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Abstract: 20LiF–xSb2O3–(79.6-x)B2O3:0.4CuO glasses with the value of x (ranging from 9.6 to 49.6mol% in steps of 10%) were prepared. Dielectric properties (constant ε′, loss tanδ, ac conductivity, σac, over a range of frequency and temperature and breakdown strength) of these glasses have been studied. The results of these studies were analyzed with the aid of data on optical absorption, and ESR spectra on these glasses. The analysis suggests that there is a gradual transformation of Cu2+ ions from covalent environment to ionic environment in the glass network with an increase in the concentration of Sb2O3. [Copyright &y& Elsevier]

Abstract: Electron spin resonance and magnetic susceptibility on some copper(II) complexes prepared from phenylazobarbituric and phenylazothiobarbituric acid compounds containing 2,5-dichloro and 2,5-dimethyl groups were discussed. The thio complexes exist in dimer–monomer mixture. The corresponding copper(II) complexes of the oxygen homologous failed to exhibit association. Singlet–triplet separation values equal to -321 and -263cm-1 for the 2,5-dimethyl and 2,5-dichloro complexes, respectively, of the thio series. An empirical measure of the amount of tetrahedral deformation based on the values of g||/A|| assigned the square-planar geometry of the dimethyl-oxygen complex while the other complexes are with tetrahedral planar geometries. The effect of temperature on the ESR data was discussed. The diamagnetic properties of the complexes derived from 2,5-dichloro and 2,5-dimethyl thiobarbituric acid suggested the formation of Cu(I) compelxes. [Copyright &y& Elsevier]

Changes that occurred on gamma irradiation of guanidine methyl methacrylate 2-acrylamido-2-methyl-2-propane sulphonic acid (GMA-AMPS) copolymer have been investigated by the electron spin resonance (ESR) and Fourier transform infrared (FTIR) spectroscopy. The ESR spectrum observed for gamma irradiated GMA-AMPS copolymer is a sextet spectrum with a hyperfine separation of 20±1 and 10±1 G. The observed spectrum is simulated to be a superposition of component spectra arising due to macroradicals ~CH 2 &sbnd;CH&sbnd;CH 2 ~, methylene radicals ~CH 2 and radicals of the type ROC and/or ~CH~. Irradiation of the copolymer to higher radiation dose has led to the formation of almost the same free radical species. The FTIR spectra of pure and irradiated copolymer have confirmed the earlier-mentioned results. [ABSTRACT FROM AUTHOR]

The reactions of copper(II) halides with 1,3-bis(benzimidazol-2-yl)benzene and its N-methylated derivative afforded binuclear and mononuclear complexes, respectively. Mononuclear perchlorate complexes have also been synthesized by the reactions of the aforesaid ligands with hydrated copper perchlorate. The complexes have been characterized by elemental analyses, conductivity and magnetic measurements, TGA studies, IR, electronic, and ESR spectral studies. [ABSTRACT FROM AUTHOR]

Abstract: [Ir(η5-C5Me5)(C3S5)] [C3S52−=4,5-disulfanyl-1,3-dithiole-2-thionate(2−)] was prepared by a reaction of [NMe4]2[C3S5] with [Ir(η5- C5Me5)Cl2]2 in ethanol. It was reacted with bromine to afford a paramagnetic species [IrBr(η5-C5Me5)(C3S5)] with the Ir–Br bond and in the one-electron-oxidized state, and a diamagnetic dinuclear species [IrBr(η5-C5Me5)(μ-C2S4)IrBr(η5-C5Me5)]. ESR spectra for the one-electron-oxidized species in solution are discussed. The X-ray crystal structural analysis for the latter complex revealed the geometry consisting of dinuclear IrBr(η5-C5Me5) moieties bridged by the C2S42− ligand. [Copyright &y& Elsevier]

