Single crystal EPR study of electronic structure and exchange interactions for copper(II)(l-arginine)2(SO4)·(H2O)6: a model system to study exchange interactions between unpaired spins in proteins

Santana, Ricardo Costa de; Cunha, R. O.; Carvalho, J. F.; Vencato, Ivo; Calvo, Rafael

doi:10.1016/j.jinorgbio.2004.10.014

Cited by 22 publications

(19 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(10) from a quantum model using the Kubo and Tomita theory. For cases where the differences in the magnitudes of the coupling are large [39,40,[52][53][54], this problem does not occur. More theoretical work is being done in this direction to solve the problem.…”

Section: Epr Results and Analysis For [Cu(gly)2 J Ii20mentioning

confidence: 99%

“…The exchange interactions produce a spin dynamics with a characteristic frequency oex that averages out the splitting of the lines. Cases where x > 1 allow simple implementations of the exchange narrowing process to evaluate exchange interactions [38,[43][44][45][46][47][48][49][50][51][52][53][54].…”

Section: Collapsed-resonance Regimementioning

confidence: 99%

“…It is similar to what is obtained with the simpler Anderson theory (Eq. (8)) and has been used in several works to calculate exchange interactions from line width data [28,[38][39][40][42][43][44][45][46][47][48][49][50][51][52][53][54][55].…”

Section: Collapsed-resonance Regimementioning

confidence: 99%

“…Another compound having H bonds studied recently is Cu(II)(L-arginine)z• SO4"(H20)6 [53]. The EPR results at 9.77 and 34.1 GHz in single-crystal samples of this ternary copper amino acid complex allowed to estimate exchange interactions IJ~l = 0.6 cm -1 and I-/21 = 0.006 cm -~ between copper neighbors at 0.5908 nm and at 1.5684 nm, respectively.…”

Section: Bridges Containing H Bondsmentioning

confidence: 99%

“…This resutt supports that when the chemical paths are long and weak, the main contribution to the magnitude of the exchange arises from the length of the path and the characteristics of their weak chemical segments, but not in the nature of the interacting unpaired electrons. Also, exchange interactions between radical ions in a protein [15,16] and between copper ions in a model compound [53] that are connected by pathways containing similar segments have very similar magnitudes. With the information available at this moment one can assume that the magnitude of the exchange coupling depends mainly on the chemical pathways connecting the unpaired spins.…”

Section: Dependence Of J On the Nature Of The Unpaired Electrons For mentioning

confidence: 99%

See 4 more Smart Citations

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

Calvo

2007

Appl. Magn. Reson.

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Epr Results and Analysis For [Cu(gly)2 J Ii20mentioning

confidence: 99%

Section: Collapsed-resonance Regimementioning

confidence: 99%

Section: Collapsed-resonance Regimementioning

confidence: 99%

Section: Bridges Containing H Bondsmentioning

confidence: 99%

Section: Dependence Of J On the Nature Of The Unpaired Electrons For mentioning

confidence: 99%

See 3 more Smart Citations

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

Calvo

2007

Appl. Magn. Reson.

Self Cite

View full text Add to dashboard Cite

show abstract

Unraveling the Electronic Structure, Spin States, Optical and Vibrational Spectra of Malaria Pigment

Ali

Oppeneer

2015

Chemistry A European J

View full text Add to dashboard Cite

A detailed knowledge of the electronic structure and magnetic and optical properties of hemozoin, the malaria pigment, is essential for the design of effective antimalarial drugs and malarial diagnosis. By employing state-of-the-art electronic structure calculations, we have performed an in-depth investigation of the malaria pigment. Specifically, molecular bond lengths and spin states of the two Fe(III) heme centers and their exchange interaction, the UV/Vis absorption spectrum, and the IR vibrational spectra were calculated and compared with available experimental data. Our density functional theory (DFT)-based calculations predict a singlet ground spin state that stems from an S=5/2 spin state on each of the Fe heme centers with a very weak antiferromagnetic exchange interaction between them. Our theoretical UV/Vis and IR spectra provide explanations for various spectroscopic studies of hemozoin and β-hematin (a synthetic analogue of hemozoin). A good comparison of calculated and measured properties demonstrates the convincing unveiling of the electronic structure of the malaria pigment. Based on the predicted vibrational spectra, we propose a unique spectral band from the nuclear resonance vibrational spectroscopy (NRVS) results that could be used as a key fingerprint for malarial detection.

show abstract

Copper(II) coordination polymer based on l-arginine as a supramolecular hybrid inorganic–organic material: synthesis, structural, spectroscopic and magnetic properties

et al. 2023

View full text Add to dashboard Cite

We report the synthesis and structural, spectroscopic and magnetic properties of new 1D coordination polymeric complex {[Cu(μ-l-Arg)2]SO4⋅1.5H2O}n (1) that contains asymmetric μ−O,O’ carboxylic bridge linking distorted square-pyramidal [Cu(μ-l-Arg)2]2+ coordination units. In 1D, the syn−anti−μ2−η1:η1zigzag polymer conformation, the adjacent Cu(II) ions are distanced by 5.707 Å, and the subsequent Cu∙∙∙Cu proximity in 1D-coordination chain equals 6.978 Å. Detailed interpretation of IR and Raman spectra of l-arginine and 1 was performed. The principal components of the g tensor determined from EPR experiments (gx = 2.059, gy = 2.075, gz = 2.228) indicate nearly axial symmetry of Cu(II) coordination sphere and correspond to the unpaired electron occupying the dx2–y2 orbital. The single broad band at 16,200 cm–1, characteristic of d−d transition, is assigned to the dominant dublet-dublet 2B1g(dx2–y2)→ 2Eg(dyz≈dxz) transition. Magnetic susceptibility measurements have revealed ferromagnetic coupling between the Cu(II) ions within the 1D-coordination chain, while the intermolecular coupling is antiferromagnetic. Graphical Abstract

show abstract

Single crystal EPR study of electronic structure and exchange interactions for copper(II)(l-arginine)2(SO4)·(H2O)6: a model system to study exchange interactions between unpaired spins in proteins

Cited by 22 publications

References 31 publications

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

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

Unraveling the Electronic Structure, Spin States, Optical and Vibrational Spectra of Malaria Pigment

Copper(II) coordination polymer based on l-arginine as a supramolecular hybrid inorganic–organic material: synthesis, structural, spectroscopic and magnetic properties

Contact Info

Product

Resources

About