Susceptibility Measurements Research Articles

Synthesis, Characterization and In-vitro Antibacterial Activity Studies of Oxovanadium (IV) Complexes of α-Amino Acid Schiff Bases and 1,10-Phenanthroline Ligands

Oxovanadium(IV) complexes of the type [VO(L)(phen)] (VO-1 to VO-5) have been synthesized and characterized by FTIR and UV-Vis spectra, molar conductance, melting points, and magnetic susceptibilities measurements, where L= N-salicylidene-β-alanine (sal-ala), N-salicylidene-glycine (sal-gly), N-salicylidene-DL-β-phenylalanine (sal-pheala), N-salicylidene-leucine (sal-leu), and N-salicylidene-DL-methionine (sal-met), and phen is 1,10-phenanthtroline. The infrared spectral data reveals that the tridentate nature of the amino acid-based Schiff base ligand and the coordination of the ligand through azomethine nitrogen, phenolic oxygen and carboxylate oxygen with vanadyl (VO2+) ion. All of these complexes were determined to be non-electrolyte in nature, according to conductivity measurements. The magnetic moment measurements have been attributed that these complexes are paramagnetic and have d1 configuration of vanadium (IV) ion. The antimicrobial activity of the synthesized complexes was evaluated against four pathogenic bacteria viz. Escherichia coli, Proteus vulgaris, Bacillus subtilis and Staphylococcus aureus.

Planar XY magnetic glass state in the Gd2ScNbO7 pyrochlore

Here a spin glass system with emergent planar ordered spin clusters is investigated. The mixed B-site pyrochlore Gd2ScNbO7has been synthesized and characterized through a variety of techniques, including x-ray diffraction, magnetic susceptibility, muon spin relaxation, heat capacity and neutron scattering. Despite a Curie-Weiss temperature of -3.93(3) K, indicating net antiferromagnetic interactions, no signs of long ranged magnetic ordering are found down toT= 0.3 K. Instead, a disordered magnetic state emerges with a small correlation length of 2.1(1) Å of single tetrahedra. A Reverse Monte Carlo analysis of the polarized neutron scattering data reveals short-range antiferromagnetic order with emergent XY spin ordering similar to the parent pyrochlore compounds. Muon spin relaxation, and AC susceptibility measurements confirm that the magnetization condenses into a glass, with 10 % of the potential entropy missing in the specific heat. This magnetic ground state is similar to what is observed in Gd2Sn2O7just above the ordering temperature, without the eventual long-range ordering at low temperature.

Freezing of short-range ordered antiferromagnetic clusters in the CrFeTi2O7system.

We report on the CrFeTi2O7(CFTO) system using a combination of x-ray diffraction, dc magnetization, ac susceptibility, specific heat and neutron diffraction measurements. CFTO is seen to crystallize in a monoclinic P21/a symmetry. It shows a glassy freezing at Tf ~ 22 K, characterized by the observation of bifurcation between ZFC and FC χ (T) curves, frequency dispersion across Tf in ac susceptibility, and follows Vogel-Fulcher and power law type critical dynamics, very slow relaxation of iso-thermal remanent magnetization with time and the absence of an anomaly in the temperature dependence of specific heat measurements. The microscopic neutron diffraction analysis of CFTO not only confirms the absence of long-range antiferromagnetic ordering but also exhibits diffuse scattering due to the presence of short-range ordered antiferromagnetically correlated spin clusters.&#xD.

A simple Urea approach to N-doped α-Mo2C with enhanced superconductivity

Abstract Chemical doping is a critical factor in the development of new superconductors or optimizing the superconducting transition temperature (T c) of the parent superconducting materials. Herein, a new simple urea approach is developed to synthesize the N-doped α-Mo2C. Benefiting from the simple urea method, a broad superconducting dome is found in the Mo2C1-x N x (0 ≤ x ≤ 0.49) compositions. XRD results show that the structure of α-Mo2C remains unchanged and that there is a variation of lattice parameters with nitrogen doping. Resistivity, magnetic susceptibility, and heat capacity measurement results confirm that the superconducting transition temperature (T c) was strongly increased from 2.68 K (x = 0) to 7.05 K (x = 0.49). First-principles calculations and our analysis indicate that increasing nitrogen doping leads to a rise in the density of states at the Fermi level and doping-induced phonon softening, which enhances electron-phonon coupling. This results in an increase in T c and a sharp rise in the upper critical field. Our findings provide a promising strategy for fabricating transition metal carbonitrides and provide a material platform for further study of the superconductivity of transition metal carbides.

