Solid Electrical Conductivity Research Articles

Gamma ray irradiated binuclear and mononuclear transition metal complexes with polydentate ligand: Template synthesis, spectral, XRD, morphology, solid electrical conductivity and antimicrobial activity

In this work, new binuclear Fe(III), Ni(II) and mononuclear Cu(II) Schiff base complexes that obtained via template condensation of Fe(III), Ni(II) and Cu(II) chlorides with N1-(3-aminopropyl) propane-1,3-diamine and 1,3-diphenylpropane-1,3‑dione (1B, 2B, 3B), respectively were prepared and well investigated. The structure of the complexes was elucidated by means of microanalyses, various spectroscopic techniques (FT–IR, UV/Vis, X–ray diffraction), thermal (TG/DTG), molar conductivity and magnetic moment measurements, Fe(III), Ni(II) complexes have an octahedral structure, while Cu(II) complex adopts distorted square pyramidal geometry. To study γ– irradiation induced modifications, powder sample of these complexes was exposed to high energetic γ–ray irradiation at a dose of 20 kGy, (hereafter referred to as 1A, 2A, 3A, respectively). Physico-chemical properties of irradiated samples were also investigated by the aforementioned tools. The results revealed no remarkable change in the molar conductivity values and little shift of the peak position and the intensity for FT–IR and electronic spectra as a result of the distortion of lattice planes. Also, TG/DTG studies revealed decreasing in the thermal stability for all irradiated samples. From the powder XRD data for non-irradiated and γ–irradiated Ni(II) (2B, 2A) and Cu(II) (3B, 3A) complexes, average crystallite size (D) and dislocation density (δ) were calculated, the γ–irradiation resulted in decrease in the crystallite size for Ni(II) (2A) complex. The irradiated (3A) showed changes in the surface morphology compared to its non-irradiated one. The solid state electrical conductivity of non-irradiated and γ–irradiated Ni(II) complexes have been investigated. Furthermore, the non-irradiated samples (1B, 3B) and their γ–irradiated (1A, 3A) were assayed for their antibacterial property against Gram–positive as Staphylococcus aureus, Gram– negative as Escherichia coli and antifungal property against fungi as Candida albicans.

Influence of high energy γ-irradiation on some binuclear transition metal complexes of pentadentate ligand: Spectral, thermal, modelling, X-ray diffraction, morphological and solid electrical conductivity

New binuclear Co(II) (1), Ni(II) (2) and Cu(II) (3) complexes of N,N'-(2,2′-azanediylbis(ethane-2,1-diyl))bis(2-aminobenzamide) have been synthesized and fully characterized by various chemical and spectral techniques. The synthesized complexes were irradiated by 60Co gamma rays to dose value of 100 kGy (hereafter referred to as 1a,2a,3a). Molar conductance, spectral, thermal, magnetic moment measurements, powder X-ray diffraction and solid electrical conductivity measurements were investigated before and after exposure to irradiation. The results showed that the current complexes slightly affected by the applied irradiation dose and that, the thermal decomposition profiles of non-irradiated and irradiated samples were changed upon irradiation. From powder X-ray diffraction the crystallite size as well as dislocation density were slightly changed. Surface morpholgical changes were observed for [Cu2LCl2(OH)2(H2O)]·2H2O (3) upon irradiation. Irradiation resulted in change in d.c solid electrical conductivity this change was, however, more pronounced for samples 2a,3a.

Improving the surface morphology and crystallite size of isonicotinohydrazide based binuclear Cr(III), Zn(II) and Sn(IV) complexes after irradiation with γ-rays

