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ABSTRACT: The reactions of 4,5,6,7-tetrathiocino-[1,2-b:3,4-b']-1,3,8,10-tetrasubstituted-diimidazolyl-2,9-dithiones (R(2) ,R'(2) -todit; 1: R=R'=Et; 2: R=R'=Ph; 3: R=Et, R'=Ph) with Br(2) exclusively afforded 1:1 and 1:2 "T-shaped" adducts, as established by FT-Raman spectroscopy and single-crystal X-ray diffraction in the case of complex 1⋅2 Br(2) . On the other hand, the reactions of compounds 1-3 with molecular I(2) provided charge-transfer (CT) "spoke" adducts, among which the solvated species 3⋅2 I(2) ⋅(1-x)I(2) ⋅x CH(2) Cl(2) (x=0.94) and (3)(2) ⋅7 I(2) ⋅x CH(2) Cl(2,) (x=0.66) were structurally characterized. The nature of all of the reaction products was elucidated based on elemental analysis and FT-Raman spectroscopy and supported by theoretical calculations at the DFT level.
Chemistry - An Asian Journal 12/2012; · 4.50 Impact Factor
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ABSTRACT: Elemental gold powder is easily oxidised under mild reaction conditions with 1 : 1 I(2)-adducts of the thioamides 3-methyl-benzothiazole-2-thione (mbtt) and 1-methyl-1H-benzimidazole-2(3H)-thione (mbit) with separation of the ionic complexes [Au(I)(mbtt)(2)]I(3) () and [(mtbiH)(2)](AuI(4))I(3) () [mtbiH = the imido protonated form of 2-(methylthio)benzimidazole] (gold oxidation yield >78% and 45%, respectively). The X-ray crystal structure of shows the Au(i) centre linearly bound by two neutral ligands via the sulphur atom, whereas the X-ray crystal structure of shows the Au(iii) centre surrounded by four iodides in a square-planar arrangement. The oxidising/complexing properties of the mbtt·I(2) and mbit·I(2) adducts were interpreted considering the S-donor to I(2) interaction that leads to a charge separation between the I(b) and I(t) iodine atoms in the fragment S-I(b)-I(t). The oxidation of gold in a non-aqueous solvent by thioamide-I(2) adducts could be a promising alternative process to the numerous hydrometallurgical ones for the recovery of gold from secondary sources.
Dalton Transactions 10/2012; · 3.84 Impact Factor
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ABSTRACT: Cu(II) complexes with 1,10-orthophenanthroline (phen) show cytotoxic and antitumoral effects. To enhance and exploit these features, we studied complexes containing one or two phen units together with N,N'-substituted-imidazolidine-2-thione (L). We synthesized and structurally characterized the precursor molecule Cu(phen)(OH(2))(2)(OClO(3))(2), and determined the complex formation constants of [Cu(phen)(L)](2+). We studied the cytotoxic activity of [Cu(phen)(2)(L)](ClO(4))(2) versus human hematologic (CCRF-CEM and CCRF-SB) and solid tumor-derived cell lines (K-MES-1, DU-145). The cytotoxic activities, in the 1-3 μM range, show that our Cu(II)-complexes possess comparable inhibitory activities against both leukemia and carcinoma cells, unlike the majority of antineoplastic agents, usually more potent against hematologic cancer cells than against solid tumor cells. Because the free Cu(II) ion is reduced by glutathione (GSH), we studied the reactivity of our complexes with GSH, providing evidence that no redox reaction occurred under the chosen experimental conditions. Complex formation equilibria were present, studied by spectrophotometric titrations. The redox properties of the prepared compounds were also investigated by cyclic voltammetry, confirming that the mixed Cu(II) complexes were resistant to reduction.
Journal of inorganic biochemistry 05/2012; 114:28-37. · 3.25 Impact Factor
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ABSTRACT: [PtL(6)X] {X = Cl or NCS and L(6) = 5-mesityl-1,3-di(2-pyridyl)-benzene} display similar luminescence in solution but, in the solid state, the packing of the molecules is different, with short PtPt interactions for X = NCS, leading to a red-shifted emission band. The effect has been used to generate OLEDs that emit squarely in the NIR region (855 nm).
