Modelling chromium biochemistry: Synthesis and characterization of [NEt3H][Cr4IIIO2(O2CPh)7(pic)2]·CH2Cl2 (Hpic = Picolinic acid)

Donald, S.; Terrell, Katisha; Vincent, John B.; Robinson, Kerry D.

doi:10.1016/0277-5387(94)00360-q

Cited by 27 publications

(9 citation statements)

References 21 publications

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“…The two picolinate ligands can bind either syn or anti to each other (with respect to the orientation of the six-membered ring of picolinate). The syn configuration is observed in the crystal structures of [M 4 O 2 (O 2 CR) 7 (pic) 2 ] - (M = Cr, Mn 40 ) and is the most likely configuration for the major component of 5 . The anti isomer is observed in the neutral complex [Mn 4 O 2 (O 2 CPh) 6 (pic) 2 (MeCN) 2 ] …”

Section: Resultsmentioning

confidence: 97%

Single-Molecule Magnets: Tetranuclear Vanadium(III) Complexes with a Butterfly Structure and an S = 3 Ground State

et al. 1998

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Reactions of VCl3(THF)3, bpy, and NaO2CR (R = Et, Ph; bpy = 2,2‘-bipyridine) in a 1:1:3 ratio in Me2CO give [V4O2(O2CR)7(bpy)2](ClO4) (R = Et, 1; R = Ph, 4) following addition of NBun 4ClO4. Use of 4,4‘-dimethyl- or 5,5‘-dimethylbipyridine (4,4‘-Me2bpy and 5,5‘-Me2bpy, respectively) and R = Et leads similarly to [V4O2(O2CEt)7(L−L)2](ClO4) (L−L = 4,4‘-Me2bpy, 2; L−L = 5,5‘-Me2bpy, 3). Yields are in the 38−90% range. The cation of 1 is isostructural with previously prepared [M4O2(O2CR)7(bpy)2]+ (M = CrIII, MnIII, FeIII) species and possesses a [V4O2] butterfly core. 1D and 2D COSY 1H NMR spectra of 1 show the solid-state structure is retained on dissolution. The effective magnetic moment (μeff) per V4 for 1 gradually rises from 5.79 μB at 300 K to a maximum of 6.80 μB at 25.0 K and then decreases rapidly to 4.72 μB at 2.00 K. The data in the 7.00−300 K range were fit to the appropriate theoretical expression (based on Ĥ = −2JS i ·S j ) to give J bb = −31.2 cm-1, J wb = +27.5 cm-1, and g = 1.82, (b = body, w = wingtip). These values indicate a S T = 3 ground state, confirmed by magnetization vs field studies. Similar results were obtained for the 2-picolinate (pic) analogue of 1 (complex 5). The S T = 3, 1, 3, and 0 ground states for the M = VIII, CrIII, MnIII, and FeIII, respectively, are rationalized using spin frustration arguments based on competition between J bb and J wb interactions. AC magnetic susceptibility studies down to 1.7 K on 1 and 5 show weak out-of-phase signals (χ‘‘M) below 4.0 K and corresponding small decreases in the in-phase signals (χ‘M), indicating that the relaxation of magnetization is unusually slow and comparable with the oscillating AC field (250−1000 Hz). This is a characteristic signature of a single-molecule magnet. Simultaneous application of AC and DC fields has the effect of increasing the barrier to magnetization relaxation, causing the χ‘‘M signal to move to higher temperature and consequently leading to a much stronger χ‘‘M signal and, for 5, the observation of a peak at ∼2.0 K. A dependence of the χ‘‘M peak position of 5 on the DC field intensity and AC field oscillation frequency is found.

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Section: Resultsmentioning

confidence: 97%

Single-Molecule Magnets: Tetranuclear Vanadium(III) Complexes with a Butterfly Structure and an S = 3 Ground State

et al. 1998

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“…Blood chemistry Blood (1.5 mL) was collected from tail snips into polypropylene tubes after 4,8,12,16,20, and 24 weeks of cation or H 2 O administration. Prior to blood collection, animals were fasted 12-15 h. Immediately after blood removal, 0.5 mg/mL heparin and 10 mg/mL NaF were added to the blood.…”

Section: Animalsmentioning

confidence: 99%

“…The existence of a multinuclear Cr(III) carboxylate assembly in an active biomolecule has spurred an interest in the synthesis and characterization of multinuclear oxo(hydroxo)-bridged chromium(III) carboxylate assemblies [11,12,13,14]. Well-characterized, watersoluble assemblies have been tested for the ability to stimulate the insulin receptor's tyrosine kinase ability in a fashion similar to chromodulin.…”