In this work, binuclear Cr(III), Zn(II) and Sn(IV) complexes with: (Z)-N'-(4-methoxybenzylidene)isonicotinohydrazide (L) have been prepared and well assigned and then exposed to gamma ray irradiation with dose up to 100 kGy using Indian 60Co γ-ray cell type GE-4000 A. The structural properties of the synthesized compounds and the structural modifications of the irradiated samples were studied by analytical, magnetic, molar conductance measurements, different spectral (FT-IR, 1H NMR, UV–Vis), powder XRD and thermogravimetry (TG) techniques. The data show that all complexes are dinuclear, Cr(III) complex supposed in distorted teteragonal geometry and Zn(II) complex supposed in distorted square planar geometry have the formula [Cr2L(OH)4]Cl2(1) and [Zn2LCl2(H2O)2]Cl2.3H2O (2), respectively and Sn(IV) has distorted octahedral geometry and the formula is Sn2LCl2(OH)4(H2O)2]Cl2.H2O(3), no geometry change was detected upon irradiation. The XRD of both non-irradiated and irradiated complexes indicate that they are in a nanometer range. A reduction in average crystallite size was observed for irradiated Cr(III) complex. Scanning electron microscopy (SEM) micrographs of [Cr2L(OH)4]Cl2 complex (1) show improving of its crystallinity after γ-irradiation. Further, the solid electrical conductivity of [Zn2LCl2(H2O)2]Cl2.3H2O complex (2) before and after γ-irradiation has been investigated, both samples behaved like insulator. The antimicrobial screening for all metal complexes before and after γ-irradiation was achieved against pathogenic bacteria Staphylococcus aureus as Gram +ve bacteria, Escherichia coli as Gram -ve bacteria and Candida albicans as fungal strain. The results pointed that the metal complexes have moderate antimicrobial activity compared to the standards and in some cases γ-irradiation enhances antimicrobial activity.

Further studies on the properties and effect of high energetic ionizing radiation on copper(II) complexes: 1H NMR, electronic absorption, ESR spectra and solid electrical conductivity

The effect of energetic γ-radiation on 1H 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 (H2L) and its copper(II) complexes; Cu(HL)(OAc)H2O, Cu(HL)BrH2O and Cu(H2L)2(NO3)2⋅3H2O before and after γ-irradiation (hereafter referred to as (B), (B1), (B2), (B3) and (A), (A1), (A2), (A3), 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)BrH2O (B2) before irradiation showed isotropic spectrum with giso = 2.075 however, after irradiation (A2) displayed axial ESR spectrum with g∥ > g⊥ > 2.0023 and d(x2−y2) 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 (Ea) were calculated for the complexes by using the Arrhenius plot.

Synthesis, spectral and thermal studies of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complex dyes based on hydroxyquinoline moiety

A series of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of azo-compounds containing hydroxyl quinoline moiety have been synthesized and characterized by elemental analysis, molar conductance, magnetic moments, IR, electronic and ESR spectral studies. The results revealed the formation of 1:1 and 1:2 (L:M) com- plexes. The molar conductance data reveal that the chelates are nonelectrolyte. IR spectra indicate that the azodyes behave as monobasic bidentate or dibasic tetradentate ligands through phenolate or carboxy oxygen, azo N for 1:1 (L:M) complexes beside phenolate oxygen and quinoline N atoms for 1:2 (L:M) complexes. The thermal analyses (TG and DTA) as well as the solid electrical conductivity measurements are also studied. The molecular parameters of the ligands and their metal complexes have been calculated.

Annual-layer determinations and 167 year records of past climate of H72 ice core in east Dronning Maud Land, Antarctica

AbstractTo determine annual layers for reconstructing the past environment at annual resolution from ice cores, we employed snow-stake data back to 1972, tritium content, solid electrical conductivity measurements (ECM) and stratigraphic properties for the 73m ice core at the H72 site, east Dronning Maud Land, Antarctica. the average annual surface mass balance at H72 is 307 mma–1w.e. during the last 27 years from continuous accumulation data, 317 mma–1 w.e. according to the densification model and 311 mma–1 w.e. according to the average surface mass balance for 167 years based on annual-layer counting. the ECM age is closely coincident with tritium age, and corresponds with the snow-stake record back to AD 1972 from the surface to 15 m depth. the H72 ice core is dated as AD 1831by ECMat 73.16 mdepth.The time series of yearly surface mass balance at H72 shows an almost constant 311 mm a–1 w.e. for the last 167 years. the oxygen-isotope records indicate a significant trend to lower values, with negative gradient of 1.7% (100 years)–1.

