1,354,351 research outputs found
Evaluation of hydroxypyridinecarboxylic acids as new possible chelating agents for aluminium: solution chemistry, cytotoxicity, octanol/water partitioning, and chelation efficiency
No full textChelation therapy is the most efficient therapeutic approach for metal ion overload [1]. The chelators presently used for Al overload therapies, desferal and deferiprone, have several drawbacks. A multidisciplinary search for alternative molecules is being actively pursued [1-5]. We proposed some hydroxy-pyridine-carboxylic acids (HP) ([6] and references therein) as potential chelating agents for Al, as they have several requirements for an ideal chelator [3]. They have negligible or low toxicity, high stability of the Al(III) complexes at physiological conditions, low affinity towards essential metal ions to reduce undesired metal depletion, low molecular mass (less than 400 Dalton) to allow oral administration, no redox activity in vivo, and their Al(III) complex at physiological pH are hydrophilic so to enhance metal ion urinary elimination. In the present poster, the following results of several HP derivatives will be reported: Al(III)/HP solution chemistry, cytotoxicity, octanol/water partitioning, and chelation efficiency.
1. C. Hershko (Guest Editor), Sem. Hematol. 2005, 42, Issue 2, Supplement 1
2. M. J. Cunningham and D. G. Nathan, Curr. Opin. Hematol., 2005, 12, 129.
3. R. C. Hider and T. Zhou, Ann. N.Y. Acad. Sci., 2005, 1054, 141.
4. R. A. Yokel, Coord. Chem. Rev., 2002, 228, 97.
5. G. J. Kontoghiorghes, Drugs Fut., 2005, 30, 1241.
6. A. Dean, M. G. Ferlin, P. Brun, I. Castagliuolo, D. Badocco, P. Pastore, A. Venzo, G. G. Bombi and V. B. Di Marco, Dalton Trans., 2008, 1689
Poetic foundations for watery terrain – three poems below Venice
No full textThe Venetian lagoon is a geographical extremity imperilled by extreme weather events. Increasingly regular flooding endangers the lives and livelihoods of Venetians, not to mention the built and natural environments around them. In response to the documentary film Saving Venice (Bulling, 2022), I have produced a short series of poems that address the existential threat that climate change poses to Venice. The first poem refers to the MOSE sea-gates project, a feat of engineering designed to prevent catastrophic flooding of the lagoon. The second takes up the motif of the foundations of Venice, specifically the use of wooden pylons that excise oxygen and moisture and prevent the city from sinking. The third poem deals with the effects of erosion caused by shipping. This poetic work builds upon my previous creative and critical output focussed on Venice as a liminal and literary space, notable for the in-between-ness that comes from being a city built on water (Venzo, 2015; Venzo 2019; Venzo 2022). Extending this scholarship on Venice as a city both real and imagined through writing, these poems represent this watery terrain as simultaneously poetic and ecological (Bryson, 2002). Using the technique of concrete poetry (Draper, 1971; Bray, 2012), each poem syncretises these hidden elements that speak to the effects of extremity, to address the “slipperiness” of this physical environment and construct new foundations in word and image
Dependence of nonadiabatic intramolecular dissociative electron transfers on stereochemistry and driving force
