Zoran D. Matović

The favored trans(O6) geometry in hexadentate copper(II) complexes of 1,3-propanediamine-N,N′-diacetic-N,N′-di-3-propionic acid. Crystal structure of trans(O6)-Na2[Cu(1,3-pddadp)]·NaNO3·2H2O. Strain analysis and spectral assignments of complexes

The octahedral copper(II) complexes of 1,3-propanediamine- N,N′- diacetic- N,N′- di-3-propionic acid (H 4 1,3-pddadp) prepared in the region of pH 2 to 7 are hexadentates. Only one ( trans ( O 6 )) of the three geometrical isomers was found to dominate. The trans ( O 6 )-Na 2 [Cu(1,3-pddadp)]·NaNO 3 ·2H 2 O complex crystallizes in the space group P 2/ c of the monoclinic crystal system with a =9.231(2), b= 11.736(14), c =10.150(2) A, β =109.33(2)° and Z =2. The conformations of the chelate rings are found to be envelope for the glycinate and skew-boat for the β-alaninate and 1,3-propanediamine rings. The complex is a tetragonally elongated octahedron ( T ∼0.8) with C 2 molecular symmetry. IR (carboxylate region) and electronic absorption spectra are assigned and discussed in relation to the structure of complexes. For hexadentate Cu(II) edta-type complexes of known structures the strain analysis is also discussed.

Some hexadentate Ni(II)-edta-type complexes containing five-membered diamine rings. The molecular and crystal structure of the trans(O5) isomer of barium(ethylenediamine)-N,N′-diacetato-N,N′-di-3-propionato_)nicklate(II) hexahydrate, trans(O5)-Ba[Ni(eddadp)]·6H2O, and strain analysis of edta-type chelates in relation to their octahedral distortion

Abstract Two paramagnetic octahedral Ni(II)-edta-type complexes, Ba[Ni(eddadp)]·6H2O(1) (eddadp) = ethylenediamine-N,N′-diacetate- N,N′-di-propionate ion) and Ba(Ni(edtp)]· 3H2O(bd2) (edtp = ethylenediamine-tetra-3-propionate Ion) have been prepared and characterized. The ligands used, forming β-alaninate rings, are likely to function as inexandentate with a larger metal ions. Because of the strain in the equatorial plane, as expected, the trans(O5) configuration of complex 1 was found to dominate and this geometry was verified crystallographically. The crystal is monoclinic with the space group C2/c, a = 11.091(3), b = 13.526(4), c = 28.064 A , β = 93.56(2)° and Z = 8 . The IR (carboxylatesregion) and electronic absorption spectra of these complexes are reported. There is no added multiplicity found in the electronic spectra of complexes that generally are seen for octahedral or pseudooctahedral Ni(II) complexes. Spectra of these complexes are discussed in comparison with those of the trans(O5)-[Ni(SS-edds)]2− complex (SS-edds = SS-ethylenediamine-N,N′-disuccinate ion) of known structure. The magnetic measurements are also reported for the complexes studied. Structural parameters and strain analysis data of M-edta-type complexes are discussed in relation to their octahedral distortion.

Antiproliferative and proapoptotic activities of methanolic extracts from Ligustrum vulgare L. as an individual treatment and in combination with palladium complex.

The aim of this study is to examine the growth inhibitory effects of methanolic leaf and fruit extracts of L. vulgare on HCT-116 cells over different time periods and their synergistic effect with a Pd(apox) complex. The antiproliferative activity of plant extracts alone or in combination with the Pd(apox) complex was determined using MTT cell viability assay, where the IC50 value was used as a parameter of cytotoxicity. Results show that antiproliferative effects of L. vulgare extracts increase with extension of exposure time, with decreasing IC50 values, except for 72 h where the IC50 values for methanolic leaf extract were lower than for the fruit extract. The Pd(apox) complex alone had a weak antiproliferative effect, but combination with L. vulgare extracts caused stronger effects with lower IC50 values than with L. vulgare extracts alone. The type of cell death was explored by fluorescence microscopy using the acridin orange/ethidium bromide method. Treatments with plant extracts caused typical apoptotic morphological changes in HCT-116 cells and co-treatments with Pd(apox) complex caused higher levels of apoptotic cells than treatment with plant extracts alone. The results indicate that L. vulgare is a considerable source of natural bioactive substances with antiproliferative activity on HCT-116 cells and which have a substantial synergistic effect with the Pd(apox) complex.

