No abstract

Metal complexes of iminodiacetamide (imda) ligands and metal ions Zn(II), Cu(II), Ni(II) and Co(II) were prepared, using eight imda ligands (L1-L8) substituted with groups of different steric and electronic properties on the central amine nitrogen atom (hydrogen atom, methyl, isopropyl, benzyl) and the para-position of phenyl rings (nitro, dimethylamino). The effect of these substituents on the stoichiometry (ML, ML2), geometry and stereochemistry (mer, transfac, cis-fac) of the complexes was studied in solid state, in solution and by DFT calculations. X-Ray single crystal and powder diffraction, thermogravimetry, and IR spectroscopy showed that in the solid state imda ligands preferentially form transfac ML2 complexes, with the exception of the cis-fac complex 7Zn. NMR spectroscopy of diamagnetic Zn(II) and paramagnetic Co(II) complexes revealed the formation of both ML and ML2 complexes in solution. Variable temperature NMR was used to study the effect of the substituent on the central amine nitrogen on the Zn─N bond strength and nitrogen inversion. Relative stabilities of isomers were rationalized by computations and the optimized structures used for the geometry analysis.

A variety of structurally different complexes of the isopropyl-bis­(2-picolyl)­amine ( i Pr-bpa) ligand were prepared with ZnA2 and CuA2 salts (A = Br–, Br–/PF6 –, BF4 –/F–, ClO4 –). The choice of different counterion affected the stoichiometry, coordination number, geometry, and formation of geometrical isomers. Crystal structures of four Zn­(II) complexes, namely, two monomers ( mer -[Zn­( i Pr-bpa)­Br 2 ] and fac -[Zn­( i Pr-bpa)­Br 2 ]), one F–-bridged dimer ([Zn 2 (μ-F) 2 ( i Pr-bpa) 2 ]­(BF 4 ) 2 ), and one ML 2 complex ([Zn­( i Pr-bpa) 2 ]­(ClO 4 ) 2 ) were determined, and their solution structures were studied by NMR spectroscopy. For the ML 2 complex, relative stabilities of geometrical isomers were determined using density functional theory calculations. For Cu­(II) complexes, five crystal structures were determined, namely, two monomers ([Cu­( i Pr-bpa)­Br 2 ] and [Cu­( i Pr-bpa)­(ClO 4 ) 2 (H 2 O)]), a Br–-bridged dimer ([Cu 2 (μ-Br)­(Br) 2 ­( i Pr-bpa) 2 ]­(PF 6 )), a F–-bridged coordination polymer ([Cu­(μ-F)­( i Pr-bpa)] n (BF 4 ) n × nCH 3 OH), and a cyclic, CO3 2–-bridged trimer ([Cu 3 (tri-μ-CO 3 )­(ClO 4 ) 3 ­( i Pr-bpa) 3 ]­(ClO 4 )). The different crystallographic structures of Cu­(II) complexes are reflected in their different magnetic properties investigated by electron spin resonance spectroscopy and magnetic susceptibility measurements.

Ferrocene derivatives with mono‐ (8a–c) and bis‐1,2,3‐triazolyl (9 and 10a–13c) chelating groups were synthesized by regioselective copper(I)‐catalysed 1,3‐dipolar cycloaddition of terminal alkynes with ferrocene azides. Metal complexes of the ligands were prepared with Cu(II) and Zn(II) salts. Crystal structures of ligands 9 and 11a were determined, as well as the structures of complexes [Cu(8a)2](CF3SO3)2 (8aCu) and [Cu(8c)2(CH3OH)2](BF4)2 (8cCu). In addition to NMR and UV–Vis spectroscopy, the metal complexes were characterized by cyclic voltammetry. The cytotoxic effect of ferrocene conjugates and their Zn(II) and Cu(II) complexes was explored, and cell cycle analysis was performed. The complex [Cu(8c)2](CF3SO3)2 showed the most prominent and selective cytotoxicity on cervical carcinoma (HeLa), ovarian cancer (MES‐OV), non‐small cell lung cancer (A549) and breast carcinoma (MDA‐MB‐231) cells. This complex increased cell population in the S and G2/M phase of the cell cycle, which was accompanied by an increase of the cells present in the sub‐G0/G1 fraction.

Click chemistry is a simple way of preparing a wide scope of ligands that can coordinate metals such as Cu(ii) and Zn(ii), forming complexes of different stoichiometries, geometries and stereochemistries.

Seven bis(2-picolyl)amine (bpa) and five iminodiacetamide (imda) ligands were prepared with different modifications in their side chain structure. The coordination properties of the ligands (L) were influenced by changes in...

This paper describes the synthesis of an amide based conjugate of ferrocene (Fc), ethylenediamine (eda) and iminodiacetamide (imda), Fc-eda-imda (2). The compound (2) is characterized by various spectroscopic, crystallographic and thermoanalytical techniques in solid state and in solution. By crystallization of the title compound 2 from methanol or chloroform, two different crystalline forms 2a and 2b were obtained, respectively. In their X-ray single crystal structures, 2a and 2b reveal similar 2D hydrogen bonding networks, but differ by supramolecular organization, namely aromatic π -π stacking interactions in the third spatial dimension.

Heme and nonheme-type flavone synthase enzymes, FS I and FS II are responsible for the synthesis of flavones, which play an important role in various biological processes, and have a wide range of biomedicinal properties including antitumor, antimalarial, and antioxidant activities. To get more insight into the mechanism of this curious enzyme reaction, nonheme structural and functional models were carried out by the use of mononuclear iron, [FeII(CDA-BPA*)]2+ (6) [CDA-BPA = N,N,N’,N’-tetrakis-(2-pyridylmethyl)-cyclohexanediamine], [FeII(CDA-BQA*)]2+ (5) [CDA-BQA = N,N,N’,N’-tetrakis-(2-quinolilmethyl)-cyclohexanediamine], [FeII(Bn-TPEN)(CH3CN)]2+ (3) [Bn-TPEN = N-benzyl-N,N’,N’-tris(2-pyridylmethyl)-1,2- diaminoethane], [FeIV(O)(Bn-TPEN)]2+ (9), and manganese, [MnII(N4Py*)(CH3CN)]2+ (2) [N4Py* = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine)], [MnII(Bn-TPEN)(CH3CN)]2+ (4) complexes as catalysts, where the possible reactive intermediates, high-valent FeIV(O) and MnIV(O) are known and well characterised. The results of the catalytic and stoichiometric reactions showed that the ligand framework and the nature of the metal cofactor significantly influenced the reactivity of the catalyst and its intermediate. Comparing the reactions of [FeIV(O)(Bn-TPEN)]2+ (9) and [MnIV(O)(Bn-TPEN)]2+ (10) towards flavanone under the same conditions, a 3.5-fold difference in reaction rate was observed in favor of iron, and this value is three orders of magnitude higher than was observed for the previously published [FeIV(O)(N2Py2Q*)]2+ [N,N-bis(2-quinolylmethyl)-1,2-di(2-pyridyl)ethylamine] species.