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Calvo, Rafael; Mesa, Manuel A.

doi:10.1103/physrevb.28.1244

Cited by 51 publications

(21 citation statements)

References 23 publications

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“…Following the methods described previously in references [65][66][67] and taking into account the crystal symmetry, we have calculated the molecular g i -tensors (i = A, B, C, D) of the individual copper ions in [Cu(Tyr) 2 ] ∞ . The nearly axial local coordination around each copper ion obtained from crystal data [58] allows us to assume that the molecular g's have components g ⊥ , in the plane defined by the ligands, and g // , along its normal, associated with the polar θ m , and azimuthal ϕ m , angles, respectively, and angle 2λ between the apical directions corresponding to copper sites in A and C (or B and D), that are included in Table 1.…”

Section: Crystal and Molecular G 2 Tensorsmentioning

confidence: 99%

Single crystal electron paramagnetic resonance spectra of CuII ions in Cu(tyrosine)2

Paredes-Garcı́a

Santana

Madrid

et al. 2012

Journal of Inorganic Biochemistry

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Section: Crystal and Molecular G 2 Tensorsmentioning

confidence: 99%

Single crystal electron paramagnetic resonance spectra of CuII ions in Cu(tyrosine)2

Paredes-Garcı́a

Santana

Madrid

et al. 2012

Journal of Inorganic Biochemistry

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“…28,[42][43][44][45][46][47][48][49]. The molecular g-tensors gA and g~ corresponding to individual metal sites can be evaluated under simple assumptions [56,57] from the crystal g-tensor obtained from the observed resonance positions and the value of CO~x is calculated by Eq. (9) from line width measurements in single-crystal samples.…”

Section: Collapsed-resonance Regimementioning

confidence: 99%

“…6 allow calculating two crystal g2 tensors, corresponding to the two sets of resonances. Also, making simple assumptions [28,56,57], the molecular g-tensors gh, g~, gc and g• corresponding to Cu ions in the four lattice sites can be calculated from the crystal g-tensors [28]. The results in Fig.…”

Section: Structure and Exchange Pathways In [Cu(gly)2 ] H20mentioning

confidence: 99%

EPR measurements of weak exchange interactions coupling unpaired spins in model compounds

Calvo

2007

Appl. Magn. Reson.

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I review electron paramagnetic resonance (EPR) measurements performed to evaluate very weak exchange interactions (defined as rYr -J,jS,$j, with 10 -3 cm-t< IJ,~l < I cm-') between unpaired spins, transmitted through long and weak chemical pathways typical of protein structures. They are performed in appropriate model compounds, mainly copper derivatives of amino acids and peptides, making use of the phenomenon of exchange narrowing and collapse of the resonances. I describe the theoretical basis and the implementations of the method to different situations, including selected experimental values of the exchange couplings J between metal centers, and briefly discuss correlations between J and the structure of the paths. Results obtained in relatively simple EPR experiments performed at room temperature in single-crystal samples are compared with those obtained from thermodynamic magnetic measurements having higher experimental difficulties. The experimental information allows describing the role of molecular segments typieal of biomolecules (H bonds, aromatic ring stacking, cation-Ÿ contacts, etc.) in the transmission of the exchange interaction. The values of J obtained in some model compounds are compared with those obtained in proteins to conclude that the magnitudes of the exchange interactions are useful to characterize long and weak biologically relevant chemical pathways. One observes that these exchange couplings are weakly dependent on the nature of the unpaired spins and strongly dependent on the chemical pathway. Thus, measurements of exchange couplings in model compounds may provide usefui information about biological function, particularly about electron transfer in proteins.

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“…[20] 9.8 GHz 33.9 GHz (g 2 ) xx ϭ 4.616(1) (g 2 ) xx ϭ 4.6036(5) (g 2 ) yy ϭ 4.366(1) (g 2 ) yy ϭ 4.3918(5) (g 2 ) zz ϭ 4.466(1) (g 2 ) zz ϭ 4.4865(5) (g 2 ) zx ϭ 0.33 (5) (g 2 ) zx ϭ 0.3255(5) (g 2 ) xy ϭ (g 2 ) zy ϭ 0 ( g 2 ) xy ϭ (g 2 ) zy ϭ 0 (g 2 ) 1 ϭ 4.197(1) (g 2 ) 1 ϭ 4.2143 (5) The components and principal directions of the copper molecular g i -tensor shown in Table 2 were evaluated following the procedure described elsewhere assuming axial symmetry. [20] θ m and ϕ m are, respectively, the polar and azimuthal angles of the symmetry axis of the Cu I site [identical to Cu III site] referred as to the a*bc crystal system, and 2α is the angle between the normals to the Cu I and Cu IV sites [identical to Cu II ϪCu III ]. The values for θ m , ϕ m and 2α are in a good agreement with the crystallographic ones (θ c ϭ 120.4°, ϕ c ϭ 29.0°, and 2α c ϭ 130.4°), supporting the assumption of axial symmetry for this copper complex.…”

Section: Crystal and Molecular G-factormentioning

confidence: 99%

Structural and Single Crystal EPR Studies of the Complex Copper L-Glutamine: A Weakly Exchange-Coupled System with syn-anti Carboxylate Bridges

Schveigkardt

Rizzi

Piro

et al. 2002

Eur. J. Inorg. Chem.

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We report the molecular structure and a single crystal EPR study at 9.8 and 33.9 GHz of a new copper(II) compound with the amino acid L-Glutamine, Cu[NH 2 CO 2 CH(CH 2 ) 2 -CONH 2 ] 2 . The Cu II ion is in an elongated octahedral environment equatorially trans-coordinated by two glutamine molecules acting as bidentate ligands through the nitrogen atom and one oxygen atom of each amino acid group, and axially by two carboxylate oxygen atoms of two neighboring glutamine molecules. Copper ions are arranged in layers connected by syn-anti carboxylate bridges that provide equatorial and apical ligands to the copper ions. Neighboring layers are connected by long chemical paths, which include two amino acid side chains connected by H bonds. Single crystal EPR spectra show a single exchange-collapsed resonance at both microwave frequencies for any magnetic field orientation. The evaluation of the molecular g-tensor from the angu-

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EPR study of electronic and magnetic properties ofbis(DL−α−amino−n−butyrato)copper(

Cited by 51 publications

References 23 publications

Single crystal electron paramagnetic resonance spectra of CuII ions in Cu(tyrosine)2

Single crystal electron paramagnetic resonance spectra of CuII ions in Cu(tyrosine)2

EPR measurements of weak exchange interactions coupling unpaired spins in model compounds

Structural and Single Crystal EPR Studies of the Complex Copper L-Glutamine: A Weakly Exchange-Coupled System with syn-anti Carboxylate Bridges

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