The nickel(II) azamacroyclic complexes [Ni(II)L1](ClO4)2 (1), [Ni(II)L2](ClO4)2 (2) and [Ni(II)L3](ClO4)2 (3) produce solvated electron on excitation using 248 nm laser in deaerated aqueous solutions where L1 = 1,4,8,11-tetraazacyclotetradecane, L2 = 1,8-diethylhydroxy-1,3,6,8,10,13-hexaazacyclotetradecane and L3 = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.16.9]octadecane. Formation of stable nickel(III) complexes occurs as a result of the scavenging of the solvated electron in the presence of acids and oxygen and as a result of the thermal reaction between the hydroperoxyl radical and the nickel(II) complexes. Continuous photolysis of the complexes using 254 nm radiation results in the photooxidation of the divalent nickel complexes to trivalent nickel complexes which are identified by ESR spectra. The mechanistic details of the formation of the photoproducts have been investigated in detail. The assignment of CTTS formalism for the reactive excited state was confirmed. Photooxidation of the nickel(II) macrocyclic complexes dissolved in acetonitrile and in a mixture of acetonitrile and dichloromethane has been investigated by flash photolysis of the complexes. Continuous photolysis of the complexes in non-aqueous solutions shows the formation of nickel(III) complexes as stable products, which was confirmed by ESR and optical spectral studies. [Copyright &y& Elsevier]

The possibility to reliably estimate the magnetic resonance parameters (MRP) can significantly increase the information content of experimentally recorded spectra. Here we consider in detail semi-empirical estimates of the ESR spectra parameters: isotropic hyperfine coupling constants, anisotropic hyperfine coupling tensors and g-tensors. The results show that the semi-empirical procedures give estimates of MRP comparable in quality with those of complicated ab initio and DFT schemes. It was underlined that a special attention should be given to geometric parameters of free radicals. The automatic procedure to determine molecular geometries of free radicals on the ground of their spectral characteristics was discussed. [ABSTRACT FROM AUTHOR]

Investigations of undoped zirconia oxide powders and stabilized by 3% or 8% of yttria with nanosize particles were carried out by electron spin resonance (ESR) method. Sizes of the particles from different series of samples were 8 nm and 30 nm. The most intensive resonance lines with g-factors 4.25 and 1.97 were observed in all the samples. The characteristic feature of the line with g = 1.97 was its complex asymmetrical form with broad shoulder to the side of smaller g-factor value. Computer analysis had shown that the line is composed from several lines. It was shown that each paramagnetic center's spectrum contains two lines: one from the bulk and another shifted to smaller g-factor side from interface region of nanosize grains. The integral intensity of the later line increases since the size of nanoparticle decrease. [ABSTRACT FROM AUTHOR]

Pathogenic mineral precipitates on human heart valves (cardiolytes) were studied by electronic paramagnetic resonance (ESR) spectroscopy. Inorganic ($\{\backslash rm\; CO\}\_2^-$, $\{\backslash rm\; CO\}\_3^\{3-\}$) and organic (CH3, etc.) radicals were recorded in the valves under irradiation. The possibility for the spectrum of the $\{\backslash rm\; CO\}\_2^-$ radical to be used for evaluating the relative amount of the crystalline apatite phase in cardiolyte was examined. [ABSTRACT FROM AUTHOR]

The synthesis, spectroscopy, and redox-reactivity towards PPh3 of bis(3,5-di-t-butyl-1,2-benzoquinone 1-oximato)manganese(II), Mn(ox)2, and its mixed-ligand complexes, Mn(ox)Lx [Lx=8-hydroxyquinolinato (L1), 2,2′-bipyridine (bpy) (L2), 1,10-Phenanthroline (phen) (L3) and N-(2-hydroxyphenyl)-3,5-di-t-butylsalicylaldiminato (L4)] complexes, are presented. While some complexes exhibit solid-state ESR spectra they were ESR-silent in toluene or CHCl3 at 300 K. The reduction of all ESR-silent complexes with an excess of PPh3, independently from the nature of secondary Lx ligands, results in the appearance of a six-line hyperfine coupling of 55Mn (I=5/2) (AMn=95–100 G) and a seven-line radical signal, which was assigned to phosphiniminophenoxyl type radicals (g=2.0056–2.0075, AP=8. 5 G and AN=1.875 G). [Copyright &y& Elsevier]

