Electron Spin Resonance Studies Research Articles

An EPR study on the radiolysis of isolated ethanol molecules in solid argon and xenon: matrix control of radiation-induced generation of radicals in cryogenic media.

This paper addresses the basic question of the impact of a chemically inert environment on the radiation-induced transformations of isolated organic molecules in icy media at cryogenic temperatures with possible implications for astrochemical issues. The radicals produced by X-ray irradiation of isolated ethanol molecules (C2H5OH and CH3CD2OH) in solid argon and xenon matrices at 7 K were characterized by electron paramagnetic resonance (EPR) spectroscopy. It was shown that methyl (CH3˙) and formyl (HCO˙) radicals resulting from the C-C bond cleavage were mainly produced in the case of solid argon, which was attributed to the significant role of "hot" ionic fragmentation and inefficient energy dissipation to medium. In contrast, irradiation in xenon results in the predominant formation of α-hydroxyethyl radicals (CH3˙CHOH or CH3˙CDOH(D) in the cases of C2H5OH and CH3CD2OH, respectively). Remarkably, the experiments with selectively deuterated ethanol provide strong indirect evidence for the primary formation of ethoxy (CH3CD2O˙) radicals due to O-H bond cleavage, which convert to the α-hydroxyethyl radicals due to isomerization occurring at 7 K. The α-hydroxyethyl radicals adopt a specific rigid conformation with a non-rotating methyl group at low temperatures, which is an unusual effect for neutral CH3˙CHX species, and exhibit free rotation in solid xenon only at ca. 65 K.

PS-C05-12: OMENTIN-1 PREDICTS MEMBRANE FLUIDITY OF RED BLOOD CELLS AND MICROCIRCULATORY FUNCTION IN HYPERTENSIVE SUBJECTS BY THE NITRIC OXIDE-DEPENDENT MECHANISM

Objective: It has been shown that abnormalities in physical properties of the cell membranes may strongly be linked to hypertension. Recent evidence indicates that omentin-1, an adipokine with anti-inflammatory properties, may actively participate in the pathophysiology of hypertension, atherosclerosis and other cardiovascular diseases. However, few studies have evaluated the association between omentin-1 and membrane function in hypertension. The present study was performed to investigate possible relationships among omentin-1, endothelial function and membrane fluidity (a reciprocal value of membrane microviscosity) of red blood cells (RBCs) in patients with essential hypertension and normotensive subjects. Design and method: We measured the membrane fluidity of RBCs with an electron spin resonance (ESR) and spin labeling method. In each ESR spectrum, we calculated the order parameter (S) for the spin-label agent (5-nitroxide stearate). The greater the value of the order parameter (S) was, the lower the membrane fluidity of RBC was. Results: (1) The order parameter (S) obtained from the ESR spectra of RBC membranes was significantly greater in hypertensive subjects (0.727 ± 0.001, n = 64) than in normotensive subjects (0.719 ± 0.001, n = 49, P < 0.0001), indicating that membrane fluidity of RBCs might be reduced in hypertensive subjects compared with normotensive subjects. (2) Plasma omentin-1 levels were lower in hypertensive subjects than in normotensive subjects (HT 0.486 ± 0.014 ng/mL, n = 64, NT 0.537 ± 0.019 ng/mL, n = 49, P < 0.05). Plamsa omentin-1 significantly correlated with plasma nitric oxide (NO)-metabolite levels (an index of endothelial function) (r = 0.392, n = 113, P < 0.0001). (3) Furthermore, the order parameter (S) of RBCs inversely correlated with both plasma omentin-1 (r = -0.347, n = 113, P < 0.001) and plasma NO-metabolites, suggesting that reduced membrane fluidity of RBCs might be associated with decreased levels of plasma omentin-1 and endothelial dysfunction. (4) Multivariate regression analysis showed that, after adjusting for confounding factors, plasma omentin-1 might be an independent predictor of membrane fluidity of RBCs. Conclusions: The ESR study demonstrated that lower plasma omentin-1 levels might have a close correlation with reduced membrane fluidity of RBCs and impaired hemorheologic behavior in hypertensive subjects by the NO-dependent mechanism. It is strongly suggested that plasma omentin-1 could be a putative biomarker for the microcirculatory function in hypertension.

