Diamagnetic Analogue Research Articles

Magnetic resonant and non-resonant investigations of LiLnF4 (Ln = Y, Tm) powders

The properties of dielectric powders of the Van Vleck paramagnet LiTmF4 and its diamagnetic analogue LiYF4 have been investigated by both resonant methods (EPR, NMR, and the mass-spectroscopy) and non-resonant ones (conductometry and magnetization measurement). On the basis of experimental data and theoretical calculations a self-consistent model for the magnetic and other properties of these powders is suggested. Two structural phase transitions induced by the magnetic field are discovered in fine LiTmF4 powder at low temperature in a high magnetic field.

Jahn-Teller Effect in Copper-Doped Spinel Group

Anomalous magnetic properties and various phase transitions observed in some spinels are due to the Jahn-Teller effect. The effect is rather effectively studied in corresponding diamagnetic analogues of such crystals.ln the present paper a group of single crystals of normal and converted spinels doped with the two-valent copper Cu 2+ has been investigated. In this group of spinels the effect of inversion splitting shows itself classically. The investigations have been done by using radiospectrometers of 10 and 37 GHz frequency in the temperature range 4-300 K.For the first time,in the low-frequency range at the frequency of 10 GHz the full complex of the EPR spectra have been registered which are due to the theory of the inversion splitting. It consists of five types of the EPR spectra which are due to allowed 3 - -3 + ,2 - -2 + ,1 - -1 + and forbidden 3 - -1 + ,1 + -2 - transitions. At passing to a higher frequency of 37 GHz there occurs the frequency transformation of the spectrum,the two EPR spectra are observed which have been observed by many authors in copper complexes in the case of Jahn-Teller effect developing.

Kinetics, mechanism, and reactivity of an activated carbon-carbon double bond in nitroxyl radicals and their diamagnetic analog in interaction with some secondary amines and polyethyleneimine

Routes for the reaction of a conjugated methylene group of nitroxyl radicals (NR) with secondary amines were suggested and analyzed. Kinetic parameters of the limiting step of this reaction for the NR-amine and diamagnetic analog of NR-amine systems were estimated. The effect of the medium on these reactions was examined. The specific behavior of polyethyleneimine in the reaction with activated methylene groups of 2,2,6,6-tetra methyl-3, 5-dimethylene-4-oxopiperidine-i-oxyl was demonstrated.

Synthetic Modeling of Nitrite Binding and Activation by Reduced Copper Proteins. Characterization of Copper(I)−Nitrite Complexes That Evolve Nitric Oxide

In an effort to provide precedence for postulated intermediates in copper-protein-mediated nitrite reduction, a series of novel complexes containing the CuI−NO2- unit, including monocopper(I), dicopper(I,I), and mixed valence dicopper(I,II) and copper(I)−zinc(II) species, were prepared, fully characterized, and subjected to reactivity studies designed to probe their ability to produce nitric oxide. Treatment of solutions of [LCu(CH3CN)]PF6 (L = Li-Pr3, 1,4,7-triisopropyl-1,4,7-triazacyclononane, or LBn3, 1,4,7-tribenzyl-1,4,7-triazacyclononane) in MeOH with excess NaNO2 yielded the novel dicopper(I,I) complexes [(LCu)2(μ-NO2)]PF6. The complex with L = Li-Pr3 was cleaved by PPh3 to afford [Li-Pr3Cu(PPh3)]PF6 and Li-Pr3Cu(NO2), a structural model for the substrate adduct of copper nitrite reductase. Oxidation of the dicopper(I,I) compound (L = Li-Pr3) with (Cp2Fe)(PF6) in CH2Cl2 yielded the deep red, mixed valent, dicopper(I,II) species [(Li-Pr3Cu)2(μ-NO2)](PF6)2, which was structurally characterized as its [B(3,5-(CF3)2C6H3)4]- salt (crystal data: triclinic space group P1̄, a = 13.439(8) Å, b = 13.777(5) Å, c = 14.471(8) Å, α = 108.22(4)°, β = 92.08(5)°, γ = 90.08(4)°, Z = 1, T = 177 K, R = 0.074, and Rw = 0.070). A diamagnetic heterodinuclear CuIZnII analog, [Li-Pr3Cu(μ-NO2)ZnLi-Pr3](O3SCF3)2, was assembled by mixing Li-Pr3Cu(NO2), Zn(O3SCF3)2, and Li-Pr3 and was shown to adopt a structure similar to that of its CuICuII relative (crystal data: monoclinic space group P21/c, a = 10.8752(1) Å, b = 15.6121(3) Å, c = 25.8020(5) Å, β = 90.094(1)°, Z = 4, R1 = 0.0472, and wR2 = 0.1082). Both compounds exhibit an intense electronic absorption feature that was assigned as a CuI → NO2- MLCT transition on the basis of resonance Raman spectroscopic results. Functional modeling of copper nitrite reductase was accomplished by treating solutions of Li-Pr3Cu(NO2) with protonic acids or Me3SiO3SCF3. Nitric oxide evolution was accompanied by the formation of Li-Pr3Cu(O2CCH3)2 and Li-Pr3Cu(O3SCF3)2 when acetic acid or Me3SiO3SCF3 was used. The latter crystallized as a water adduct [Li-Pr3Cu(H2O)(O3SCF3)](O3SCF3) (crystal data: monoclinic space group P21/c, a = 8.59(1) Å, b = 26.04(1) Å, c = 12.838(4) Å, β = 108.26(6)°, Z = 4, T = 173 K, R = 0.067, and Rw = 0.064). The involvement of the CuICuII species as an intermediate in the reaction of Li-Pr3Cu(NO2) with Me3SiO3SCF3 at low temperature and a mechanism for NO generation involving both Li-Pr3Cu(NO2) and [(Li-Pr3Cu)2(μ-NO2)]2+ are discussed.

