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Herein, the effect of changing the alkaline earth metal cations type on the structure-properties of cobalt zinc borate glass was demonstrated. A series of spectroscopic analyses such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), optical absorption, electron spin resonance (ESR) spectra, and mass density were carried out to scrutinize these effects. The glass structure was confirmed using XRD. The mass density and molar volume increased in the order of Ca < Sr < Ba, increasing the densification and connectivity of glass network. FT-IR analysis exhibited that the increased number of B O 4 units and decreased number of nonbridging oxygen (NBO) are attributed to the decrease in cation field strength in the order of Ca > Sr > Ba. Optical absorption spectra showed a single optical transition of Co 2 + cations in octahedral sites at ⁓ 502 nm, which is owing to 4 T 1 g (F) → 2 T 1 g H , and two transitions at ⁓ 572 nm and 1577 nm, which are owing to 4 A 2 (4 F) → 4 T 1 4 P and 4 A 2 (4 F) → 4 T 1 g 4 F of Co 2 + cations in tetrahedral sites, respectively. These optical transitions were exploited to evaluate the effect of changing the type of alkaline earth cations using ligand field theory. The crystal field strength (Dq) and inter-electronic repulsion (B and C) suggest that the ionic environment around the cobalt cations increases from Ca to Ba. Finally, ESR spectra indicated that cobalt ions exist in divalent states with more domination of tetrahedral sites than octahedral ones, in good accordance with the increase in mass density, the conversion to tetrahedrally-coordinated boron atoms ( BO 4 ), the decrease in NBOs, and the increase in optical band gap energy. The obtained values of covalency parameter ( K 0 ) increased from 0.833 for Ca, 0.878 for Sr, and 0.893 for Ba confirm the ionic nature. These obtained findings render these glasses a decent contender as optical material in the optics realm. [ABSTRACT FROM AUTHOR]

A coronene-like graphitic nanoribbon was recently synthesised as a potential candidate for applications in nanoelectornics due to its unique structural characteristics in contrast with other nanomaterials. It is a planar, thin, finite, and quasi-one-dimensional carbon-based material with novel characteristics. The coronene-like graphitic nanoribbon is constructed using multiple units of a finite dimensional coronene structure linked together in a chain of armchair and zigzag isomers. In this article, we compute the topological properties based on distance and degrees of armchair and zigzag nanoribbon isomers by adopting the orthogonal partition techniques. Our results on entropy measures demonstrate that armchair and zigzag nanoribbon isomers exhibit isentropic structures. We have computed the vertex partitions, 13 C NMR and ESR spectra using distance degree sequence vectors and spectra of armchair and zigzag isomers. Furthermore graph spectral properties of the two isomers are computed which reveal that the zigzag nanoribbons are kinetically more stable than the corresponding armchair isomers. [ABSTRACT FROM AUTHOR]

Solution-based and solid-state reactions of copper(ii) compounds, 1,10-phenanthroline and l-threonine were investigated. Eight new ternary coordination compounds were obtained:[Cu(l-Thr)(H2O)(phen)]2SO4∙10H2O (1a∙10H2O), [Cu(l-Thr)(H2O) (phen)]2SO4∙4.3H2O (1a∙4.3H2O), {[Cu(μ-l-Thr)(phen)]2SO4∙3.5H2O}n (1b∙3.5H2O), [Cu(l-Thr)(H2O)(phen)][Cu(l-Thr)(CH3OH)(phen)]SO4∙2H2O∙CH3OH (1c∙2H2O∙CH3OH), [Cu(l-Thr)(H2O)(phen)][Cu(l-Thr)(CH3OH)(phen)]SO4∙4H2O (1c∙4H2O), [Cu(l-Thr)(CH3OH)(phen)]2SO4∙H2O (1d∙H2O), [Cu(l-Thr)(H2O)(phen)][Cu(l-Thr)(CH3OH)(phen)][Cu(SO4)(l-Thr)(phen)]HSO4∙H2O∙3CH3OH (1e·H2O·3CH3OH), [Cu(l-Thr)(H2O)(phen)][Cu(l-Thr)(phen)(py)]SO4 (1f) (phen = 1,10-phenanthroline, l-Thr = l-threoninate, py = pyridine). X-ray crystal structure analysis of the prepared ternary coordination compounds revealed extensive hydrogen bonding and π-interactions that link complex species, anions and solvent molecules into 3D architectures. The water/methanol solvent molecules are found in pockets and/or channels in seven solvates. ESR spectra of different types of compounds were also investigated. In all measured compounds the unpaired electron of the copper(II) ion is located in the dx2-y2 orbital which is in agreement with elongated square-pyramidal geometry. Compound 1a∙10H2O showed substantial cytotoxic activity toward human hepatocellular carcinoma (HepG2) and acute monocytic leukaemia (THP-1) cell lines.