Hyperfine effects and electron spin relaxation of 51V4+ doped into scandium orthosilicate Sc228SiO5: CW and pulsed X-band electron spin resonance studies

Hyperfine effects and electron spin relaxation of 51V4+ doped into scandium orthosilicate Sc228SiO5: CW and pulsed X-band electron spin resonance studies

Theory of shallow and deep boron defects in 4H -SiC

Abstract Despite advances toward improving the quality of $p$-type 4H-SiC substrates and layers, we still have no model capable of accounting for the multitude of boron-related optical, junction, and paramagnetic resonance experiments available in the literature. A conspicuous puzzle is the observation of two shallow boron defects with rather distinct axial orientations as found by electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) data. This feature is not observed in material doped with other group-III elements. Another open issue involves conflicting conclusions from photoluminescence and EPR studies of a deeper boron center, which has been linked to rather distinct models, either based on substitutional or vacancy-related boron defects. We unlock these and other problems by means of first-principles calculations, where the temperature-dependent stability, the electronic activity, and the paramagnetic response of boron defects in 4H-SiC are investigated.

Reciprocating thermal behavior in a magnetic field induced slow spin relaxation of [Gd2(H2O)6(C2O4)3]∙2.5H2O

Static and alternating magnetic susceptibility, magnetization, and electron-spin resonance studies of Gd(III) complex [Gd2(H2O)6(C2O4)3]∙2.5H2O enabled its identification as an S = 7/2 magnet with easy-axis anisotropy D/kB = −91.2 mK and magnetic interaction effectively mediated by dipolar coupling │J/kB│ ≈ 12 mK. The magnetic field–induced slow relaxation at high temperatures is ascribed to direct relaxation with a pronounced effect of phonon bottleneck and Raman process. In contrast, relaxation at low temperatures displays reciprocating thermal behavior, where spin dynamics accelerates upon cooling. The potential origin of the observed behavior is discussed.

Redox Active cAAC-Fluorene/Indene Systems Displaying Solvatochromism, Green Luminescence and pH Sensing: Functionalization of Fluorenyl/Indenyl Rings with Radical Carbene.

Two new series of air stable compounds of cAACX = fluorene/indene (X = Me2 , Et2 , Cy) [cAAC = cyclic (alkyl) amino carbene] have been isolated and well characterized by X-ray single crystal diffraction, photoluminescence, cyclic voltammogram (CV) and electron paramagnetic resonance (EPR) studies. Fluorescence studies reveals green light emission of cAAC bonded fluorene, whereas free fluorene generally displays a violet emission. Interestingly, the sterically crowded cAAC-fluorene analogue display solvatochromism and CF3 CO2 H sensing in solution. CV of the these compounds show a quasi-reversible electron transfer process, indicating the functionalization of fluorene/indene with radical anionic form of carbene, confirmed by CV/EPR measurements. DFT/TDDFT calculations and energy decomposition analysis coupled with natural orbital for chemical valence (EDA-NOCV) have been carried out to study different aspects of bonding and electronic transitions. Such a class of redox active and thermally stable organic molecules may be suitable for molecule based spin memory devices in future.

Study of electron paramagnetic resonance as a tool to discriminate between boron related defects in barium disilicide

Barium disilicide (BaSi2), composed of Earth-abundant and nontoxic elements, is a promising material for thin-film solar cells. The control of carrier type and carrier concentration by impurity doping is particularly important for the application of BaSi2 to solar cells. However, the presence of defects in semiconductors such as BaSi2 may have a significant impact on the electrical and optical properties of solar cells. In this study, we chose boron to act as a p-type impurity in BaSi2 and studied boron-related defects using the Quantum Espresso method with density functional theory. The formation energy of interstitial boron defects was found to be lower than that of boron in Si vacancy sites. The hyperfine coupling constants of 137Ba with antisite boron defects (BSi) are very localized and differ significantly from those of 137Ba with interstitial boron defects (Bi). This suggests that neutral BSi and Bi can be identified by electron paramagnetic resonance.

