absorption spectra of substituted azocalix[4]arenes

A series of novel azocalix[4]arene dyes (1-12) were prepared by linking o-, m-, p-chloroaniline, o-, m-, p-nitroaniline, o-, m-, p-toluidine, m-, p-anisidine and aniline to calix[4]arene through a diazo-coupling reaction. These compounds were characterized by UV-vis, FT-IR and H-1-NMR spectroscopic techniques and elemental analysis. The effect of varying pH and solvent upon the absorption ability of azocalixarenes substituted with electron-donating and electron-withdrawing groups at their o-, m-, p- position was examined. Observed results were compared with those found for unsubstituted azocalix[4]arene. Concentration effects on the visible absorption maxima of the dyes are also reported. (C) 2003 Elsevier Ltd. All rights reserved

Dependence of the Structural, Electrical and Magnetic Properties of the Superconductive YBCO Thin Films on the Deposition Rate

International Conference on Superconductivity and Magnetism (ICSM) -- AUG 25-29, 2008 -- Ankara Univ, Side, TURKEYWOS: 000298993000016In this study, YBCO thin films on single crystal LaAlO(3) (100) substrates have been grown using DC inverted cylindrical magnetron sputtering technique and the effect of the deposition rate on these films is investigated. Three different deposition rates are used to produce superconducting YBCO thin films with 150 nm of thickness on (100) LaAlO(3) single crystal substrate at 780 degrees C. The samples are analyzed in detail by means of XRD, R-T, chi-T, M-H and AFM characterizations and also the critical current densities (J(c)) are derived from the magnetic hysteresis curves using the modified Bean formula [1]. The critical current density at 50 K was found to be in the range of 3.10(7) A/m(2) to 8. 10(7) A/m(2) with a deposition rate between 2nm/min and 1.2nm/min. A correlation has been obtained so that as the film deposition rate increases, the surface smoothness and crystalline quality of the films significantly deteriorate, resulting in a significant decrease in J(c)

Trapping Center Parameters in TlInS 2

Thermally stimulated current measurements are carried out on TlInS2 layered single crystal with the current flowing perpendicular to the c-axis in the temperature range of 10 to 90 K. The results are analyzed according to various methods, such as curve fitting, heating rate, and initial rise methods, which seem to be in good agreement with each other. Experimental evidence is found for one trapping center in TlInS2 crystal in the low-temperature region

of hetarylazo disperse dyes derived from calix[4]arene

Synthesis of some novel hetarylazocalix[4]arene dyes was achieved by diazotisation of six heterocyclic amines using nitrosyl sulphuric acid, coupling with calix[4]arene. The absorption spectra of the dyes are discussed, both the effect of varying pH and solvent upon the absorption ability of azocalixarenes. The hetarylazocalix[4]arene readily undergo acidic dissociation into the common anion in DMF and DMSO. Absorption maxima of the dyes showed large bathochromic effects in comparison with analogues dyes containing carbocyclic amine residue. The colour of the dyes is discussed with respect to the nature of the heterocyclic ring and substituents there in. Concentration effects on the visible absorption maxima of the dyes arc also reported. (C) 2004 Elsevier Ltd. All rights reserved.C1 Pammukale Univ, Fac Sci Arts, Dept Chem, TR-20017 Denizli, Turkey.Ankara Univ, Fac Sci, Dept Chem, TR-06100 Ankara, Turkey