb V(TPP)(OH) 2] + cation.

Photoluminescence of thorium(IV) 2-methyl-8-quinolinolate

Thorium(IV)(2-methyl-8-quinolinolate) 4 shows an intraligand fluorescence at λ max=510 nm. In addition, the complex displays a heavy-atom-induced intraligand phosphorescence ( λ max=775 nm) which appears at room temperature in solution and can be quenched by oxygen. It is suggested that Th(IV) is generally suited as an excellent probe for the phosphorescence of organic ligands.

Photoluminescent properties and molecular structure of [{Au(PPh3)}2(µ-bbzim)] and[{Au(PPh3)}4(µ-bbzim)][ClO4]2(bbziM = 2,2′-bibenzimidazolate)

The tetranuclear [{Au(PPh3)}4(µ-bbzim)][ClO4]2 and dinuclear [{Au(PPh3)}2(µ-bbzim)] complexes with 2,2′-bibenzimidazolate (bbzim) as bridging ligand have been characterized by X-ray crystallography. The intramolecular Au–Au separations in [{Au(PPh3)}4(µ-bbzim)][ClO4]2 are 3.157(1)–3.222(1)A. Upon excitation at 330 nm, both complexes display intense intraligand fluorescence and phosphorescence in fluid solution at room temperature.