Assessing soil erosion risk through geospatial analysis and magnetic susceptibility: A study in the Oued Ghiss dam watershed, Central Rif, Morocco

In northern Morocco, water erosion presents a critical risk for soil degradation and dam sedimentation, attributable to extreme climatic conditions, variegated topography, lithological vulnerabilities, and anthropogenic pressures. This study quantitatively and spatially evaluates soil erosion susceptibility within the catchment area of the Oued Ghiss dam in Central Rif, Morocco. Utilizing the Revised Universal Soil Loss Equation (RUSLE) integrated with Geographic Information Systems (GIS) and calibrated through magnetic susceptibility metrics, the study provides a detailed analysis of erosion factors. The model was applied using GIS to spatially analyze data on rainfall, soil type, topography, land cover, and management practices, with magnetic susceptibility measurements used to calibrate the model by identifying stable and erosion-prone areas. The resultant soil loss map reveals a mean erosion rate of 24 t/ha/year. Specifically, 37.28 % of the catchment area exhibits an erosion rate under 5 t/ha/year, 40.16 % between 5 and 10 t/ha/year, 22.77 % between 10 and 20 t/ha/year, and 0.86 % surpasses 20 t/ha/year. Magnetic susceptibility measurements across various soil profiles indicated that stable soils showed increased susceptibility towards the surface, while eroded soils displayed decreased susceptibility, with significant correlations found between magnetic susceptibility variations and the final risk map. This innovative calibration of the RUSLE model through magnetic susceptibility improves erosion vulnerability assessments and results in a more detailed soil loss map. The findings provide critical information for policymakers to develop targeted management plans for erosion-prone areas, particularly benefiting the Ghiss dam watershed, where these insights will aid in preventing dam siltation and enhancing water resource management. This confirms magnetic susceptibility's reliability in assessing soil erosion vulnerability and improving numerical models.

Phase-sensitive pump-probe measurement of the complex nonlinear susceptibility of silicon across the direct band edge

The nonlinear response of materials, an increasingly important aspect of light-matter interaction, can be challenging to measure in highly absorbing materials. Here, we introduce an interferometric technique that enables a direct measurement of the nonlinear complex permittivity in a bulk medium from reflectivity alone. We demonstrate the utility of pump-probe supercontinuum (SC) spectral interferometry in reflection by measuring time-dependent variations in the complex dielectric function (n, k) over the visible wavelength range in bulk silicon. Transient phase shifts in the reflected SC due to a near infrared pump pulse allow us to track modifications to k, whereas changes in n are derived from transient fluctuations in the reflected SC probe amplitude. The ultrafast response is attributed to effective two-photon absorption (β) and Kerr (n2) coefficients. We observe the onset of strong two-photon absorption as the two-photon energy is tuned through the direct band edge of silicon (E1=3.4eV). This technique allows straightforward spectroscopic measurements of the χ(3) nonlinear response at the surface of absorbing materials.

Novel α-N-heterocyclic thiosemicarbazone complexes: synthesis, characterization, and antimicrobial of properties investigation.

In this paper, eight novel α-N-heterocyclic thiosemicarbazone complexes were synthesized in search of new biologically active compounds, and characterized via organic elemental analysis, nuclear magnetic resonance spectroscopy, infrared spectra, thermogravimetric analysis, ultraviolet-visible spectroscopy, molar conductance and magnetic susceptibility measurements. The in vitro antimicrobial activity of these complexes was examined against ten disease-causing pathogens: Gram-positive bacteria (Micrococcus luteus ATCC9341, Staphylococcus epidermidis ATCC12228, Bacillus cereus RSKK863) and Gram-negative bacteria (Pseudomonas aeroginosa ATCC27853, Klebsiella pneumonia ATCC27853, Enterobacter aerogenes ATCC51342, Salmonella typhi H NCTC9018394, Shigella dysenteria NCTC2966, Proteus vulgaris RSKK96026) and yeast (Candida albicans Y-1200-NIH). The results revealed that the α-N-heterocyclic thiosemicarbazone compounds showed potent activity. It was observed that all thiosemicarbazone complexes were more susceptible to Gram-negative strains based on the presence of an electron-withdrawing substituent (-Br/-Cl/-F). It was determined that thiosemicarbazone Cu2+complexes showed stronger antifungal effects.

