1240324-65-5Relevant academic research and scientific papers
Characteristic features of formation, synthesis, and properties of binuclear zinc(II) helicates with alkyl-substituted 3,3'-bis(dipyrrolylmethenes)
Antina,Dudina,Guseva,Antina,Berezin,V'Yugin
, p. 261 - 269 (2012)
On the basis of spectrophotometric studies, it was demonstrated that complexation of hydrobromides of seven alkylated 3,3'-bis(dipyrrolylmethenes) (H2L · 2HBr) with zinc(II) acetate dihydrate in DMF (298.15 K) includes successive steps of formation of binuclear helicates of two types: [Zn2(AcO)2L] (heteroleptic single-helix complex) and [Zn2L2] (homoleptic double-helix complex). An increase in the degree of alkylation of the pyrrole rings of the ligands from 4 to 10 methyl groups induces an increase of overall complexation constants (logK°) from 7.60 to 13.73. The synthesis of helicates [Zn2L2] was described. The products were studied by elemental analysis and IR, 1H NMR, U/Vis, and fluorescence spectroscopy. The effect of the helicand structure and the solvent nature on the chromophore and fluorescence properties of [Zn2L2] was discussed. The kinetic stability of zinc(II) with decamethyl-substituted 3,3'-bis(dipyrrolylmethene) in HCl-DMF medium was estimated. Pleiades Publishing, Ltd., 2012.
Regularities of the formation of binuclear homo- and heteroleptic complexes of d metals with 3,3′-Bis(dipyrrolylmethenes) in DMF
Dudina,Antina,Guseva
, p. 333 - 342 (2011/08/03)
The reactions of seven symmetrically alkylated tetradentate ligands 3,3′-bis(dipyrrolylmethenes) (H2L) with d-metal acetates (M(AcO)2) in DMF solutions at 298.15 K were studied by spectrophotometry. Helicands H2L were found to be structurally preorganized to form stable binuclear homoleptic two-helix helicates [M2L 2] with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) acetates. The coordination of the ligands by the metal ions included consecutive stages of formation of the heteroleptic [M2L(AcO)2] and homoleptic [M2L2] complexes. The [M2L(AcO)2] complexes were spectrally revealed in solutions containing a ligand excess (c H 2 L / c M(AcO) 2 > 1). An increase in the salt concentration shifted the system of equilibria to the homoligand product [M2L2]. The thermodynamic constants of the reactions increased in the series of complexing agents: Cu(II) 2L2] helicate formation in solutions and the earlier obtained results of the IR and 1H NMR studies of the hydrobromic salts of the ligands (H 2L ? 2HBr) showed that the key regularities of the influence of the structural factors on the coordination properties of the ligands were in an increase in the stability of the [M2L2] complexes with an increase in the basicity of the ligands.