No full textAbstract: The intramolecular dissociative electron transfer (ET) across donor-bridge-acceptor (D-B-A) systems consisting in a series of trans ring-substituted 4-benzoyloxy-1-methylcyclohexyl bromides in N,N-dimethylformamide has been studied by cyclic voltammetry. X-Ray diffraction crystallography and 1H NMR spectroscopy showed that the investigated D-B-A molecules have the trans(cyclohexane) axial(benzoyloxy)-axial(bromide) conformation and the same D/A orientation. As previously found with the corresponding cis equatorial,axial conformers (S. Antonello, F. Maran, J. Am. Chem. Soc. 120 (1998) 5713), electroreduction entails initial formation of a benzoate radical anion (donor D) followed by intramolecular dissociative ET to the C-Br bond (acceptor A) through the 1,4-cyclohexanediyl spacer (bridge B). The intramolecular ETs are exergonic, with driving force in the range from 0.5 to 1.2 eV. The electrode process follows the same mechanism previously established for the cis series of isomers, but the ET rate constants obtained with the trans axial,axial isomers are larger by 1.1 order of magnitude. Molecular models and X-ray crystallography structures show that the rate increase cannot be ascribed to a decrease of the distance between the electron-exchanging centers and, therefore, the results witness a remarkable stereochemical effect on the ET rate. Application of the German-Kuznetsov theory of nonadiabatic dissociative ET (E. D. German, A. M. Kuznetsov, J. Phys. Chem. 99 (1995) 9095) shows that the rate increase is caused by a more favorable coupling between the electronic wave functions describing the reagent and product states. The data and trends are discussed in comparison with other nonadiabatic intramolecular dissociative ET processes
Al(III) Complexes of Saccharic Acid and Mucic Acid: a Solution and a Solid State Study
No full textThe AlIII-binding abilities of two aldaric acids, D-saccharic acid and mucic acid (the neutral form is denoted as H2L), were studied in solution by means of pH potentiometric, 1H and 13C NMR, and ESI-MS techniques. The most probable conformations and isomeric binding modes of the complexes formed in solution were determined by density functional theory (DFT) calculations. A solid D-saccharic acid complex K2[{Al(LH−2)(H2O)}2]⋅H2O was isolated and crystallographically characterised. The two alcoholic hydroxy groups α to the terminal COO− groups were found to take part in the coordination, but in different ways. One of them coordinates in a bridging mode. Detailed ESI-MS and NMR studies proved that the complex retains its structure in solution. However, depending on the ligand and the pH, such complexes may exist in two isomeric forms. DFT calculations on the ion [{Al(LH−2)(H2O)}2]2− revealed that several orbitals participate in stabilizing the dimeric arrangement
Scuola e itinerari formativi dallo Stato pontifico a Roma Capitale
No full textIl volume affronta la storia dello sviluppo dell'istruzione primaria nello Stato pontificio e a Roma capital
Al-III ion complexes of saccharic acid and mucic acid: A solution and solid-state study
No full textThe Al-III-binding abilities of two aldaric acids, D-saccharic acid and mucic acid (the neutral form is denoted as H,L), were studied in solution by means of pH potentiometric, H-1 and C-13 NMR, and ESI-MS techniques. The most probable conformations and isomeric binding modes of the complexes formed in solution were determined by density functional theory (DFT) calculations. A solid D-saccharic acid complex K-2[{Al(LH-2)(H2O)}(2)](H2O)-H-. was isolated and crystallographically characterised. The two alcoholic hydroxy groups a to the terminal COO- groups were found to take part in the coordination, but in different ways. One of them coordinates in a bridging mode. Detailed ESI-MS and NMR studies proved that the complex retains its structure in solution. However, depending on the ligand and the pH, such complexes may exist in two isomeric forms. DFT calculations on the ion [{Al(LH-2)(H2O)}(2)](2-) revealed that several orbitals participate in stabilizing the dimeric arrangement
Scuola e itinerari formativi dallo Stato pontifico a Roma capitale. L'istruzione secondaria
No full textIrreversible Insertion of Benzonitrile into Platinum(II)-Nitrogen Bonds of Nucleobase Complexes. Synthesis and Structural Characterisation of Stable Azametallacycle Compounds