Self-Assembled Lanthanide Phosphinate Square Grids (Ln = Er, Dy, and Tb): Dy4 Shows SMM/SMT and Tb4 SMT Behavior.

Tetranuclear [2 × 2] square-grid-like LnIII clusters have been synthesized by reacting LnCl3·6H2O salts with bis[α-hydroxy(p-bromophenyl)methyl]phosphinic acid [R2PO2H, where R = CH(OH)PhBr] and pivalic acid. Single-crystal X-ray diffraction studies show the formation of [Me4N]2[Ln4(μ2-η1:η1-PO2R2)8(η2-CO2But)4(μ4-CO3)] [Ln = Er (1), Dy (2), and Tb (3)]. Direct-current studies reveal significant ferromagnetic interactions between DyIII in 2 and TbIII in 3 and an antiferromagnetic interaction between ErIII in 1. Dynamic magnetic susceptibility measurements confirm a single-molecule magnet (SMM) behavior in both 0 and 1200 Oe applied magnetic fields for 2. Complexes 2 and 3 show single molecular toroic (SMT) behavior with a mixed magnetic moment.

Crystal and thermodynamic properties of [formula omitted], (X = Al, Ga)

The crystal and thermodynamic properties of Tb2Ni2X (X = Al, Ga) are reported through measurements of X-ray diffraction (XRD), magnetic susceptibility, χ(T), magnetization, M(μ0H) and heat capacity, Cp(T). XRD pattern analysis confirms the orthorhombic W2CoB2-type structure with the space group of Immm. χ(T) at high temperature for both compounds follows the Curie – Weiss relationship giving an effective magnetic moment close to that expected for the trivalent Tb ion. The low-temperature χ(Cp) data indicate that both compounds order antiferromagnetically at TN = 41 K (40.4 K) and 41.5 K (41.4 K) for Al and Ga compounds, respectively. Cp(T) data of the nonmagnetic counterparts Y2Ni2X (X = Al, Ga) are well described by the Debye model giving a Debye temperature, θD = 236.9(4) K and 225.3(2) K for Al and Ga compounds, respectively. The low-temperature part of the 4f-magnetic contribution to the total heat capacity, C4f(T) can be described by the antiferromagnetic spin-wave dispersion, giving an energy gap Δsw = 47(3) K and 26(2) K for Al and Ga compounds, respectively. The 4f – magnetic entropy S4f(T) for both compounds reaches the value of 2Rln(2) close to their respective TN values.

Mineral composition of lake Sabakty sediments as an indicator of paleoclimate, Southern Urals, Russia

