Spectrophotometric Determination of Co ( II ) , Ni ( II ) and Cu ( II ) Complexes with Schiff Base Containing Nitrogen and Sulphur Donor Sites SANJAY

Coordination compounds of Co(II), Ni(II) and Cu(II) are synthesized by the reaction of 3-propyl-(N-ortho toludine) quinazoline thiosemicarbazone. An attempt has been made to probe the structures, bonding pattern and geometries of their coordination compounds by the molar mass, elemental analyses, infrared spectra, electronic spectra, molar conductance data and decomposition temperature.


INTRODUCTION
The chemistry of transition metal complexes has been rapidly expanding not only because their potential applications, but also due to the intriguing variety of architecture exhibited by these compounds [1][2][3][4][5] .Schiff base derivative incorporating a fluorescent moiety are a useful tool for optical sensing of metal ions.Thin organic and organometallic films have attracted research interest due to their technologically important optical and electronic properties.These materials exhibit luminescence, they are use as conductors, semiconductors and organic light emitting diodes (OLED) [6][7] .A considerable interest has been shown to biologically active transition metal complexes, largely due to their ability to interact with DNA 8 .The complexes which can bind or cleave DNA at specific sites, may play an important role in genomic research and in photodynamic therapy against cancer 9 .It is well known that some coordination compounds can inhibit the multiplication of cancer cells by binding and damaging DNA 10 .Motivated from the above mentioned biochemical significance of Schiff base and their transition metal complexes with nitrogen and sulphur containing Schiff bases and in continuation of our earlier research work [11][12][13][14][15][16][17][18][19][20] in this field we are hereby reported the synthesis and characterization of coordination compounds of Co(II), Ni(II) and Cu(II) with Schiff base ligand.3-propyl-(N-orthotoludine) quinazoline thiosemicarbazone (PTQT).

EXPERIMENTAL
All reagent were analytical grade and used without further purification.The metal contents were analysed by standard procedure 21 .The electronic spectra of the complexes were recorded on Cary-2390 spectrophotometer in the 10000-25000 cm -1 .The infrared spectra of the ligand and metal complexes in the region 200-4000 cm -1 were recorded on Perkin Elmer 577 spectrophotometer.The magnetic susceptibility was measured using Gouy balance using mercury tetraisothicyanato cobaltate as a calibrant.The molar conductance was measured by Systronics conductivitymeter model 303 using DMF as a solvent.
Analytical data, electronic spectral data, molar conductance value, magnetic susceptibility value, decomposition temperature and molecular formula of the ligand as well as their complexes are recorded in Table .1 and the salient features of IR bands are recorded in Table -2.

Preparation of the ligand
Ethanolic solution of 3-propyl (N-ortho toludine) quinazoline (0.01m) in ethanol and thiosemicarbazide hydrochloride dissolved in 10% solution of sodium acetate in ethanol.The resulting mixture was refluxed on water bath for 2 h with occasional stirring.The solvent was concentrated to half of its volume and then poured in ice cold water.A solid precipitated out immediately which was filtered, washed with distilled water and cold ethanol.

Preparation of the complexes
The following general method was adopted for the pr eparation of the halide complexes of cobalt(II), nickel(II) and copper(II).
The complexes were prepared by reacting metal halides (0.05 g) of the cobalt(II), nickel(II) and copper(II) in ethanol with ethanolic solution of the ligand 3-propyl(N-ortho-toludine) thiosemicarbazone (0.1g).The mixture was then refluxed under stirring condition.The mixture was then refluxed for 3 h.
The product was precipitated out and was collected by filteration followed by washing with cold water.Then the product was dried in oven.Yield 75-80%.
The following general method was adopted for the preparation of nitrate and perchlorate complexes.The complexes were prepared by using metal nitrates/ perchlorate salts of cobalt(II), nickel(II) and copper(II) to a hot ethanolic solution of the ligand 3-propyle (N-ortho toludine) thiosemicarbazone.The mixture was in the molar ratio 1:2.The mixture was then refluxed under stirring condition.The mixture was then refluxed for 4 hours.The product was precipitated out and was collected by filtration followed by washing with cold water.Then the product was dried in oven.Yield 75-80%.

Infrared Spectral Study
The IR spectrum of the complexes was compared with those of the free ligand in order to determine the involvement of the coordination sites in the chelation.Analysis by IR results in the absorption spectra in the IR region and registered bands or signals.IR spectra of the ligand, PTQT exhibited the characteristic strong band at 1560 cm 1 assignable 22,24 to azomethine (>C=N).In the spectra of the complex this band shows red shift with slightly reduced intensity.The shift of the band and change in intensity proposes possible linkage of the azomethine nitrogen with metal ions.The infrared spectra of the ligand shows a strong and broad band at 780 cm -1 assigned [22][23][24][25] to ν C=S .After complex formation this band also shows red shift proposes coordination of metal through thione sulphur atom of thiosemicarbazone moiety.