Melt-quenching technique was used to prepare borosilicate glasses of composition xSiO2- (75-x) B2O3–24.7Li2O-0.3Cr2O3 (x = 0, 10, 20, 30, 40 and 50 mol%). With increasing the former content, both Cr6+ and Cr3+ optical transitions undergo strong intensity variations. The crystal field strength (10Dq) is increased, while Racah parameters (C,B) are decreased with increasing SiO2 content. The ratio estimated Dq/B values confirmed a weak crystal field environment for Cr3+ions, and further suggest a more covalent bond character. The ESR results revealed that Si-contained samples exhibit a strong microwave absorption signal, and justified the presence of both Cr3+ and Cr6+(charge transfer into 3d0 2p6+ = 3d1Cr5+) oxidation states. The fingerprints of borate and silicate relevant structural groups were clearly identified from FTIR spectroscopy. [ABSTRACT FROM AUTHOR]

3-Phenyl-4-methoxybenzaldehyde undergoes condensation with semicarbazide hydrochloride to form a Schiff base i.e. 3-phenyl-4-methoxybenzaldehyde semicarbazone (abbreviated as MBS). It undergoes complexation with Vanadium(II), Manganese(II), and Copper(II). The comparison of FTIR-spectra of complexes with that of free ligand helps ascertain the coordination points of ligand through the nitrogen of -CH=N- group and oxygen of group. The axial ligands have been varied by chloride, acetate and nitrate ions. The UV/Visible and ESR spectra of complexes predicts their tetragonally distorted octahedral (D4h) symmetry. The tetragonal distortion parameter (Dt) is observed maximum for chloride while it is minimum for nitrate along z-axis. Both vanillin and semicarbazide are established biologically active compounds and hence their biological activities may be enhanced by their complexation and than a versatile field may be developed for further exploration. [ABSTRACT FROM AUTHOR]

The main advances in the synthesis and studies of the properties of new stable heterocyclic verdazyl radicals and verdazyl radical coordination chemistry are reviewed. The promising applications of these radicals are also discussed. [ABSTRACT FROM AUTHOR]

• Eu doped BiFeO 3 and YMnO 3 nanoparticles are synthesized separately and then physically mixed using hydrothermal method to prepare (1-x)Bi 0.96 Eu 0.04 FeO 3 -(x)YMnO 3 (x = 0.0,0.25,0.50,0.75,1) nanocomposites. • XRD and Rietveld Refinement have confirmed the presence of rhombohedral (R 3c) as well as hexagonal (P 63 cm) phases in the nanocomposites. • FESEM images have shown irregular distribution of spherical like particles for parent as well as nanocomposites. • Addition of YMnO 3 decreases the band-gap of the nanocomposites, as compared to Eu-doped BiFeO 3 nanoparticles. • Magnetic studies on the parent as well as nanocomposites have revealed the presence of weak ferromagnetic ordering along with the presence of anti-ferromagnetic component. • Room-temperature X-band ESR analysis have corroborated the magnetic results. The results of structural and magnetic properties of (1-x)Bi 0.96 Eu 0.04 FeO 3 -(x)YMnO 3 (x = 0.0,0.25,0.50,0.75,1) nanocomposites, synthesized using physical mixing method are presented in this work. The Eu doped bismuth ferrite and yttrium manganite nanoparticles are synthesized separately and then physically mixed using hydrothermal method. The physical mixing of the parent materials helps to retain the properties of both the materials in the nanocomposites. XRD patterns show the presence of both phases (R 3c and P 63cm) in the nanocomposites, without any structural distortion or presence of other intermediate phases. Morphological analysis of the samples is done using FESEM and HRTEM techniques. The FESEM results show that the particles in the parent as well as nanocomposites are irregularly distributed with agglomeration of particles in Eu doped BiFeO 3 and the nanocomposite (BY-50). The interplanar distances corresponding to crystal planes of both phases are calculated for BY-50 nanocomposite from the HRTEM results. Chemical state analysis of BY-50, using XPS confirms the formation of nanocomposite. Multiple valence states for Fe (Fe2+ and Fe3+) and Mn (Mn2+, Mn3+ and Mn4+) are formed as a result of charge compensation phenomenon. The dominant Fe3+ and Mn3+ plays an important role in the magnetic properties of nanocomposites. Magnetic studies on the parent as well as the nanocomposites are done using room-temperature VSM. The M−H loops show wasp-waisted nature with the presence of weak ferromagnetism along with anti-ferromagnetic or paramagnetic ordering. The constricted nature of loops has been confirmed using ΔH (loop-width) versus M (magnetization) loops. The addition of YMnO 3 in the nanocomposites slightly increases the maximum magnetization from 0.149 emu/g for Eu doped BiFeO 3 nanoparticles to 0.364 emu/g for BY-75 nanocomposites. The maximum magnetization in the nanocomposites increases because of the constructive alignment of the spins at the interface. The presence of interfacial magnetic interaction in the samples has been corroborated through room-temperature X-band ESR analysis. [ABSTRACT FROM AUTHOR]

New tetradentate Schiff base transition metal complexes have been derived from salicylidene-4-imino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one and histidine were characterized by CHN analysis, magnetic susceptibility measurements, molar conductance, FAB-MS, IR, 1H-NMR, UV, CV, EPR, Fluorescence emission, AFM and Powder XRD techniques. AFM images and Powder XRD data endure that the complexes are nano-size grains with polycrystalline structure. The spectral evidences showed that all the metal chelates are square planar geometry except [VOL] complex which exist square-pyramidal geometry. Electrochemical data (CV) for [CuL] and [VOL] complexes in acetonitrile solution indicates that the redox potential of metal ions is affected by the coordinated ligand. Electron Spin Resonance (ESR) spectra of [CuL] and [VOL] complexes were well coinciding with proposed geometries and other reported complexes. CT-DNA interaction studies of [CuL] complex reveals that an intercalation binding mode occurs between complex and DNA base pairs. The in vitro antimicrobial activity of complexes has been tested against the growth of some fungal and bacterial species persist that chelates have better control than ligand.