The reduction of poly(biphenylenesulfophthalide) ( 1), poly(fluorenylenesulfophthalide) ( 2), and poly(terphenylenesulfophthalide) ( 3) by metallic lithium in DMSO was studied using UV-visible and ESR spectroscopies. The reduction of compounds 1 and 2 affords blue diamagnetic color centers with absorption bands at 568 and 350 nm (shoulder) for 1 and at 576 and 360 nm (shoulder) for 2. The color centers were attributed to quinoid structures of the Chichibabin"s hydrocarbon type, being biradicals in the ground singlet state. The spectra of compounds 1 and 2 also exhibit weak absorption bands at ∼420 nm, which are assigned to monoradicals of the triarylmethyl type. The reduction of compound 3, for which the formation of quinoid structures is energetically unfavorable, leads to polyradicals of the triarylmethyl type with a high content (∼100%) of unpaired electrons in the main polymer chain. These radicals are characterized by absorption bands at 430 nm (allowed transition) and 638 nm (forbidden transition). The paramagnetic centers in all polymers under study give singlet lines with g = 2.0028 and Δ H ∼ 10 Oe in the ESR spectra. The color centers and radicals of the triarylmethyl type observed for the poly(arylenesulfophthalides) under study are assumed to be formed upon the dissociative electron transfer from lithium to the sulfophthalide cycles of the polymeric molecules. The PM3 calculations show a high electron affinity of the sulfophthalide cycle and a higher propensity of the fluorenyl bridge to form quinoid structures than that of the biphenyl bridge. [ABSTRACT FROM AUTHOR]

The paramagnetic compounds exo,exo-bis(η5-isodicyclopentadienyl)chlorotitanium(III) (3) and its analogue with trimethylsilyl-substituted isodicyclopentadienide (isodiCp) ligand (4), and the similar pair of diamagnetic exo,exo-bis(isodicyclopentadienyl)[η2-bis(trimethylsilyl)ethyne]titanium(II) complexes 5 and 6 were obtained by common reduction procedures from exo,exo-bis(isodicyclopentadienyl)titanium(IV) dichloride (1) and exo,exo-bis[η5-2-(trimethylsilyl)isodicyclopentadienyl]titanium(IV) dichloride (2), respectively. As indicated by ESR spectroscopy compound 3 is a dimer in the solid state and in frozen toluene glass but monomeric in toluene solution. Compound 4 is monomeric in solution as well as in the solid state. As judged from the red shift of the ν(C&z.tbnd6;C) vibration, compound 6 binds bis(trimethylsilyl)ethyne more strongly than compound 5. A comparison of their wavenumbers with those of the [Ti(C5H5−nMen)2(η2-Me3SiC&z.tbnd6;CSiMe3)] (n=2–5) complexes shows that Lewis acidity of the central titanium atom decreases in the order of ligands 1,3-dimethylcyclopentadienyl>isodiCp∼1,2,3-trimethylcyclopentadienyl>(trimethylsilyl)isodiCp∼tetramethylcyclopentadienyl. The crystal structure of the most bulky complex 6 shows a bis-lateral (anti) conformation of the isodiCp ligands with the π-coordinated five-membered rings nearly eclipsed. [Copyright &y& Elsevier]

The electrical resistivities and electronic absorption spectra of several charge-transfer complexes and radical salts with tetramethoxydibenzotetrathiafulvalene (TMO-DBTTF) as the donor were studied. Furthermore, ESR measurements, crystal structure analyses, and energy band structure calculations were carried out for a single crystal of [TMO-DBTTF]3[Cu(NCS)2]2·dichloroethane (DCE). [Copyright &y& Elsevier]

Tri- tert-butoxyaluminum reacts with tert-butyl hydroperoxide to produce di- tert-butoxy- tert-butyl alumotrioxide, which decomposes heterolytically to form singlet dioxygen and homolytically with the O—O bond cleavage. The ButOO·, (ButO)2AlOO·, ButO·, and (ButO)2AlO· radicals were identified by ESR using spin traps. These findings confirm the formation of aluminum-containing trioxide. The above radicals initiate alkylarene oxidation by the tri- tert-butoxyaluminum— tert-butyl hydroperoxide system. The carbon-centered and alkylperoxy radicals originated from the oxidized substrates were identified. [ABSTRACT FROM AUTHOR]