Square-planar copper(II) complexes with a novel tetradentate amido-carboxylate ligand. Crystal structure of [Co(H2O)6][Cu(mda)] · 2H2O

A novel O—N—N—O-type tetradentate ligand H4mda (H4mda = malamido-N,N′-diacetic acid) and the corresponding square-planar copper(II) complexes have been prepared and characterized. The mda4− ligand coordinates to the copper(II) ion via two pairs of deprotonated ligating atoms (two carboxylate oxygens and two deprotonated amide nitrogens) with in-plane square chelation. A four-coordinate, square-planar geometry has been established crystallographically for the [Co(H2O)6][Cu(mda)] · 2H2O complex. Structural data correlating the square-planar geometry of the [Cu(mda)]2− unit are discussed in relation to information obtained for similar complexes. The i.r., electronic, absorption and reflectance spectra of the complexes are analysed in comparison with related complexes of known geometries.

The favored uns-cis geometry in octahedral nickel(II) complexes containing linear tetradentate edda-type ligands forming six-membered rings. Crystal structure of uns-cis-[Ni(1,3-pdda)(H2O)2]

Two paramagnetic octahedral nickel(II) complexes containing the tetradentate 1,3-propanediamine-N,N′-diacetate (1,3-pdda) or ethylenediamine-N,N′-propionate (eddp) anions and water in the remaining two coordination positions were prepared and characterized. In both cases, only one (uns-cis) of the three geometrical isomers, was found to dominate. The 1,3-pdda and eddp ligands prefer the uns_cis configuration, indicating that six-membered chelate rings have a profound effect on the distribution of geometrical isomers. The infrared and electronic absorption spectra of these complexes are discussed in comparison with those of an edda-Ni(II) complex (eedda=ethylenediamine-N,N′-diacetate ion) of known s-cis configuration. The electronic absorption spectra have been treated in terms of Oh symmetry but the splitting of the 3T2g(Oh) bands of the complexes indicates that the tetragonal field is enhanced. The splitting patterns are assigned with the D4h model: 3B1g→3B2gand 3B1g→3Eg. The magnetic measurements are also reported for the complexes studied. The uns-cis-[Ni(1,3-pdda)(H2O)2] complex crystallizes in the space group P212121 of the orthorhombic crystal system with a=15.982(4), b=8.502(2), c=8.032(2) (A) and Z=4. The six-membered diamine ring assumes the stable ‘chair’ conformation. The five-membered glycinate rings show a relatively small puckering resembling an ‘envelope’ conformation.

SQUARE-PYRAMIDAL COPPER(II) COMPLEXES OF LINEAR TETRADENTATE EDDA-TYPE LIGANDS FORMING SIX-MEMBERED RINGS. MOLECULAR STRUCTURES OF CU(1,3-PDDA) (H2O) AND CU(EDDP) (H2O).3.5H2O

Abstract Three square-pyramidal copper(II) complexes containing a linear O-N-N-O-type tetradentate ligand have been prepared and characterized. The ligands used are 1,3-propanediamine-N,N′-diacetate ion (1,3-pdda), ethylenediamine-N,N′-di-3-propionate ion (eddp) and 1,3-propanediamine-N,N′-di-3-propionate ion (1,3-pddp). In the three compounds a water molecule is in the axial position while the four atoms of ligand are in the basal plane. A five-coordinate, square-pyramidal geometry has been established crystallographically for the complexes [Cu(1,3-pdda)(H2O)] (1) (orthorhombic, Pnma, a = 8.937(4), b = 11.770(5), c = 10.269(5) A, V = 1080.2(8) A3, Z = 4 and R = 0.0699) and [Cu(eddp)(H2O)]·3.5H2O (2) (monoclinic, C2/c, a = 24.430(8), b = 12.195(3), c = 10.514(2) A, β = 110.92(2) V = 2926(1) A3, Z = 8 and R = 0.0515). The Cu(II) ions of these structures are lifted out of plane of the four in-plane ligand atoms by distances ϱ = 0.182(5) and 0.154(1) A, respectively. The six-membered diamine ring of complex 1 assumes the stable chair conformation. The other rings of chelates have expected conformations. The structural data correlating the square-pyramidal stereochemistry are discussed in relation to those obtained for similar complexes. The IR and electronic absorption spectra of [Cu(edda-type)(H2O)] complexes are discussed in comparison with those of related complexes of known geometries. The magnetic measurements are also reported for the complexes studied.