A new series of binuclear oxovanadium(IV), cerium(III) and dioxouranium(VI) complexes of a bis (bidentate) ligand (4,6-diacetylresorcinol; H 2 L) have been synthesized. The metal complexes were characterized by using different techniques such as elemental and thermal analyses, IR, 1H NMR, electronic, ESR, mass spectra and powder XRD, TEM and magnetic susceptibility and conductivity measurements. The ligand acts as a bis (monobasic bidentate) or bis (neutral bidentate) chelating agent forming binuclear complexes, formulated as: [(VO) 2 (L) 2 ], [(VO) 2 (H 2 L)(SO 4) 2 (H 2 O) 2 ], [Ce 2 (L)(NO 3) 3 (H 2 O) 5 (EtOH) 2 ]NO 3 , [Ce 2 (L)(NO 3) 4 (H 2 O) 3 (EtOH) 3 ], [(UO 2) 2 (L)(OAc) 2 (MeOH) 4 ]·nH 2 O; n = 2 or zero. Kinetic parameters (ΔE, A, ΔH, ΔS and ΔG) of the thermal decomposition stages have been calculated by Coats–Redfern equations. The geometry of the ligand and its oxovanadium(IV) complexes has been optimized using density functional theory (DFT). Total energy, energy of HOMO and LUMO, dipole moment and structure activity relationship were performed and confirmed practical antitumor results. The antimicrobial activity of the ligand and its metal complexes was investigated against the microorganisms S. aureus , B. subtilis , S. typhimurium, E. coli, C. albicans and A. fumigatus. The antitumor activity of the ligand and its oxovanadium(IV) complexes was investigated against human Hepatocelluar carcinoma cell lines. The ligand showed low antimicrobial and antitumor activities, which were improved upon complexation. Image 10312 • A new series of binuclear VO(IV), Ce(III) and UO 2 (VI) complexes were synthesized and characterized. • The metal complexes were characterized by different techniques. • DFT calculations were carried out for the ligand and its VO(IV) complexes. • The antimicrobial and antitumor activities of the ligand and its metal complexes were examined. [ABSTRACT FROM AUTHOR]

Abstract Co-precipitation synthesizing technique was adopted to prepare manganese doped zinc ferrite nanoparticles with varying concentrations 0.5, 0.6, 0.7. EDX proved the consistency of stoichiometry of compositions in the ferrite samples considered under preparation. XRD patterns authenticated the ferrite phase in the investigating samples. The experimental lattice parameter (8.412–8.438 Å) is increasing and crystallite size (7.6–6.4 nm) appears to be decreasing with substitution of Mn2+. The grain size (1.1 µm) in the sample (x = 0.7) with smaller crystallites (6.4 nm) is found to be bigger than that of remaining compositions (x = 0.5, 0.6). The vibrational frequencies detected in the FTIR spectra also authorized the obtained spinel phase in the current ferrite systems. The elastic moduli illustrate the mechanical strength of ferrite systems which are dependent on interatomic distances. The variation of line width and Lande's g –factor in ESR studies revealed the possibility of core-shell morphology of present ferrite nanoparticles. [ABSTRACT FROM AUTHOR]

We report crystal growth, magnetic properties and electron spin resonance (ESR) study of the one dimensional zigzag-chain compound FeNbO 4 . The single crystals were grown by the flux method using Na 2 WO 4 ·12H 2 O and Na 2 W 2 O 7 as the flux. Magnetic susceptibility and specific heat data show an antiferromagnetic ordering below 44 K. High-field magnetization data reveal a spin-flop transition at 12 T when magnetic field is applied along the magnetic easy axis. Multi-frequency ESR study on the single crystals reveal three resonance modes which can be understood by the molecule-field theory. Using a simple model with easy-axis type anisotropy, we estimate that the anisotropy field H A and the exchange field H E are 2.67 T and 27 T, respectively. The zero-frequency resonance field at 11 T corresponds to the spin-flop transition, demonstrating a close correlation between the high-field magnetization and the ESR spectra. [ABSTRACT FROM AUTHOR]

A 4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazole-3-oxide-1-oxyl lithium derivative was found to react with 2-methoxypentafluoro-1,4-naphthoquinone to form a product of addition at the carbonyl function: radical 2-(3,5,6,7,8-pentafluoro-1-hydroxy-2-methoxy-4-oxo-1,4-dihydronaphthalen-1-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1 H -imidazole-3-oxide-1-oxyl. The yield of the addition product increased with temperature and reached 84% at 0 °C. The reaction of the lithium derivative with hexafluoro-1,4-naphthoquinone gave rise to a product of addition at both carbonyl groups, namely, nitronyl nitroxide diradical 2,3,5,6,7,8-hexafluoro-1,4-bis(4,4,5,5-tetramethyl-3-oxide-1-oxyl-4,5-dihydro-1 H -imidazole-2-yl)-1,4-dihydronaphthalene-1,4-diol in a 16% yield. The structures of both mono- and diradical were solved by X-ray diffraction analysis, which revealed formation of an intramolecular H-bond between the OH group and nitroxide oxygen. According to electron paramagnetic resonance (EPR) spectroscopy, the obtained mono- and dinitroxide are prone to spontaneous deoxygenation in a toluene solution to give corresponding iminonitroxides. In water, they are much more stable. [ABSTRACT FROM AUTHOR]