Relevance. Reconstruction of climatic changes based on the lacustrine sediments of lakes makes it possible to identify climatic trends and events in the late Quaternary. The Urals is considered as one of the climatic divisions, therefore, studies of the conditions of lake sedimentation, including climatic ones, are relevant in this area. Aim. To study mineral composition as an indicator of paleoclimate of Lake Sabakty sediments. Object. Core of Lake Sabakty sediments (length is 298 cm). The age of the core is ~25 thousand years old. Materials and methods. Sampling was carried out taking into account seismoacoustic data, lithological description, as well as measurements of magnetic susceptibility and radiometric dating data. The granulometric analysis was carried out by laser granulometry using a Bluewave particle size analyzer (Microtrac, USA) combined with a sample loading and circulation system with an integrated ultrasonic dispersant. Mineral composition of the sediments was determined using the D2 PHASER X-ray diffractometer and the Merlin auto-emission scanning electron microscope. Results. The predominance of the siltstone fraction was established. The mineral composition is characterized by the predominance of allotigenic minerals in sediments (quartz, microcline, albite, mica, chlorite, mixed-layer clay minerals, hornblende, kaolinite) according to X-ray diffraction and electron microscopy. Autigenic minerals include biogenic silica (cristobalite, tridymite), pyrite, carbonates (calcite, dolomite), sulfates (gypsum, barite). Conclusions. The ratio of allogenic and autogenic components reflects the changes in the accommodation of the reservoir and the supply of clastic material associated with changes in climate humidity. Changes in climate humidity are reflected in changes in the contents of carbonate and sulfate minerals. At the beginning of sedimentation, Lake Sabakty was shallow and mineralized due to climate aridization, which probably included the global Bond 8 event (~26000–11700 BP). The study of the mineral composition of the sediments of Lake Sabakty allowed us to establish the events of climate aridization: ~10000 BP, ~7600 BP, ~6900 BP ~1900 BP and ~1400 BP. In Sabakty Lake, there is a bright episode of a decrease in climate humidity in the range of ~7300-5200 BP, which is marked by an increase in carbonate content up to 70% and the detection of gypsum at ~6900 BP.

Magnetic properties of binary alloys Ni[formula omitted]Mo[formula omitted] and Ni[formula omitted]Cu[formula omitted] close to critical concentrations

The search for the ferromagnetic quantum critical point (FM QCP) has always been a captivating research topic in the scientific community. In pursuit of this goal, we introduced nonmagnetic transition metals to alloy with elemental nickel, and studied the magnetic properties of nickel binary alloys Ni1−xMox and Ni1−yCuy as a function of x and y up to the critical concentrations xcr and ycr at which the FM transition TC disappears. TC−x(y) phase diagrams were constructed via the Arrott–Noakes scaling of magnetization data. An enhanced Sommerfeld coefficient (the value of C/T as T→0) is observed near xcr and ycr, manifesting the effect of quantum fluctuations. However, the spin glass behavior is identified through the ac magnetic susceptibility measurements. This observation rules out the possibility of the existence of the FM QCP in both systems.

Single‐Step Synthesis of An Ideal Chain Antiferromagnet [H2(4,4′‐bipyridyl)](H3O)2Fe2F10 with Spin S = 5/2

One‐dimensional (1D) magnets are of great interest owing to their intriguing quantum phenomena and potential application in quantum computing. We successfully synthesized an ideal antiferromagnetic spin S = 5/2 chain compound [H2(4,4′‐bpy)](H3O)2Fe2F10 (4,4′‐bpy = 4,4′‐bipyridyl) 1, using a single‐step low‐temperature hydrothermal method under conditions that favors the protonation of the bulky bidentate ligand 4,4′‐bpy. Compound 1 consists of well‐separated (Fe3+−F−)¥ chains with a large Fe−F−Fe angle of 174.8°. Both magnetic susceptibility and specific heat measurements show that 1 does not undergo a magnetic long‐range ordering down to 0.5 K, despite the strong Fe−F−Fe intrachain spin exchange J with J/kB = –16.2(1) K. This indicates a negligibly weak interchain spin exchange J′. The J′/J value estimated for 1 is extremely small (< 2.8×10‐6), smaller than those reported for all other S = 5/2 chain magnets. Our hydrothermal synthesis incorporates both [H2(4,4′‐bpy)]2+ and (H3O)+ cations into the crystal lattice with numerous hydrogen bonds, hence effectively separating the (Fe3+−F−)¥ spin chains. This single‐step hydrothermal synthesis under conditions favoring the protonation of bulky bidentate ligands offers an effective synthetic strategy to prepare well‐separated 1D spin chain systems of magnetic ions with various spin values.

