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1.
Nat Commun ; 11(1): 1992, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32332751

RESUMO

Polarization change induced by directional electron transfer attracts considerable attention owing to its fast switching rate and potential light control. Here, we investigate electronic pyroelectricity in the crystal of a mononuclear complex, [Co(phendiox)(rac-cth)](ClO4)·0.5EtOH (1·0.5EtOH, H2phendiox = 9, 10-dihydroxyphenanthrene, rac-cth = racemic 5, 5, 7, 12, 12, 14-hexamethyl-1, 4, 8, 11-tetraazacyclotetradecane), which undergoes a two-step valence tautomerism (VT). Correspondingly, pyroelectric current exhibits double peaks in the same temperature domain with the polarization change consistent with the change in dipole moments during the VT process. Time-resolved Infrared (IR) spectroscopy shows that the photo-induced metastable state can be generated within 150 ps at 190 K. Such state can be trapped for tens of minutes at 7 K, showing that photo-induced polarization change can be realized in this system. These results directly demonstrate that a change in the molecular dipole moments induced by intramolecular electron transfer can introduce a macroscopic polarization change in VT compounds.

2.
Nat Commun ; 10(1): 5510, 2019 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-31796745

RESUMO

The study of transition metal clusters exhibiting fast electron hopping or delocalization remains challenging, because intermetallic communications mediated through bridging ligands are normally weak. Herein, we report the synthesis of a nanosized complex, [Fe(Tp)(CN)3]8[Fe(H2O)(DMSO)]6 (abbreviated as [Fe14], Tp-, hydrotris(pyrazolyl)borate; DMSO, dimethyl sulfoxide), which has a fluctuating valence due to two mobile d-electrons in its atomic layer shell. The rate of electron transfer of [Fe14] complex demonstrates the Arrhenius-type temperature dependence in the nanosized spheric surface, wherein high-spin centers are ferromagnetically coupled, producing an S = 14 ground state. The electron-hopping rate at room temperature is faster than the time scale of Mössbauer measurements (<~10-8 s). Partial reduction of N-terminal high spin FeIII sites and electron mediation ability of CN ligands lead to the observation of both an extensive electron transfer and magnetic coupling properties in a precisely atomic layered shell structure of a nanosized [Fe14] complex.

3.
Rev Sci Instrum ; 90(11): 113101, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31779391

RESUMO

We present results obtained with a new soft X-ray spectrometer based on transition-edge sensors (TESs) composed of Mo/Cu bilayers coupled to bismuth absorbers. This spectrometer simultaneously provides excellent energy resolution, high detection efficiency, and broadband spectral coverage. The new spectrometer is optimized for incident X-ray energies below 2 keV. Each pixel serves as both a highly sensitive calorimeter and an X-ray absorber with near unity quantum efficiency. We have commissioned this 240-pixel TES spectrometer at the Stanford Synchrotron Radiation Lightsource beamline 10-1 (BL 10-1) and used it to probe the local electronic structure of sample materials with unprecedented sensitivity in the soft X-ray regime. As mounted, the TES spectrometer has a maximum detection solid angle of 2 × 10-3 sr. The energy resolution of all pixels combined is 1.5 eV full width at half maximum at 500 eV. We describe the performance of the TES spectrometer in terms of its energy resolution and count-rate capability and demonstrate its utility as a high throughput detector for synchrotron-based X-ray spectroscopy. Results from initial X-ray emission spectroscopy and resonant inelastic X-ray scattering experiments obtained with the spectrometer are presented.

4.
Nanoscale ; 11(32): 15131-15138, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31372609

RESUMO

The enhancement of toroic motifs through coupling toroidal moments within molecular nanomagnets is a new, interesting and relevant approach for both fundamental research and potential quantum computation applications. We investigate a Dy8 molecular cluster and discover it has a antiferrotoroic ground state with slow magnetic relaxation. The experimental characterization of the magnetic anisotropy axes of each magnetic center and their exchange interactions represents a considerable challenge due to the non-magnetic nature of the toroidal motif. To overcome this and obtain access to the low energy states of Dy8 we establish a multi-orientation single-crystal micro Hall sensor magnetometry approach. Using an effective Hamiltonian model we then unpick the microscopic spin structure of Dy8, leading to a canted antiferrotoroidic tetramer molecular ground state. These findings are supported with electrostatic calculations that independently confirm the experimentally determined magnetic anisotropy axes for each DyIII ion within the molecule.