Chemical Communications 02/2012; 48(26):3182-4. · 6.17 Impact Factor
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ABSTRACT: The new mineral sarrabusite Pb(5)CuCl(4)(SeO(3))(4) has been discovered in the Sardinian mine of Baccu Locci, near Villaputzu. It occurs as small lemon-yellow spherical aggregates of tabular crystals (< 10 µm) of less than 100 µm in diameter. The crystal structure has been solved from and refined against electron diffraction of a microcrystal. Data sets have been measured by both a manual and an automated version of the new electron-diffraction tomography technique combined with the precession of the electron beam. The sarrabusite structure is monoclinic and consists of (010) layers of straight chains formed by alternating edge-sharing CuO(4)Cl(2) and PbO(8) polyhedra parallel to the c axis, which share corners laterally with two zigzag corner-sharing chains of PbO(6)Cl(2) and PbO(4)Cl(4) bicapped trigonal prisms. These blocks are linked together by SeO(3)(2-) flat-pyramidal groups.
Acta crystallographica. Section B, Structural science 02/2012; 68(Pt 1):15-23. · 1.80 Impact Factor
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ABSTRACT: The new mineral sarrabusite Pb5CuCl4(SeO3)4 has been
discovered in the Sardinian mine of Baccu Locci, near
Villaputzu. It occurs as small lemon–yellow spherical aggregates
of tabular crystals (< 10 mm) of less than 100 mm in
diameter. The crystal structure has been solved from and
refined against electron diffraction of a microcrystal. Data sets
have been measured by both a manual and an automated
version of the new electron-diffraction tomography technique
combined with the precession of the electron beam. The
sarrabusite structure is monoclinic and consists of (010) layers
of straight chains formed by alternating edge-sharing CuO4Cl2
and PbO8 polyhedra parallel to the c axis, which share corners
laterally with two zigzag corner-sharing chains of PbO6Cl2 and
PbO4Cl4 bicapped trigonal prisms. These blocks are linked
together by SeO2�
3 flat-pyramidal groups.
Acta crystallographica. Section B, Structural science 01/2012; 68:15-23. · 1.80 Impact Factor
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ABSTRACT: The I(2)-adducts of drugs propylthiouracil (PTU) and methimazole (MeImSH) oxidize liquid mercury in dichloromethane to separate in good yield the neutral complexes [HgI(2)(PTU)(2)·MeOH] (1), [HgI(2)(PTU)(2)·HgI(2)] (2), and [Hg(2)I(4)(MeImSH)(2)] (3). The single crystal X-ray diffraction analysis of 1-2 shows that the Hg(II) center is coordinated by two sulfur atoms and by two iodine atoms in a tetrahedral geometry. In complex 2 almost linear molecules of HgI(2) result encapsulated in the crystal packing enfolded by the hydrophobic propyl appendages of coordinated units of PTU. X-ray analysis of complex 3 shows the presence of dimeric [Hg(2)I(4)(MeImSH)(2)] molecules to form Hg(2)S(2)I(4) cores. The intra- and intermolecular hydrogen bonds concerning PTU and MeImSH have been evaluated. The oxidation of Hg(0) to Hg(II) requires a two-electron transfer process accomplished by an oxidative addition from the "activated" iodine moiety. The oxidizing and complexing properties of PTU-I(2) and MeImSH-I(2) have been interpreted considering the S-donor to I(2) interaction that leads to a charge separation between the sulfur-bound iodine atom S-I and the terminal I atom. Compounds 1, 2, and 3 react with tetraethylammonium iodide to separate the compound (Et(4)N)(2)[HgI(4)] with the release of free PTU and MeImSH, respectively. The reported dissolution technique could be applied to the recovery of mercury from waste electrical and electronic equipment (WEEE) scrap, the nature of complexes 1-3 makes it possible the easy separation of the mercury as tetraiodomercurate anion and the recycling of the donors.
Dalton Transactions 03/2011; 40(17):4505-13. · 3.84 Impact Factor
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ABSTRACT: The synthesis, crystal structures, physicochemical properties and complex formation constants of [Cu(phen)(2)(L)](ClO(4))(2) complexes, where phen is 1,10-ortho-phenanthroline and L is a series of substituted imidazolidine-2-thione, have been studied. Single crystal X-ray diffraction revealed a distorted trigonal-bipyramidal geometry for all the molecules. The complex formation constants were determined in nonaqueous media by spectrophotometric measurements. Testing copper(II) complexes in mouse neuroblastoma N2a cells persistently infected with the 22L strain of the scrapie prion protein (22L-N2a) resulted in high cytotoxicity but no antiprion activity at nontoxic doses.
