Electron Spin Resonance Studies Research Articles

The influence of acid hydrolysis on physicochemical properties of starch-oleic acid mixtures and generation of radicals

The aim of this paper was to evaluate the effect of acid hydrolysis on formation of the starch-oleic acid mixtures, their structure and functional properties. The potato starch was hydrolyzed with hydrochloric acid for 0.5–4.0 h, then obtained acid-hydrolyzed starches were mixed with oleic acid to prepare the starch-oleic acid mixtures. Measurements of molecular size distribution, lipids content, fatty acid composition, and complexing index of gelatinized mixtures revealed that performed modifications were effective. The water binding capacity at 80 °C of tested starch-fatty acid mixtures ranged from 14.51 (g/g) for untreated potato starch to 11.24 (g/g) for starch hydrolyzed for 4 h. The addition of oleic acid reduced the solubility in water at 80 °C of modified starches by 70-61% compared to their counterparts. The highest DPPH radical scavenging activity (15.1%) was found for the starch hydrolyzed for 0.5 h and mixed with oleic acid. Hot paste and final viscosities of the starch-fatty acid mixtures gradually decreased with the increasing of acid treatment time. The lowest values of these parameters were determined in mixture of starch hydrolyzed for 4 h (364 mPa s and 536 mPa s, respectively). Incorporation of oleic acid into starch hydrolyzed for 4 h increased by approximately 90% content of the resistant starch fraction compared to the non-mixed counterpart. Electron paramagnetic resonance studies showed that acid hydrolysis promoted the generation of stable carbon centered radicals in starch, whereas the introduction of oleic acid strongly inhibited this process.

Photoinduced Paramagnetic Centers in Nanocomposites Formed by Titanium Dioxide and Myristic Acid

An electron paramagnetic resonance (EPR) study has been carried out on the hybrid layered nanocomposite formed by TiO2 and myristic acid. The samples were characterized by means of X-ray diffractio...

Natural fractures in tight gas sandstones: a case study of the Upper Triassic Xujiahe Formation in Xinchang gas field, Western Sichuan Basin, China

AbstractThe Upper Triassic Xujiahe Formation is a typical tight gas reservoir in which natural fractures determine the migration, accumulation and production capacity of tight gas. In this study, we focused on the influences of natural fractures on the tight gas migration and production. We clarified characteristics and attributes (i.e. dips, apertures, filling degree and cross-cutting relationships) of the fractures based on image logging interpretations and core descriptions. Previous studies of electron spin resonance, carbon and oxygen isotopes, homogenization temperature of fluid inclusions analysis and basin simulation were considered. This study also analysed the fracture sequences, source of fracture fillings, diagenetic sequences and tight gas enrichment stages. We obtained insight into the relationship between fracture evolution and hydrocarbon charging, particularly the effect of the apertures and intensity of natural fractures on tight gas production. We reveal that the bedding fractures are short horizontal migration channels of tight gas. The tectonic fractures with middle, high and nearly vertical angles are beneficial to tight gas vertical migration. The apertures of fractures are controlled by the direction of maximum principal stress and fracture angle. The initial gas production of the vertical wells presents a positive correlation with the fracture abundance, and the intensity and aperture of fractures are the fundamental factors that determine the tight gas production. With these findings, this study is expected to guide the future exploration and development of tight gas with similar geological backgrounds.

Site-Selective Csp3-Csp/Csp3-Csp2 Cross-Coupling Reactions Using Frustrated Lewis Pairs.

The donor–acceptor ability of frustrated Lewis pairs (FLPs) has led to widespread applications in organic synthesis. Single electron transfer from a donor Lewis base to an acceptor Lewis acid can generate a frustrated radical pair (FRP) depending on the substrate and energy required (thermal or photochemical) to promote an FLP into an FRP system. Herein, we report the Csp3–Csp cross-coupling reaction of aryl esters with terminal alkynes using the B(C6F5)3/Mes3P FLP. Significantly, when the 1-ethynyl-4-vinylbenzene substrate was employed, the exclusive formation of Csp3–Csp cross-coupled products was observed. However, when 1-ethynyl-2-vinylbenzene was employed, solvent-dependent site-selective Csp3–Csp or Csp3–Csp2 cross-coupling resulted. The nature of these reaction pathways and their selectivity has been investigated by extensive electron paramagnetic resonance (EPR) studies, kinetic studies, and density functional theory (DFT) calculations both to elucidate the mechanism of these coupling reactions and to explain the solvent-dependent site selectivity.