Electron-acceptor effect of aminoxyl radicals

Acidic properties of several compounds with aminoxyl-based spin labels were found to be abnormally strong when compared with those of diamagnetic analogues. Analysis of this phenomenon in terms of both Taft constants and Hinze–Jaffe–Huheey group electronegativities enabled us to attribute it to the strong electron-acceptor effect of the aminoxyl group that results in high electronegativity of aminoxyl-containing substituents. Quantitative estimates of this effect for two spin labels were obtained. Group electronegativity of imidazoline-based spin label is close to that of the -CF3 substituent, while the electron-acceptor effect of piperidine-based spin label is intermediate between those of -CHF2 and -CH2F groups. The strong electron-acceptor effect of aminoxyl spin labels should be taken into account when using them in biological and other studies.

The solution conformations of ferrichrome and deferriferrichrome determined by 1H‐nmr spectroscopy and computational modeling

We have applied computational procedures that utilize nmr data to model the solution conformation of ferrichrome, a rigid microbial iron transport cyclohexapeptide of known x-ray crystallographic structure [D. van der Helm et al. (1980) J. Am. Chem. Soc. 102, 4224-4231]. The Al3+ and Ga3+ diamagnetic analogues, alumichrome and gallichrome, dissolved in d6-dimethylsulfoxide (d6-DMSO), were investigated via one- and two-dimensional 1H-nmr spectroscopy at 300, 600, and 620 MHz. Interproton distance constraints derived from proton Overhauser experiments were input to a distance geometry algorithm [T. F. Havel and K. Wüthrich (1984) Bull. Math. Biol. 46, 673-691] in order to generate a family of ferrichrome structures consistent with the experimental data. These models were subsequently optimized through restrained molecular dynamics/energy minimization [B. R. Brooks et al. (1983) J. Comp. Chem. 4, 187-217]. The resulting structures were characterized in terms of relative energies and conformational properties. Computations based on integration of the generalized Bloch equations for the complete molecule, which include the 14N-1H dipolar interaction, demonstrate that the x-ray coordinates reproduce the experimental nuclear Overhauser effect time courses very well, and indicate that there are no significant differences between the crystalline and solution conformations of ferrichrome. A similar study of the metal free peptide, deferriferrichrome, suggests that at least two conformers are present in d6-DMSO at 23 degrees C. Both are different from the ferrichrome structure and explain, through conformational averaging, the observed amide NH and CH alpha multiplet splittings. The occurrence of interconverting peptide backbone conformations yields an increased number of sequential NH-CH alpha and NH-NH Overhauser connectivities, which reflects the mean value of r-6 dependence of the dipolar interaction. Our results support the idea that, in the case of structurally rigid peptides, moderately accurate distance constraints define a conformational subspace encompassing the "true" structure, and that energy considerations reduce the size of this subspace. For flexible peptides, however, the straight-forward approach can be misleading since the nmr parameters are averaged over substantially different conformational states.