A series of binuclear copper(ii) complexes with acyldihydrazones of aliphatic dicarboxylic acids (from malonic to adipic) and fluorinated β-diketones (trifluoro- and hexafluoroacetylacetone) of composition Cu2L·2Py (H4L is acyldihydrazone) were studied by ESR spectroscopy. The ESR spectra of solutions of complexes with trifluoroacetylacetone acyldihydrazones have an isotropic signal with a seven-line hyperfine structure from two equivalent copper nuclei ( g = 2.112, aCu = (39—40)·10–4 cm–1), which is indicative of weak exchange interactions between the paramagnetic centers due to spin density delocalization through a chain of the σ-bonds of the polymethylene bridge. On going to hexafluoroacetylacetone derivatives, the coupling is suppressed and the ESR spectra of solutions of such complexes show a signal with a four-line hyperfine structure ( g = 2.121—2.131, aCu = (55—63)·10–4 cm–1) typical of mononuclear copper complexes. [ABSTRACT FROM AUTHOR]

Bis(1,4-di- tert-butyl-1,4-diazabutadiene)copper(i) [(3,6-di- tert-butyl- o-benzosemiquinono)(3,6-di- tert-butylcatecholato)cuprate(ii)] ( 1) was synthesized. Complex 1 contains the 1,4-di- tert-butyl-1,4-diazabutadiene and 3,6-di- tert-butyl- o-benzoquinone ligands in the reduced form. The structure of 1 was established by X-ray diffraction analysis. The ESR spectra indicate that dissolution of complex 1 in organic solvents (toluene, THF, CH2Cl2, etc.) leads to its symmetrization to give neutral complex 2, which occurs in solutions as an equilibrium mixture of two redox isomers, viz., catecholate (Cat) complex 2c and semiquinone (SQ) complex 2s. In the coordination sphere of the copper atom, the reversible intramolecular metal—ligand electron transfer can proceed as successive steps as exemplified by the reactions of 2 with CO and 2,6-dimethylphenylisonitrile. Copper(i) o-semiquinone complex 2s can be reversibly transformed into copper(ii) catecholate complex 2c through electron transfer from the copper(i) atom to the SQ ligand. The subsequent addition of the neutral ligand (CO or CNAr) to 2c induces, in turn, electron transfer from the Cat ligand to the copper(ii) atom accompanied by the transformation of the catecholate complex into the o-semiquinone complex. In the case of CO, this transformation is also reversible and is efficiently controlled by the temperature. [ABSTRACT FROM AUTHOR]

Reaction between 3-formylsalicylic acid and bis-(2-aminophenyl)-disulphide yields a septadentate Schiff base with NSO donor frame of which the inner compartment is NSO and the outer is OO type. It forms several complexes with inner copper centre and outer nontransition/transition metal ions. The complexes have been characterised by elemental analyses, spectral (IR, absorption, diffused reflectance), thermal and magnetic data. Dinuclear copper complexes exhibit subnormal magnetic moments (≈ 0.80 BM), showing magnetic exchange, and six-line solid-state ESR spectra at 77 K. [ABSTRACT FROM AUTHOR]

Glasses with the composition x V 2 O 5 -(15- x) Li 2 O-70B 2 O 3 -15ZnO, for x varies from 0 to 4 mol. %, were synthesized using standard quenching technique. The amorphous nature for selected samples (x = 0, 1 and 4 mol. %) was ensured from X-ray diffraction (XRD) measurements. The samples were found to compose mainly from BO 3 and BO 4 basic structural units as inferred from Fourier transform infrared (FTIR) data. The number of BO 4 (BO 3) structural units was found to decrease (increase) with increasing the number of NBOs. These structural modifications within the glass network are responsible for the here observed composition dependence optical energy gap (E otp) and Urbach band tail (ΔE). The electron spin resonance (ESR) results revealed a tetragonal compression for VO2+ ions present in octahedral coordination, with distinct optical transitions in the visible spectral regime. [ABSTRACT FROM AUTHOR]

