Coumarins, as a family of molecules, exhibit a wide range of fluorescence emission properties. In many cases, this fluorescence is extremely sensitive to the local environment of the molecule, especially the local polarity and microviscosity. In addition, coumarins show a wide range of size, shape, and hydrophobicity. These properties make them especially useful as fluorescent probes of heterogeneous environments, such as supramolecular host cavities, micelles, polymers and solids. This article will review the use of coumarins to probe such heterogeneous systems using fluorescence spectroscopy.

https://www.mdpi.com/1420-3049/14/1/210/pdf

The use of coumarins as environmentally-sensitive fluorescent probes of heterogeneous inclusion systems

Amazon Photochemistry of Polypyridine and Porphyrin Complexes.The second part deals with rutheniumII polypyridyl complexes linked. Photochemistry of Polypyridine and Porphyrin Complexes Academic Press.A series of RuII complexes were synthesized pdf417 activex crack with the deprotonated forms of. Ruthenium coordination compounds containing polypyridyl ligands. Photochemistry and Photobiology, 2010, 86: 12301236.

Photochemistry of polypyridine and porphyrin complexes

This review describes new reactions catalyzed by recently discovered types of metal complexes and catalytic systems (catalyst + co-catalyst). Works of recent years (mainly 2010–2016) devoted to the oxygenations of saturated, aromatic hydrocarbons and other carbon–hydrogen compounds are surveyed. Both soluble metal complexes and solid metal compounds catalyze such transformations. Molecular oxygen, hydrogen peroxide, alkyl peroxides, and peroxy acids were used in these reactions as oxidants.

New Trends in Oxidative Functionalization of Carbon–Hydrogen Bonds: A Review

/pdf/investigation-of-sds-dtab-and-ctab-micelle-microviscosities-rz6ug564eu.pdf

Investigation of SDS, DTAB and CTAB micelle microviscosities by electron spin resonance

In spite of the fact that cadmium(II) has been recognized as a highly toxic element and that excessive exposure to this metal ion has been reported to have many adverse effects on human health, very few selective and specific fluorescent probes are available for imaging Cd(2+) in living cells. Herein, we report the spectroscopic and photochemical characterization of 5-(5-chloro-8-hydroxyquinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane (L) as a fluorescent sensor for the selective imaging of Cd(2+) in living cells. In particular, the response of L to Cd(2+) was first assessed in aqueous solutions, sodium dodecyl sulfate micelles, and liposomes, and subsequently in living cells by fluorescence microscopy techniques. Cytofluorimetric analyses of leukemic HL-60 cells loaded with L also allowed evaluation of the toxicity of the probe and the selective analysis of its intracellular fluorescence in the presence of Cd(2+). Furthermore, the 1:1 complex species [Cd(L)H(2)O](2+) responsible for the OFF-ON chelation enhancement of fluorescence (CHEF) effect on L was structurally characterized; time-dependent DFT calculations allowed the prediction of theoretical excitations, which were comparable with the experimental ones.

A Selective, Nontoxic, OFF–ON Fluorescent Molecular Sensor Based on 8‐Hydroxyquinoline for Probing Cd2+ in Living Cells

Kinetic study of meso‐tetraphenylporphyrin synthesis under microwave irradiation

The oxidation of styrene and derivatives with H 2 O 2 catalyzed by manganese porphyrins in acetonitrile is described. The effect of the imidazolium substituent on the catalytic efficiency has been also considered. The thermodynamic analysis has indicated that enthalpy rules styrene oxidation when catalysts Mn(Porph)-1 and Mn(Porph)-2 are used whereas the entropy is the driven force for Mn(Porph)-3 and Mn(Porph)-4 catalyzed reactions. Interestingly, an enthalpy–entropy compensation phenomenon is observed when comparing the thermodynamic results obtained for catalysts Mn(Porph)-3 and Mn(Porph)-4 . Hammett plots for the studied manganese porphyrins provided small ρ -values, and this is typical for multi-step reactions, indicating that there is no significant charge separation in the transition state. For Mn(Porph)-1 and Mn(Porph)-2 the formation of multiple active species can be put forward whereas for Mn(Porph)-3 and Mn(Porph)-4 a concerted-type mechanism, via metalloxetane intermediate, fits well with the values obtained for those catalysts. The imidazolium-based catalysts have shown to be efficient catalysts in styrene and derivatives oxidation with hydrogen peroxide.

Oxidation of styrene and of some derivatives with H2O2 catalyzed by novel imidazolium-containing manganese porphyrins: A mechanistic and thermodynamic interpretation

Homogeneous olefin epoxidation catalysed by an imidazolium-based manganese porphyrin

It was shown that 3-benzoxazol-2-yl-7-( N , N -diethylamino)-chromen-2-one is suitable to perform as a fluorescent probe, to analyse physical parameters related to organised systems. Micropolarity, microviscosity, critical aggregation and micelle concentration data, in SDS and CTAB micelles, using the proposed compound as fluorescent probe show the compound is allocated, in both micelles, in a strongly polar hydrophilic region (the parameter E T (30) is equal to 61.3 and 61.9 kcal/mol, respectively, in SDS and CTAB micelles, whereas Lippert’s Δ f parameter is equal to 0.35). The CMC of SDS in pure water (7.5×10 −3  mol/dm 3 ) agrees with the reported values. For SDS and CTAB micelles in buffered medium (PBS buffer, pH 7.4, NaCl 0.9%, w/w), the estimated critical aggregation concentrations (4.6×10 −3 and 9.2×10 −4  mol/dm 3 , respectively, for SDS and CTAB) also agree with the results obtained using equivalent conditions.

3-Benzoxazol-2-yl-7-(N,N-diethylamino)-chromen-2-one as a fluorescence probe for the investigation of micellar microenvironments

Cheap and abundant natural products can be transformed into products of higher commercial value One of the approaches for the functionalization of organic compounds is their oxidation in the presence of an oxygen atom donor, under the infl uence of a suitable catalyst Metalloporphyrins, with structures based on the well known meso-tetraphenylporphyrin (TPPH2), are amongst the catalysts commonly studied and have demonstrated to be effi cient in the oxygenation of organic compounds These transformations have been studied in the presence of different oxygen atom donors However, our biomimetic oxidative approach is based on the use of clean and environmentally benign hydrogen peroxide in the presence of metalloporphyrins This approach will be outlined in this review

Rodrigo De Paula

Papers

Kinetic study of meso‐tetraphenylporphyrin synthesis under microwave irradiation

Oxidation of styrene and of some derivatives with H2O2 catalyzed by novel imidazolium-containing manganese porphyrins: A mechanistic and thermodynamic interpretation

Homogeneous olefin epoxidation catalysed by an imidazolium-based manganese porphyrin

3-Benzoxazol-2-yl-7-(N,N-diethylamino)-chromen-2-one as a fluorescence probe for the investigation of micellar microenvironments

Metalloporphyrins in the biomimetic oxidative valorization of natural and other organic substrates