Fluorescence Detection of Free Radicals by Nitroxide Scavenging

The fluorescence quantum yield of 4-(1-napthoyloxy)-2,2,6,6-tetramethylpiperidine-1-oxyl (I) in acetonitrile and hexane is 55 and 30-fold lower, respectively, than those of diamagnetic analogs. Experiments described herein demonstrate that this property makes possible the fluorescence detection of radical scavenging reactions in which the paramagnetic nitroxide-substituted naphthalene is converted to a diamagnetic N-alkoxy derivative. 2-Cyanopropyl free radicals were generated by the thermal decomposition of azobisisobutyronitrile (AIBN) in cyclohexane or in acetonitrile containing I. The fluorescence intensity of the sample increased proportionally to the decrease in its ESR signal intensity, indicating the conversion of the paramagnetic nitroxide to the diamagnetic product. The linear relationship between the increase in fluorescence intensity and decrease in ESR signal intensity shows that the changes in the fluorescence intensity can serve as a sensitive means for optically detecting radicals.

Crystal-field effects on the thermodynamic properties of the KLn(MoO4)2 isostructural compounds

We deal with a series of rhombic isostructural crystals: diamagnetic KLu(MoO4)2 and paramagnetic KLn(MoO4)2 (Ln = Tb, Dy, Ho, Er, and · Yb). The Schottky contributions to the paramagnetic crystals were extracted from the heat capacities measured earlier. The absorption and luminiscence spectra were measured at low temperatures as well. It was found that the lattice heat capacity of a paramagnetic crystal is approximated sufficiently well by the heat capacity of its diamagnetic analogue KLu(MoO4)2. The energies and degeneracies of the ground-term manifolds were obtained for the Er3+, Dy3+, Ho3+, Tb3+, and Yb3+ paramagnetic ions by comparing the spectroscopic quantities with the Schottky contributions. The kind of splitting for the ground terms of the non-Kramers Ho3+ and Tb3+ ions led us to the conclusion that the above splitting is caused mainly by the crystal field of the D4 tetragonal space group, which is the result of the nearest surroundings of a rare-earth ion, e.g. eight O2− ions.

ChemInform Abstract: Chemically Mediated Fluorescence Yield Switching in Nitroxide‐Fluorophore Adducts: Optical Sensors of Radical/Redox Reactions.

AbstractWhile the absorption and emission energies of the paramagnetic compounds (Ia), (IIa), and (IIc) as compared to their diamagnetic analogues (Ib), (Ic), (IIb), and (IId) are unaffected by the presence of the nitroxyl radical substituent(s), the fluorescence quantum yields of the paramagnetic derivatives (Ia), (IIa), and (IIc) are 2.9‐ to 60‐fold lower than those of the corresponding diamagnetic derivatives (Ib), (Ic), (IIb), and (IId), respectively.

Structure and properties of the smectic phase in a mesogenic complex of copper with a schiff base

The structural arrangement and the structure of the mesogenic copper compound {C7H15O-C6H3(O)CH-C6H4OC8H17}2Cu(II) were investigated in the dilute solution, the isotropic melt, the mesophase, and the crystalline state by ESR in conjunction with calorimetry and polarization microscopy. The complex exhibits smectic polymorphism with the following transitions: K 415 SC 430 SA 438 I. It was found by ESR that the complexes in the solution and in the isotropic melt have a square-planar trans configuration. In the mesophase part the planar molecules undergo tetrahedral distortion; the planar molecules form the smectic phase, while the distorted molecules are concentrated into microscopic isotropic drops, i.e., the system becomes heterogeneous in the mesophase. In the SA → SC transition the mesophase is oriented anomalously in the magnetic field (compared with the diamagnetic analogs) with the director orthogonal to the direction of the field.

