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Caneschi A, Cornia A, Fabretti AC, Gatteschi D, Malavasi W. Polyiron(III)-Alkoxo Clusters: a Novel Trinuclear Complex and Its Relevance to the Extended Lattices of Iron Oxides and Hydroxides. Inorg Chem 2002. [DOI: 10.1021/ic00122a024] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bencini A, Benelli C, Caneschi A, Dei A, Gatteschi D. Crystal and molecular structure and magnetic properties of a trinuclear complex containing exchange-coupled GdCu2 species. Inorg Chem 2002. [DOI: 10.1021/ic00224a036] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Caneschi A, Gatteschi D, Laugier J, Rey P, Zanchini C. Synthesis, x-ray crystal structure, and magnetic properties of two dinuclear manganese(II) compounds containing nitronyl nitroxides, imino nitroxides, and their reduced derivatives. Inorg Chem 2002. [DOI: 10.1021/ic00309a040] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bencini A, Caneschi A, Dei A, Gatteschi D, Zanchini C, Kahn O. Low-lying electronic energy levels in a series of heterodinuclear complexes containing octahedral nickel(II) and tetrahderal metal(II) (copper, cobalt, and manganese) species. Inorg Chem 2002. [DOI: 10.1021/ic00229a016] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Benelli C, Caneschi A, Gatteschi D, Pardi L, Rey P, Shum DP, Carlin RL. Magnetic properties of lanthanide complexes with nitronyl nitroxides. Inorg Chem 2002. [DOI: 10.1021/ic00301a023] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Caneschi A, Gatteschi D, Renard JP, Rey P, Sessoli R. Magnetic phase transitions in manganese(II) pentafluorobenzoate adducts with nitronyl nitroxides. J Am Chem Soc 2002. [DOI: 10.1021/ja00184a085] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Brunel LC, Caneschi A, Dei A, Friselli D, Gatteschi D, Hassan AK, Lenci L, Martinelli M, Massa CA, Pardi LA, Popescu F, Ricci I, Sorace L. How and why the characterization of magnetic materials can give directions in the methodological development in high field–high frequency EPR. RESEARCH ON CHEMICAL INTERMEDIATES 2002. [DOI: 10.1163/156856702320267127] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Caneschi A, Gatteschi D, Lalioti N, Sessoli R, Sorace L, Tangoulis V, Vindigni A. Ising-type magnetic anisotropy in a cobalt(II) nitronyl nitroxide compound: a key to understanding the formation of molecular magnetic nanowires. Chemistry 2002; 8:286-92. [PMID: 11822459 DOI: 10.1002/1521-3765(20020104)8:1<286::aid-chem286>3.0.co;2-d] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The compound [Co(hfac)2-(NITPhOMe)2] (2) (hfac = hexafluoroacetylacetonate, NITPhOMe = 4'-methoxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) crystallizes in the triclinic P1 space group, a= 10.870(5), b = 11.520(5), c = 19.749(5) A, alpha = 78.05(5), beta = 84.20(5), gamma = 64.51(5) degrees, Z = 2. It can be considered a model system for studying the nature of the magnetic anisotropy of [Co(hfac)2(NITPhOMe)] (1), which was recently reported to behave as a molecular magnetic wire. The magnetic anisotropy of 2 was investigated by EPR spectroscopy and SQUID magnetometry both in the polycrystalline powder and in a single crystal. The experimental magnetic anisotropy was related to the anisotropy of the central ion and to the exchange interaction between the cobalt(II) ion and the radicals.