Heterocyclic Schiff Base Complexes of Bivalent Transition Metals: Microwave-Assisted Green Synthesis, Structure Elucidation and Antimicrobial Studies

A heterocyclic Schiff base ligand [LH] namely {5‐[(E)‐[(1H‐pyrrol‐2‐yl)methylidene]amino]‐ 1,3,4‐thiadiazole‐2‐thiol}(NNN donor) and its divalent transition metals (Co2+, Ni2+, Cu2+ and Zn2+) mononuclear complexes were synthesised efficiently in relatively very short times (from one-two hours to 6-15 minutes) with higher yields [from 59% (conventional method) to 90% (green method)] by microwave-assisted greener process is presented here. The ligand and its complexes were characterised by elemental analysis, molar conductance, and magnetic susceptibility measurements and spectroscopic (IR, electronic, and NMR) analyses. All investigated complexes were found to be six coordinated ML2 [1:2 (metal: Ligand) ratio] type which possessed mononuclear octahedral geometry. The ligand and its metal complexes were screened for antimicrobial activity by the disc diffusion method, and the results indicate that the metal complexes are better antimicrobial agents compared to the Schiff base and the metal complexes have followed antimicrobial trends: Cu(II) complex > Co(II) complex > Ni(II) complex > Zn(II) complex > Schiff base

Magnetic symmetries of terbium tetraboride (TbB4) revealed by resonant x-ray Bragg diffraction

A recent experimental study of TbB4 at a low temperature using resonant x-ray Bragg diffraction implies a magnetic symmetry not found in any other rare-earth tetraboride. The evidence for this assertion is a change in the intensity of a TbB4 Bragg spot on reversing the handedness (chirality) of the primary x-ray beam [R. Misawa, K. Arakawa, T. Yoshioka, H. Ueda, F. Iga, K. Tamasaku, Y. Tanaka, and T. Kimura, ]. It reveals a magnetic chiral signature in TbB4 that is forbidden in phases of rare-earth tetraborides known to date, as the previous magnetic symmetries are parity-time (PT) symmetric with anti-inversion present in the magnetic crystal class. Misawa appeal to a PT-symmetric diffraction pattern to interpret their interesting diffraction patterns. In addition to the use of symmetry that does not permit a chiral signature, calculated patterns impose cylindrical symmetry on Tb sites with no justification. We review magnetic symmetries for TbB4 consistent with a published neutron powder diffraction pattern and susceptibility measurements. On the basis of this information, noncollinear antiferromagnetic order exists below a temperature ≈44 K with no ferromagnetic component. Our symmetry-informed patterns encapsulate Tb electronic degrees of freedom in terms of multipoles consistent with established sum rules for dichroic signals. The investigated symmetry templates are noncentrosymmetric, noncollinear antiferromagnetic constructions with propagation vector k=(0,0,0). An inferred chiral signature for a parity-even absorption event has an interesting composition. There is the anticipated product of Tb axial dipoles and chargelike quadrupoles (from Templeton-Templeton scattering). Beyond this contribution, though, symmetry allows a product of dipoles in the chiral signature. A predicted change in the intensity of a Bragg spot with rotation of the crystal about the reflection vector (an azimuthal angle scan) can be tested in future experiments. Likewise contributions to Bragg diffraction patterns from Tb anapoles and higher-order Dirac multipoles. Published by the American Physical Society 2024

Weyl fermion excitations in the ideal Weyl semimetal CuTlSe2

An ideal Weyl semimetal is characterized by a dispersion in which only Weyl cones intersect the Fermi level, with low-energy behavior being governed by Weyl fermions. Although ideal Weyl semimetals have long been anticipated, only a few are realized in nonmagnetic materials. In this study, we confirm the presence of Weyl-fermion excitations in the ideal Weyl semimetal CuTlSe2 via a combination of magnetoresistance, Hall-effect, magnetic-susceptibility, nuclear magnetic resonance (NMR), and muon-spin relaxation (µSR) experiments. Magnetoresistance measurements reveal a negative longitudinal magnetoresistance (LMR), which scales as B2, while Hall-effect results indicate a predominant contribution from Weyl fermions with a hole-type charge. Magnetic susceptibility and µSR measurements indicate the lack of any intrinsic spontaneous magnetic moments down to base temperature. Finally, the NMR results can be modeled by a two-component effective Hamiltonian, which reproduces well the temperature-dependent Cu63 NMR (T1T)−1 factor, shown to scale as T2 below 100 K and as T1 above 100 K. Overall, we find that the extremely low concentration (1017cm−3) of carriers in CuTlSe2 originates from an ideal nonmagnetic Weyl semimetallic state, persisting up to a thermal excitation energy of 9 meV (100 K), above which trivial electronic bands close to EF take over. Our findings highlight CuTlSe2 as a new member of the intriguing class of Weyl semimetals. Published by the American Physical Society 2024