The EPR spectrum of CpCr(CO) 3 in a single crystal of CpMn(CO) 3 at 20 K

The EPR spectrum of cyclopentadienylchromium tricarbonyl has been detected in single crystals of the diamagnetic manganese analog at temperatures below 25 K. Its g and 53Cr hyperfine matrices have been assembled in the crystal-axis system of the host. Both tensors are orthorhombic and their principal axes are almost coincident: g = (1.9969, 2.0353, 2.1339); a 53 = (3, 27, 44) MHz. The proximity of the principal directions of the maximum and intermediate values of these tensors to certain directions in the host crystal shows that the chromium center substitutes for CpMn(CO) 3 with little or no deformation. The single unpaired electron in CpCr(CO) 3 is believed to occupy an a′ orbital (in C s symmetry) which is composed of d x 2− y 2 and d yz chromium atomic orbitals, z being the molecular axis which connects Cr to the centers of Cp and the three CO ligands.

1H NMR studies of heme pocket conformation in zinc-substituted leghemoglobin, a diamagnetic analog of deoxyleghemoglobin

Reconstitution of apoleghemoglobin with zinc protoporphyrin IX is reported, NMR spectra show that the reconstitution is orientation specific and that there is no detectable heme isomerism or conformational heterogeneity. Resonances of heme substituents and distal and proximal amino acid protons have been assigned. Only minor differences in porphyrin-protein packing occur between zinc leghemoglobin and the CO complex of ferrous leghemoglobin. The zinc is five-coordinate and is ligated by the proximal histidine. Comparisons with diamagnetic six-coordinate complexes show that the distal His-61 and Leu-65 side chains move away from the binding site upon coordination of exogenous ligands. Conformational changes are minimal when the ligand is O 2.

7Li, 31P, and 1H NMR studies of interactions between ATP, monovalent cations, and divalent cation sites on rabbit muscle pyruvate kinase.

The interactions between ATP, monovalent cations, and divalent cations on rabbit muscle pyruvate kinase have been examined using 7Li, 31P, and 1H nuclear magnetic resonance. Water proton nuclear relaxation studies are consistent with the binding of Li+ to the K+ site on pyruvate kinase with an affinity of 120 mM in the absence of substrates and 16 mM in the presence of P-enolpyruvate. Titrations with pyruvate demonstrate that pyruvate binds to the enzyme with an affinity of 0.65 mM in the presence of Li+ and 0.4 mM in the presence of K+. 7Li+ nuclear relaxation rates in solutions of pyruvate kinase are increased upon titration with the metal-nucleotide analogue, Cr(H2O)4ATP. Mn2+ EPR spectra were used to determined the distribution of the enzyme between the so-called isotropic and anisotropic conformations of the enzyme (Ash, D. E., Kayne, F., and Reed, G.H. Arch. Biochem. Biophys. (1978) 190, 571-577). Li-Cr distances of 5.6 and 11.0 A were calculated for the anisotropic and isotropic forms, respectively, in the absence or presence of pyruvate. When the divalent cation site on the enzyme was saturated with Mg2+, these distances increased to 6.7 and 9.5 A, respectively, regardless of the presence or absence of pyruvate. 31P nuclear relaxation studies with the diamagnetic metal-nucleotide analogue, Co(NH3)4ATP, indicated that addition of Mn2+ ion to the divalent cation site on the enzyme increased the longitudinal relaxation rates of all three phosphorus nuclei of the analogue. The 31P data indicate that the presence of pyruvate at the active site effects a decrease in the Mn-P distances, bringing Mn2+ and Co(NH3)4ATP closer together at the active site. The data also permit an evaluation of the role of the metal coordinated to the beta-P and gamma-P of ATP at the active site.

ChemInform Abstract: SYNTHESIS OF 3‐FUNCTIONALLY‐SUBSTITUTED 4‐OXIMINOPIPERIDINE NITROXYLS

Abstract3‐Chlorund 3‐Brom‐2,2,6,(v‐tetramethyl‐4‐ox0piperidin‐1‐oxyl (I) reagieren nicht mit nucleophilen Reagentien.