ESR spectra of liquid and frozen benzene solutions of isotope-enriched95,97,98MoVO(dtc)3 complexes ([ x Mo]>95%, dtc is the N,N-diethyl dithiocarbamate ligand) and their solid solutions in a matrix of tetraethylthiuram disulfide were studied in the X-range. Comparison of the experimental and calculated parameters of the ESR spectra shows that the axial symmetry of the magnetic tensors does not contradict the low symmetry of the complex, in which the “ylic” oxygen and five of six S atoms in three dithiocarbamate ligands form the coordination sphere of the metal. [ABSTRACT FROM AUTHOR]

Low-temperature (77 K) γ- and UV irradiation of substituted N′-furfurylidenebenzhydrazides produces paramagnetic particles in radiation-chemical yields of (0.05–0.5)/100 eV and quantum yields of 4·10−5–10−3, respectively. ESR study showed that hydrazyl radicals and HC·O and N·O2 are the main products of radiolysis and photolysis, and the latter decay upon heating of the sample to 190 K, whereas the hydrazyl radicals survive up to 423 K. Further heating results in thermodestruction of the hydrazides, and the ESR spectrum exhibits only a singlet with splitting at 1 mT, which is characteristic of polyconjugated compounds. [ABSTRACT FROM AUTHOR]

A new semiquinone rhodium complex, viz., (2,2′-dipyridyl)(3,6-di- tert-butyl- o-benzosemiquinone)(3,6-di- tert-butylcatecholate)rhodium(III) ( 1), which is a structural analog of the known redox-isomeric cobalt complex, was prepared, isolated in the individual state, and characterized by X-ray analysis, magnetochemistry, and IR and ESR spectroscopy. At room temperature, compound 1, unlike the cobalt analog, is a complex of trivalent low-spin rhodium with one catecholate and one semiquinone ligand. However, broadening of the lines in the ESR spectra both of a solution and a powder of complex 1 with increasing temperature indicates that the redox-isomeric transformation occurs in this case as well. The equilibrium of this transformation is virtually completely shifted toward the low-spin semiquinone-, catecholate isomer. [ABSTRACT FROM AUTHOR]

The product of the interaction of fullerene C60 with dibenzenechromium (DBC) was studied by ESR and IR spectroscopy. The ESR spectrum contains a signal of the radical cation DBC+. A signal of the C60 − anion is virtually absent, which is most likely related to its broadening. The IR spectrum contains bands characteristic of the DBC+ cation in the (DBC)I molecule and four bands characteristic of C60 −. The data obtained indicate the interaction of C60 molecules with the environment in the crystal structure of the complex. [ABSTRACT FROM AUTHOR]

An equilibrium conformation of the perfluoroalkyl ∼CF2·CF2 radical at 77 K in matrices of polytetrafluoroethylene and n-perfluoroalkanes was studied. Upon cooling from 300 to 77 K at temperatures below 200 K, the ESR spectrum of this radical changes, and the well-resolved hyperfine structure appears. The hyperfine splitting constants on nuclei of two nonequivalent Fβ atoms were determined: 2.2 and 1.1 mT, respectively. The A ∥ and A ⊥ values for the Fα atoms are 22.5 and 3.3 mT, respectively. The conformational angle between the axis of the orbital of an unpaired electron and projection of the Cβ−Cγ bond is 5.6°. [ABSTRACT FROM AUTHOR]

New cyanato-copper(II) complexes of the type Cu(NCO) L ( L=2,3-, 2,5-, 3,4- or 3,5-lutidine, 3- or 4-ethylpyridine) and Cu(NCO) L ( L=2,3- or 2,5-lutidine, 2-ethylpyridine) were prepared. Solid state electronic, ESR and IR spectral results show, that Cu(NCO) L complexes have tetragonal structures varying from pseudooctahedral to practically planar forms, also involving a square-pyramidal arrangement. The β-form of Cu(NCO)(2-picoline) was isolated and found to be a distortion isomer of the known α-form. According to physical results, Cu(NCO) L complexes exhibit highly distorted five-coordinate structures. Further knowledge about the influence of type, number and position of L ligand alkyl groups on the structure-bonding properties of cyanato-copper(II) complexes was obtained. [ABSTRACT FROM AUTHOR]

