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Int. J. Chem. Sci.: 7(2), 2009, 644-654 SYNTHESIS AND CHARACTERIZATION OF METAL CHELATES WITH 1, 5-DIARYL-3- (2-HYDROXYPHENYL) FORMAZANS A. K. ABDUL RAHIM∗, M. JAHFAR and K. KRISHNANKUTTYa a Department of Chemistry, Farook College, KOZHIKODE –673 632 (Kerala) INDIA Department of Chemistry, University of Calicut, CALICUT - 673 635 (Kerala) INDIA ABSTRACT Copper, cobalt and nickel chelates of 1, 5-diaryl-3- (2-hydroxyphenyl) formazans were synthesized and characterized by physical and spectrosc
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     Int. J. Chem. Sci.: 7(2), 2009, 644-654 SYNTHESIS AND CHARACTERIZATION OF METALCHELATES WITH 1, 5-DIARYL-3- (2-HYDROXYPHENYL)FORMAZANS A. K. ABDUL RAHIM ∗∗∗∗ , M. JAHFAR and K. KRISHNANKUTTY a   Department of Chemistry, Farook College, KOZHIKODE –673 632 (Kerala) INDIA a Department of Chemistry, University of Calicut, CALICUT - 673 635 (Kerala) INDIA ABSTRACT Copper, cobalt and nickel chelates of 1, 5-diaryl-3- (2-hydroxyphenyl) formazans weresynthesized and characterized by physical and spectroscopic methods. Their stability constants werealso determined. Key words : Formazans, Copper, Cobalt, Nickel INTRODUCTION Metal complexes of organic compounds have found increasing applications indiverse fields 1, 2 . Formazans and their metal chelates can be used together with dispersedyes in single step dyeing of cellulosic-polyester blends, for dyeing or printing of paper,leather and polyamide fibres 3 . HO NH NCR  2 R  1  N N   Fig. 1 ∗ Author for correspondence   Int. J. Chem. Sci.: 7 (2), 2009   645 Compound R  1 R  2   1a1b1c1d  C 6 H 5 C 6 H 5 C 6 H 5 C 6 H 5  C 6 H 5 C 10 H 7 C 6 H 4 ( COOH)C 3 H 2  NSThey are also used to detect the presence of trace elements in ores 4 and in thedevelopment of new type of oxidative and reductive chromogenic reagents in clinicalanalysis as an indicator of cell viability with less cytotoxicity 5, 6 . Some metal chelates oformazans can be used reliably to measure metabolic activity of cell cultures in vitro for the assessment of growth characteristics and in various biological researches 7 . Thoughseveral such applications have been reported for metal chelates of formazans, structuralaspects of these chelates were not much discussed earlier. The present paper deals with thesynthesis and characterization of the copper (II), nickel (II) and cobalt (II) complexes withthe formazans EXPERIMENTAL Synthesis of 1, 5-diaryl-3- (2-hydroxyphenyl) formazans The compounds were synthesized by the reaction of phenylhydrazone osalicylaldehyde with aryldiazonium salts. Preparation of salicylaldehyde phenylhydrazone A solution of salicylaldehyde (12 g, 0.1 mol) in 75% v/v ethanol-water mixture(250 mL) was mixed with an ethanolic solution (250 mL) of phenyl hydrazine (12.2 g, 0.1mol) and refluxed on boiling water bath for about 3 h. The precipitate formed on cooling toroom temperature was filtered, washed with water, recrystallised from ethanol (m. p.144ºC reported. 142ºC). Preparation of the formazan The aryl diazonium salts of aniline, 1-aminonaphthalene, anthranilic acid and 2-aminothiazole were prepared as reported 13 .The diazonium salt solution (0.025 mol) was added slowly with stirring to an icecooled aqueous methanolic solution of the salicylaldehyde phenylhydrazone (400 mL)containing sodium hydroxide (10.5 g) also. Stirring was continued for about 1 h. The     A. K. A. Rahim et al.: Synthesis and… 646  precipitate formed was filtered, washed with water and extracted into ether. The ether extract was dried using anhydrous magnesium sulphate. On evaporation of ether, pureformazan was obtained. Preparation of metal chelates The 1, 5-diaryl-3- (2-hydroxyphenyl) formazans (0.025 mol) was extracted in to a boiling methanolic solution (150 mL) of metal (II) acetate (0.05 mol) and glacial aceticacid (1 mL). The precipitate was collected, washed with the boiling methanol and dried. Itwas recrystallised from methanol. RESULTS AND DISCUSSION The metal complexes (II) were prepared using the above formazans ( 1a , 1b , 1c and 1d ) and they were characterized by physical, analytical and spectral studies. Their stabilityconstants were also determined. COHNNMNNR 2 R 1 COHNNNNR 2 R 1   Fig. 2 Physical, analytical and spectral results are given in the following tables. Table 1 : Physical, analytical and U. V. spectral data of metal complexes of 1, 5-diphenyl-3- (2-hydroxyphenyl) formazan (1a )Elemental analysis found (calcd) in %MetalM. P.( 0 C)C H N metalλmax(nm) Cu (II) >30066.54(65.74)4.54(4.32)15.84(16.16)8.95(9.16)296261Co (II) >30065.87(66.18)3.85(4.06)15.82(16.25)8.68(8.53)295261   Int. J. Chem. Sci.: 7 (2), 2009   647 Elemental analysis found (calcd) in %MetalM. P.( 0 C)C H N metalλmax(nm)  Ni (II) >30069.45(69.98)4.34(4.35)16.87(16.26)8.532(8.52)804306262 Table 2 : Physical, analytical and U. V. spectral data of metal chelates of 1-phenyl-5-(1-naphthyl-3- (2-hydroxyphenyl)formazan (1b)Elemental analysis found (calcd) in %MetalM. P.( 0 C)C H N Metalλmax(nm) Cu (II) >300 69.2(69.56)4.62(4.28)14.81(14.2)7.92(8.01)429310Co (II) >300 69.25(69.95)3.95(4.31)14.50(16.17)8.2(7.46)429310 Ni (II) >300 68.92(69.98)3.85(4.36)14.54(14.2)8.23(7.44)433309 Table 3.Physical, analytical and U. V. spectral data of metal chelates of 1-phenyl-5-(2- carboxy phenyl)-3- (2-hydroxyphenyl)formazan (1c)Elemental analysis found (calcd) in %MetalM. P.( 0 C)C H N metalλmax(nm) Cu (II) >280 55.48(56.79)3.37(3.31)13.68(13.25)15.01(15.03)730, 470310, 285Co (II) >280 56.84(57.54)3.39(3.36)14.2(13.43)15.5(14.13)455310 Ni (II) >280 55.3(57.59)3.54(3.35)13.68(13.43)15.5(14.08)630315204
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