Materials Science Forum Vol. 699

Abstract: In this work, lead sulphide has been characterized using X- ray diffraction, SEM, EDX and UV-Visible techniques. X-ray analysis is done by using the Rietveld refinement method of matching the observed and calculated profiles, and then the results obtained from the refinement process are used in finding the electron density distribution by using maximum entropy method (MEM). The local structure analysis of PbS is done by the pair distribution function (PDF). Particle size analysis is done with the use of XRD data, SEM analysis is done in finding the surface structure and EDX in finding the elemental composition of PbS sample. The energy gap of PbS is found from UV-Visible spectrum.

Abstract: An effort has been made to understand the charge density distribution of the Si and Ge based diluted magnetic semiconductors. A theoretical analysis has been done on the variation of charge densities when the semiconductors Si and Ge are doped with the transition metal atoms of V, Mn and Co with different concentrations of x (0.02, 0.04, 0.06, 0.08, and 0.10), in Si_1-xM_x and Ge_1-xM_x. Two dimensional electron density contour maps have been plotted for all the compositions studied in this work. The theoretical mid bond densities were found out for the compounds which can be taken as the reference values for comparison of the experimental values of the same compositions.

Abstract: New software using VEE Pro was developed to integrate the various components of photoacoustic spectrometer through RS-232 interface and this is the first time such an effort is made not only to integrate but also to automatically acquire the data for depth profile and wave length scanning. The performance and validity was rigorously tested for repeatability and standard error for samples like air, glass and silicon wafer. As an application towards NDE, the thermal parameters obtained from photoacoustics are compared with ultrasonics and discussed.

Abstract: This paper documents the detailed investigation of the relationship between molecular structure and biological activity of few tetraaza macrocyclic metal (II) complexes equipped by the template condensation of o-bromoaniline, ethylenediamine and salbenz in 2:1:1 ratio with metal (II) salts (1mM). All these complexes are found to be stable in air and soluble in CN₃CN or DMSO, and are characterized through spectral (UV-Vis, IR, EPR) and electrochemical methods. A square planar geometry is proposed for Cu(II), Ni(II) and Co(II) complexes, while an octahedral geometry is suggested for Mn(II) and Fe(II). The IR spectra indicate that the NH groups of the amine exist as such even after complexation without deprotonation, and all the complexes show a strong band in 1580-1590 cm^-1 region corresponding to ν(C=N), due to coordinated azomethine group to the metal. The solution electronic spectra of these complexes show intense LMCT bands around 400 nm. Intense electronic absorption spectra as well as the four line pattern in EPR spectra with broad g_⊥ suggests that the copper(II) complexes have distorted square planar geometry. On titration with herring sperm DNA, CuN_4, CoN_4, NiN₄ and MnN₄ complexes exhibit an abrupt amend in their electronic spectrum and cyclic voltammogram. The intense intraligand π-π* transition in the region 350–420 nm is found to show hypochromicity on titration with DNA in all these complexes, due to their electrostatic interaction with DNA. All these complexes show one well–defined quasi-reversible redox couple with values ranging from ∆Ep 137 to 337 mV. Their spectral and electrochemical outcome designate that the square planar complexes Cu(II), Co(II) and Ni(II) interact much better than the axially coordinated octahedral complexes Mn(II) and Fe(II). The decrease found in the negative absorption peak, characteristic peak due to helicity of DNA, in circular dichroism studies reflects the perversion in the helical nature of B-DNA upon the addition of complex. The binding of plasmid DNA by these complexes has also been investigated by agarose gel electrophoresis, remarkably Ni(II) complex was found to cleave the DNA double helix.

Abstract: A series of copper(II) complexes with positive reduction potential have been synthesized by an in situ fashion by the reaction of a Knoevenagel condensate, salicylidenebenzoylacetone (salbenz) with 4-X-anilines and copper(II) chloride. The electronic spectra of these complexes in acetonitrile show d–d bands around 540 nm with high molar extinction coefficient (ε~1600-1800 cm^-1) due to lowering of symmetry around metal center, and MLCT band around 400 nm. The EPR spectral features with four g₍₍ lines having g₍₍ >2.0 >g_⊥, and a broadening of g_⊥ component suggest a lowered site symmetry around Cu(II) monomer. The cyclic voltammetric studies of Cu(II) complexes in CH₃CN shows a positive reduction potential (Epc = 492-451 mV) with moderately high peak to peak separation (∆Ep=126-163mV). All these results are comparable with the results of natural blue copper proteins even in the absence of S-coordination, and suggest that they can mimic the functional properties of blue copper proteins. These complexes on interaction with herring sperm DNA, the intense intraligand (IL) π-π^* transition around 300 nm is found to be hypochromic with a slight red shift. The hypochromism and moderate binding constant are indicative of binding of the complexes with DNA with an affinity less than the classical intercalators, due to the possible substitution of the two chlorides with the DNA base pairs and relatively bulky structure of ligand molecule. Additional evidence of DNA-Cu(II) complex interaction was obtained by CD studies. The experimental results reveal that these complexes may serve as a model for blue copper proteins and as a tool for probing the structure of DNA.