Quantitative EPR study of poly(vinylidene fluoride) activated by electron beam treatment

The electron paramagnetic resonance (EPR) spectra of poly (vinylidene fluoride) (PVDF) films were studied in order to identify type and intensity of trapped radicals after an electron treatment with 150 kGy in air at room temperature. The observed EPR spectra consist of superimposed spectra of eight different radicals. The individual spectra were simulated by first derivatives of normalized Gaussian functions including intensity, linewidth, g value, and hyperfine splitting constants of the unpaired electron with hydrogen or fluorine atoms in α or β positions. In addition, the number of trapped radicals was estimated using a standard sample of known spin concentrations. Although initially generated radicals tend to be converted to peroxy radicals in the presence of oxygen, the predominant radical is the CH-based mid-chain radical (–CF2–C*H-CF2-) with a relative intensity of 62.3%. This is attributed to CH-based radicals in the crystalline domains with low molecular mobility leading to an enhancement in its linewidth (ΔHpp ⁓ 3.6 mT). A fraction of 20.7% of all radicals are peroxy radicals with anisotropic g values, g∥ = 2.0210 and g⊥ = 2.0095. The relative intensity of allyl, dienyl and polyenyl radicals amounts to 4.9%.

Magnetic, electron paramagnetic resonance, and photocatalytic analysis of diluted magnetic semiconductor CdS:V nanoparticles

Diluted magnetic semiconductors related to II–VI-based compounds are of significant interest for the development of spin-based operating electronic devices such as magneto-optical instruments, spintronics, and nonvolatile memory devices. Thus, studies of electron paramagnetic resonance, magnetic characteristics, and the photocatalytic properties of transition metal-doped II–VI-based semiconductors are of great importance. We therefore comprehensively studied the structural, electron spin resonance, magnetic hysteresis, and photocatalytic characteristics of CdS:V4+ nanoparticles (NPs) fabricated by the rapid microwave route for the first time. The structural analyses revealed the authentic substitution of V4+ dopant ions into the CdS matrix. The widening of the optical band gap and relevant quantum confinement phenomenon are discussed in terms of the inclusion of V4+ ions into the CdS matrix. The electron paramagnetic resonance (EPR) spectroscopy results were corroborated by the increase in the number of magnetic spins with increasing V4+ dopant concentration. The assessed number of magnetic spins was nearly equal to 3.601597 × 106 and 7.254048 × 106 for the CdS:V (2 and 4 at%) NPs, respectively. Room-temperature magnetic hysteresis loops also revealed the existence of a large number of magnetic spins through the formation of clear paramagnetism in the CdS:V (2 and 4 at%) NPs. The CdS:V (4 at%) system displayed enriched visible light-driven photocatalytic degradation efficiency compared to bare CdS through the degradation of RhB dye in contaminated water.

Photocatalytic Hydrogen Evolution Over Pt/Co-TiO2 Photocatalysts

Aims: In this study, the photocatalytic hydrogen evolution reaction from aqueous methanol was investigated upon simulated solar light using platinum loaded on cobalt doped TiO2 (Pt/Co-TiO2) composites. Background: Controversial results of cobalt-based composites create doubts about their photocatalytic activity. Thus, cobalt doped TiO2 composites were synthesized differently, and the photocatalytic activity was examined for the photocatalytic hydrogen generation. Objective: The current study aims to investigate the influence of cobalt doping and platinum loading on the photocatalytic activities of TiO2 nanoparticles for the photocatalytic H2 generation. Methods: The 0.5 wt.% Co-TiO2 and bare TiO2 photocatalysts were synthesized using two different methods, namely, reflux and hydrothermal synthesis. Additionally, the Pt deposition on the prepared Co-TiO2 and TiO2 catalysts (1 wt.% Pt) was performed using a photo-platinization method. : The as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy/ energy dispersive X-ray analysis (SEM/EDX), transmission electron microscopy (TEM), ultraviolet- visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and electrochemical impedance spectroscopy (EIS). Result: The XRD and EPR studies clearly indicated that the Co was incorporated into the titanium dioxide lattice. The EIS results suggested that the reduction of protons over Co-TiO2 and bare TiO2 materials was possible from a thermodynamic point of view. However, the photocatalytic results revealed that the formed amount of H2 was extremely low and close to the detection limit. The evolution of H2 from aqueous methanol (10 vol%) showed higher rates when employing 1 wt.% Pt loaded on 0.5 wt.% Co-TiO2 photocatalysts under simulated solar light irradiation. A maximum of 317 ± 44 μmol.h-1 was observed over the Pt/Co-TiO2-HT photocatalyst. Conclusion: EPR results confirmed that the cobalt ions were introduced into the TiO2 lattice by trapping the photogenerated conduction band electrons and decreasing the defects in the crystal cell. The Mott−Schottky analysis of electrochemical impedance measurements showed that all catalysts were ntype semiconductors and that cobalt doping induces impurity level within the band gap of TiO2. The experimental results of photocatalytic H2 generation from methanol-reforming demonstrated that no significant impact of Co-doping on the photocatalytic H2 formation was observed neither for bare TiO2 samples nor for the platinized materials. Based on these experimental findings, a possible mechanism for the continuous photocatalytic activity of Pt/Co-TiO2 photocatalysts under simulated solar light was proposed.

