The ligational behavior of a phenolic quinolyl hydrazone towards copper(II)- ions

<p>Abstract</p> <p>Background</p> <p>The heterocyclic hydrazones constitute an important class of biologically active drug molecules. The hydrazones have also been used as herbicides, insecticides, nematocides, redenticides, and plant growth regulators as well as plasticizers and stabilizers for polymers. The importance of the phenolic quinolyl hydrazones arises from incorporating the quinoline ring with the phenolic compound; 2,4-dihydroxy benzaldehyde. Quinoline ring has therapeutic and biological activities whereas, phenols have antiseptic and disinfectants activities and are used in the preparation of dyes, bakelite and drugs. The present study is planned to check the effect of the counter anions on the type and geometry of the isolated copper(II)- complexes as well as the ligational behavior of the phenolic hydrazone; 4-[(2-(4,8-dimethylquinolin-2-yl)hydrazono)methyl] benzene-1,3-diol; (H₂L).</p> <p>Results</p> <p>A phenolic quinolyl hydrazone (H₂L) was allowed to react with various copper(II)- salts (Cl‾, Br‾, NO₃‾, ClO₄‾, AcO‾, SO₄^2-). The reactions afforded dimeric complexes (ClO₄‾, AcO‾ ), a binuclear complex (NO₃‾ ) and mononuclear complexes (the others; Cl‾, Br‾, SO₄^2-). The isolated copper(II)- complexes have octahedral, square pyramid and square planar geometries. Also, they reflect the strong coordinating ability of NO₃‾, Cl‾, Br‾, AcO‾ and SO₄^2-anions. Depending on the type of the anion, the ligand showed three different modes of bonding <it>viz</it>. (NN)⁰for the mononuclear complexes (<b>3, 4, 6</b>), (NO)^-with O- bridging for the dimeric complexes (<b>1, 5</b>) and a mixed mode [(NN)⁰+ (NO)^-with O- bridging] for the binuclear nitrato- complex (<b>2</b>).</p> <p>Conclusion</p> <p>The ligational behavior of the phenolic hydrazone (H₂L) is highly affected by the type of the anion. The isolated copper(II)- complexes reflect the strong coordinating power of the SO₄^2-, AcO‾, Br‾, Cl‾ and NO₃‾ anions. Also, they reflect the structural diversity (octahedral, square pyramid and square planar) depending on the type of the counter anion.</p

The ligational behavior of an isatinic quinolyl hydrazone towards copper(II)- ions

<p>Abstract</p> <p>Background</p> <p>The importance of the isatinic quinolyl hydrazones arises from incorporating the quinoline ring with the indole ring. Quinoline ring has therapeutic and biological activities whereas, the indole ring occurs in Jasmine flowers and Orange blossoms. As a ligand, the isatin moiety is potentially ambidentate and can coordinate the metal ions either through its lactam or lactim forms. In a previous study, the ligational behavior of a phenolic quinolyl hydrazone towards copper(II)- ions has been studied. As continuation of our interest, the present study is planned to check the ligational behavior of an isatinic quinolyl hydrazone.</p> <p>Results</p> <p>New homo- and heteroleptic copper(II)- complexes were obtained from the reaction of an isatinic quinolyl hydrazone (HL) with several copper(II)- salts <it>viz. </it>Clˉ, Brˉ, NO₃ˉ, ClO₄^-, SO₄^2-and AcO^-. The obtained complexes have O_h, T_dand D_4h- symmetry and fulfill the strong coordinating ability of Clˉ, Brˉ, NO₃ˉ and SO₄^2-anions. Depending on the type of the anion, the ligand coordinates the copper(II)- ions either through its lactam (NO₃ˉ and ClO₄^-) or lactim (the others) forms.</p> <p>Conclusion</p> <p>The effect of anion for the same metal ion is obvious from either the geometry of the isolated complexes (O_h, T_dand D_4h) or the various modes of bonding. Also, the obtained complexes fulfill the strong coordinating ability of Clˉ, Brˉ, NO₃ˉ and SO₄^2-anions in consistency with the donor ability of the anions. In case of copper(II)- acetate, a unique homoleptic complex (<b>5</b>) was obtained in which the AcO^-anion acts as a base enough to quantitatively deprotonate the hydrazone. The isatinic hydrazone uses its lactim form in most complexes.</p

Original scientific paper

Potentiometric and spectrophotometric studies of the complexation of Schiff-base hydrazones containing the pyrimidine moiet

حسابات ثوابت الاستقرار لمتراكبات اللنثانيدات مع الآزو- بيتا- داي كيتونات

The stability constants of the complexes between the trivalent lanthanide series of cations and series of azo-B-diketone ligands are reported. The measurements were conducted at 30°C and zero ionic strength (free KN03), in 100 % methanol. The relation between the overall stability constant (Log B;) and atomic number of lanthanide elements, shows a gadolinium-break. The relation between (Log Bz) and the basicity of the studied ligands ( 2 pKi + pKz) are, also discussed. The overall stability values obtained reflected a great affinity of the organic ligands for chelation with lanthanide ions.‏‏ قد ورث ثوابت الاستقرار لمتراكبات كاتيونات اللنثانيدات الثلاثية مع بعض ليجاندات الآزو - بيتا - داي كيتون . واجريت القياسات عند ٣٠ ‏م وعند تركيز ايوني مقداره صفر باستخدام ١٠٠٠ ‏% ميثانول . وقد اظهرت العلاقة بين محصلة ثابت الاستقرار ‏ (loj B2) وبين الاعداد الذرية للنثانيدات منطقة منظمة عند الجاد ولينيوم . كما نوقشت العلاقة بين (loj B2) وقاعديه الليجاندات المدروسة وشرحت قيم ثوابت الاتزان . وقد اظهرت الدراسة من خلال حساب قيم ثوابت الاستقرار القابلية الكبيرة لليجاندات المستخدمة لتكوين متراكبات مع ايونات اللنثانيدات

Potentiometric and spectrophotometric studies of the complexation of Schiff-base hydrazones containing the pyrimidine moiety

Three Schiff-base hydrazones (ONN donors) were prepared by condensation of 2-amino-4-hydrazino-6-methylpyrimidine with 2-hydroxyacetophenone, 2-methoxybenzaldehyde and diacetyl to yield 2-OHAHP, 2-OMeBHP and DHP, respectively. The structures of these ligands were elucidated by elemental analysis, UV, IR, 1H-NMR and mass spectra. The metalligand stability constants of Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, UO22+ and Th4+ chelates were determined potentiometrically in two different media (75 % (v/v) dioxanewater and ethanolwater) at 283, 293, 303 and 313 K at an ionic strength of 0.05 M (KNO3). The thermodynamic parameters of the 1:1 and 1:2 complexes were evaluated and are discussed. The dissociation constants of 2-OHAHP, 2-OMeBHP and DHP ligands and the stability constants of Co2+, Ni2+ and Cu2+ with 2-OHAHP were determined spectrophotometrically in 75 % (v/v) dioxanewater