Showing papers by "Vieri Fusi published in 2009"

Phosphates sensing: two polyamino-phenolic zinc receptors able to discriminate and signal phosphates in water.

Abstract: Two Zn(II)-dinuclear systems were studied as receptors for phosphates; they were obtained by using the two polyamino-phenolic ligands 3,3′-bis[N,N-bis(2-aminoethyl)aminomethyl]-2,2′-dihydroxybiphen...

Polynuclear complexes: two amino-phenol macrocycles spaced by several linear polyamines; synthesis, binding properties, and crystal structure.

Abstract: The synthesis and characterization of the new polytopic ligands 1,14-bis(3,6,9-triaza-15-hydroxybicyclo[9.3.1]pentadeca-11,13,1(15)-trien-6-yl)-3,6,9,12-tetraazatetradecane L1, 1,15-bis(3,6,9-triaza-15-hydroxybicyclo[9.3.1]pentadeca-11,13,1(15)-trien-6-yl)-3,6,10,13-tetraazapentadecane L2, and 1,16-bis(3,6,9-triaza-15-hydroxybicyclo[9.3.1]pentadeca-11,13,1(15)-trien-6-yl)-3,7,10,14-tetraazahexadecane L3, containing two equal amino-phenol macrocycles spaced by several linear tetraamines, are reported. The basicity and coordination behavior toward the Cu(II) ion were potentiometrically determined in aqueous solution at 298.1 K. All the ligands show similar acid-base properties behaving as octaprotic bases in the examined pH range (pH = 2-12). The acid protons of L1-L3 cannot be removed under the experimental conditions used; thus, the main deprotonated species obtainable in aqueous solution are the neutral ligands, having amphionic character as demonstrated by UV-vis experiments. These species are able to form mono-, di-, and trinuclear Cu(II) complexes having stoichiometry [CuL](2+), [Cu(2)L](4+), and [Cu(3)L](6+), respectively, that can lose one or two protons giving rise to [CuH(-1)L](+), [Cu(2)H(-2)L](2+), and [Cu(3)H(-2)L](4+). Depending on the used ligand to metal molar ratio, the mono-, di-, or trinuclear species prevail over the others in solution. Both di- and trinuclear complexes are able to add secondary ligands (such as OH(-)), and in some cases two Cu(II) can cooperate to stabilize them by coordinating the guest in a bridged conformation. The structure of the [Cu(2)L3](4+) cation was resolved by X-ray analysis of the {[Cu(2)L3](ClO(4))(4) x 3 H(2)O}(2) x H(2)O crystalline complex. It shows that each Cu(II) is penta-coordinated by one phenolate oxygen, two amine functions, belonging to one macrocyclic unit, and two amine functions of the spacer; in this species the distance between the two Cu(II) is about 5.3 A.

Two polyaminophenolic fluorescent chemosensors for H+ and Zn(II). Spectroscopic behaviour of free ligands and of their dinuclear Zn(II) complexes

Abstract: The UV-Vis and fluorescence optical properties of the two polyamino-phenolic ligands 3,3′-bis[N,N-bis(2-aminoethyl)aminomethyl]-2,2′-dihydroxybiphenyl (L1) and 2,6-bis{[bis(2-aminoethyl)amino]methyl}phenol (L2) were investigated in aqueous solution at different pH values as well as in the presence of Zn(II) metal ion. Both ligands show two diethylenetriamine units separated by the 1,1′-bis(2-phenol) (BPH) or the phenol (PH) for L1 and L2, respectively. Both ligands are fluorescence-emitting systems in all fields of pH examined, with L1 showing a higher fluorescence emission than L2. In particular, the emission of fluorescence mainly depends on the protonation state of the phenolic functions and thus on pH. The highest emitting species is H3L3+ for both systems, where the BPH is monodeprotonated (in L1) and the PH is in the phenolate form (in L2). On the contrary, when BPH and PH are in their neutral form both ligands show the lowest fluorescence, since H-bonds occurring between the phenol and the closest tertiary amine functions decrease fluorescence. The Zn(II)-dinuclear species are also fluorescent in the pH range where they exist; the highest emitting species being [Zn2(H−2L1)]2+ and [Zn2(H−1L2)]3+ which are present in a wide range of pH including the physiological one. Fluorescence experiments carried out at physiological pH highlighted that, in the case of L1, the presence of Zn(II) ion in solution produces a simultaneous change in λem with a drop in fluorescence due to the formation of the [Zn2(H−2L1)]2+ species, while, in the case of L2, it gives rise to a strong CHEF effect (a twenty-fold enhancement was observed) due to the formation of the [Zn2(H−1L2)]3+ species. These results, supported by potentiometric, 1H and 13C NMR experiments, are of value for the design of new efficient fluorescent chemosensors for both H+ and Zn(II) ions.

Derivatives of [(3-hydroxy-4 pyron-2-yl)methyl]-amine and use thereof as anti-neoplastic drugs

Abstract: The present invention relates to compounds having general formula (I), i.e. poly- alkyl -bis -maltolic molecules and in particular to derivates of [ (3 -hydroxy- 4 -pyron- 2 -yl) methyl] -amine and pharmaceutically acceptable salts thereof, and to the use thereof as anti -neoplastic drugs, in particular, for the preparation of a medicament for the treatment of neoplastic diseases.