Exploring the Mechanism of Peroxodisulfate Activation with Silver Metavanadate to Generate Abundant Reactive Oxygen Species

AbstractReactive oxygen species (ROS) containing sulfate and hydroxyl radicals can act as Fenton type reagents to remove organic contaminants from water. Here, a catalytic system silver metavanadate is reported for the activation of peroxodisulfate in an aqueous medium to generate ROS, which is further utilized for the efficient degradation of the water‐soluble pollutants such as phenols, pesticides, antibiotics, and organic dyes. Remarkably, complete carbon mineralization of the water‐soluble contaminants is achieved to form carbon dioxide as the major product. In‐situ electron paramagnetic resonance (EPR) studies combined with ex‐situ methods reveal that a massive amount of hydroxyl radicals (•OH) are formed through sulfate radical anions (SO4•−) and act as the ROS for the organic pollutant degradation. In addition, the stability of the catalyst is monitored by various characterization techniques.

Pair‐Emission‐Induced Near‐Infrared Lasing from Ceramic Ga:LaCrO3 Microcrystals at Room Temperature

Lasing is observed in microcrystals of the Ga:LaCrO3 (LaCr0.5Ga0.5O3) perovskite system due to the pair emission of the Cr3+ ions, with a lifetime in the sub‐nanosecond range. Lasing due to pair emission is difficult to achieve in single‐crystal materials because of the difficulty in obtaining the dopant's compositional uniformity. This captivating ceramic material reveals an appreciable lasing profile with a 488 nm laser pumping. Characteristic laser emission centered at 740 nm is observed, with a linewidth of 2.09 nm and a threshold power of 73 W cm−2 at room temperature. Photoluminescence (PL) spectra show enhanced lasing characteristics at low‐temperature ranges. The time‐resolved PL spectrum of the sample illustrates a sub‐nanosecond lifetime of which 99.2% of the lifetime contribution is from pair emission. The short lifetime can be attributed to the high concentration of the Cr3+ ions, which enhances the Cr3+–Cr3+ exchange interaction, and pair emission, which is evidenced by an electron spin resonance study.

Characterization and Reconstitution of Human Lipoyl Synthase (LIAS) Supports ISCA2 and ISCU as Primary Cluster Donors and an Ordered Mechanism of Cluster Assembly.

Lipoyl synthase (LIAS) is an iron–sulfur cluster protein and a member of the radical S-adenosylmethionine (SAM) superfamily that catalyzes the final step of lipoic acid biosynthesis. The enzyme contains two [4Fe–4S] centers (reducing and auxiliary clusters) that promote radical formation and sulfur transfer, respectively. Most information concerning LIAS and its mechanism has been determined from prokaryotic enzymes. Herein, we detail the expression, isolation, and characterization of human LIAS, its reactivity, and evaluation of natural iron–sulfur (Fe–S) cluster reconstitution mechanisms. Cluster donation by a number of possible cluster donor proteins and heterodimeric complexes has been evaluated. [2Fe–2S]-cluster-bound forms of human ISCU and ISCA2 were found capable of reconstituting human LIAS, such that complete product turnover was enabled for LIAS, as monitored via a liquid chromatography–mass spectrometry (LC–MS) assay. Electron paramagnetic resonance (EPR) studies of native LIAS and substituted derivatives that lacked the ability to bind one or the other of LIAS’s two [4Fe–4S] clusters revealed a likely order of cluster addition, with the auxiliary cluster preceding the reducing [4Fe–4S] center. These results detail the trafficking of Fe–S clusters in human cells and highlight differences with respect to bacterial LIAS analogs. Likely in vivo Fe–S cluster donors to LIAS are identified, with possible connections to human disease states, and a mechanistic ordering of [4Fe–4S] cluster reconstitution is evident.