Ternary host-guest complexes have been first obtained from cucurbituril CB[8] as a host molecule and two guest molecules: nitroxyl probes of different structures and biologically important amino acids (AA) and aromatic compounds. To characterize the binding of the guests, parameters of the polarity of the environment and the rotational mobility of the spin probes have been used. These parameters have been shown to depend on the nature of the analytes. For the ternary complexes, in addition to the usual triplet ESR spectra from nitroxyl probes (S3), supramolecular ensembles consisting of three equivalent ternary complexes (“triads”) have been found, whose ESR spectra have a seven-component hyperfine structure (S7) due to delocalization of the unpaired electron over three nitrogen nuclei. The relative intensity of the S7 spectra increases with increasing NaCl concentration in the solution, and also depends significantly on the nature of the analyte and the spin probe. Quantum chemical calculations have shown that (1) to determine the stability of the complexes, it is necessary to allow for the van der Waals interaction, and (2) the complexes involving the zwitterionic form of AA are much more stable than those with the neutral form of AA. [ABSTRACT FROM AUTHOR]

The compound in the title (L) was synthesized and reacted with Cu(II) metal ion with different anions (OAc − , NO 3 − , SO 4 2– , ClO 4 − , Cl − and Br − ) in absence and presence of auxiliary ligands (L′); N,O-donor; or N,N-donor; to form binary and ternary Cu(II)-chelates. The metal complexes were fully characterized by analytical and spectral techniques in addition to thermal, conductivity and magnetic susceptibility measurements. The obtained results showed that the ligand behaves as a neutral bidentate, forming chelates with molar ratios: 1:1, 1:2 and 1:3; M:L for binary and 1:2:1 and 1:1:1; M:L:L′ for ternary complexes, which can be formulated as: [L m CuX n (H 2 O) y ]·zH 2 O, m = 1 or 2, n = 0, 1 or 2, X = OAc − , SO 4 2− , Cl − or Br − , y = 0 or 2, z = 0 or 0.5; [L m Cu(H 2 O) n ]X 2 ·zMeOH, m = 2 or 3, n = 0 or 2, X = ClO 4 − or NO 3 − , z = 0 or 1 and [L m L'Cu(H 2 O) n ](NO 3 ) x ·yS, m = 1 or 2, n = 0 or 2, X = 1 or 2, y = 0.5 or 4, S = H 2 O or MeOH. The ESR spin Hamiltonian parameters of some complexes were calculated. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages have been evaluated using Coats–Redfern equations. The structural parameters of the ligand and its metal complexes have been calculated and correlated with the experimental data. The metal complexes exhibited octahedral and square planar geometrical arrangements according to the nature of the anion. The ligand and its metal complexes showed antibacterial activity towards Gram–positive bacteria, Gram–negative bacteria, yeast and fungus. [ABSTRACT FROM AUTHOR]

The conversion of phenylone polymer (poly- m-phenylene isophthalamide) at 293 K under the action of a nitrogen dioxide−oxygen gaseous mixture and nitrogen dioxide and oxygen individually is studied by the ESR method. In the first case, aryliminooxyl and arylacylaminoxyl free radicals are recorded, whereas in the second, diarylaminoxyl and phenoxy free radicals. The presence of phenolic and phenyl benzoate polymeric products in nitrated phenylone is detected by IR spectroscopy. The mechanisms of reactions occurring in both the oxidation modes are considered. [ABSTRACT FROM AUTHOR]

Naturally occurring flavonoids, delphinidin, pelargonidin and malvin, were investigated experimentally and theoretically for their ability to scavenge hydroxyl and nitric oxide radicals. Electron spin resonance (ESR) spectroscopy was used to determine antiradical activity of the selected compounds and M05-2X/6-311+G(d,p) level of theory for the calculation of reaction enthalpies related to three possible mechanisms of free radical scavenging activity, namely HAT, SET-PT and SPLET. The results obtained show that the molecules investigated reacted with hydroxyl radical via both HAT and SPLET in the solvents investigated. These results point to HAT as implausible for the reaction with nitric oxide radical in all the solvents investigated. SET-PT also proved to be thermodynamically unfavourable for all three molecules in the solvents considered. [ABSTRACT FROM AUTHOR]