Cr(III), Fe(III), Co(II), Ni(II) and Cu(II) complexes of diethylenetriamine bis(dithiocarbamate), L, have been synthesized and characterized by elemental analysis, magnetic measurements, electronic, esr and infrared spectral studies. The Cr(III) and Fe(III) complexes are octahedral with composition [M(L)(H0)Cl], whereas Co(II), Ni(II) and Cu(II) derivatives, [CoL]·2H0, [NiL] and [CuL], are square-planar. The esr spectral features indicate significant distortion from ideal symmetry. [ABSTRACT FROM AUTHOR]

Different molar reactions of Fe(OPr), and FeCl with benzothiazolines having an NSH donor system. derived by the condensation of o-aminothiophenol with heterocyclic aldehydes. viz. pyridine-2-aldehyde. furfuraldehyde and thiophene-2-aldehyde. lead to the formation of [Fe.Pr(NS)], [Fc(NS)] and [Fe(NS)Cl¦ type of complexes. The resulting derivatives have been characterized by elemental analysis, conductivity measurements, molecular weight determinations and magnetic studies. IR, electronic, Mössbauer and ESR spectral data have been used to deduce the structures of the resulting derivatives. [ABSTRACT FROM AUTHOR]

Complexes of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with 3-(2-pyridyl)-1-(2-hydroxy phenyl)-2-propen-1-one (PHPO), 3-(1-naphthyl)-1-(2-hydroxy phenyl)-2-propen-1-one (NHPO) and 3-(3,4-dimethoxy phenyl)-1-(2-hydroxy phenyl)-2-propen-1-one (DMPHPO) have been synthesized and characterized by analytical, conductivity, thermal, magnetic, infrared, electronic and electron spin resonance data. Based on analytical data the stoichiometry of the complexes has been found to be 1 : 2. The conductivity data show that all these complexes are non-electrolytes. The infrared spectral data indicate that the ligand PHPO acts as uninegative tridentately towards Co(II) and Ni(II) and bidentately with Cu(II), Zn(II) and Cd(II). Ligands like NHPO and DMPHPO act as uninegative bidentately with all the metal ions. The electronic spectral data suggest that all the Co(II) complexes and Ni(II) of PHPO complex are octahedral and all the Cu(II) and Ni(II) of NHPO and DMPHPO complex are square-planar. The complex of Zn(II) and Cd(II) are tetrahedral. ESR parameters of Cu(II) complexes have been calculated and relevant conclusions have been drawn with respect to the nature of bonds present in them. [ABSTRACT FROM AUTHOR]

A brief account of the work carried out on the title compounds in our laboratories during the last few years is presented in the perspective of existing knowledge on the topic. [ABSTRACT FROM AUTHOR]

New dicyanamide complexes of the type M[N(CN)] L ( M=Cu or Ni; L=2-, 3-, 4-aminopyridine, 2-amino-5-nitropyridine) and Co[N(CN)] (2-amino-5-nitropyridine) were prepared and studied by spectroscopic methods as well as by room-temperature magnetic moments. The results show that the Cu(II) complexes have elongated pseudooctahedral structures while the Ni(II) and Co(II) complexes are octahedral. In most cases the N(CN) groups are in bridging function and through their cyanide nitrogens, or-more rarely-amide and cyanide nitrogens connect the basic structure units into polymeric conglomerates. In the Cu(II) systems exchange coupling is seen from the μ value or ESR spectrum. [ABSTRACT FROM AUTHOR]

A new simple method was developed for the preparation of organometallic bi- and triradicals by the heterogeneous reaction of γ-Al2O3 or analogous oxides with free radicals generated in solution through the interaction of 3,6-di- tert-butyl- o-benzoquinone with 3,6-di- tert-butylpyrocatechol. An explanation was offered for the plus sign of the dipoledipole coupling constant observed previously in the ESR spectra recorded in a superstrong field at low temperatures. [ABSTRACT FROM AUTHOR]