Catalytic activation of peroxydisulfate by secondary mineral derived self-modified iron-based composite for florfenicol degradation: Performance and mechanism

The advanced oxidation processes (AOPs) driven by iron-based materials are the highly efficient technology for refractory organic pollutants treatment. In this work, self-modified iron-based catalysts were prepared using secondary mineral as the precursor by one-step pyrolysis process without additional dopants. The prepared catalysts exhibited excellent performance in catalytic degradation of florfenicol (FF), especially C-AJ, which was derived from ammoniojarosite [(NH4, H3O)Fe3(OH)6(SO4)2], activated PDS to degrade 93% FF with initial concentration of 50 mg/L. Quenching tests and electron paramagnetic resonance (ESR) studies showed that SO4•−, •OH, and •O2− were the main reactive species for FF degradation and their contribution degree was SO4•− > •OH > •O2−. The Fe0 and the cycle of Fe(II)/Fe(III) both contributed to the PDS activation, and the reduction of Fe(III) to Fe(II) was accelerated by S2− on the catalyst surface. In addition, Fe3O4 on the C-AJ indirectly catalyzes PDS by promoting electron transfer. The effects of catalyst dosage, PDS concentration, pH, inorganic anions, and real aqueous matrices on FF degradation, TOC analysis, and cycling test were investigated. The results showed that iron-based catalysts have superior environmental durability due to their excellent catalytic properties in the real aqueous matrices with common inorganic anions and pH 3–9 and its steady catalytic capacity with multiple cycles. Overall, this study sheds new light on the rational design of self-modified iron-based composite and develops low-cost technology toward remediation of FF-contaminated wastewater.

Aluminothermic Synthesis of Dispersed Electrides Based on Mayenite: XRD and EPR Study.

The evolution of the structure and the phase composition of a dispersed mayenite at its interaction with metallic aluminum was studied in a temperature range from 900 to 1400 °C in both argon and air atmospheres. The aluminum loading was varied from 0 to 50 wt%. It was found that the addition of aluminum significantly affects the stability of the mayenite and other calcium aluminate phases within the studied temperature range. The formation of the electride state registered by the appearance of a characteristic electron paramagnetic resonance (EPR) signal from F+-like centers (g~1.994) in an argon atmosphere was shown to take place already at 1150 °C due to an aluminothermic reduction of this material. The super-narrow (Hp-p < 0.5 G) EPR spectra from F+-like centers, which were recently observed for the core−shell structures of the C12A7@C type only, were registered for mayenite for the first time. The results obtained in the present study testify firstly towards the possibility of significantly diminishing the temperatures required for the formation of the electride state in such systems and secondly towards the ability to stabilize the size of small electride nanoparticles within the synthesized calcium aluminate matrix.

Mononuclear/Binuclear [VIVO]/[VVO2] Complexes Derived from 1,3-Diaminoguanidine and Their Catalytic Application for the Oxidation of Benzoin via Oxygen Atom Transfer.