Journal of inorganic biochemistry 03/2011; 105(3):329-38. · 3.25 Impact Factor
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ABSTRACT: Organic complexes of lanthanides trivalent ions such as Nd3+ and Er3+ are receiving increasing attention
in view of their use as dopants in polymeric telecommunication devices. Their employment is however
currently limited by their small emission quantum yield (QY) due to non-radiative deactivation of near
infrared (NIR) transitions through electronic-vibrational energy transfer (ET). A complete modeling of
this quenching effect is presented here and successfully tested on a purpose-made Er3+ complex. This
method provides “a priori” information/predictions regarding the emission properties of new complexes
thus establishing useful guidelines for the design and synthesis of new molecules and for the engineering
of materials suitable in technological applications.
Synthetic Metals 01/2011; · 1.83 Impact Factor
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Adriana Valore,
Marcella Balordi,
Alessia Colombo,
Claudia Dragonetti,
Stefania Righetto,
Dominique Roberto,
Renato Ugo,
Tiziana Benincori,
Giovanni Rampinini,
Francesco Sannicolò, Francesco Demartin
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ABSTRACT: Various Ru(II) complexes with substituted 1,10-phenanthroline or 4,5-diazafluorene are characterized by a good to very large second order NLO response, as determined by EFISH. Among these complexes, [Ru(9-fulleriden-4,5-diazafluorene)(PPh(3))(2)Cl(2)] is particularly appealing due to its huge second-order NLO response and its transparency to the second harmonic generation. The structure of cis-Cl,trans-PPh(3)-[Ru(5-NO(2)-1,10-phen)(PPh(3))(2)Cl(2))] was determined by single-crystal X-ray diffraction.
Dalton Transactions 10/2010; 39(42):10314-8. · 3.84 Impact Factor
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Marta Mameli,
M Carla Aragoni,
Massimiliano Arca,
Claudia Caltagirone, Francesco Demartin,
Giovanna Farruggia,
Greta De Filippo,
Francesco A Devillanova,
Alessandra Garau,
Francesco Isaia,
Vito Lippolis,
Sergio Murgia,
Luca Prodi,
Anna Pintus,
Nelsi Zaccheroni
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ABSTRACT: 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.
Chemistry 11/2009; 16(3):919-30. · 5.93 Impact Factor
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M Carla Aragoni,
Massimiliano Arca,
Andrea Bencini,
Silvia Biagini,
Alexander J Blake,
Claudia Caltagirone, Francesco Demartin,
Greta De Filippo,
Francesco A Devillanova,
Alessandra Garau,
Karsten Gloe,
Francesco Isaia,
Vito Lippolis,
Barbara Valtancoli,
Marco Wenzel
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ABSTRACT: Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L(4)) and 2,8-diaza-5-thia[9]-(2,9)-1,10-phenanthrolinophane (L(7)) have been synthesized and characterized. The coordination behavior of L(4) and L(7) toward the metal ions Cu(II), Zn(II), Pb(II), Cd(II), Hg(II), and Ag(I) was studied in aqueous solution by potentiometric methods, in CD3CN/D2O 4:1 (v/v) by (1)H NMR titrations and in the solid state. The data obtained were compared with those available for the coordination behavior toward the same metal ions of structurally analogous mixed donor macrocyclic ligands L(1)-L(3), L(5), L(6): all these contain a phenanthroline subunit but have only S/O/N(aromatic) donor groups in the remaining portion of the ring and are, therefore, less water-soluble than L(4) and L(7). The complexes [Cd(NO3)2(L(5))], [Pb(L(7))](ClO4)2 x 1/2MeCN, [Pb(L(4))](ClO4)2 x MeCN, and [Cu(L(7))](ClO4)2 x 3/2MeNO2 were characterized by X-ray crystallography. The efficacy of L(1)-L(7) in competitive liquid-liquid metal ion extraction of Cu(II), Zn(II), Cd(II), Pb(II), Ag(I), and Hg(II) was assessed. In the absence of Hg(II), a clear extraction selectivity for Ag(I) was observed in all systems investigated.