Solid electrical conductivity (ECM) from four Agassiz ice cores, Ellesmere Island NWT, Canada: high-resolution signal and noise over the last millennium and low resolution over the Holocene

The solid DC electrical conductivity (ECM – Electrical Conductivity Method) of polar ice cores has become an important tool in identifying and quantifying volcanic acid layers, and this paper addresses the question of how much signal and noise there is in single ECM series. A number of high-resolution (10 samples/year) ice-core ECM records from the Agassiz Ice Cap are correlated over the last 900 years. Corre lations decrease with distance apart due to local drift and melt layer noise, but correlations are probably reduced also by differences in methodology and core storage. It is found that only peak sizes in the uppermost two percentiles retain their ranking and recognizability from core to core. With continuous sampling, however, the smaller peaks can be cross-identified between cores, even though they lose their size rank. Averaging or stacking several ECM records reduces the noise. Five-year averages of ECM for the Holocene are presented for the Agassiz cores and their correlations interpreted as functions of distance apart and differences in method. The large-scale melting in the early Holocene (8ka to 10ka) almost completely de-acidifies the ice in all the Agas siz cores.

Photochromism and thermochromism of Sn(IV) complexes with 8-aminoquinoline and salicylidene-8-aminoquinoline

Tin(IV) complexes with 8-aminoquinoline (complexes (1) and (2)) and with salicylidene-8-aminoquinoline (complex (3)) have been prepared and characterized. Complexes (1) and (3) are thermochromic, and display irreversible and reversible thermochromism, respectively. The origin of the thermochromism is discussed in terms of lattice imperfections, phase change and charge transfer (CT). The phenomena were investigated by means of DTA, TGA, X-ray diffraction, electronic spectra and solid electrical conductivity.

The Renland ice core. A Northern Hemisphere record of aerosol composition over 120,000 years

The Renland ice core from East Greenland covers a full glacial cycle from the Holocene into the previous Eem interglacial. The first northern hemispheric record of both anions (Cl - , NO 3 - , SO 4 2- , CH 3 SO 3 - ), cations (Na + , NH 4 + , K + , Mg 2+ , Ca 2+ ), total amount of insoluble dust and acidity (measured as solid electrical conductivity) is extracted from this ice core in continuous profiles between 10 and 120 ka b.p. and from the 19th century. The ions measured are in balance during the interglacials but there is a large deficiency of anions during the glacial period. The ice is alkaline during most parts of the glacial period and Ca 2+ is the totally dominating ion therefore the deficiency of anions is probably due to carbonates (not measured). The concentration of most impurities is higher during glacial stages than the interglacials. The largest increase is found for crustally derived impurities (up to a factor of 10) while the sea salt elements are only slightly enhanced (less than a factor of 2). The concentration of impurities with a strong biogenic component is generally lower during glacial stages than the interglacials. A simple model tests the effect of changes in the physical conditions of the atmosphere influencing transport and deposition processes while keeping the source area and production rate constant. The model results show that the increased glacial concentrations observed for some impurities can be explained entirely by changes in transport and deposition, while the decrease in others may indicate a change in source emissions. The total content of impurities in the glacial atmosphere is higher if physical changes in the atmosphere rather than source emission changes are responsible for the variations observed in the Renland ice core. Thus, physical changes in the atmosphere can have a large impact on the radiative properties of the atmosphere and a climate forcing mechanism may be found in the dynamics of the atmosphere. However, a better understanding of the hydrological cycle and the general circulation of the atmosphere during glacial conditions has to be attained to be able to interpret influences on the global climate of a changed composition of the atmosphere from ice core data. DOI: 10.1034/j.1600-0889.1994.t01-4-00005.x

Thermochromic phase transitions in manganese(II) and cobalt(II) Schiff base complexes

Mn(II) and Co(II) complexes of salicylidene-4-aminoantipyrine display a change of colour upon heating. The change is reversible in air. The thermochromism in these complexes has been attributed to a first-order phase transition. The phase transition obtained was investigated by means of DTA, TG, X-ray powder diffraction and solid electrical conductivity. The kinetic and thermodynamic parameters of the obtained phase transition were determined.