Conversion of Human Neuroglobin into a Multifunctional Peroxidase by Rational Design.

Protein design has received much attention in the last decades. With an additional disulfide bond to enhance the protein stability, human A15C neuroglobin (Ngb) is an ideal protein scaffold for heme enzyme design. In this study, we rationally converted A15C Ngb into a multifunctional peroxidase by replacing the heme axial His64 with an Asp residue, where Asp64 and the native Lys67 at the heme distal site were proposed to act as an acid-base catalytic couple for H2O2 activation. Kinetic studies showed that the catalytic efficiency of A15C/H64D Ngb was much higher (∼50-80-fold) than that of native dehaloperoxidase, which even exceeds (∼3-fold) that of the most efficient native horseradish peroxidase. Moreover, the dye-decolorizing peroxidase activity was also comparable to that of some native enzymes. Electron paramagnetic resonance, molecular docking, and isothermal titration calorimetry studies provided valuable information for the substrate-protein interactions. Therefore, this study presents the rational design of an efficient multifunctional peroxidase based on Ngb with potential applications such as in bioremediation for environmental sustainability.

Symmetry breaking in single-crystal SrTiO3 plates: EPR manifestations

Results of the electron paramagnetic resonance (EPR) studies of Fe3+ and Mn4+ impurity centers in high-quality single-crystal SrTiO3 plates with thickness are presented. Impurities served the paramagnetic probes of the crystal structure. Analysis of the collected data indicates that the symmetry of the crystal structure of thin (001) and (110) oriented strontium titanate plates above lowers in the bulk from the cubic to tetragonal. The structure of this high-temperature tetragonal state is different from that of the conventional low-temperature antiferrodistorsive phase and has not been reported for SrTiO3 before. It is shown that the effect does not originate from the residual stress; its magnitude and particular manifestations depend on plate orientation, surface quality and geometry of a sample. Peculiarities of the observed phenomenon are presented and the possible scenario of its realization is discussed.

Uncovering the Mechanism of Dystrophin through Spectroscopic Characterization

Human dystrophin is a cytoplasmic protein that consists mainly of 24 spectrin domains positioned in tandem. Mutations in these highly conserved spectrin motifs are known to cause muscle degeneration, highlighting their role in maintaining the integrity of muscle fibers during movement. Through circular dichroism (CD), fluorescence spectroscopy (FS), and differential scanning calorimetry (DSC), the spectrins in their monomeric (S17), dimeric (S17-18), and trimeric (S17-19) forms were thermally denatured. Global fitting of CD and FS data, constrained with DSC, revealed a non-additive change in ΔGunfolding consistent with a negative coupling mechanism where the spectrins undergo mutual destabilization. This mechanism was further explored by means of Electron Paramagnetic Resonance (EPR) and Nuclear Magnetic Resonance (NMR) studies with the hypothesis that the addition of spectrin repeats confers increased structural disorder. EPR scans of S17 and S17-19 show that the trimer experiences a higher degree of mobility as compared to the monomer, supporting our hypothesis. Additionally, we will continue to investigate the conformational disorder and overall stability of hydrated spectrin constructs through Overhauser Dynamic Nuclear Polarization (ODNP), which will provide a better understanding of the local water matrix and spatial heterogeneity surrounding the hydration layer of the spectrins. From the cumulative spectroscopic data obtained through these integrated approaches, we aim to derive a more comprehensive understanding of dystrophin's elusive mechanism.