Section: Introductionmentioning

confidence: 99%

The biomimetic [Cr3O(O2CCH2CH3)6(H2O)3]+ decreases plasma insulin, cholesterol, and triglycerides in healthy and type II diabetic rats but not type I diabetic rats

et al. 2002

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The in vivo effects of administration of the synthetic, functional biomimetic cation [Cr(3)O(O(2)CCH(2)CH(3))(6)(H(2)O)(3)](+) to healthy and type I and type II diabetic model rats are described. In contrast to current chromium-containing nutrition supplements, which only serve as sources of absorbable chromium, the trinuclear cation has been shown in in vitro assays to interact with the insulin receptor, activating its kinase activity, presumably by trapping the receptor in its active conformation. Thus, treatment of rats with the trinuclear cation would be expected to result in changes in lipid and carbohydrate metabolism related to insulin action. After 24 weeks of intravenous administration (0-20 micro g Cr/kg body mass), the cation results in a concentration-dependent lowering of levels of fasting blood plasma LDL cholesterol, total cholesterol, triglycerides, and insulin and of 2-h plasma insulin and glucose levels after a glucose challenge; these results confirm a previous 12-week study examining the effect of the synthetic cation on healthy rats and are in stark contrast to those of administration of other forms of Cr(III) to rats, which have no effect on these parameters. The cation has little, if any, effect on rats with STZ-induced diabetes (a type I diabetes model). However, Zucker obese rats (a model of the early stages of type II diabetes) after 24 weeks of supplementation (20 micro g/kg) have lower fasting plasma total, HDL, and LDL cholesterol, triglycerides, and insulin levels and lower 2-h plasma insulin levels. The lowering of plasma insulin concentrations with little effect on glucose concentrations suggests that the supplement increases insulin sensitivity.

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“…The distance between Cr and O in the slightly distorted octahedral coordinated Cr centers was estimated to be 1.973(9) Å, implying that the oxidation state of Cr was +3 (Table S1). − In contrast, molybdenum, the other metal source, retained the original tetrahedral geometry of MoO 4 2– , which is characteristic of stable Mo(VI) species . The metal–oxo ligands of MoO 4 2– were also observed to form bridges with the Cr centers.…”

Section: Resultsmentioning

confidence: 99%

Anisotropic Electrical Conductivity of a Single-Crystalline Oxo-Bridged Cr₄^IIIMo₂^VI Heterometallic Complex

Koo

Hyun

et al. 2021

Inorg. Chem.

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A new oxo-bridged chromium–molybdenum heterometallic complex, O-CrMoHC ([Cr4(MoO4)2O2(OAc)4(DMF)4]·2DMF), was synthesized by using a simple solvothermal reaction. In this complex, the octahedrally coordinated Cr(III) and tetrahedrally coordinated Mo(VI) metal centers are bridged by oxo ligands. O-CrMoHC has in-plane π-conjugation systems, which are interconnected by noncoordinating DMF molecules. The crystals show anisotropic conductivity with respect to the crystal planes, and theoretical calculations were used to study their origins. The O-CrMoHC single crystals exhibited that a relatively high electrical conductivity with an average value of 5.37 × 10–7 S/cm was observed along the [01–1] direction, but the current level was very low along the [100] direction. This is the first report of anisotropic conductivity observed in the single crystal of a monomeric heterometallic complex.

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Modelling chromium biochemistry: Synthesis and characterization of [NEt3H][Cr4IIIO2(O2CPh)7(pic)2]·CH2Cl2 (Hpic = Picolinic acid)

Cited by 27 publications

References 21 publications

Single-Molecule Magnets: Tetranuclear Vanadium(III) Complexes with a Butterfly Structure and an S = 3 Ground State

Single-Molecule Magnets: Tetranuclear Vanadium(III) Complexes with a Butterfly Structure and an S = 3 Ground State

The biomimetic [Cr3O(O2CCH2CH3)6(H2O)3]+ decreases plasma insulin, cholesterol, and triglycerides in healthy and type II diabetic rats but not type I diabetic rats

Anisotropic Electrical Conductivity of a Single-Crystalline Oxo-Bridged Cr₄^IIIMo₂^VI Heterometallic Complex

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Modelling chromium biochemistry: Synthesis and characterization of [NEt3H][Cr4IIIO2(O2CPh)7(pic)2]·CH2Cl2 (Hpic = Picolinic acid)

Cited by 27 publications

References 21 publications

Single-Molecule Magnets: Tetranuclear Vanadium(III) Complexes with a Butterfly Structure and an S = 3 Ground State

Single-Molecule Magnets: Tetranuclear Vanadium(III) Complexes with a Butterfly Structure and an S = 3 Ground State

The biomimetic [Cr3O(O2CCH2CH3)6(H2O)3]+ decreases plasma insulin, cholesterol, and triglycerides in healthy and type II diabetic rats but not type I diabetic rats

Anisotropic Electrical Conductivity of a Single-Crystalline Oxo-Bridged Cr4IIIMo2VI Heterometallic Complex

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Anisotropic Electrical Conductivity of a Single-Crystalline Oxo-Bridged Cr₄^IIIMo₂^VI Heterometallic Complex