Inorganic Chemistry 10/2008; 47(18):8391-404. · 4.60 Impact Factor
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M. Carla Aragoni,
Massimiliano Arca,
Andrea Bencini,
Silvia Biagini,
Alexander J. Blake,
Claudia Caltagirone, Francesco Demartin,
Greta De Filippo,
Francesco A. Devillanova,
Alessandra Garau,
Karsten Gloe,
Francesco Isaia,
Vito Lippolis,
Barbara Valtancoli,
Marco Wenzel
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ABSTRACT: Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L4) and 2,8-diaza-5-thia[9]-(2,9)-1,10-phenanthrolinophane (L7) have been synthesized and characterized. The coordination behavior of L4 and L7 toward the metal ions CuII, ZnII, PbII, CdII, HgII, and AgI was studied in aqueous solution by potentiometric methods, in CD3CN/D2O 4:1 (v/v) by 1H NMR titrations and in the solid state. The data obtained were compared with those available for the coordination behavior toward the same metal ions of structurally analogous mixed donor macrocyclic ligands L1-L3, L5, L6: all these contain a phenanthroline subunit but have only S/O/N(aromatic) donor groups in the remaining portion of the ring and are, therefore, less water-soluble than L4 and L7. The complexes [Cd(NO3)2(L5)], [Pb(L7)](ClO4)2·1/2MeCN, [Pb(L4)](ClO4)2·MeCN, and [Cu(L7)](ClO4)2·3/2MeNO2 were characterized by X-ray crystallography. The efficacy of L1-L7 in competitive liquid−liquid metal ion extraction of CuII, ZnII, CdII, PbII, AgI, and HgII was assessed. In the absence of HgII, a clear extraction selectivity for AgI was observed in all systems investigated.
08/2008;
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Francesco Isaia,
M Carla Aragoni,
Massimiliano Arca, Francesco Demartin,
Francesco A Devillanova,
Giovanni Floris,
Alessandra Garau,
Michael B Hursthouse,
Vito Lippolis,
Rosaria Medda,
Fabio Oppo,
Marilena Pira,
Gaetano Verani
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ABSTRACT: The antithyroid drug methimazole (MMI) reacts with molecular iodine to form, in a multistep process, 1-methylimidazole as final product. In this process, the charge transfer complex MMI-I 2 and the ionic disulfide [(C 4H 6N 2S-) 2] (2+) ( 1, dication MMI disulfide) have been isolated and their X-ray crystal structures solved. Dication MMI disulfide perchlorate acts effectively both in reducing I 2 to I (-) ions and in showing antioxidant properties in inactivating the enzyme lactoperoxidase compound I.
Journal of Medicinal Chemistry 08/2008; 51(13):4050-3. · 4.80 Impact Factor
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ABSTRACT: The suitability of a poly(sodium methacrylate, methyl methacrylate) (NaPMM), a novel mucoadhesive material, to prepare fast-dissolving microparticles containing nifedipine (NIF) in the range of 25-75% w/w was verified. Microparticles made of a low-viscosity hydroxypropylmethylcellulose (HPMC), were also prepared to compare the NIF release profile and bioadhesive properties. The release test was carried out in oversaturation conditions. The physical state of microparticles was also investigated. The formulation stability was evaluated over a 3-month period in long-term and accelerated conditions. The presence of amorphous NIF within freshly prepared microparticles was attributed to interactions between the drug and both polymers. NaPMM conferred to microparticles suitable mucoadhesive properties and significantly increased NIF dissolution rate in comparison to HPMC. Nevertheless, NIF apparent solubilities obtained by NaPMM microparticles were lower than those obtained by the HPMC set. After 3-month storage in the case of HPMC microparticles, NIF dissolution rate and supersaturation degree significantly decreased due to drug crystallization. As far as NaPMM microparticles are concerned, neither NIF dissolution rate nor apparent solubility significantly changed.
