Search results for "PORP"
showing 10 items of 567 documents
Thermal broadening of the Soret band in heme complexes and in heme-proteins: role of iron dynamics
1994
We report the thermal broadening of the Soret band in heme-CO, heme-OH and protoporphyrin IX in the temperature range 300-20 K. For protoporphyrin IX the temperature dependent Gaussian line broadening follows the behavior predicted by the harmonic approximation in the entire temperature range investigated. In contrast, for heme-CO and heme-OH the harmonic behavior is obeyed only up to about 180 K and an anomalous line broadening increase is observed at higher temperatures. This effect is attributed to the onset of anharmonic motions of the iron atom with respect to the porphyrin plane. Comparison with previously reported analogous data for heme proteins enables us to suggest that the onset …
POSS-based 3D functional networks as catalysts for the conversion of carbon dioxide
2023
Oggi lo sviluppo di processi sostenibili è al centro dell'attenzione a causa delle emergenze climatiche. La Chimica Verde, con i suoi dodici principi sviluppati da Paul Anastas, si concentra sullo sviluppo di processi alternativi e più rispettosi dell'ambiente. Questa branca della chimica mostra come concetti quali la prevenzione dei rifiuti, l'uso di materie prime rinnovabili e la catalisi siano di grande importanza per rendere un processo più sostenibile. In questo contesto, l'anidride carbonica (CO2) rappresenta una delle materie prime più abbondanti, non tossiche e rinnovabili. La possibilità di riutilizzare la CO2 e di trasformare questa molecola in prodotti a valore aggiunto come i ca…
Apoptosis and cell growth arrest in A375 human melanoma cells by diorganotin(IV) and triorganotin(IV) complexes of [meso-Tetra(4-sulfonatophenyl)porp…
2011
In previous studies we have demonstrated that two derivatives of meso-Tetra(4-sulfonatophenyl)porphine (TPPS), (Bu2Sn)2TPPS and (Bu3Sn)4TPPS, cause apoptotic death of A375 melanoma cells and, at lower concentrations, arrest of cell proliferation. In the present study, we examined if the manganese metal inside the porphyrin cavity could improve the efficacy of this class of compounds. Thus, [meso- Tetra(4-sulfonatophenyl)porphine]Mn(III)Cl (=MnTPPS) derivatives, namely (Me2Sn)2MnTPPS, (Bu2Sn)2MnTPPS, (Me3Sn)4MnTPPS and (Bu3Sn)4MnTPPS, were tested on the A375 human melanoma cell line. A cytotoxicity assay showed that (Bu2Sn)2MnTPPS and (Bu3Sn)4MnTPPS were highly cytotoxic by inducing apoptosi…
Hydrogenolysis of carbon–carbon σ-bonds using water catalysed by semi-rigid diiridium(iii) porphyrins
2019
Semi-rigid diiridium(III) porphyrin alkyls with m-xylyl and p-xylyl diether linkers were synthesized. They were found to be catalysts for the carbon–carbon σ-bond hydrogenolysis of [2.2]paracyclophane under neutral conditions using water as the hydrogen source. The ether linkages in semi-rigid diiridium(III) porphyrins are unstable and undergo cleavage during the reaction.
Porphyrin and phthalocyanine photosensitizers designed for targeted photodynamic therapy of colorectal cancer
2020
Colorectal cancer is of particular concern due to its high mortality rate count. Recent investigations on targeted phototherapy involving novel photosensitizers and drug-delivery systems have provided promising results and realistic prospects for a successful medical treatment. New research trends have been focused particularly on development of advanced molecular systems offering effective photoactive species which could be selectively delivered directly into the affected cells. Porphyrins and phthalocyanines have been considered extremely attractive for this purpose due to their molecular versatility, excellent photochemical properties and multifunctional nature. In this review it has bee…
The Difficult Marriage of Triarylcorroles with Zinc and Nickel Ions.