5.
Inorg Chem ; 58(15): 10160-10166, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31294551

RESUMO

The ability to switch a molecule between different magnetic states is of considerable importance for the development of new molecular electronic devices. Desirable properties for such applications include a large-spin ground state with an electronic structure that can be controlled via external stimuli. Fe42 is a cyanide-bridged stellated cuboctahedron of mixed-valence Fe ions that exhibits an extraordinarily large S = 45 spin ground state. We have found that the spin ground state of Fe42 can be altered by controlling the humidity and temperature. Dehydration results in a 15 µB reduction of the saturation magnetization that can be partially recovered upon rehydration. The complementary use of UV-vis, IR, L2,3-edge X-ray absorption spectroscopy and X-ray magnetic circular dichroism is applied to uncover the mechanism for the observed dynamic behavior. It is identified that dehydration is concurrent with metal-to-metal electron transfer between Fe pairs via a cyanide π hybridization. Upon dehydration, electron transfer occurs from low-spin {FeII(Tp)(CN)3} sites to high-spin FeIII centers. The observed reduction in magnetization upon dehydration of Fe42 is inconsistent with a ferrimagnetic ground state and is proposed to originate from a change in zero-field splitting at electron-reduced high-spin sites.

6.
Pediatr Pulmonol ; 54(6): 822-827, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30843378

RESUMO

BACKGROUND: Neuroendocrine cell hyperplasia of infancy (NEHI) is a rare pediatric interstitial lung disease (ILD). Distinct chest computed tomography (CT) define its radiographic appearance-specifically, ground-glass (GG) opacities most prominent in the right middle lobe (RML) and lingula. We sought to quantitatively validate this description and correlate radiologic findings with clinical presentation. METHODS: Twenty-one children with NEHI were identified retrospectively, alongside 10 age-matched controls without lung disease. Clinical histories were reviewed for NEHI subjects. Semiautomated image analysis was used to measure lung volume and density. A patient-specific Hounsfield unit threshold defining GG was developed to quantify GG and assess its distribution in each subject. RESULTS: NEHI subjects had more GG than controls (37.9 ± 11.3% vs 14.0 ± 2.7%, P < 0.0001). The proportion of GG in the RML and lingula was greater in NEHI patients compared to controls (1.43 ± 0.37 vs 0.45 ± 0.21, P < 0.0001). GG preferentially involved the RML and lingula in 20/21 NEHI subjects. There was more GG distribution in NEHI subjects who were prescribed continuous oxygen compared with those using only nocturnal oxygen (45.7 ± 8.9% vs 29.3 ± 6.1%, P = 0.003). CONCLUSIONS: We confirm the previously reported finding that most patients with childhood ILD and a distinctive pattern of GG distribution on CT scan are likely to have NEHI. The amount of GG may be a biomarker for severity of respiratory disease.