A new Schiff base, H2L, was prepared by condensation of 4,6-diacetylresorcinol witho-phenylenediamine in molar ratio 1 : 1. The ligand reacted with copper(II), nickel(II), cobalt(II), iron(III), zinc(II), oxovanadium(IV), and dioxouranium(VI) ions in the absence and presence of LiOH to yield mononuclear and homobinuclear complexes. The mononuclear dioxouranium(VI) complex [(HL)-(UO2)(OAc)(H2O)]·5H2O was used to synthesize heterobinuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR,1H-, and13C-NMR, electronic, ESR and mass spectra, conductivity, and magnetic susceptibility measurements as well as thermal analysis. In the absence of LiOH, mononuclear complexes (1,4, and9) were obtained; in the presence of LiOH, binuclear complexes (3,5,7, and10) as well as mononuclear complexes (2,6, and8) were obtained. In the mononuclear complexes, the coordinating sites are the phenolic oxygen, azomethine nitrogen, and amino nitrogen. In addition to these coordinating sites, the free carbonyl and phenolic OH are involved in coordination in binuclear complexes. The metal complexes exhibited octahedral, tetrahedral, and square planar geometries while the uranium is seven-coordinate. The antimicrobial and antioxidant activities of the ligand and its complexes were investigated. The ligand and the metal complexes showed antitumor activity against Ehrlich Acites Carcinoma. [ABSTRACT FROM PUBLISHER]

The mononuclear radical anionic complex [N-hydrogenpyridinium][Pd(mnt) 2 ] (mnt = malonitrile-2,3-dithiolate) with a new countercation has been prepared and its crystal structure determined by X-ray crystallography. In the mononuclear radical anionic complex the palladium ion assumes a slightly distorted square-planar geometry and is bridged by four S atoms of two mnt anionic ligands. There are two kinds of slipped π–π stacking interactions between adjacent mononuclear radical anionic complexes in the crystal (i.e., PS-1 and PS-2). The ESR spectra, the variable-temperature susceptibilities, and the theoretical calculations reveal a very strong antiferromagnetic interaction between the adjacent mononuclear radical anionic complexes, leading to diamagnetism of the present complex. Further, the theoretical calculations indicate that the strong antiferromagnetic strength should be attributed to the PS-1 slipped π–π stacking interaction; the large spin densities on the associated short contact atoms should be a major factor leading to the strong magnetic coupling strength. This study is the first to reveal the mechanism of the strong antiferromagnetic interaction of a mononuclear radical anionic palladium complex with mnt as ligand. [ABSTRACT FROM AUTHOR]

Abstract: Li2O–PbO–B2O3–P2O5 glasses containing different concentrations of Cr2O3 ranging from 0 to 1mol% were synthesized by melt quenching technique. The amorphous nature of the glasses was asserted by X-ray diffractometry. The dielectric properties i.e., dielectric constant (ε′), loss factor (tanδ) and a.c. conductivity (σac) over a range of frequency 103–106 Hz in the temperature range 303–573K have been carried out on these samples. The results have been analyzed in the light of different oxidation states of chromium ions with the help of data on infrared, optical absorption and ESR spectra. The analysis of the results indicates that when the concentration of Cr2O3 is increased in the glass matrix the Cr3+ ions which act as modifiers with CrO6 structural units increase. The Cr6+ ions which enter the network as glass formers with CrO4 2− structural units decrease with increase in dopant concentration. [Copyright &y& Elsevier]

Highlights: [•] Two new hydrazone ligands were synthesized and characterized. [•] Copper(II) complexes were synthesized and characterized by analytical and spectral methods. [•] The spin Hamiltonian parameters of some complexes were calculated and discussed. [•] The complexes exhibited octahedral and square planar geometrical arrangements. [•] The ligands and some complexes showed antimicrobial activity. [ABSTRACT FROM AUTHOR]

The effect of energetic γ-radiation on H NMR, electronic absorption, ESR spectra, differential thermal analysis (DTA) and solid state dc electrical conductivity of the ligand N-phenyl-2-(2-(phenylamino)acetyl)hydrazine carbothioamide (HL) and its copper(II) complexes; Cu(HL)(OAc)HO, Cu(HL)BrHO and Cu(HL)(NO)⋅3HO before and after γ-irradiation (hereafter referred to as ( B), ( B), ( B), ( B) and ( A), ( A), ( A), ( A), respectively) has been studied. Electronic spectral bands of the complexes after irradiation exhibited some better resolved shapes with a remarkably higher absorbance, ESR spectrum of complex Cu(HL)BrHO ( B) before irradiation showed isotropic spectrum with g = 2.075 however, after irradiation ( A) displayed axial ESR spectrum with g > g > 2.0023 and d ground state. DTA of the compounds reveals that γ-irradiation induced generation of new peaks as well as changes in the peak intensities. Solid state dc electrical conductivity for complexes was investigated before and after γ-irradiation. Complexes were found to be semiconductors, the activation energies ( E) were calculated for the complexes by using the Arrhenius plot. [ABSTRACT FROM AUTHOR]

BaO-GaO-PO glasses containing different concentrations of MoO ranging from 0 to 0.5 mol% have been prepared. Spectroscopic studies viz., infrared, optical absorption and ESR spectra of these glasses have been carried out as a function of molybdenum ion concentration. The results suggest that molybdenum ions exist in Mo state with Mo(V)O complexes that act as modifiers in addition to Mo state with MoO and MoO structural groups in these glasses. [ABSTRACT FROM AUTHOR]