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Caneschi A, Gatteschi D, Lalioti N, Sessoli R, Sorace L, Tangoulis V, Vindigni A. Ising-Type Magnetic Anisotropy in a Cobalt(II) Nitronyl Nitroxide Compound: A Key to Understanding the Formation of Molecular Magnetic Nanowires. Chemistry 2002. [DOI: 10.1002/1521-3765(20020104)8:1%3c286::aid-chem286%3e3.0.co;2-d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Armelao L, Bandoli G, Barreca D, Bettinelli M, Bottaro G, Caneschi A. Synthesis and characterization of nanophasic LaCoO3 powders. SURF INTERFACE ANAL 2002. [DOI: 10.1002/sia.1264] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Lee D, Sorace L, Caneschi A, Lippard SJ. Hydroxo-bridged Cubane-type tetrairon(II) clusters supported by sterically-hindered carboxylate ligands. Inorg Chem 2001; 40:6774-81. [PMID: 11735490 DOI: 10.1021/ic010726b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of hydroxo-bridged cubane-type tetrairon(II) clusters, [Fe(4)(mu-OH)(4)(mu-O(2)CAr(4)(-)t(BuPh))(2)(mu-OTf)(2)L(4)] (L = C(5)H(5)N (1), 4-(t)BuC(5)H(4)N (2), 3-FC(5)H(4)N (3)), were synthesized by using a sterically hindered carboxylate ligand, 2,6-di(4-tert-butylphenyl)benzoate (Ar(4)(-)t(BuPh)CO(2)(-)). Three different bridging units that mediate weak antiferromagnetic coupling interactions between the metal centers support the unprecedented cubane-type [Fe(4)(mu-OH)(4)](4+) cores in 1-3. The solution structures of 1 and 3 probed by FT-IR and (19)F NMR spectroscopy are consistent with the solid-state geometry determined by X-ray crystallography. Zero-field Mössbauer spectra of 1-3 at 4.2 K are characteristic of high-spin iron(II) centers in nearly identical coordination environments. Compound 1 undergoes two irreversible oxidation processes at ca -10 and +880 mV (vs Fc/Fc(+)), the former approaching quasi-reversible behavior with increased scan rates and a narrow potential sweep range. Comparisons are made with analogous known [Fe(4)X(4)](n)()(+) (X = O, S) units, and the structural integrity of tetrairon fragments upon a change in oxidation state is discussed together with some possible biological implications.
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Bodnar SH, Caneschi A, Dei A, Shultz DA, Sorace L. A bis-bidentate dioxolene ligand induces thermal hysteresis in valence tautomerism interconversion processes. Chem Commun (Camb) 2001:2150-1. [PMID: 12240207 DOI: 10.1039/b106192p] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of a bis-bidentate ligand in a solid cobalt dioxolene complex affords the necessary cooperative properties that lead to thermal hysteresis in a valence tautomeric interconversion equilibrium.
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Caneschi A, Dei A, Fabrizi de Biani F, Gütlich P, Ksenofontov V, Levchenko G, Hoefer A, Renz F. Pressure- and temperature-induced valence tautomeric interconversion in a o-dioxolene adduct of a cobalt-tetraazamacrocycle complex. Chemistry 2001; 7:3926-30. [PMID: 11596934 DOI: 10.1002/1521-3765(20010917)7:18<3926::aid-chem3926>3.0.co;2-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An electronic switch at the molecular level has been realized by using a class of ionic compounds of the formula [Co(L)(diox)]Y (L = tetraazamacrocyclic ligand, Y = mononegative anion). Such compounds undergo temperature- and pressure-induced intramolecular one-electron transfer equilibria. The transition temperature of interconversion varies with the nature of the counterions Y (Y = PF6, BPh4, I). Surprisingly the effect of the anion on the transition temperature is not only governed by its volume but also by its coulombic interaction.