Stabilization of Short‐ and Long‐Range Magnetic Ordering through the Cooperative Effect of 1D [CuO4]∞ Chains and [CuO2X2] Quadrilateral in Quasi‐1D Spin‐1/2 Systems

AbstractQuasi‐1D chain antiferromagnets with reduced structural dimensionality are a rich playground for investigating novel quantum phenomena. We report the synthesis, crystal structure, and magnetism of two novel quasi‐1D antiferromagnets, β‐PbCu2(TeO3)2Cl2 (I) and PbCu2(TeO3)2Br2 (II). Their magnetic frameworks are constructed via Cu‐based quasi‐1D [Cu(2)O4]∞ zigzag chains with square‐planar [Cu(1)O2X2] (X=Cl or Br) separated among 1D chains. Specific heat measurements show λ peaks at ~9 K and ~19 K for I and II, respectively. Moreover, both broad maximums (χmax=90 K for I and 80 K for II) and small kinks (TN≈9 K for I and 19 K for II) have been observed in magnetic susceptibility measurements of I and II. Bonner–Fisher model fitting, and theoretical analyses were performed to evaluate the magnetic exchange interactions. Our experimental and theoretical results and structure‐properties relationship analysis reveal the coexistence of short‐ and long‐range magnetic ordering from the cooperative effect of 1D [CuO4]∞ chains and [CuO2X2] quadrilateral.

Stabilization of Short- and Long-Range Magnetic Ordering through the Cooperative Effect of 1D [CuO4]∞ Chains and [CuO2X2] Quadrilateral in Quasi-1D Spin-1/2 Systems.

Quasi-1D chain antiferromagnets with reduced structural dimensionality are a rich playground for investigating novel quantum phenomena. We report the synthesis, crystal structure, and magnetism of two novel quasi-1D antiferromagnets, β-PbCu2(TeO3)2Cl2 (I) and PbCu2(TeO3)2Br2 (II). Their magnetic frameworks are constructed via Cu-based quasi-1D [Cu(2)O4]∞ zigzag chains with square-planar [Cu(1)O2X2] (X=Cl or Br) separated among 1D chains. Specific heat measurements show λ peaks at ~9 K and ~19 K for I and II, respectively. Moreover, both broad maximums (χmax=90 K for I and 80 K for II) and small kinks (TN≈9 K for I and 19 K for II) have been observed in magnetic susceptibility measurements of I and II. Bonner-Fisher model fitting, and theoretical analyses were performed to evaluate the magnetic exchange interactions. Our experimental and theoretical results and structure-properties relationship analysis reveal the coexistence of short- and long-range magnetic ordering from the cooperative effect of 1D [CuO4]∞ chains and [CuO2X2] quadrilateral.

Iron Behaviour and Soil Properties in Hydromorphic Soils of Beni Moussa, Tadla Plain, Morocco

Abstract This study aims to determine the behaviour of iron and its relation to the physicochemical properties in the hydromorphic soils of the Tadla plain (Morocco). An extensive analysis using Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) from a statistical perspective was employed to ensure a comprehensive examination. The results reveal that the organic matter (OM) shows very high values, likely due to the collected samples near the sewerage network. Magnetic susceptibility (MS) measurements indicate that all the samples have positive and low values, indicating an abundance of paramagnetic minerals (such as ilmenite, siderite, and clay minerals). The iron concentration [ppm] increases from the top to the bottom of the Rivers, suggesting migration in a reduced form. Pearson’s correlation coefficients indicate that OM is positively correlated with cation exchange capacity (CEC) (r = 0.83) and electrical conductivity (EC) (r = 0.85) but negatively correlated with MS (r = –0.57) and iron oxide (r = 0.42). Calcium carbonate content (CaCO3) is positively correlated with sand (r = 0.49), but negatively with MS (r = –0.7). Iron (Fe) is positively correlated with frequency-dependent (FD) (r = 0.7), but negatively with sand (r = –0.608). Clay is strongly negatively correlated with silt (r = –0.88) and oxalate extractable iron oxides (Feo) (r = –0.55), respectively. These findings suggest that the physicochemical features of Beni Moussa hydromorphic soils are strongly linked and that iron in the soil is required for the stability of specific soil components.