Highlights: [•] Metal complexes of unsymmetrical Schiff bases have been prepared and characterized. [•] Spectral studies of complexes show variations in bonding mode and stereochemistry. [•] ESR shows axial interaction of solvent molecules in a square planar Cu(II) complex. [•] DFT is used to correlate experimental and calculated data of the Ni(II) complexes. [•] TDDFT interprets M→L charge transfer and d–d transitions high and low energy bands. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new dicompartmental Schiff base was synthesized and characterized. [•] Binuclear complexes were synthesized and characterized. [•] The ligand and its complexes showed antibacterial and antifungal activities. [•] The DNA-binding properties of copper complexes were investigated. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new series of metal complexes of 4,6-diacetylresorcinol with Co(II) and Cu(II) have been synthesized. [•] Complexes have been characterized by the analytical and spectral methods. [•] The spin Hamiltonian parameters of the complexes were calculated and discussed. [•] Molecular orbital calculations were performed. [•] Some complexes showed antibacterial and antifungal activities. [Copyright &y& Elsevier]

Two polymeric ligands, diacetyl oxaloyldihydrazone (DODH), diacetyl malonoylhydrazone (DMDH) and their Co(II), Ni(II), Cu(II) and Zn(II) complexes were synthesized and characterized by elemental analyses, IR, mass, H & C NMR, ESR and electronic spectral studies. The ligands and their complexes are highly insoluble in water and common organic solvents and decompose at high temperature. The metal atoms are embedded between two polymeric chains of the organic ligands and the monomeric unit of the polymeric chain behaves as a neutral bidentate ligand and coordinate through two >C=N groups to different metals as indicated by H & C NMR and IR spectral studies. The molecular weights determined by H NMR and mass spectral studies suggest oligomeric nature of the ligands and their Zn(II) complexes. The magnetic susceptibility measurements and electronic spectral studies indicate a square planar geometry around the metal ion in Co(II) and Ni(II) complexes. Electronic and ESR spectral studies for Cu(II) complexes suggest a distorted octahedral stereochemistry around the metal atom and B as the ground state. Thermal studies (TGA and DTA) of some of the complexes in inert atmosphere show a multi-step exothermic decomposition of the bonded organic ligand at high temperature and metal (II) chloride as the end product. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A series of metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) with 2-amino benzoic acid thiophen-2-ylmethylene hydrazide (Habth) and 2-hydroxy benzoic acid thiophen-2-ylmethylene hydrazide (Hhbth) have been synthesized. The complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, electronic, IR, NMR, ESR spectra and thermal studies (TGA and DTA). Molecular structure of the Habth ligand was determined by single crystal X-ray diffraction technique. Habth acts as a monobasic bidentate ligand in all its complexes bonding through a deprotonated CO− and >C=N groups whereas, Hhbth acts as a monobasic bidentate in its Co(II) and Ni(II) complexes, bonding through a deprotonated C-O− and >C=N groups and as monobasic tridentate in Cu(II) and Zn(II) complexes bonding through >C=O, >C=N and deprotonated (C-O)− groups with the metal ion. Electronic spectra suggest a square planar geometry for Co(II), Ni(II) and Cu(II) complexes of Habth and Co(II) and Ni(II) complexes of Hhbth. However, the Cu(II) and Zn(II) complexes of Hhbth have octahedral geometry. The ESR spectra of Cu(II) complex of Hhbth in the solid state and in DMSO frozen solution show axial signals and suggest the presence of unpaired electron in dx2-y2 orbital of Cu(II). The Cu(II) complex of Habth in solid state shows isotropic signal, whereas, axial signal in DMSO frozen solution in the range of tetragonally distorted octahedral geometry due to interactions of DMSO molecules at axial positions. Thermal studies of some of the metal complexes show a multi-step decomposition pattern of bonded ligands in the complex. [ABSTRACT FROM AUTHOR]

Abstract: Transparent glasses with the composition 20RO–10Na2O–69B2O3–1Fe2O3 (where R=Ca, Sr and Ba) were prepared by melt quenching technique. The amorphous nature of the glass was confirmed by X-ray diffraction pattern of the sample. Physical parameters and spectroscopic studies such as EPR, optical absorption and FTIR were carried out for the glass samples. Besides dielectric properties i.e. dielectric constant (ε′), and loss (tan δ), a.c. conductivity (σac) in the frequency range 103–106 Hz and the temperature range 30–300°C in air of the present glasses were also investigated. The dielectric and spectroscopic properties have been analyzed in the light of different oxidation states of iron ions in order to understand the influence of alkaline earth oxides as modifier oxide on the structure and insulating strength/conductivity of glass matrix. [Copyright &y& Elsevier]

Abstract: Copper guanine and barbital complexes were prepared and characterized by elemental analyses and spectral measurements. The data typified the formation of stoichiometries 1:1 (M:L) with possible Cu–Cu interaction “association”. The complexes are with different geometries: square planar, square pyramidal and tetrahedral. The mode of bonding was identified by IR spectra. EPR spectra of the powdered complexes were recorded at X band at the room temperature. Different ESR parameters were calculated and discussed: g //, g ⊥, A //, 〈g〉, G, F, K, α 2. Molecular modeling techniques and quantum chemical methods have been performed for copper complexes to correlate the chemical structures of the complexes with their physical molecular properties. Bond lengths, bond orders, bond angles, dihedral angles, close contact, dipole moment (μ), sum of the total negative charge (STNC), electronegativity (χ), chemical potential (Pi), global hardness (η), softness (σ), the highest occupied molecular orbital energy (E HOMO), the lowest unoccupied molecular orbital energy (E LUMO) and the energy gap (ΔE) were calculated using PM3 semi-empirical and Molecular Mechanics (MM+) methods. The study displays a good correlation between the theoretical and experimental data which confirms the reliability of the quantum chemical methods. [Copyright &y& Elsevier]