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Caneschi A, Dei A, Lee H, Shultz DA, Sorace L. Ferromagnetically coupled bis(semiquinone) ligand enforces high-spin ground states in bis-metal complexes. Inorg Chem 2001; 40:408-11. [PMID: 11170550 DOI: 10.1021/ic000440r] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Chiorescu I, Giraud R, Jansen AG, Caneschi A, Barbara B. Phonon-assisted tunneling in the quantum regime of Mn12 acetate. PHYSICAL REVIEW LETTERS 2000; 85:4807-4810. [PMID: 11082657 DOI: 10.1103/physrevlett.85.4807] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2000] [Indexed: 05/23/2023]
Abstract
Longitudinal or transverse magnetic fields applied on a crystal of Mn12 acetate allows one to observe independent tunnel transitions between m = -S+p and m = S-n-p ( n = 6-10, p = 0-2 in longitudinal field and n = p = 0 in transverse field). We observe a smooth transition (in longitudinal) from coherent ground-state to thermally activated tunneling. Furthermore, two ground-state relaxation regimes show a crossover between quantum spin relaxation far from equilibrium and near equilibrium, when the environment destroys multimolecule correlations. Finally, we stress that the complete Hamiltonian of Mn12 should contain odd spin operators of low order.
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Pontillon Y, Bencini A, Caneschi A, Dei A, Gatteschi D, Gillon B, Sangregorio C, Stride J, Totti F. Spin-Density Map of the Triplet Ground State of a Titanium(IV) Complex with Schiff-Base Diquinone Radical Ligands: An Investigation Using Polarized-Neutron Diffraction and Density-Functional Theory This work was supported by the 3MD EU network (contract ERB 4061 PL 97-0197). Angew Chem Int Ed Engl 2000; 39:1786-1788. [PMID: 10934361 DOI: 10.1002/(sici)1521-3773(20000515)39:10<1786::aid-anie1786>3.0.co;2-i] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Braga D, Maini L, Prodi L, Caneschi A, Sessoli R, Grepioni F. Anions derived from squaric acid form interionic pi-stack and layered, hydrogen-bonded superstructures with organometallic sandwich cations: the magnetic behaviour of crystalline. Chemistry 2000; 6:1310-7. [PMID: 10840952 DOI: 10.1002/(sici)1521-3765(20000417)6:8<1310::aid-chem1310>3.0.co;2-t] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Depending on the stoichiometric ratio, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione, H2SQA) reacts with [(eta6-C6H6)2Cr] in THF to form the crystalline material [(eta6-C6H6)2Cr][HSQA] (1) and in water to yield [[(eta6-C6H6)2Cr]2][SQA] x 6H2O (3); it also reacts with [(eta5-C5H5)2Co][OH] in water to form [[(eta5-C5H5)2Co]2][SQA] x 6H2O (4). Compound 1 is almost isostructural with the previously reported salt [(eta5-C5H5)2Co][HSQA] (2); its structure is based on pi-pi stacks between the benzene ligands and the hydrogen squarate anionic chains (pi-pi distance 3.375 A). Compounds 3 and 4 are isomorphous and have a structure in which layers of organometallic cations intercalate with layers of water molecules hydrogen bonded to squarate dianions. All crystals contain charge-assisted C-Hdelta+...Odelta- hydrogen bonds between the organometallic and the organic components, while negative O-H(-)...O(-) and O-H...O(2-) interactions are present in the pairs 1/3 and 2/4, respectively. In constrast to most organic salts of [(eta6-C6H6)2Cr]+ and [(eta5-C5H5)2Co]+ which are yellow, crystals of compounds 1-4 are orange. Reflectance spectra measured on the crystalline material 1 show the presence of an intense tail that can be assigned to a charge-transfer transition through the [(eta6-C6H6)2Cr]+/[HSQA]- pi-stacking interactions, while the pi stacking in 2 causes only a broadening of the band. The magnetic behaviour of 1 and 3 has been investigated by SQUID magnetometry. Both compounds are characterised by a weak antiferromagnetic interaction between the S=1/2 Cr centres of the [(eta6-C6H6)2Cr]+ cations, which is significantly stronger in 1 due to the pi-stacking with the HSQA- anions.