The effect of the procedure of preparation of lanthanum-graphite electrodes and the regime of their evaporation in the electric arc on the yield of endometallofullerene La@C82 has been studied. La@C82 was identified by ESR spectroscopy, optical spectroscopy, and mass spectrometry. The fractional extraction of the fullerene-containing soot with o-xylene makes it possible to separate La@C82 from higher fullerenes containing no metal atorns and to obtain fullerene extracts enriched in La@C82. [ABSTRACT FROM AUTHOR]

The formation of mixed Cu and Cu polynuclear complexes with dialkyl sulfide, which are active in the catalytic isomerization of chloroolefins, has been investigated by UV-Vis and ESR spectroscopy. The role of these complexes in catalysis is discussed. [ABSTRACT FROM AUTHOR]

The action of a pulse of elastic waves on polycrystalline mixtures of donors and acceptors (for example, 3,6-di- tert-butylcatechol and 3,6-di- tert-butyl-1,2-benzoquinone with the addition of sulfur and polystyrene) results in the formation of monoradicals and radical pairs. The study of the products by ESR spectroscopy and X-ray analysis shows that the solid powder is dispersed to submicroscopic particles, including those of the mixed composition. [ABSTRACT FROM AUTHOR]

The formation of Ag and Ag clusters upon freezing out of aqueous-alcohol glassy solutions of AgClO by γ-irradiation at 77 K was established by ESR and optical spectroscopies. The Ag cluster is formed by subsequent addition of Ag ions to a silver atom, and the Ag cluster is most probably formed by the reduction of the Ag cluster by alcohol radicals. The energies of optical transitions and energy gaps far the Ag cluster (m = 0 to 3) were calculated. The absorption bands of the clusters shift to the UV region as the charge increases, which agrees with the experimental results. [ABSTRACT FROM AUTHOR]

Radical anions C70- and C70 2- were obtained in vacuo by the reaction of I-amino3-propanol (AP) and 1,5-diaminopentane (DAP) with fullerene C70. The radical anions were identified by visible/near IR (X = I372 and I172 nm, respectively) and ESR spectroscopies. The temperature dependences of the ESR spectra were studied for the C-AP, C-AP, and C70-DAP systems. At low temperatures (I5-45 K), the ESR spectrum for C60 is close to that for species with axial symmetry of the g-factor (q = 2.000 and g, = I.995). The anisotropy of the g-factor is averaged, when the temperature increases. At T > I48 K the averaged line is broadened, and the sharp signal with g = 2.0001 overlaps this broad line. The intensity of the narrow line increases, when the temperature increases. The ESR spectrum observed in the C-AP system at I2.5 K may be tentatively described as a superposition of two ESR spectra, namely, the ESR spectra of a radical with g = 2.0042 and g, = 2.0015 (presumably a radical cation) and of C with q = 2.000 and g = I.994. The spectra of the sample in which C70 is present mainly as C exhibit only a line with g = 2.0004. [ABSTRACT FROM AUTHOR]

The intramolecular dynamics of a silicon biradical complex with o-semiquinone ligands was studied in a frozen toluene solution. Analysis of the broadening and shifts of the canonical components in the ESR spectrum of this biradical allows one to detect the abrupt reorientation of the magnetic axes due to intramolecular single bond-unpaired electron exchange. The frequencies of chemical exchange at low temperatures were estimated. [ABSTRACT FROM AUTHOR]

Thermodynamic and kinetic acidities of 6- tert-butyl-2-hydroxy-4-triphenylmethylphenoxyl during its interaction with triethylamine in toluene have been studied by ESR. It has been shown that the protolysis of this radical is a two-pathway process, since tautomeric transitions, i.e. ammonium ion migration between oxygen atoms of the semiquinone radical anion, have been detected in the reaction products, that is, in contact ion pairs of the corresponding semiquinone radicals. [ABSTRACT FROM AUTHOR]