7.
Proc Natl Acad Sci U S A ; 116(8): 2854-2859, 2019 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-30718404

RESUMO

Hemoglobin and myoglobin are oxygen-binding proteins with S = 0 heme {FeO2}8 active sites. The electronic structure of these sites has been the subject of much debate. This study utilizes Fe K-edge X-ray absorption spectroscopy (XAS) and 1s2p resonant inelastic X-ray scattering (RIXS) to study oxyhemoglobin and a related heme {FeO2}8 model compound, [(pfp)Fe(1-MeIm)(O2)] (pfp = meso-tetra(α,α,α,α-o-pivalamido-phenyl)porphyrin, or TpivPP, 1-MeIm = 1-methylimidazole) (pfpO2), which was previously analyzed using L-edge XAS. The K-edge XAS and RIXS data of pfpO2 and oxyhemoglobin are compared with the data for low-spin FeII and FeIII [Fe(tpp)(Im)2]0/+ (tpp = tetra-phenyl porphyrin) compounds, which serve as heme references. The X-ray data show that pfpO2 is similar to FeII, while oxyhemoglobin is qualitatively similar to FeIII, but with significant quantitative differences. Density-functional theory (DFT) calculations show that the difference between pfpO2 and oxyhemoglobin is due to a distal histidine H bond to O2 and the less hydrophobic environment in the protein, which lead to more backbonding into the O2 A valence bond configuration interaction multiplet model is used to analyze the RIXS data and show that pfpO2 is dominantly FeII with 6-8% FeIII character, while oxyhemoglobin has a very mixed wave function that has 50-77% FeIII character and a partially polarized Fe-O2 π-bond.


Assuntos
Ferro/química , Oxigênio/química , Oxiemoglobinas/química , Porfirinas/química , Domínio Catalítico , Compostos Férricos/química , Heme/química , Metaloporfirinas/química , Modelos Moleculares , Mioglobina/química , Espalhamento de Radiação , Espectroscopia por Absorção de Raios X , Raios X
8.
Chem Sci ; 9(33): 6813-6829, 2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-30310614

RESUMO

Transition metals in inorganic systems and metalloproteins can occur in different oxidation states, which makes them ideal redox-active catalysts. To gain a mechanistic understanding of the catalytic reactions, knowledge of the oxidation state of the active metals, ideally in operando, is therefore critical. L-edge X-ray absorption spectroscopy (XAS) is a powerful technique that is frequently used to infer the oxidation state via a distinct blue shift of L-edge absorption energies with increasing oxidation state. A unified description accounting for quantum-chemical notions whereupon oxidation does not occur locally on the metal but on the whole molecule and the basic understanding that L-edge XAS probes the electronic structure locally at the metal has been missing to date. Here we quantify how charge and spin densities change at the metal and throughout the molecule for both redox and core-excitation processes. We explain the origin of the L-edge XAS shift between the high-spin complexes MnII(acac)2 and MnIII(acac)3 as representative model systems and use ab initio theory to uncouple effects of oxidation-state changes from geometric effects. The shift reflects an increased electron affinity of MnIII in the core-excited states compared to the ground state due to a contraction of the Mn 3d shell upon core-excitation with accompanied changes in the classical Coulomb interactions. This new picture quantifies how the metal-centered core hole probes changes in formal oxidation state and encloses and substantiates earlier explanations. The approach is broadly applicable to mechanistic studies of redox-catalytic reactions in molecular systems where charge and spin localization/delocalization determine reaction pathways.

10.
Chem Sci ; 9(14): 3555-3562, 2018 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-29780487

RESUMO

The Cr7Co ring represents a model system to understand how the anisotropy of a CoII ion is transferred to the effective anisotropy of a polymetallic cluster by strong exchange interactions. Combining sizeable anisotropy with exchange interactions is an important point in the understanding and design of new anisotropic molecular nanomagnets addressing fundamental and applicative issues. By combining electron paramagnetic resonance and inelastic neutron scattering measurements with spin Hamiltonian and ab initio calculations, we have investigated in detail the anisotropy of the CoII ion embedded in the antiferromagnetic ring. Our results demonstrate a strong and anisotropic exchange interaction between the Co and the neighbouring Cr ions, which effectively transmits the anisotropy to the whole molecule.