A Tetranuclear copper(II) Complex with a Pyridine‐2,6‐dicarboxamide Ligand: Structural and Magnetic Properties and In vitro Antiproliferative Activity Against Human Cancer Cells

AbstractA pentadentate diamide ligand, N,N′‐di(pyridine‐2‐yl)pyridine‐2,6‐dicarboxamide (L1H2) and its tetranuclear Cu(II) complex [Cu4(L1)2(μ3‐OH)2(H2O)3(ClO4)](ClO4) ⋅ H2O are reported. X‐ray crystal structure of the complex reveals that it has an open‐book type architecture. Two central copper atoms are connected to each other by two hydroxo bridges. Each of these two hydroxo bridges also connects the two central copper atoms to one of the two terminal copper atoms. Variable temperature susceptibility measurements show that χMT decreases with the temperature, indicating a strong antiferromagnetic behavior. With the help of DFT calculations the magnetic data was analyzed using the spin Hamiltonian H=−2 J1S3 ⋅ S4 −2 J2(S3 ⋅ S1+ S3 ⋅ S2+ S4 ⋅ S1+ S4 ⋅ S2)−2 J3S1 ⋅ S2 (where subscripts 1 and 2 refer to the terminal copper atoms and 3 and 4 refer to the central copper atoms). The best fit was obtained with 2 J1=−322 cm−1, 2 J2=+34.8 cm−1, 2 J3=−8.8 cm−1 and g=2.18, indicating a δ‐type interaction between terminal copper atoms. The complex proves to be an avid binder of ct‐DNA, with apparent binding constant (Kapp) value estimated as 1.536×107 M−1. In vitro experiments indicate that the Cu(II) complex reduced the proliferation of HCT116 cells among other cell lines. This reduction of cell proliferation may be attributed to the enhancement of intracellular ROS, along with modulation and disruption of cell cycle associated proteins. SKC conceptualized the project, arranged funding and involved in overall coordination among collaborators, analyzing the data, and writing the paper. AM was involved in doing the experimental work on synthesis of the compounds, carrying out analytical and spectroscopic measurements, collecting X‐ray crystallographic data and DNA binding experiments. MS, SM and KDS were involved in study of anticancer activities of the complex. SS helped in refining X‐ray structure of the complex. MC did the magnetic measurements and analysis whereas AF did the DFT calculations.

A polymeric Co(II) oxalate salt containing pyridinium type cations: Synthesis, structure, spectroscopy, thermal behavior and magnetism

A Co(II) oxalate coordination polymer, (C7H11N2)2[Co(C2O4)2]·5H2O (1) (C7H11N2+ = 2-amino-4,6-dimethylpyridinium cation), has been synthesized and characterized by elemental and thermal analyses, FT-IR and UV/Vis spectroscopies, powder X-ray diffraction (PXRD), single-crystal X-ray diffraction and variable temperature magnetic susceptibility measurements. Compound 1 is a polymerized organic–inorganic hybrid salt, the asymmetric unit of which consists of one Co(II) ion, one bidentate C2O42− ligand, two halves of bidentate C2O42− ligands, two 2-amino-4,6-dimethylpyridinium C7H11N2+ cations and five crystal water molecules. Each CoII center is six-coordinated in a distorted octahedral geometry fulfilled by six oxygen atoms from three chelating C2O42− ligands. The [Co(C2O4)2]2− ions act as complex ligands and efficiently bridge neighboring Co2+ ions, forming chains of complex anions linked by hydrogen bonded water molecules. Hydrogen bonding interactions of the type OH∙∙∙O and NH∙∙∙O along with π–π stacking interactions between pyridine rings contribute to the stabilization of the 3D supramolecular framework. Temperature-dependence magnetic moment (µ) collected under zero-field cooled (ZFC) and field-cooled (FC) conditions revealed weak antiferromagnetic ordering at low temperatures.