Solution-based and solid-state reactions of copper(ii) compounds, 1,10-phenanthroline and l-threonine were investigated. Eight new ternary coordination compounds were obtained: [Cu(l-Thr)(H 2 O)(phen)] 2 SO 4 ∙10H 2 O ( 1a∙10H 2 O ), [Cu(l-Thr)(H 2 O) (phen)] 2 SO 4 ∙4.3H 2 O ( 1a∙4.3H 2 O ), {[Cu( μ -l-Thr)(phen)] 2 SO 4 ∙3.5H 2 O} n ( 1b∙3.5H 2 O ), [Cu(l-Thr)(H 2 O)(phen)][Cu(l-Thr)(CH 3 OH)(phen)]SO 4 ∙2H 2 O∙CH 3 OH ( 1c∙2H 2 O∙CH 3 OH ), [Cu(l-Thr)(H 2 O)(phen)][Cu(l-Thr)(CH 3 OH)(phen)]SO 4 ∙4H 2 O ( 1c∙4H 2 O) , [Cu(l-Thr)(CH 3 OH)(phen)] 2 SO 4 ) (phen = 1,10-phenanthroline, l-Thr = l-threoninate, py = pyridine). X-ray crystal structure analysis of the prepared ternary coordination compounds revealed extensive hydrogen bonding and π-interactions that link complex species, anions and solvent molecules into 3D architectures. The water/methanol solvent molecules are found in pockets and/or channels in seven solvates. ESR spectra of different types of compounds were also investigated. In all measured compounds the unpaired electron of the copper(II) ion is located in the d 2 O ( 1d∙H 2 O ), [Cu(l-Thr)(H 2 O)(phen)][Cu(l-Thr)(CH 3 OH)(phen)][Cu(SO 4 )(l-Thr)(phen)]HSO 4 ∙H 2 O∙3CH 3 OH ( 1e·H 2 O·3CH 3 OH ), [Cu(l-Thr)(H 2 O)(phen)][Cu(l-Thr)(phen)(py)]SO 4 ( 1f ) (phen = 1,10-phenanthroline, l-Thr = l-threoninate, py = pyridine). X-ray crystal structure analysis of the prepared ternary coordination compounds revealed extensive hydrogen bonding and π-interactions that link complex species, anions and solvent molecules into 3D architectures. The water/methanol solvent molecules are found in pockets and/or channels in seven solvates. ESR spectra of different types of compounds were also investigated. In all measured compounds the unpaired electron of the copper(II) ion is located in the d x2-y2 orbital which is in agreement with elongated square-pyramidal geometry. Compound 1a∙10H 2 O showed substantial cytotoxic activity toward human hepatocellular carcinoma (HepG2) and acute monocytic leukaemia (THP-1) cell lines., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

Heterobimetallic complexes [Cu x Zn1− x (dadb) · yH2O] n {where dadb = 2,5-diamino-3,6-dichloro-1,4-benzoquinone (1); x = 1 (2), 0.5 (4), 0.25 (5), 0.125 (6), 0.0625 (7), and 0 (3); y = 2; n = degree of polymerization} were synthesized and characterized. All metal complexes are stable at room temperature but weakly absorb moisture on exposure to air. Monometallic 2 exhibits subnormal magnetic moment whereas 3 exhibits diamagnetism. Heterobimetallic complexes exhibit normal magnetic moments. Heterobimetallic complexes are characterized from powder X-ray diffraction, thermal analysis, and electron spin resonance (ESR) spectral studies. Delocalization of unpaired electron from metal to ligand has been inferred from ESR and natural bond orbital (NBO) analysis. Greater delocalization of unpaired electron of Cu(II) on ligand of 4 as compared to that of 2 is reflected from NBO analysis. Heterobimetallic complexes show higher conductivity than monometallic complexes; all the complexes exhibit semiconductor behavior. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis, structural characterization, and magnetic properties of two new Cu(II) coordination polymers with formula {[Cu(2-nica)(H2O)2]∙H2O} n (1) and [Cu(6-nica)(H2O)2] n (2) (where 2-H2nica = 2-hydroxynicotinic acid and 6-H2nica = 6-hydroxynicotinic acid) are reported. 1 exhibits 1D chain structure formed by the sequence of [Cu(II)h name="sbnd" />Cu(II)]. For 2, nitrogen atoms and μ 1,3-COO carboxylic groups of 6-nica2− bridge Cu(II) ions forming an infinite chain structure. The ESR spectra, as well as the variable temperature magnetic susceptibilities were analyzed, which suggests ferromagnetic coupling in 1 and antiferromagnetic coupling in 2, respectively. [Copyright &y& Elsevier]