European Journal of Pharmaceutics and Biopharmaceutics 04/2008; 68(3):579-88. · 4.27 Impact Factor
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M. Carla Aragoni,
Massimiliano Arca,
M. Bonaria Carrea,
Alessandra Garau,
Francesco A. Devillanova,
Francesco Isaia,
Vito Lippolis,
Gian Luca Abbati, Francesco Demartin,
Cristian Silvestru,
Serhiy Demeshko,
Franc Meyer
Berichte der deutschen chemischen Gesellschaft 08/2007; 2007(29):4607 - 4614. · 2.94 Impact Factor
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ABSTRACT: Two polymorphic forms of the 1:1 charge-transfer adduct between N-methylthiazolidine-2-thione and IBr have been isolated: their structural analyses by a recently reported procedure for comparison of multiple crystal forms of the same molecular structure reveal some interesting geometrical 3D similarity relationships that can be interpreted in terms of different sets of halogen ···π···halogen weak interactions. The 1:1 charge-transfer adduct with I2 has also been isolated and structurally characterized and proven to be isostructural with one of the two polymorphic forms of the IBr adduct.
06/2007;
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ABSTRACT: This paper presents some copper(II) complexes of salen analogues in which the two salicylaldehyde moieties carry different (electron donor, D, and acceptor, A) substituents in position 5, producing a push-pull charge asymmetry. The X-ray structures of some compounds show the presence of pairs of stacked molecules with head-to-tail intermolecular associations. The geometries of all complexes have been optimized through density functional theory (DFT) studies, which have shown that a major influence on the coordination bond lengths is given by the presence of the electron acceptor NO2 group. Such an influence operates mainly on the Cu-phenolato bonds: elongation of the Cu-O distance of the 5-nitrosalicylaldehyde moiety, with a concomitant decrease of the other Cu-O distance; the Cu-N bonds are less affected. The D groups have only a minor influence. The nonlinear optical responses, microgBetavec, of some molecules have been determined by EFISH measurements, and the Beta-vec values have been obtained using the DFT-calculated microg values because solubility problems hampered the experimental measurements of microg of some derivatives; the former, however, have been found to be in agreement with the experimental values that could be obtained. Deconvolution of the absorption bands in the near-UV region has allowed recognition of the charge-transfer (CT) transition, assigned to a ligand-to-metal CT (LMCT) by time-dependent DFT computations; we have then used the solvatochromism of this transition to obtain Beta0 and BetaCT values using the two-state model. These values were compared with those obtained by computational studies, which have also allowed evaluation of the influence of the substituents on the directions of microg and Betatot.
Inorganic Chemistry 01/2007; 45(26):10976-89. · 4.60 Impact Factor
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ABSTRACT: The arene-perfluoroarene stacking interaction was studied by experimental and theoretical methods. A series of compounds with different possibilities for formation of this recognition motif in the solid state were synthesized, and their crystal structures determined by single-crystal X-ray diffraction. The crystal packing of these compounds, as well as the packing of related compounds retrieved from crystallographic databases, were analyzed with quantitative crystal potentials: total lattice energies and the cohesive energies of closest molecular pairs in the crystals were calculated. The arene-perfluoroarene recognition motif emerges as a dominant interaction in the non-hydrogen-bonding compounds studied here, to the point that asymmetric dimers formed over the stacking motif carry over to asymmetric units made of two molecules in the crystal both for pure compounds and for molecular complexes; however, inter-ring distances and angles range from 3.70 to 4.85 A and from 5 to 21 degrees , respectively. Pixel energy partitioning reveals that whenever aromatic rings stack, the largest cohesive energy contribution comes from dispersion, which roughly amounts to 20 kJ mol(-1) per phenyl ring, while the coulombic term is minor but significant enough to make a difference between the arene-arene or perfluoroarene-perfluoroarene interactions on the one hand, and arene-perfluoroarene interactions on the other, whereby the latter are favored by about 10 kJ mol(-1) per phenyl ring. No evidence of special interaction which can be attributed to HF confrontation was recognizable.
Chemistry 04/2006; 12(13):3538-46. · 5.93 Impact Factor
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M. Carla Aragoni,
Massimiliano Arca,
M. Bonaria Carrea, Francesco Demartin,
Francesco A. Devillanova,
Alessandra Garau,
Michael B. Hursthouse,
Susanne L. Huth,
Francesco Isaia,
Vito Lippolis,
Helen R. Ogilvie,
Gaetano Verani
Berichte der deutschen chemischen Gesellschaft 11/2005; 2006(1):200 - 206. · 2.94 Impact Factor