Abstract: Methylene blue is a heterocyclic aromatic chemical compound with the molecular formula C₁₆H₁₈N₃SCl. It has used in the biology and chemistry field. At room temperature, it appears as a solid, odourless dark green powder that yields blue solution when dissolved in water. As a part of removal of methylene blue dye from textile and leather industrial wastes, using activated carbon as adsorbents namely, commercial activated carbon (CAC), rose apple carbon (RAC), coconut shell carbon (CSC) and saw dust carbon (SDC). The percentage of Methylene blue adsorbed increases with decrease in initial concentration and particle size of adsorbent and increased with increase in contact time, temperature and dose of adsorbents. The pH is highly sensitive for dye adsorption process. The adsorption process followed first order kinetics and the adsorption data the modeled with Freundlich and Langmuir isotherms. The first kinetic equations like Natarajan Khalaf, Lagergren, Bhattacharya and Venkobhachar and intra particle diffusion were found to be applicable. A comparative account of the adsorption capacity of various carbons has been made. These activated carbons are alternative to commercial AC for the removal dyes in General and MB is particular. These results are reported highly efficient and effective and low cost adsorbent for the MB. The thermodynamics parameters are also studied and it obeys spontaneous process. The results are confirmed by before and after adsorption process with the help of the following instrumental techniques viz., FT-IR, UV-Visible Spectrophotometer and SEM photos.

Abstract: A series of metal complexes have been synthesized by the reaction of Schiff base with metal (II) salt solution. The complexes were characterized by UV and FT- IR studies. The study reveals that the geometry of the complexes were octahedral. The electronic spectra of these complexes show a strong absorption band in 550 - 580nm region. This confirms the coordination of ligand with metal. The FT-IR shows a very strong band at 1616cm^-1 assigned to C=N stretching vibration. It is shifted to lower wave number because of the complex formation, suggesting that coordination of the Schiff base groups through N- atoms with the metal ion. The band at 3496 cm^-1 is due to aromatic N-H stretching, It is noted that a broad band of the asymmetric and symmetric O-H stretching mode around the region 3400 cm^-1 presumably due to H-O-H bending vibrations are not observed in the spectrum of complexes, which are indicating of the absence of the water molecule.

Abstract: A series of metal complexes have been synthesized by the reaction of Schiff base with metal (II) salt solution. The complexes were characterized by UV and FT- IR studies. The study reveals that the geometry of the complexes were octahedral. The electronic spectra of these complexes show a strong absorption band in 550 – 580 nm region. This confirms the coordination of ligand with metal. The FT-IR shows a very strong band at 1606cm^-1 assigned to C=N stretching vibration. It is shifted to lower wave number because of the complex formation, suggesting that coordination of the Schiff base groups through N- atoms with the metal ion. The band at 3056cm^-1 is due to aromatic O-H stretching, the sharp peak at 750 cm^-1 and 688 cm^-1 are due to halogens substituted in the para position.

Abstract: This paper represents a simple method for preparing and characterizing of low-cost ion exchangers of sulfonated carbon prepared from Aegle Marmelos., as a source of cheap plant material blended with phenol-formaldehyde as a cross linking agent. The prepared ion exchange resins (IERS) are characterized by infrared (IR) spectral and thermal studies. All the important physico chemical properties of the ion exchangers have been determined. It is concluded from the present study that PER sample could be blended with 30% (W/W) of sulfonated Aegle Marmelos charcoal (SAMC) without affecting its physico chemical, spectral and thermal properties. Hence blending with SAMC will be finitely lower the cost of the ion exchange resin. Ion exchange process is suitable in the treatment of waste water containing metal ions discharge from plating and other industries. Also, it is a convenient way to concentrate and remove the ions of valuable metals like copper, mercury, cadmium, Nickel and Barium special processes using selective IERS are also available for the recovery of precisious noble metals like gold, platinum and silver. The present study is aimed at to synthesize and characterize new composite ion exchangers of PhOH – HCHO type, blended with SAMC and to determine the column/cation exchange capacity (or) ion exchange capacity (IEC) for some selective metal ions.