Degradation of diclofenac sodium using Fenton-like technology based on nano-calcium peroxide

A nano-calcium peroxide (nCaO2) powder with a purity of 89.1% was prepared using an improved traditional method. Then, the as-prepared nCaO2 was used as the source of hydrogen peroxide (H2O2) for the Fenton-like degradation of diclofenac sodium (DCF). The results showed that nCaO2 performed better for DCF removal when compared to nCaO2 prepared by a conventional method and commercial calcium peroxide (CaO2). Further experimental results indicated that 97.5% of DCF could be removed in 180 min at a nCaO2/Fe2+-EDTA/DCF molar ratio of 16/8–8/1, which was more efficient than in the H2O2/EDTA-Fe2+/DCF and nCaO2/Fe2+/DCF systems. The best removal rate of DCF was at pH 6.0, unlike previous claims that stated that the lower the pH in the buffer system, the better the degradation of DCF. In addition, the influence of water quality parameters, such as Cl−, NO3−, SO42−, HCO3−, and humic acid (HA), on DCF removal were evaluated. A free radical masking experiment revealed the existence of hydroxyl radical (OH), superoxide radical (O2−) and singlet oxygen (1O2), and indicated that the degradation of DCF was mainly due to oxidation caused by OH. Electron paramagnetic resonance (EPR) studies for different systems and different active oxygen species were carried out, and it was further confirmed that OH radicals have high intensity in the Fenton-like system based on nCaO2. EPR results also showed that the addition of EDTA can promote the production of OH. According to the identification of the dominant reactive species and GC–MS, the possible theoretical DCF degradation pathways were proposed.

Ferromagnetism in Mn doped 3C-SiC: A variable temperature ESR study

This paper discusses the effect of defects and role of charge carriers in setting up the long range magnetic order in Mn doped 3C-SiC. Using complementary experiments like temperature variation of Electron Spin Resonance (ESR) and DC magnetic susceptibility, the nature of magnetic interactions, spin dynamics and anisotropy have been investigated. The variation of ESR parameters such as, gvalue, peak to peak line width(ΔHpp), spin density (Ns) and spin–spin relaxation time (T2) as a function of temperature and dopant concentration confirms the presence of exchange interaction present in the system. The decrease in resonance field Hr as a function of temperature indicates the strengthening of internal field already existing in Mn doped 3C-SiC samples. This result confirms that defect induced magnetism could be enhanced by introducing holes in to the host wide band gap semiconductor.

Chemical and biological analysis of 4-acyloxy-3-nitrocoumarins as trypanocidal agents

Chagas disease is the most widespread contagious tropical disease in Latin America, being an important public health problem. Treatments against this disease are still very ineffective, presenting several side effects. Therefore, the search for alternative therapeutic solutions is urgent. In the present work, we evaluate the trypanocidal activity and the mechanism of action of a select series of synthetic 4-acyloxy-3-nitrocoumarins. All the coumarin derivatives showed moderate trypanocidal activity in trypomastigotes, along with low cytotoxicity. In addition, compound 1 decreased the number of infected Vero cells in an intracellular T. cruzi model. Electron spin resonance and electrochemical studies showed the formation of nitro radical anions. The Fukui index provided additional information to elucidate the proposed reduction mechanism. Furthermore, in vitro radical formation studies demonstrated the potential of these compounds to achieve higher concentrations of intracellular free radicals, proposing oxidative stress as a possible trypanocidal mechanism. Furthermore, no correlation was observed between the diffusion of these compounds, which shows that lipophilicity is not a predominant factor for activity. Elsevier Ltd. All rights reserved.

Easily Regenerated CuO/γ-Al2O3 for Persulfate-Based Catalytic Oxidation: Insights into the Deactivation and Regeneration Mechanism.

In this work, γ-Al2O3-supported CuO (c-CuO/Al2O3) materials are successfully synthesized using a novel impregnation-precipitation-decomposition method. The obtained c-CuO/Al2O3 catalyst shows excellent catalytic activities for bisphenol A (BPA) degradation with sodium persulfate (PDS) as an oxidant. Radical quenching tests and electron paramagnetic resonance (EPR) studies indicate that PDS activation is a combined mechanism involving both free radical and nonfree radical pathways. In a continuous large-scale degradation process, about 1.78 L of 20 ppm BPA can be completely removed within 480 min. Although c-CuO/Al2O3 can be deactivated after several reaction cycles, the catalytic activity can be regenerated after simple aerobic calcination. X-ray photoelectron spectroscopy (XPS) and Raman analysis confirm that the deactivation of c-CuO/Al2O3 should be attributed to the conversion of Cu(II) to Cu(I). The aerobic calcination could oxidize Cu(I) back to Cu(II), thus recovering the catalytic activity. In addition, the density functional technology (DFT) and temperature-programmed oxidation (TPD) results reveal that γ-Al2O3 can not only serve as a carrier to anchor the CuO particles but also can adsorb and activate PDS by introducing more basic sites on the surface. c-CuO/Al2O3 has high activity and can be regenerated easily, thus having great potential applications for wastewater treatment.