2022
The coordination chemistry of corrole has witnessed a great improvement in the past few years and its Periodic Table has been widened to be so large that it is compared with that of porphyrins. However, Ni and Zn ions, commonly used with porphyrins for both synthetic and theoretical purposes, are sparsely reported in the case of corroles. Here, we report synthetic protocols for preparing Ni and Zn triarylcorrole complexes. In the case of Zn, the preliminary oxidation of the free base corrole in DMSO to the neutral corrole radical is a necessary step to obtain the coordination of the metal ion, because the direct reaction led to the formation of an open-chain tetrapyrrole. The Ni complex cou…
αα- and αβ-Zinc-meso-A2B2-tetraarylporphyrins with large optical responses to triethylamine
2012
Synthesis and separation of αα- and αβ-meso-A(2)B(2)-zinc(II) tetraarylporphyrin atropisomers with A = mesityl and B = ortho-phenylethynyl-phenyl are reported. Both isomers exhibit large optical responses upon axial NEt(3) coordination which are visible to the human eye and could therefore be beneficial for the design of smart amine sensing materials. The larger spectral changes as compared to Zn(TPP) are attributed to pronounced distortions of the porphyrin π-system due to steric interactions of the coordinating amine with the porphyrin periphery. This effect as well as the coordination site of NEt(3) at the αα-isomer have been studied by NMR experiments and were rationalized by DFT calcul…
Investigation of the Enantioselectivity Observed in Epoxidation Reactions Catalysed by Bis‐Strapped Chiral Porphyrins Derived from L ‐Proline
2002
The enantiomeric excesses obtained during the epoxidation reactions of p-chlorostyrene or 1,2-dihydronaphthalene catalysed by two different series of chiral porphyrins are reported. An attempt is made to correlate the enantioselectivity with the steric hindrance generated by the straps of these catalysts. It is shown that this steric hindrance is influenced by the nature of the strap and that it can be approximated. Additionally, the same strap is tethered in two different fashions on each side of the porphyrin, leading to either D2- or C2-symmetrical catalysts, for which the two sides are identically functionalised.
Tuning Reductive and Oxidative Photoinduced Electron Transfer in Amide‐Linked Anthraquinone–Porphyrin–Ferrocene Architectures
2014
Porphyrin amino acids 3a–3h with meso substituents Ar of tunable electron-donating power (Ar = 4-C6H4OnBu, 4-C6H4OMe, 4-C6H4Me, Mes, C6H5, 4-C6H4F, 4-C6H4CF3, C6F5) have been linked at the N terminus to anthraquinone Q as electron acceptor through amide bonds to give Q-PAr dyads 4a–4h. These were conjugated to ferrocene Fc at the C terminus as electron donor to give the acceptor-chromophore-donor Q-PAr-Fc triads 6a–6h. To further modify the energies of the electronically excited and charge-separated states, the triads 6a–6h were metallated with zinc(II) to give the corresponding Q-(Zn)PAr-Fc triads Zn-6a–Zn-6h. The Q-PAr1 dyad (Ar1 = C6H5) was further extended with a second porphyrin PAr2 (…
Aminoferrocene and Ferrocene Amino Acid as Electron Donors in Modular Porphyrin–Ferrocene and Porphyrin–Ferrocene–Porphyrin Conjugates
2014
New amide-linked porphyrin–ferrocene conjugates [M(PAr)–Fc] were prepared from aminoferrocene and a carboxy-substituted meso-tetraaryl-porphyrin [M = 2H, Zn; Ar = mesityl (Mes), C6F5: 3a, 3e, Zn-3a, Zn-3e]. A further porphyrin building block was attached to the second cyclopentadienyl ring of the ferrocene moiety to give the metallopeptides M(PMes)–Fc–M(PAr) (M = 2H, Zn; Ar = C6H5, 4-C6H4F: 6b, 6c, Zn-6b, Zn-6c). The effects of the Ar substituents, the porphyrin central atom M and the presence of the second porphyrin at the ferrocene hinge on the excited-state dynamics was studied by optical absorption spectroscopy, electrochemistry, steady-state emission, time-resolved fluorescence measure…