No full textDeprotonation of 1-methylcytosine (1-MeCy) and 9-methyladenine (9-MeAd) promoted by cis-[L2Pt(μ-OH)]2(NO3)2 (L = PPh3, PMePh2, 1/2dppe) in PhCN causes the irreversible insertion of a nitrile molecule into the Pt−N4 and Pt−N6 bonds of the cytosinate and adeninate ligands, respectively, to form the stable azametallacycle complexes cis-[L2PtNH═C(Ph){1-MeCy(−2H)}]NO3 (L = PPh3, 1; PMePh2, 2; 1/2dppe, 3) and cis-[L2PtNH═C(Ph){9-MeAd(−2H)}]NO3 (L = PPh3, 4; PMePh2, 5) containing the deprotonated form of the molecules (Z)-9-N-(1-methyl-2-oxo-2,3-dihydropyrimidin-4(1H)-ylidene)benzimidamide and (Z)-N-(9-methyl-1H-purin-6(9H)-ylidene)benzimidamide. Single-crystal X-ray analyses of 2 and 4 show the metal coordinated to the N3 cytosine site [Pt−N3 = 2.112(7) Å̊] and to the N1 site of adenine [Pt−N1 = 2.116(6) Å̊] and to the nitrogen atom of the inserted benzonitrile [Pt−N2 = 2.043(6) and 2.010(6) Å̊ in 2 and 4, respectively], with the exocyclic nucleobase amino nitrogen bound to the carbon atom of the CN group. Complex 2, in solution, undergoes a dynamic process related to a partially restricted rotation around Pt−P bonds, arising from a steric interaction of the oxygen atom of the cytosine with one ring of the phosphine ligands. The reaction of 4 with acetylacetone (Hacac) causes the quantitative protonation of the anionic ligand, affording the acetylacetonate complex cis-[(PPh3)2Pt(acac)]NO3 and the free benzimidamide NH═C(Ph){9-MeAd(−H)}. In the same experimental conditions, complex 3 reacts with Hacac only partially
New Perspectives in Chelation Therapy of Aluminium(III) and Iron(III) Overload
No full textThe overload of metal ions may produce several pathologies because of toxic degenerative processes in the involved parenchyma[1]. In particular, iron (Fe) overload is a common adverse consequence of the chronic transfusional therapies for thalassemic patients, and aluminium (Al) overload may be observed in uremic patients. The overload of Fe and Al in central nervous system has been suggested to be involved in neurodegenerative disorders like Alzheimer’s and Parkinson’s disease.
Current treatment options for metal ion overload are designed to remove tissue deposits which cause the toxic
effects. Chelation therapy is the most efficient therapeutic approach for metal ion overload[2]. The chelators presently
used for Al(III) and Fe(III) overload therapies, desferal and deferiprone, have several drawbacks. A multidisciplinary research for alternative molecules is being actively pursued [2-5].
We proposed some isomeric 3,4- and 4,3-hydroxypyridinecarboxylic acids (HP) ([7] and references therein) as potential chelating agents for aluminium and iron, as they have several requirements of an ideal chelator [3]. They have negligible or low toxicity, high stability of the metal complexes at physiological conditions, low affinity towards essential metal ions to reduce undesired metal depletion, low molecular mass (less than 400 Dalton) to allow oral administration, no redox activity in vivo. Their metal complexes at physiological pH are hydrophilic so to enhance metal ion urinary elimination. In the present poster, the following results for some HP derivatives will be reported: synthesis of the ligands, metal/HP solution chemistry, cytotoxicity, octanol/water partitioning, and chelation efficiency.
1. N. C. Andrews, N. Eng. J, Med., 1999, 341, 1986
2. C. Hershko (Guest Editor), Sem. Hematol. 2005, 42, Issue 2, Supplement 1
3. M. J. Cunningham and D. G. Nathan, Curr. Opin. Hematol., 2005, 12, 129.
4. R. C. Hider and T. Zhou, Ann. N.Y. Acad. Sci., 2005, 1054, 141.
5. R. A. Yokel, Coord. Chem. Rev., 2002, 228, 97.
6. G. J. Kontoghiorghes, Drugs Fut., 2005, 30, 1241.
7. A. Dean, M. G. Ferlin, P. Brun, I. Castagliuolo, D. Badocco, P. Pastore, A. Venzo, G. G. Bombi and V. B. Di
Marco, Dalton Trans., 2008, 1689
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