Ligands H4sal-dag (I) and H4Brsal-dag (II) derived from 1,3-diaminoguanidine and salicylaldehyde or 5-bromosalicylaldehyde react with one or 2 mol equivalent of vanadium precursor to give two different series of vanadium complexes. Thus, complexes [VIVO(H2sal-dag) (H2O)] (1) and [VIVO(H2Brsal-dag) (H2O)] (2) were isolated by the reaction of an equimolar ratio of these ligands with [VIVO(acac)2] in MeOH. In the presence of K+/Cs+ ion and using aerially oxidized [VIVO(acac)2], the above reaction gave complexes [K(H2O){VVO2(H2sal-dag)}]2 (3), [Cs(H2O){VVO2(H2sal-dag)}]2 (4), [K(H2O){VO2(H2Brsal-dag)}]2 (5), and [Cs(H2O){VVO2(H2Brsal-dag)}]2 (6), which could also be isolated by direct aerial oxidation of complexes 1 and 2 in MeOH in the presence of K+/Cs+ ion. Complexes [(H2O)VIVO(Hsal-dag)VVO2] (7) and [(H2O)VIVO(HBrsal-dag)VVO2] (8) were isolated upon increasing the ligand-to-vanadium precursor molar ratio to 1:2 under an air atmosphere. When I and II were reacted with aerially oxidized [VIVO(acac)2] in a 1:2 molar ratio in MeOH in the presence of K+/Cs+ ion, they formed [K(H2O)5{(VVO2)2(Hsal-dag)}]2 (9), [Cs(H2O)2{(VVO2)2(Hsal-dag)}]2 (10), [K2(H2O)4{(VVO2)2(Brsal-dag)}]2 (11), and [Cs2(H2O)4{(VVO2)2(Brsal-dag)}]2 (12). The structures of complexes 3, 4, 5, and 9 determined by single-crystal X-ray diffraction study confirm the mono-, bi-, tri-, and tetra-anionic behaviors of the ligands. All complexes were found to be an effective catalyst for the oxidation of benzoin to benzil via oxygen atom transfer (OAT) between DMSO and benzoin. Under aerobic condition, this oxidation also proceeds effectively in the absence of DMSO. Electron paramagnetic resonance and 51V NMR studies demonstrated the active role of a stable V(IV) intermediate during OAT between DMSO and benzoin.

Adsorption processes on a carbonaceous surface: Electron spin resonance study

The effect of pyrolysis at T ∼700 °C of the low-rank coal samples was studied using scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), and Raman scattering of light methods. The kinetics of adsorption-desorption processes on a carbon surface was first investigated based on the dynamics of the spin characteristics of paramagnetic defects (carbon dangling bonds). The EPR signals of these defects in the air are characterized by the anomalously large broadening up to ΔBpp = 32 mT, nearly two orders of magnitude in comparison with the initial samples. It is established that broadening is caused by the interaction of the spins of defects with molecular oxygen. The latter is adsorbed on the surface of the samples in a high concentration because the samples have a high porosity formed with the participation of ash nanoclusters, including FexOy. The observed EPR dynamics are very complex. It depends on the initial conditions of signal observation, the occurrence of other gases, e.g. nitrogen, and drastically on the humidity of the environment. For example, holding samples in the water vapor at T = 100 °C reduces the ΔBpp from ∼17.5 mT to 3.2 mT for a time of nearly t ∼24 s. Using the strong effect of oxygen on the broadening of the studied samples, the kinetics of competitive processes of adsorption/desorption of N2↔O2↔H2O on the carbon surface is studied in detail. The unusual adsorption kinetics for the mixture of O2 and N2 gases, caused by a difference in the diffusion rates, was found.

Integrating anodic sulfate activation with cathodic H2O2 production/activation to generate the sulfate and hydroxyl radicals for the degradation of emerging organic contaminants

Conventional electrocatalytic degradation of pollutants involves either cathodic reduction or anodic oxidation process, which caused the low energy utilization efficiency. In this study, we successfully couple the anodic activation of sulfates with the cathodic H2O2 production/activation to boost the generation of sulfate radical (SO4·−) and hydroxyl radical (·OH) for the efficient degradation of emerging contaminants. The electrocatalysis reactor is composed of a modified-graphite-felt (GF) cathode, in-situ prepared by the carbonization of polyaniline (PANI) electrodeposited on a GF substrate, and a boron-doped diamond (BDD) anode. In the presence of sulfates, the electrocatalysis system shows superior activities towards the degradation of pharmaceutical and personal care products (PPCPs), with the optimal performance of completely degrading the representative pollutant carbamazepine (CBZ, 0.2 mg L−1) within 150 s. Radicals quenching experiments indicated that ·OH and SO4·− act as the main reactive oxygen species for CBZ decomposition. Results from the electron paramagnetic resonance (EPR) and chronoamperometry studies verified that the sulfate ions were oxidized to SO4·−radicals at the anode, while the dissolve oxygen molecules were reduced to H2O2 molecules which were further activated to produce ·OH radicals at the cathode. It was also found that during the catalytic reactions SO4·−radicals could spontaneously convert into peroxydisulfate (PDS) which were subsequently reduced back to SO4·−at the cathodes. The quasi-steady-state concentrations of ·OH and SO4·−were estimated to be 0.51×10−12 M and 0.56×10−12 M, respectively. This study provides insight into the synergistic generation of ·OH/SO4·− from the integrated electrochemical anode oxidation of sulfate and cathode reduction of dissolved oxygen, which indicates a potential practical approach to efficiently degrade the emerging organic water contaminants.