11.
Inorg Chem ; 57(9): 5449-5462, 2018 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-29634280

RESUMO

The 3d transition metals play a pivotal role in many charge transfer processes in catalysis and biology. X-ray absorption spectroscopy at the L-edge of metal sites probes metal 2p-3d excitations, providing key access to their valence electronic structure, which is crucial for understanding these processes. We report L-edge absorption spectra of MnII(acac)2 and MnIII(acac)3 complexes in solution, utilizing a liquid flatjet for X-ray absorption spectroscopy in transmission mode. With this, we derive absolute absorption cross-sections for the L-edge transitions with peak magnitudes as large as 12 and 9 Mb for MnII(acac)2 and MnIII(acac)3, respectively. We provide insight into the electronic structure with ab initio restricted active space calculations of these L-edge transitions, reproducing the experimental spectra with excellent agreement in terms of shapes, relative energies, and relative intensities for the two complexes. Crystal field multiplet theory is used to assign spectral features in terms of the electronic structure. Comparison to charge transfer multiplet calculations reveals the importance of charge transfer in the core-excited final states. On the basis of our experimental observations, we extrapolate the feasibility of 3d transition metal L-edge absorption spectroscopy using the liquid flatjet approach in probing highly dilute biological solution samples and possible extensions to table-top soft X-ray sources.

12.
J Chem Phys ; 147(21): 214201, 2017 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-29221417

RESUMO

We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100-2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique ability to characterize frozen solutions of radiation- and temperature-sensitive samples.

13.
Coord Chem Rev ; 345: 182-208, 2017 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-28970624

RESUMO

Continual advancements in the development of synchrotron radiation sources have resulted in X-ray based spectroscopic techniques capable of probing the electronic and structural properties of numerous systems. This review gives an overview of the application of metal K-edge and L-edge X-ray absorption spectroscopy (XAS), as well as K resonant inelastic X-ray scattering (RIXS), to the study of electronic structure in transition metal sites with emphasis on experimentally quantifying 3d orbital covalency. The specific sensitivities of K-edge XAS, L-edge XAS, and RIXS are discussed emphasizing the complementary nature of the methods. L-edge XAS and RIXS are sensitive to mixing between 3d orbitals and ligand valence orbitals, and to the differential orbital covalency (DOC), that is, the difference in the covalencies for different symmetry sets of the d orbitals. Both L-edge XAS and RIXS are highly sensitive to and enable separation of and donor bonding and back bonding contributions to bonding. Applying ligand field multiplet simulations, including charge transfer via valence bond configuration interactions, DOC can be obtained for direct comparison with density functional theory calculations and to understand chemical trends. The application of RIXS as a probe of frontier molecular orbitals in a heme enzyme demonstrates the potential of this method for the study of metal sites in highly covalent coordination sites in bioinorganic chemistry.

14.
Ann Am Thorac Soc ; 13(12): 2174-2183, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27684511

RESUMO

RATIONALE: Refractory lung function decline in association with recurrent pulmonary exacerbations is a common, yet poorly explained finding in cystic fibrosis (CF). To investigate the histopathologic mechanisms of pulmonary deterioration during adolescence and early adulthood, we reviewed clinically-indicated lung biopsy specimens obtained during a period of persistent decline. OBJECTIVES: To determine if peribronchiolar remodeling is prominent in lung biopsy specimens obtained in adolescents with CF refractory to conventional therapy. METHODS: Six adolescents with CF (mean age, 16.2 y; mean FEV1, 52% predicted at biopsy) with significant pulmonary deterioration over 12-24 months (mean FEV1 decline of 14% predicted/year) despite aggressive intervention underwent computed tomography imaging and ultimately lung biopsy to aid clinical management. In addition to routine clinical evaluation, histopathologic investigation included staining for transforming growth factor-ß (TGF-ß, a genetic modifier of CF lung disease), collagen deposition (a marker of fibrosis), elastin (to evaluate for bronchiectasis), and α-smooth muscle actin (to identify myofibroblasts). MEASUREMENTS AND MAIN RESULTS: All computed tomography scans demonstrated a mix of bronchiectasis and hyperinflation that was variable across lung regions and within patients. Lung biopsy revealed significant peribronchiolar remodeling, particularly in patients with more advanced disease, with near complete obliteration of the peribronchiolar lumen (constrictive bronchiolitis). Myofibroblast differentiation (a TGF-ß-dependent process) was prominent in specimens with significant airway remodeling. CONCLUSIONS: Constrictive bronchiolitis is widely present in the lung tissue of adolescents with CF with advanced disease and may contribute to impaired lung function that is refractory to conventional therapy (antibiotics, antiinflammatories, and mucolytics). TGF-ß-dependent myofibroblast differentiation is prominent in areas of active fibrogenesis and may foster small airway remodeling in CF lung disease.


