The main metabolites of caffeic and ferulic acids (ferulic acid-4′-O-sulfate, caffeic acid-4′-O-sulfate, and caffeic acid-3′-O-sulfate), the most representative phenolic acids in fruits and ...vegetables, and the acyl glucuronide of ferulic acid were synthesized, purified, and tested for their antioxidant activity in comparison with those of their parent compounds and other related phenolics. Both the ferric reducing antioxidant power (FRAP) assay and the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging method were used. Ferulic acid-4′-O-sulfate and ferulic acid-4′-O-glucuronide exhibited very low antioxidant activity, while the monosulfate derivatives of caffeic acid were 4-fold less efficient as the antioxidant than caffeic acid. The acyl glucuronide of ferulic acid showed strong antioxidant action. The antioxidant activity of caffeic acid-3′-O-glucuronide and caffeic acid-4′-O-glucuronide was also studied. Our results demonstrate that some of the products of phenolic acid metabolism still retain strong antioxidant properties. Moreover, we first demonstrate the ex vivo synthesis of the acyl glucuronide of ferulic acid by mouse liver microsomes, in addition to the phenyl glucuronide.
The insertion of a -NO2 group onto the corrole framework represents a key step for subsequent synthetic manipulation of the macrocycle based on the chemical versatility of such a functionality. Here ...we report results of the investigation of a copper 3-NO2-triarylcorrolate in nucleophilic aromatic substitution reactions with "active" methylene carbanions, namely diethyl malonate and diethyl 2-chloromalonate. Although similar reactions on nitroporphyrins afford chlorin derivatives, nucleophilic attack on carbon-2 of corrole produces 2,3-difunctionalized Cu corrolates in acceptable yields (ca. 30%), evidencing once again the erratic chemistry of this contracted porphyrinoid.
Methoxy Ge Triphenylcorrole Ge(TPC)OCH
3
has been recently synthesized and deposited as thin film by the Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. In the last few years, corroles ...have been the object of an increasing number of studies and MAPLE technique seems to be a very promising deposition method for organic and polymeric films, producing good results for applications in chemical gas sensing layers production. In this work Ge(TPC)OCH
3
thin films were deposited by both spin coating and MAPLE techniques for comparison. The morphology of the films was investigated by Atomic Force Microscopy (AFM), while their optical properties were analyzed by photoluminescence (PL) and UV-vis absorption measurements and were compared with the ones of the starting solution. The film absorption spectrum presented the same peaks with the same relative intensities of that recorded in solution. The luminescence spectra were acquired periodically to evaluate the aging effects and no detectable variations were recorded over a period of 1 month.
We study the infrared emission at 1.54 μm of an organolanthanide complex, Er(III)-tetraphenylporphyrin Er(TPP)acac, both as a result of direct optical excitation and via energy transfer from host ...π-conjugate polymers of type poly(arylene–ethynylene) PAE. In the first case, the emission of the neat complex is characterized in inert transparent materials and a value of the quantum yield at 1.54 μm
φ
IR=4×10
−4 is measured. Then, fluorescence resonance transfer is investigated in blends of Er(TPP)acac with PAEs by monitoring the quenching of the polymer fluorescence along with the enhancement of both the visible emission of the ligand and the near-infrared band of Er
3+. These different procedures allow a detailed analysis of the transfer efficiency within a specific implementation of the Förster model for polymeric donors. The experimental values of the critical radius
R
0, ranging from 1.3 to 2.5 nm for the different blends, are in good agreement with theory for a wide interval of the physical and spectroscopic parameters. This suggests that other mechanisms for excitation transfer do not play a significant role in these materials.
Two 1530-nm emitting
co-polymers have been synthesized by incorporating differently substituted erbium–porphyrin complexes into the conjugated backbone of a polyaryleneethynylene structure. The near ...infrared emission presents an excitation spectrum that extends in the red range more than in any other organolanthanide molecule indicating the formation of highly π-conjugated systems.
Two 1530-nm emitting
co-polymers have been synthesized by incorporating differently substituted erbium–porphyrin complexes into the conjugated backbone of a polyaryleneethynylene structure. While the near infrared (NIR) emission exhibits the typical narrow width of lanthanide ions, the absorption and excitation spectra are quite broad and extend in the red range more than in any other organolanthanide molecule. This indicates that highly π-conjugated systems are effectively formed. For both polymers, however, the quantum efficiency is as low as in the isolated complexes, which suggests that the increased conjugation does not influence the intramolecular transfer and the quenching processes of the erbium ion.
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