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Wernsdorfer W, Caneschi A, Sessoli R, Gatteschi D, Cornia A, Villar V, Paulsen C. Effects of nuclear spins on the quantum relaxation of the magnetization for the molecular nanomagnet Fe8. PHYSICAL REVIEW LETTERS 2000; 84:2965-2968. [PMID: 11018987 DOI: 10.1103/physrevlett.84.2965] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/1999] [Indexed: 05/23/2023]
Abstract
The strong influence of nuclear spins on resonant quantum tunneling in the molecular cluster Fe8 is demonstrated for the first time by comparing the relaxation rate of the standard Fe8 sample with two isotopic modified samples: (i) 56Fe is replaced by 57Fe, and (ii) a fraction of 1H is replaced by 2H. By using a recently developed "hole digging" method, we measured an intrinsic broadening which is driven by the hyperfine fields. Our measurements are in good agreement with numerical hyperfine calculations. For T>1.5 K, the influence of nuclear spins on the relaxation rate is less important, suggesting that spin-phonon coupling dominates the relaxation rate.
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Barra AL, Caneschi A, Cornia A, Fabrizi de Biani F, Gatteschi D, Sangregorio C, Sessoli R, Sorace L. Single-Molecule Magnet Behavior of a Tetranuclear Iron(III) Complex. The Origin of Slow Magnetic Relaxation in Iron(III) Clusters. J Am Chem Soc 1999. [DOI: 10.1021/ja9818755] [Citation(s) in RCA: 402] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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S. Sall A, Gaye M, Sarr O, Caneschi A, Di Noto V, Vidali M. Preparation of the New Binucleating Ligand 2,6-Bis(carboxymethylsulfanylmethyl)-4-methylphenol and its Mono- and Bi-nuclear Complexes. JOURNAL OF CHEMICAL RESEARCH 1997. [DOI: 10.1039/a701315i] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bartolomé F, Bartolomé J, Benelli C, Caneschi A, Gatteschi D, Paulsen C, Pini MG, Rettori A, Sessoli R, Volokitin Y. Effect of Chiral Domain Walls on the Specific Heat of Gd(hfac)3NITR (R=Ethyl,Isopropyl,Methyl,Phenyl) Molecular Magnetic Chains. PHYSICAL REVIEW LETTERS 1996; 77:382-385. [PMID: 10062437 DOI: 10.1103/physrevlett.77.382] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Bandinelli G, Lagi A, Caneschi A, Urso C. [Physical exercise and increase in arterial pressure and temperature in a female heterozygote for anhidrotic ectodermal dysplasia]. ANNALI ITALIANI DI MEDICINA INTERNA : ORGANO UFFICIALE DELLA SOCIETA ITALIANA DI MEDICINA INTERNA 1996; 11:59-61. [PMID: 8645533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A 51-year-old woman suffered from an increase in body temperature from 37 degrees to 38.4 degrees C after physical exercise. She did not sweat. The patient also had labile hypertension with maximum values reaching 210/130 mmHg. Tests were carried out to explore the possibility of a link between the increase in body temperature and her hypertension. Evaluation of the patient's blood pressure and temperature changes after exercise and after environmental modification suggests a pathogenetic link between hyperthermia and hypertension.
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Gatteschi D, Caneschi A, Pardi L, Sessoli R. Large Clusters of Metal Ions: The Transition from Molecular to Bulk Magnets. Science 1994; 265:1054-8. [PMID: 17832894 DOI: 10.1126/science.265.5175.1054] [Citation(s) in RCA: 747] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Clusters of metal ions are a class of compounds actively investigated for their magnetic properties, which should gradually change from those of simple paramagnets to those of bulk magnets. However, their interest lies in a number of different disciplines: chemistry, which seeks new synthetic strategies to make larger and larger clusters in a controlled manner; physics, which can test the validity of quantum mechanical approaches at the nanometer scale; and biology, which can use them as models of biomineralization of magnetic particles.
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Goldberg D, Caneschi A, Lippard S. Synthesis and magnetochemistry of a new decanuclear manganese complex. J Inorg Biochem 1993. [DOI: 10.1016/0162-0134(93)85514-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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