Assuntos
Remodelação das Vias Aéreas , Bronquiolite Obliterante/diagnóstico , Bronquiolite Obliterante/patologia , Fibrose Cística/complicações , Fibrose Cística/patologia , Pulmão/fisiopatologia , Adolescente , Estudos de Casos e Controles , Criança , Progressão da Doença , Elastina/metabolismo , Feminino , Fibrose , Humanos , Masculino , Miofibroblastos , Espirometria , Tomografia Computadorizada por Raios X , Fator de Crescimento Transformador beta/metabolismo , Adulto Jovem
15.
Pediatr Surg Int ; 32(4): 417-24, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26790674

RESUMO

Tracheobronchial mucoepidermoid carcinomas (MEC) are rare in the pediatric population with literature limited primarily to case reports. Here we present our institutional experience treating MEC in three patients and review the literature of 142 pediatric cases previously published from 1968 to 2013. Although rare, tracheobronchial MEC should be included in the differential diagnosis in a child with recurrent respiratory symptoms. Conservative surgical management is often sufficient to achieve complete resection and good outcomes.


Assuntos
Neoplasias Brônquicas/diagnóstico , Carcinoma Mucoepidermoide/diagnóstico , Neoplasias da Traqueia/diagnóstico , Adolescente , Neoplasias Brônquicas/complicações , Neoplasias Brônquicas/cirurgia , Broncoscopia , Carcinoma Mucoepidermoide/complicações , Carcinoma Mucoepidermoide/cirurgia , Criança , Humanos , Masculino , Pneumonectomia , Pneumonia/etiologia , Tomografia Computadorizada por Raios X , Neoplasias da Traqueia/complicações , Neoplasias da Traqueia/cirurgia
16.
Chemistry ; 22(5): 1779-88, 2016 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-26748964

RESUMO

The spin dynamics of Cr8 Mn, a nine-membered antiferromagnetic (AF) molecular nanomagnet, are investigated. Cr8 Mn is a rare example of a large odd-membered AF ring, and has an odd-number of 3d-electrons present. Odd-membered AF rings are unusual and of interest due to the presence of competing exchange interactions that result in frustrated-spin ground states. The chemical synthesis and structures of two Cr8 Mn variants that differ only in their crystal packing are reported. Evidence of spin frustration is investigated by inelastic neutron scattering (INS) and muon spin relaxation spectroscopy (µSR). From INS studies we accurately determine an appropriate microscopic spin Hamiltonian and we show that µSR is sensitive to the ground-spin-state crossing from S=1/2 to S=3/2 in Cr8 Mn. The estimated width of the muon asymmetry resonance is consistent with the presence of an avoided crossing. The investigation of the internal spin structure of the ground state, through the analysis of spin-pair correlations and scalar-spin chirality, shows a non-collinear spin structure that fluctuates between non-planar states of opposite chiralities.

17.
Inorg Chem ; 54(12): 5732-8, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-26010987

RESUMO

The incorporation of paramagnetic ligands within rare-earth ion clusters exhibiting large magnetic anisotropy has provided significant advancement in the design of single-molecule magnets (SMMs) with large blocking temperatures. However, the exchange interaction in such systems is complex and difficult to probe by conventional magnetometry techniques, and little is known about the structural relationships. Inelastic neutron scattering and terahertz electron paramagnetic resonance measurements are used complimentarily to investigate the large exchange interaction between a rare earth-radical pair in a Tb(III)-based SMM complex. The origin of the exchange interaction is investigated for two molecular species in the crystallographic unit cell that exhibit different bonding structures between Tb(III) and a 2pyNO radical. A correlation between the Tb-O-N-C torsion angles and the magnitudes of exchange couplings is found. Interestingly, a large nondegeneracy within the ground-state doublet is present for the larger torsion angle species. It is essential to consider the balance of two channels of exchange coupling, 2p-4f hybridization and 2p-5d charge transfer, to explain this characteristic behavior. The former channel gives the antiferromagnetic interaction, and the latter gives the ferromagnetic one. When an effective J = (1)/2 Ising-type Hamiltonian is applied, the exchange couplings are evaluated to be antiferromagnetic J(z) = 9.89 meV (79.8 cm(-1)) for the low torsion angle (3.8°) species and J(z) = 7.39 meV (59.6 cm(-1)) for the larger torsion angle (15.8°) species. It is also found that a small percentage of the transverse exchange component must be included for the larger torsion angle to account for the observed nondegenerate ground state. The symmetry of the exchange couplings is discussed by considering the characters of d and f orbitals.