Mixed-ligand lanthanide complexes—II : Complexes of β-diketone and heterocyclic amine. Synthesis and spectroscopic studies

The imidazole adducts of tris(heptafluorooctanedionato)lanthanide(III), [Ln(fod) 3 · im] have been synthesized and characterized. The electronic spectra in the visible region have been analysed and spectral parameters ( β , b 1/2, δ and T λ) and oscillator strengths calculated and discussed. These complexes are more covalent than the analogous [Ln(fod) 3 · pz] complexes, pz = pyrazole. The covalency is more in solution than in the solid state. The experimental and the calculated oscillator strengths are in good agreement. The band shape for the hypersensitive transition in the solid and solution spectra is compared with the other known systems and discussed. The difference in the band shape of the hypersensitive transition in the solid and in solution is indicative of solvent molecule coordination. The Mössbauer spectrum of [Eu(fod) 3 · im] is reported. The dipolar shift produced in the NMR spectrum of [Eu(fod) 3 · im] is upfield in comparison to the signal of the organic moiety itself as well as in its diamagnetic analogues. The coordinated base does not dissociate even in DMSO solution. Due to their poor solubility these compounds are not suitable for use as induced NMR shift reagents.

Investigations of the metal ion-binding sites of yeast inorganic pyrophosphatase.

Yeast inorganic pyrophosphatase was found to bind two Mn2+ per subunit in the absence of phosphate and three Mn2+ per subunit in the presence of phosphate. Kinetic studies of the pyrophosphatase-catalyzed hydrolysis of Cr(NH3)4PP and Cr(H2O)4PP were carried out with Mn2+ and with Mg2+ as activators. The results from these studies suggest that three divalent cations per pyrophosphatase active site are required for catalysis. NMR and EPR studies were conducted to evaluate the relative location of the metal ion binding sites on the enzyme. The two Mn2+ ions bound to the free enzyme are in close enough proximity to magnetically interact. Analysis of the NMR and EPR data in terms of a dipolar relaxation mechanism between Mn2+ ions provides an estimate of the distance between them of 10-14 A. When the diamagnetic substrate analog [Co(NH3)4PNP]- or intermediate analog [Co(NH3)4 (P)2]- are bound to pyrophosphatase, two Mn2+ ions still bind to the enzyme and their magnetic interaction increases. In the presence of these Co3+ complexes, the Mn2+--Mn2+ separation decreases to 7-9 A. Several NMR and EPR experiments were conducted at low Mn2+ to pyrophosphatase ratios (approximately 0.3), where only one Mn2+ ion binds per subunit, in the presence of Cr3+ or Co3+ complexes of PNP or PP. Analysis of the Mn2+--Cr3+ dipolar relaxation evident in proton NMR and EPR data provided for the calculation of Mn2+--Cr3+ distances. When the substrate analog CrPNP was present, the Mn2+--Cr3+ distance was congruent to 7 A whereas, when Cr(P)2 was bound to pyrophosphatase, the Mn2+--Cr3+ distance was congruent to 5 A. These results strongly support a model for the catalytic site of pyrophosphatase that involves three metal ion cofactors.

Influence of the radical center on the basic hydrolysis reaction of 4-dihalomethyl-3-imidazoline-3-oxide

1. The nitroxyl group in 4-dihalomethyl-3-imidazoline-3-oxide-1-oxyls substantially modifies the reactivity of the dihalomethyl group, giving it greater activity in comparison with the diamagnetic analog in the basic hydrolysis reaction and greater inclination to oxidation by the radical center. 2. The main products of hydrolysis in aqueous alcohol of diamagnetic 4-dihalomethyl-3-imidazoline-3-oxide are 4-dialkoxymethyl derivatives, and of nitroxyl radicals with the 4-dihalodimethyl group, a mixture of paramagnetic and diamagnetic 4-carboxy-3-imidazoline-3-oxides. 3. In contrast to the diamagnetic, in the paramagnetic derivatives of 4-dihalodimethyl-3-imidazoline-3-oxides the reactivity changes in going from the dibromomethyl to the dichloromethyl derivative, i.e., the rate of basic hydrolysis increases. 4. Under the reaction conditions of basic hydrolysis the paramagnetic 4-dihalomethyl-3-imidazoline-3-oxides are oxidized by radicals of the 3-imidazoline-3-oxide, 2- and 3-imidazoline and imidazolidinone series; the radical centers of these are easily reduced to amino groups.