Reduction of poly(diphenylene phthalide) (PDP) with metallic lithium in DMF at room temperature was studied by electronic and ESR spectroscopies. The main feature of the process is the presence of a long induction period (about 50 to 80 min) which is probably caused by the formation of small lithium particles and by adsorption of the polymer on the metal. At least four types of nonparamagnetic color centers characterized by overlapping absorption bands at 570, 660, 750, and 810 nm were detected in the reduced solution. The amounts of all types of the color centers in the solution show a complex dynamic behavior. Reduction of the polymer in the bulk of the solution is due to lithium colloid particles which give rise to a narrow asymmetric ESR singlet ( g = 2.0023, Δ H = 0.03 mT, A/B ≈ 1.1-1.8) and absorb light in the region λ ∼300-400 nm. Paramagnetic species with quartet ESR signal with a splitting of 0.1 mT and g = 2.0045 observed in the solutions being reduced at a polymer concentration of 0.2 mol L were attributed to radical anions of terminal anthraquinone groups (TAGs). The electron affinities of some molecules simulating the phthalide-containing unit of the polymer backbone, TAG, and a defect anthrone group were calculated in the B3LYP/6-311+G(d,p) approximation. For diphenylphthalide, the vertical electron affinity EA = 0.21 eV, the adiabatic electron affinity EA = 0.66 eV, the effective electron affinity EA (with allowance for cleavage of C-O bond in the phthalide ring) = 1.23 eV. For anthrone group, one has EA ∼1.2 eV and for anthraquinone group, EA ∼2 eV. The electron affinities of the model compounds were also calculated with inclusion of the energy of solvation in two solvents (DMF and DMSO) and the energy of polarization in the PDP film. The electronic spectra of some compounds chosen as models for the expected products of reduction (anions and dianions) of the main phthalide-containing fragments in the polymer, TAGs, and defect anthrone groups were also calculated by the TD DFT B3LYP/6-311G(d,p) method. The presence of three types of chemical electron traps and the possibility of manifestation of strong absorption bands of these anions and dianions in the spectral region 500-900 nm precludes unambiguous selection and assignment of complex experimental electronic spectra observed in the course of PDP reduction. The possible role of TAGs in the electronic and photophysical processes in PDP is discussed. [ABSTRACT FROM AUTHOR]

Abstract: The mononuclear neutral Cr(III) complex, [Cr(L)3] (1) (where LH=4-methyl-2,6-dibenzoylphenol (mdbpH)) has been synthesized and characterized by elemental analysis, conductivity measurement, mass spectrometry, IR, electronic and ESR spectroscopy, cyclic voltammetry and X-ray crystallography. Crystal structure determination reveals that 1 comprises three monoanionic bidentate ligands (2,6-PhCO)2(4-Me)C6H2O− coordinating through phenolic O and benzoyl O atoms to give a mer-CrO3O3 octahedral configuration. The optimized geometry and the electronic transitions of the complex were calculated using methods based on the density functional theory. The ESR spectra indicate a weak tetragonal distortion. The redox behavior was studied by cyclic voltammetry and was compared with that observed for the free ligand. [Copyright &y& Elsevier]

Cyclic dinitrones underwent nucleophilic substitution of the hydrogen atom in the reaction with a paramagnetic carbanion, the lithium derivative of 4,4,5,5-tetramethyl-4,5-dihydro-1 H-imidazol-1-oxyl 3-oxide, to give polyfunctional nitronyl nitroxyls. [ABSTRACT FROM AUTHOR]

Cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with two new unsymmetrical ligands, isatin salicylaldehyde oxalic acid dihydrazide (isodh) and isatin salicylaldehyde malonic acid dihydrazide (ismdh) were synthesized and characterized by elemental analyses, electrical conductance, magnetic moments, electronic, NMR, ESR and IR spectral studies. The isodh acts as a dibasic tetra dentate ligand bonding through two >C==N-, a deprotonated phenolate and deprotonated indole enolate groups to the metal. The ismdh ligand shows monobasic tetra dentate behaviour in bonding with metal ion through two >C==N-, indole >C==O and a deprotonated phenolate group. The electronic spectral data suggest 4-coordinate square planar geometry for Co(II), Ni(II) and Cu(II) complexes of isodh, whereas, 6-coordinate octahedral structure for the ismdh complexes. The ESR studies also indicate a square planar and distorted octahedral environment around Cu(II) for isodh and ismdh complexes, respectively. Most of the metal complexes show better antifungal activity than the standard and a significant antibacterial activity against various fungi and bacteria. [ABSTRACT FROM AUTHOR]

Abstract: Homogeneous 40.0 MgO–(10–x) PbF2 –50.0 SiO2: x CuO glasses were prepared using melt-quenching technique under controlled conditions. Spectroscopic studies (UV–vis absorption, ESR, FT-IR) are carried out for these glasses. One broad characteristic visible absorption band is observed around 700–850nm in these glasses, the optical band gap decreases as the content of the CuO increases in the glass network up to 0.7mol % then reversal trend is observed. ESR spectra of all these glasses show resonance peaks characteristic of Cu2+ ions and hyperfine splitting is resolved with increasing the CuO content in the glass network. From the observed ESR spectra, the spin-Hamiltonian parameters have been evaluated and indicate that Cu2+ ions have octahedral coordination with a strong tetragonal distortion in these glasses. By correlating ESR and optical absorption data, the molecular orbital coefficients have been evaluated. FT-IR spectra give important information about the nature of bonds in the glass matrix. The density of the glasses is also measured and is found to decrease with the increase CuO contents in the glass matrix. The physical parameters along with spectroscopic parameters are measured. [Copyright &y& Elsevier]