Template synthesis and thermal behaviour of some metal complexes of 2,6-diacetylpyridine-mono(carbohydrazone) ligand

The chelating behaviour of neutral and deprotonated 2,6-diacetylpyridine-mono(carbohydrazone) (Hdapc) has been studied in some new complexes of Pd(II), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Ba(II) and UO 2(VI). Spectroscopic, magnetic susceptibility and other analytical studies reveal that the ligand behaves as an NN-chelating agent in the neutral form and as an ONNO- or NNO-chelating agent in the deprotonated form. Molar conductance measurements indicate the presence of coordinated chloride ion and acetate group. The geometry of some of the metal complexes is also discussed. In addition, the thermal behaviour and the nature of the interaction of the water of crystallisation of some of the metal complexes have been studied using DTA, TG, X-ray powder diffraction, IR and solid electrical conductivity techniques.

The Laki and Tambora Eruptions as Revealed in Greenland Ice Cores from 11 Locations

Major volcanic eruptions deposit large amounts of strong acids in polar ice. Two such volcanic eruptions are Laki, A.D. 1783, at high latitude (64 °N), and Tambora, A.D. 1815, close to the Equator (8°S). The acid ice layers from these eruptions are easily reached by shallow drilling, and the acidity of the ice cores obtained has been determined by a solid electrical conductivity method (ECM), and in some cases by liquid pH measurements. The strong acid is identified by chemical anion analysis. Sulfate is the dominant anion in both of these volcanic events.Atmospheric thermonuclear-bomb tests ejected radioactive debris into the atmosphere. Two major groups of such tests are those carried out by the Americans in 1952-54 at low latitude (11°N) and by the Russians in 1961-62 at high latitude (75°N). Radioactive debris from these events was deposited in polar snow, and can be detected by specific total β activity measurements. The radioactive layers serve as dating horizons in the firn. The total β activities were measured at least 10 years after ejection, thus the measured activities were mainly due to 90Sr and 137Cs.The amount of 90Sr and 137Cs ejected into the atmosphere is known. We assumed a similar global distribution pattern of bomb-produced total β activity and strong acids from violent volcanic activity, and were able to calculate that both major volcanic events produced some 300 million tons of sulphuric acid. This is in agreement with other estimates of the Tambora eruption, which are based on studies of ice cores from Antarctica.

The Laki and Tambora Eruptions as Revealed in Greenland Ice Cores from 11 Locations

Major volcanic eruptions deposit large amounts of strong acids in polar ice. Two such volcanic eruptions are Laki, A.D. 1783, at high latitude (64 °N), and Tambora,A.D.1815, close to the Equator (8°S). The acid ice layers from these eruptions are easily reached by shallow drilling, and the acidity of the ice cores obtained has been determined by a solid electrical conductivity method (ECM), and in some cases by liquid pH measurements. The strong acid is identified by chemical anion analysis. Sulfate is the dominant anion in both of these volcanic events.Atmospheric thermonuclear-bomb tests ejected radioactive debris into the atmosphere. Two major groups of such tests are those carried out by the Americans in 1952-54 at low latitude (11°N) and by the Russians in 1961-62 at high latitude (75°N). Radioactive debris from these events was deposited in polar snow, and can be detected by specific total β activity measurements. The radioactive layers serve as dating horizons in the firn. The total β activities were measured at least 10 years after ejection, thus the measured activities were mainly due to90Sr and137Cs.The amount of90Sr and137Cs ejected into the atmosphere is known. We assumed a similar global distribution pattern of bomb-produced total β activity and strong acids from violent volcanic activity, and were able to calculate that both major volcanic events produced some 300 million tons of sulphuric acid. This is in agreement with other estimates of the Tambora eruption, which are based on studies of ice cores from Antarctica.

The Byrd Ice Core: Continuous Acidity Measurements and Solid Electrical Conductivity Measurements

The Byrd Ice Core: Continuous Acidity Measurements and Solid Electrical Conductivity Measurements

The Byrd Ice Core: Continuous Acidity Measurements and Solid Electrical Conductivity Measurements

The Byrd Ice Core: Continuous Acidity Measurements and Solid Electrical Conductivity Measurements