Visible-light-responsive polyoxometalate-based metal–organic framework for highly efficient photocatalytic oxidative coupling of amines

The exploration of new highly efficient and durable for the oxidation of amines to imines has gained immense attention. In this work, a new polyoxometalate-based metal–organic framework (POMOF) {Cu4(C26H16N4O4)4(CH3CN)2[SiW12O40]}·4H2O (SiW-Cu-DPNDI) was constructed with a catalytic oxidant Keggin-type [SiW12O40]4− anion, a photosensitizer N,N'-bis(4-pyridylmethyl)naphthalene diimide (DPNDI) ligand, and a Cu(I) cation via self-assembling. Although single-crystal X-ray diffraction, power X-ray diffraction (PXRD), infrared (IR) spectroscopy, etc., were employed to confirm the hierarchical structure of SiW-Cu-DPNDI, critical analyses through, such as the magnetic susceptibility measurements, the Mott–Schottky measurements, and the electron spin resonance studies were successfully applied to elucidate the properties of POMOF. SiW-Cu-DPNDI was highly active in the heterogeneous photocatalysis of the oxidation of amines to imines under mild conditions. Additionally, this catalyst exhibited high stability and reusability without losing its activity during the photocatalysis. The possible mechanism of the oxidation coupling was extensively investigated under visible-light (Vis)-irradiation.

Structural and Functional Aspects of Electron Transport Thermoregulation and ATP Synthesis in Chloroplasts.

The review is focused on analysis of the mechanisms of temperature-dependent regulation of electron transport and ATP synthesis in chloroplasts of higher plants. Importance of photosynthesis thermoregulation is determined by the fact that plants are ectothermic organisms, whose own temperature depends on the ambient temperature. The review discusses the effects of temperature on the following processes in thylakoid membranes: (i) photosystem 2 activity and plastoquinone reduction; (ii) electron transfer from plastoquinol (via the cytochrome b6f complex and plastocyanin) to photosystem 1; (iii) transmembrane proton transfer; and (iv) ATP synthesis. The data on the relationship between the functional properties of chloroplasts (photosynthetic transfer of electrons and protons, functioning of ATP synthase) and structural characteristics of membrane lipids (fluidity) obtained by electron paramagnetic resonance studies are presented.

Structural diversity in the coordination compounds of cobalt, nickel and copper with N-alkylglycinates: crystallographic and ESR study in the solid state.

Reactions of N-methylglycine (HMeGly), N-ethylglycine-hydrochloride (H2EtGlyCl) and N-propylglycine-hydrochloride (H2PrGlyCl) with cobalt(ii), nickel(ii) and copper(ii) ions in aqueous solutions resulted in ten new coordination compounds [Co(MeGly)2(H2O)2] (1), [{Co(MeGly)2}2(μ-OH)2]·2H2O (1d), [Cu(MeGly)2(H2O)2] (2α), [Co(EtGly)2(H2O)2] (3), [Ni(EtGly)2(H2O)2] (4), [Cu(μ-EtGly)2]n (5p), [Co(PrGly)2(H2O)2] (6), [Ni(PrGly)2(H2O)2] (7), and two polymorphs of [Cu(PrGly)2(H2O)2] (8α and 8β). Compounds were characterized by single-crystal and powder X-ray diffraction, infrared spectroscopy, thermal analysis and X-band electron spin resonance (ESR) spectroscopy. These studies revealed a wide range of structural types including monomeric, dimeric and polymeric architectures, as well as different polymorphs. In all monomeric compounds, except 2α, and in the coordination polymer 5p hydrogen bonds interconnect the molecules into 2D layers with the alkyl chain pointing outward of the layer. In 2α and in the dimeric compound 1d hydrogen bonds link the molecules into 3D structures. 1d with cobalt(iii), and 4 and 7 with nickel(ii) are ESR silent. The ESR spectra of 1, 3 and 6 are characteristic for paramagnetic high-spin cobalt(ii). The ESR spectra of all copper(ii) coordination compounds show that the unpaired copper electron is located in the dx2−y2 orbital, being in agreement with the elongated octahedral geometry.