Thermal annealing of neutron irradiation generated paramagnetic defects in transparent Al2O3 ceramics

It is fundamentally important to understand, control, and predict the effect of irradiation on the structure and optical properties of functional materials. In this work, the thermal stability of fast-neutron induced point defects has been investigated in polycrystalline transparent alumina ceramics. The results of a combined study of electron paramagnetic resonance (EPR) and photoluminescence spectroscopy are presented in this paper. The EPR signals related to different trapped-hole centers as well as electron-type F+ centers have been observed after neutron irradiation. Rapid decay of the total EPR signal intensity occurs after annealing in 600–750 K temperature range. The selective luminescence bands related to the F- and F2-type centers are detected under irradiated corundum ceramics photoexcitation within relevant defect absorption bands (i.e. intracenter excitation/emission).

Engineered mesoporous hollow carbon spheres for pollutant degradation: Disclosing catalytic activity, matrix effect, transport, and aquatic ecotoxicity

Remediation of organic contaminants through advanced oxidation process hold great promise for both ground and surface water environments. Despite the fact, the treatment efficiency depends on multiple factors, i.e., catalyst dosage, persulfate/peroxymonosulfate activation capability, and catalyst toxicity to aquatic creatures. Herein, we aimed to demonstrate the potential of the mesoporous carbon hollow sphere (MCHS) catalyst in persulfate activation for advanced oxidation in pure and groundwater matrix by choosing tetracycline as a model compound. Surface properties of MCHS were examined using multiple characterization techniques and the data revealed that MCHS is benefited by high specific surface area, numerous mesopores, and an excellent degree of particle dispersion. The results of this study indicate that pH, catalyst dosage, and persulfate and tetracycline concentrations influence tetracycline’s degradation rate. Features like colloidal nature, high specific surface area (>1200 m2/g), and porosity of MCHS allow for very low catalyst dosage (10 mg L−1). Electron spin resonance (ESR) and scavenger studies showed that the TC degradation in persulfate/MCHS system is dominated by 1O2 rather than OH, and SO4– radical species. Electrochemical study confirmed that electrons are transferred from tetracycline to the persulfate/MCHS complex during oxidation reaction. Additionally, the tetracycline degradation performance in natural groundwater matrices outperforms the persulfate/MCHS pure water system. Ecotoxicity study revealed the survival rate of Daphnia magna neonates is >95% if MCHS is <12 mg L−1.

Inhibitory effect of coriander (Coriandrum sativum L.) extract marinades on the formation of polycyclic aromatic hydrocarbons in roasted duck wings

Coriander (Coriandrum sativum L.) is recognized for its antioxidant property, as a kind of natural phenolic-rich ingredient. Polycyclic aromatic hydrocarbons (PAHs) present a class of heat-driven hazards in foods, especially the processed meat. In this study, the effect of coriander root and leaf extract on the formation and inhibition of PAH8 in roasted duck wings was firstly investigated. Coriander root extract (CRE) and coriander leaf extract (CLE) with five concentration groups (200, 400, 600, 800, 1000 mg/L) were prepared respectively to marinate the duck wings. CRE marinade exhibited greater inhibitory effect on PAH8 formation in roasted duck wings that ranged from 65.0 %–87.4 %. The electron spin resonance study indicated a significantly positive correlation between PAH8 and free radical level, suggesting the participation of radicals in PAHs formation. Also, it was speculated that the inhibitory effect on PAH8 was related to the phenolic compounds identified in coriander marinades. CRE made greater inhibitory effect on the formation of PAH8 and could be considered as a kind of natural source to mitigate PAHs in heat-processed meat products.

