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A Schiff base ligand 2-{(E)-[2-hydroxyphenyl)imino]methyl}phenol [LF] was prepared by condensation of salicylaldehyde with 2-aminophenol. The [LF] ligand was characterized by using melting point measurement, F.T.IR and UV-Vis spectroscopy. New series of transition metal complexes of Cu (II), Co (II) and Rh (III) ions were synthesized with this Schiff base. The complexes were characterized by using FTIR, UV-Vis spectroscopy, metal analysis spectrophotometer, conductivity and magnetic susceptibility measurements. The metal coordinated with Schiff base through nitrogen azomethine and phenolic hydroxyl oxygen atoms of the ligand. Magnetic susceptibility data coupled with electronic spectra and suggest a square planar geometry for the Cu(II) complex and octahedral structure for the Co(II) and Rh(III) complexes.

A novelSchiff base 2-{(E)-[(2,4dichlorophenyl)imino]methyl}phenol (L B ) was synthesized from the condensation reaction of 2,4-dichloroaniline with salicyladehyde in [1:1] ratio in the presence of glacial acetic acid as catalyst. Complexation reaction of this Schiff base with copper (II), cobalt (II) as nitrate salts and with Rhodium (III) as chloride salt to produce three coordinate metal complexes, with a Schiff base: Metal ion ratio of 2:1. These compounds have been characterized by a variety of physico-chemical and spectroscopic techniques. The ligand and its metal complexes were expected to show an interesting bioactivity and cytotoxicity.

Citrate-capped gold nanoparticle (GNP) was used as a ligand for chromium chelating, and chromium ions reaction led to GNP aggregation. The color change of GNP by aggregation in the presence of chromium is a simple and rapid colorimetric test for these ions in an aqueous solution. GNP capped citrate was prepared by the citrate method and characterized by TEM, and its particle size was 20 nm. Also, the surface plasmon resonance (SPR) peak was 520 nm. In the presence of chromium ions, the color of GNP at 520 nm was shifted to 650 nm because of aggregation to give a signal as a ratio of A650/520 more than one and proportional with chromium concentration directly. The optimum conditions were studied to obtain the high signal represented by the volume of GNP, reaction kinetic of A650 with time, selectivity, and interferences of Zn(II), Fe(III), Fe(II), Sn(II), Ni(II), Ca(II), Al(III), Sr(II), Cu(II), Mn(II), Co(II), Mg(II), Ag(I), and Pb(II) ions. The calibration curve is linear in the range of 100–500 ppb, and the regression was 0.9951 and applied on tap water chromium ions in the same range in the regression of 0.95. This method was simple, rapid reaction, consumed low volumes of sample, and had low detection limits. It can be recommended as a new method for chromium (III) detection in aqueous solutions.

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