2• Quinoline-3-carboxaldehyde ligand was synthesized and characterized. 2• A new binary and ternary Cu(II) complexes were synthesized and characterized. 2• The complexes exhibited square planar and octahedral geometrical arrangements. 2• The Cu(II) complexes showed antimicrobial and antitumor activities. 2• Molecular modeling of the ligand and its Cu(II) complexes has been calculated using Hyperchem 7.52 program. 6-Ethyl-4-hydroxy-2,5-dioxo-5,6-dihydro-2 H -pyrano[3,2- c ]quinoline-3-carboxaldehyde (HL) was synthesized as a ligand and subject to chelate with Cu(II) ion of different anions (AcO–, NO 3 –, SO 4 2–ClO 4 –, Cl– and Br–) in presence and absence of auxiliary ligands (L′); N,O-donor; or N,N-donor such as 8-hydroxyquinoline, 1,10-phenanthroline and 2,2′-bipyridyl. The obtained results revealed that the ligand behaves as a neutral/monoanionic bidentate, forming chelates with molar ratio 1:1, (M:L). The metal complexes were fully characterized by analytical and spectral techniques in addition to thermal, magnetic susceptibility and conductivity measurements. The metal complexes displayed square planar and octahedral geometrical arrangements depending on the nature of the anion. The ligand and its complexes were screened for their antimicrobial activity against Gram–positive bacteria which are Staphylococcus aureus and Bacillus subtilis , Gram–negative bacteria which are E. coli and S. typhimurium , yeast (Candida albicans) and fungus (Aspergillus fumigatus). The antitumor activity of the HL ligand and its Cu(II) complexes were examined against Ehrlich Ascites Carcinoma cell line (EAC) from ascetic fluid of the female Swiss albino mice. To explore the most probable structure and the nature of bonding of HL ligand to metal ions; semi-emperical (PM3) calculations were achieved in gas phase. All theoretically possible structural data of the free ligand (HL) and its complexes have been correlated with the experimental data to explore the most probable structure. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Synthesis and Characterisation of Cu(II),Ni(II),Co(II),Mn(II) and Zn(II) complexes were carried out. • Pharmacological activities of chelates possess enhanced activity than free ligand. • Potential antimicrobial scenery of synthesized complexes. • Doping of the synthesized compounds with protein using HEX-8.0 software. Neutral [CuL 2 ], [NiL 2 ], [CoL 2 ], [MnL 2 ] and [ZnL 2 ] complexes were synthesized using Schiff base derived from Benzalidene-4-imino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one and tyrosine. All the compounds were characterized by elemental analysis, magnetic susceptibility, ESI-Mass spectra, Powder XRD, SEM, FTIR, UV–Vis., 1H &13C NMR, EPR and Cyclic voltammogram techniques. The general formula of the complexes [ML 2 ] was confirmed by analytical data and ESI-mass spectra. The polycrystalline nature of the complexes was proved by powder XRD and surface morphology studies ensure that the complexes exist in nano size grain. The octahedral geometry of synthesized complexes was examined by magnetic susceptibility measurements and electronic absorption spectra. ESR parameters of copper complex clearly indicate that the complex is axially elongated octahedral geometry. Pharmacological activities like analgesic, antipyretic, anti-inflammatory and CNS activities of Schiff base and its metal complexes were studied using albino mice which show that chelates have higher activities than free ligand. The good antioxidant activity of chelates was observed through DPPH free radical scavenging assay method. The antimicrobial activities of Schiff base and its complexes reveal that the complexes have superior antimicrobial activity than Schiff base. The DNA binding interaction study of [CuL 2 ] by UV–Vis. spectroscopy shows the strong binding of [CuL 2 ] complex on DNA with high binding constant value (K b = 7.4 × 105) and the respective binding occurs through intercalation mode. The prediction of activity spectra of substance (PASS) expounds the drug-like nature of the compound. The in silico ADMET studies expose that Schiff base acquires enhanced biological potential. This was further confirmed by molecular docking studies of complex with DNA and (PDB ID: 6COX) protein. [ABSTRACT FROM AUTHOR]