Charge and spin state of dilute Fe in NaCl and LiF

There is an apparent mismatch between electron paramagnetic resonance and M\"ossbauer spectroscopy results on the charge and spin states of dilute Fe impurities in NaCl; M\"ossbauer spectroscopy data have been interpreted in terms of high-spin ${\mathrm{Fe}}^{2+}$, while electron paramagnetic resonance studies suggest low-spin ${\mathrm{Fe}}^{1+}$. In the present study, the charge and spin states of dilute substitutional Fe impurities in NaCl and LiF have been investigated with $^{57}\mathrm{Mn}\ensuremath{\rightarrow}^{57}\mathrm{Fe}$ emission M\"ossbauer spectroscopy. A scheme is proposed which takes into account the effects of nearest-neighbor distances and electronegativity difference of the host atoms on the M\"ossbauer isomer shift and allows for the unequivocal differentiation between high-spin ${\mathrm{Fe}}^{2+}$ and high/low-spin ${\mathrm{Fe}}^{1+}$ in M\"ossbauer spectroscopy. From these considerations, the M\"ossbauer results are found to be consistent with dilute Fe impurities in NaCl and LiF in a low-spin ${\mathrm{Fe}}^{1+}$ state. These conclusions are supported by theoretical calculations of isomer shifts and formation energies based on the density-functional theory. The experimental results furthermore suggest that charge compensation of dilute ${\mathrm{Mn}}^{2+}$ dopants in NaCl and LiF is achieved by Na vacancies and ${\mathrm{F}}^{\ensuremath{-}}$ interstitials, respectively.

Biochar supported magnetic ZIF-67 derivatives activated peroxymonosulfate for the degradation of ciprofloxacin: Radical and nonradical pathways

Developing highly efficient and reusable heterogeneous catalysts is the key to achieve peroxymonosulfate (PMS) activation for pollution degradation. Herein, a novel magnetically recoverable composite catalyst BC/CoNC derived from ZIF-67 and peanut shell was designed and applied for peroxymonosulfate (PMS) activation to degrade Ciprofloxacin (CIP). The results of structural characterization showed that ZIF-67 derived CoNC was uniformly distributed on peanut shell biochar and there was no obvious agglomeration. The 1.0-BC/CoNC exhibited the optimal removal efficiency, CIP was degraded by 95.9% within 30 min, and the removal efficiency of TOC was 42.0%. In the meantime, the catalyst demonstrated a high PMS activation capacity over a wide pH range of 3–11. Both electron paramagnetic resonance (EPR) studies and radical quenching experiments revealed that SO4•−, •OH, O2•− and 1O2 were involved in the degradation of CIP. In addition, the 1.0-BC/CoNC/PMS system can effectively degrade different pollutants in water, and the potential application for the degradation of CIP in actual water samples (the tap water and lake water) were also investigated. This work proposes new ideas for the preparation of low-cost biomass/MOFs derived catalysts for the application of water treatment.

Combustion synthesis of copper-doped perovskite SrFe1-xCuxO3-δ nanomaterials and its potential application on hydroxylation of anisole, a biomass model component

A series of copper-doped strontium ferrites with a perovskite structure, SrFe1-xCuxO3-δ; x = 0–0.45 (SFCx), were successfully prepared via a combustion synthesis method using hexamine as fuel followed by heat treatment at 1000 °C for 3h. The obtained SFCx materials were characterized using various analytical and spectroscopic techniques. X-ray diffraction patterns of the perovskite exhibited a cubic structure with a Pm-3m (221) space group. The presence of Fe4+, Fe3+, Cu2+, Cu+, and oxygen vacancies was confirmed via X-ray photoelectron spectroscopy. The formation of nanoparticles was confirmed by scanning electron microscopy images of the perovskite phase. The surface area was investigated using the Brunauer–Emmett–Teller method. SFCx materials were systematically evaluated for catalytic hydroxylation of anisole using hydrogen peroxide, an environmentally benign oxidant, and acetonitrile as solvent. Effects of various reaction parameters, such as the catalyst concentration, H2O2/substrate molar ratio, solvent, reaction temperature, and time, were thoroughly studied. A maximum anisole conversion (76.9%) with 62.5% of guaiacol selectivity was observed in the presence of the SFC0.45 catalyst at 80 °C for 6 h using H2O2 as an oxidant. The proposed hydroxyl radical mechanism for catalytic hydroxylation of anisole is well supported by electron paramagnetic resonance (EPR) studies, where the quenching of signal corresponds to paramagnetic Cu(II) species by the introduction of hydrogen peroxide. Catalytic test results suggest that the synergistic effect of copper and oxygen vacancies facilitates anisole hydroxylation.