18.
Nat Commun ; 6: 5955, 2015 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-25562786

RESUMO

Self-assembly of artificial nanoscale units into superstructures is a prevalent topic in science. In biomimicry, scientists attempt to develop artificial self-assembled nanoarchitectures. However, despite extensive efforts, the preparation of nanoarchitectures with superior physical properties remains a challenge. For example, one of the major topics in the field of molecular magnetism is the development of high-spin (HS) molecules. Here, we report a cyanide-bridged magnetic nanocage composed of 18 HS iron(III) ions and 24 low-spin iron(II) ions. The magnetic iron(III) centres are ferromagnetically coupled, yielding the highest ground-state spin number (S = 45) of any molecule reported to date.

19.
Pediatr Transplant ; 19(1): E15-8, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25440410

RESUMO

We present the unique case of a pediatric patient who received chemotherapy for a diagnosis of CD, while mechanically supported with a Berlin EXCOR LVAD secondary to restrictive cardiomyopathy. A four-yr-old previously healthy male with restrictive cardiomyopathy required MCS after cardiac arrest but was diagnosed with multicentric CD, a non-malignant lymphoproliferative disorder fueled by excessive IL-6 production. Treatment with IL-6 blockade (tocilizumab) every two wk and methylprednisolone had no effect on his lymph nodes or cardiac function while on temporary RotaFlow. A Berlin LVAD was placed for treatment with rituximab, COP, vincristine, and methylprednisolone. After three courses of chemotherapy, his inflammatory markers normalized and his lymphadenopathy decreased but cardiac function remained severely depressed. He tolerated chemotherapy on the Berlin but required frequent titrations of his anti-coagulation regimen and he did suffer a hemorrhagic stroke. His clinical status improved significantly with rehabilitation, and he tolerated heart transplantation without further complications. MCS is a feasible option as a bridge to recovery or heart transplant eligibility for patients with hemodynamic collapse requiring chemotherapy but it does necessitate close titration of the anti-coagulation regimen to coincide with changes in the inflammatory state.


Assuntos
Cardiomiopatia Restritiva/cirurgia , Hiperplasia do Linfonodo Gigante/tratamento farmacológico , Coração Auxiliar , Cardiomiopatia Restritiva/complicações , Hiperplasia do Linfonodo Gigante/complicações , Pré-Escolar , Humanos , Masculino
20.
J Am Chem Soc ; 136(27): 9763-72, 2014 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-24968057

RESUMO

Compounds of general formula [Cr7MF3(Etglu)(O2C(t)Bu)15(Phpy)] [H5Etglu = N-ethyl-d-glucamine; Phpy = 4-phenylpyridine; M = Zn (1), Mn (2), Ni (3)] have been prepared. The structures contain an irregular octagon of metal sites formed around the penta-deprotonated Etglu(5-) ligand; the chirality of N-ethyl-d-glucamine is retained in the final product. The seven Cr(III) sites have a range of coordination environments, and the divalent metal site is crystallographically identified and has a Phpy ligand attached to it. By using complementary experimental techniques, including magnetization and specific heat measurements, inelastic neutron scattering, and electron paramagnetic resonance spectroscopy, we have investigated the magnetic features of this family of {Cr7M} rings. Microscopic parameters of the spin Hamiltonian have been determined as a result of best fits of the different experimental data, allowing a direct comparison with corresponding parameters found in the parent compounds. We examine whether these parameters can be transferred between compounds and compare them with those of an earlier family of heterometallic rings.

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