Metalmetal interactions in enzymes: EPR and NMR investigations

Our recent work has dealt with an evaluation of metal-metal interactions in enzymes that require more than one divalent cation as active site components. Two enzymes we have extensively investigated are glutamine synthetase and inorganic pyrophosphatase. Glutamine synthetase catalyzes the formation of glutamine from glutamate. ATP and NH 3 as shown below. ▪ The enzyme requires two divalent cations for catalysis. An EPR method was to utilized calculate the distance between metal ions bound at the two metal ion sites β,γ-Cr 3+ ATP was used to study the interaction between Mn(II) at the n 1 site and Cr(III) of the nucleotide complex bound at the n 2 site. Addition of a saturating amount of β,γ-CrATP produced a decrease in the EPR spectrum of enzyme-bound Mn(II). This dipolar spin-spin interaction was analyzed at 35 GHz to calculate the distance between Mn(II) and Cr(III) (∼7 Å). Similarly, the EPR signal amplitude of enzyme-Mn(n 1) was diminished by addition of Mn(II) to the n 2 site. Analysis of the data indicated that this phenomenon was due to a dipolar spin-spin interaction. NMR results also corroborated this conclusion. Distances between the two metal ion sites were calculated from both sets of data. The Mn(II)Mn(II) distances were found to be 8.1–11.2 Å with nucleotide and 11.5–13 Å without nucleotide. Thus, nucleotide binding induced a conformational change which brings the two metals closer together. The two metal ions are in close enough proximity to be involved in substrate binding, orientation, and activation. The distances measured for Mn(II) at both the n 1 and n 2 sites are larger than those measured for Mn(II) at n 1 and Cr-nucleotides at n 2. This suggests that the Cr(III) moiety of a Cr-nucleotide does not bind directly to the n 2 metal ion site, but is several angstroms displaced from the ‘true‘ metal ion active site. NMR and EPR studies were conducted to evaluate the number of metal ion binding sites on yeast inorganic pyrophosphatase (PPase). Apo-PPase binds two Mn 2+ per subunit and these metal ions are in close enough proximity to magnetically interact. Analysis of the NMR and EPR data in terms of dipolar relaxation mechanism between Mn 2+ ions provides an estimate of the distance between them (10–14 Å). When the diamagnetic substrate analogs Co(NH 3) 4PNP or Co(NH 3) 4PP are bound to PPase, two Mn 2+ ions still binds to the enzyme and their magnetic interaction increases. In the presence of these Co 3+ substrate analogs the Mn 2+Mn 2+ separation decreases to 7–9 Å. Several NMR and EPR experiments were conducted at low Mn 2+ to PPase ratios (∼0.3), where only one Mn 2+ ion binds per subunit, in the presence of Cr 3+ or Co 3+ complexes of PNP or PP. Analysis of the Mn 2+Cr 3+ dipolar relaxation evident in NMR and EPR data resulted in calculation of Mn 2+Cr 3+ distances. When the substrate analog PNP was present, the Mn 2Cr 3+ distance was ∼7Å whereas when the product complex formed from PP was bound to PPase the Mn 2+-Cr 3+ distance was ∼5 Å. These results strongly support a model for the catalytic site of PPase that involves three metal ions in binding and catalysis.

New synthesis of mixed-metal clusters from H2Os3(CO)10. Crystal and molecular structure of the paramagnetic cluster H3(.eta.5-C5H5)CoOs3(CO)9 and its diamagnetic structural analog H3(.eta.C5H5)NiOs3(CO)9

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew synthesis of mixed-metal clusters from H2Os3(CO)10. Crystal and molecular structure of the paramagnetic cluster H3(.eta.5-C5H5)CoOs3(CO)9 and its diamagnetic structural analog H3(.eta.C5H5)NiOs3(CO)9Sheldon G. Shore, Wen Liang Hsu, Clemens R. Weisenberger, Maureen L. Caste, Melvyn Rowen Churchill, and Clifford BuenoCite this: Organometallics 1982, 1, 10, 1405–1407Publication Date (Print):October 1, 1982Publication History Published online1 May 2002Published inissue 1 October 1982https://doi.org/10.1021/om00070a028RIGHTS & PERMISSIONSArticle Views56Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (390 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Synthesis of diamagnetic structural analogs of representative doxyl, proxyl, piperidine, and pyrroline nitroxide spin labels

Synthesis of diamagnetic structural analogs of representative doxyl, proxyl, piperidine, and pyrroline nitroxide spin labels