EPR Analysis of Cu2+ ion Doped Potassium borodicitrate Single Crystal

In our present investigation single crystals of Potassium borodicitrate (KBDC) (for a fixed content- host lattice) with Cu2+, a guest species, as a dopant (at four 0.2, 0.5, 1 and 2 g) in weight ratio have been synthesized at room temperature by using slow evaporation method. These as-synthesized 4 crystals have been subjected to Electron Paramagnetic Resonance (EPR) studies. The EPR spectrum shows that 0.5 g dopant KBDC give a 4 equidistant hyperfine lines with the perfect symmetry confirms that the localization of Cu2+, a paramagnetic impurity, within it reveals that the maximum absorption of EPR signals happens at 0.5 g Cu2+ than any other concentrations with reference to 20° in horizontal plane than the normal and vertical recording in the same angular projection. The Spin Hamiltonian calculations are used to obtain spectroscopic field splitting factor g-tensor values, gxx = 2.0421, gyy = 2.1962, gzz = 2.2827 and hyperfine splitting factor A-tensor values Axx = 150, Ayy = 112 and Azz = 134. The K–O bond length associated with directional cosines of gzz tensor reveal that the Cu2+ is located interstitially. This optimized single crystal has furtherance been subjected to Single cystal X-ray diffraction (SXRD), Fourier transform infrared Spectrascopy (FTIR). Scanning electron microscope (SEM) Energy dispersive X-ray analysis (EDAX) and compared with pure KBDC single crystal. The XRD unit cell crystalline parameter variations reveal that there is doping effect of Cu2+ into the host lattice brings forth structural coordination of Cu2+ with KBDC. The FTIR confirms that complexation of host and guest through molecular interactions in the finger print region. The EDAX mapping shows Cu2+ presence in the crystal. HIGHLIGHTS SXRD are taken to confirm that structure of pure KBDC and Cu2+ doped KBDC are same The spin Hamiltonian parameters of KBDC-Cu2+ single crystal are calculated through EPR spectra On analyzing the spectra, it is found that the doped ion site location symmetry is identified as interstitial and experience orthorhombic local field symmetry In addition to the above studies FTIR and EDX confirms the presence of Cu2+ ion GRAPHICAL ABSTRACT

Host-Guest Chemistry in Discrete Polyoxo-12-Palladate(II) Cubes [MO8Pd12L8]n- (M = ScIII, CoII, CuII, L = AsO43-; M = CdII, HgII, L = PhAsO32-): Structure, Magnetism, and Catalytic Hydrogenation.

A family of five host-guest assemblies comprising different metal ions inside a cuboid 12-palladium-oxo cage, [MO8Pd12L8]n- (MPd12L8, M = ScIII, CoII, CuII, L = AsO43-; M = CdII, HgII, L = PhAsO32-), was synthesized and structurally characterized in the solid state by single-crystal X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis, and their solution and gas-phase stability were validated by multinuclear NMR spectroscopy and electrospray-ionization mass spectrometry (ESI-MS). The polyoxopalladates (POPs) ScPd12As8, CoPd12As8, and CuPd12As8 represent the first three examples of the MPd12As8 archetype. The unique cubic ligand field of {MO8} allows for collecting the speciation profiles of the POPs in solution using 45Sc and 113Cd NMR techniques. Detailed magnetic and electron paramagnetic resonance (EPR) studies were performed on CuPd12As8. Catalytic studies on MPd12As8 (M = CuII and CoII) supported on SBA-15 unveiled a guest metal-dependent structure-function relationship, with CuPd12As8 being the more efficient precatalyst for the hydroconversion of o-xylene in a fixed-bed reactor.