Characterization of the two geometrical isomers of (1,3-propanediamine-N,N′-diacetato-N,N′-di-3-propionato)-nickelate(II). X-ray structure of the binuclear complex trans(O5)-[Ni2(1,3-pddadp)(H2O)4]·4H2O and octahedral distortion of edta-type chelates

Abstract Nickel(II) complexes with the hexadentate ligand 1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate (1,3-pddadp) have been prepared, chromatographically separated into the two geometrical isomers, trans(O5)-Na2[Ni(1,3-pddadp)]·2H2O (1) and trans(O5O6)-Na2[Ni(1,3-pddadp)]·3H2O (2), and characterized. The trans(O5) configuration of compound 1 was found to dominate and this geometry was verified crystallographically in the binuclear complex [Ni2(1,3-pddadp)(H2O)4]·4H2O (1). The complex crystallizes in the triclinic P 1 space group. The structure converged to R=0.0521 for 5210 reflections. The conformations of the chelate rings are those usually observed for these kinds of chelates [a six-membered diamine (T) ring in a twist-boat conformation, the two β-alaninate (G1 and G2) rings in an envelope-like conformation, and the two glycinate rings, R1 in a twist and R2 in an envelope conformation]. The structural data correlating an octahedral distortion are discussed with reference to those of related complexes. The IR and electronic absorption spectra are discussed in comparison with those of similar complexes.

Synthesis and structure of palladium(II) mixed complexes with DNA purine or pyrimidine bases and imidazole derivatives. Part I

SummaryPalladium(II) mixed ligand complexes with purine or pyrimidine and imidazole derivatives were prepared and characterized by i.r., Raman and electronic spectroscopy. The compounds have the general formula [Pd(L1)(L2)(X2)]; where L1 = adenine, guanine, hypoxanthine, cytosine, 2-aminopyrimidine, 4(6)-hydroxypyrimidine; L2 = N-methylimidazole, N-ethylimidazole or N-propylimidazole; X = Cl or Br. The complexes are square planar with cis-halogens. The purine, pyrimidine and imidazole bases act as monodentate ligands coordinated via the N(7) of purine and N(3) of pyrimidine and imidazole.

Reaction products distribution between square-planar gold(III) complexes and N,N,N′,N′-tetramethylthiuram disulfide. Crystal structure of bis(N,N-dimethyldithiocarbamato)gold(III) bromide dihydrate, [Au(Me2NCS2)2]Br·2H2O

SummaryThe reactions of N,N,N′,N′-tetramethylthiuram disulfide (tmtds) with gold(III) complexes of the [Au(L)X3] type [L = N-methylimidazole (N-Melm), 2-methylbenzoxazole (2-MeBO) and 2,5-dimethylbenzoxazole (2,5-diMeBO), X = Cl, Br or I] are reported, and yielded two main types of product - [Au(Me2dtc)X2] (A) and [Au(Me2dtc)2]X (B) (Me2dtc = N,N-dimethyldithiocarbamato anion). The ratio of the product yields (B/A) depends upon the nature of the ligand (L) and halogen (X). The ratio B/A for the reaction: [Au(L)Cl3] + tmtds = A + B, increases in the sequence N-MeIm < 2- MeBO < 2,5-diMeBO, which correlates well with the level of cytotoxic activity exhibited by the [Au(L)Cl3] complexes. A and B were characterized by their i.r., u.v-vis. and 1-n.m.r. spectra. The magnetic measurements were also recorded. The data support a squareplanar geometry for gold(III) complexes with the Me2dtc ligand bonded in a bidentate fashion; a conjecture has been verified crystallographically for [Au(Me2NCS2)2]-Br·2H2O. The X-ray analysis confirmed that the complex is composed of ionic units: [Au(Me2dtc)2] + and Br− and H2O molecules. The Au—S distances are markedly similar, falling in the 2.343(4)–2.350(3) ∘A range.

Interaction between tigecycline and human serum albumin in aqueous solution

The interaction between tigecycline (TGC) and human serum albumin (HSA) in aqueous solution was investigated by fluorescence, UV–Vis spectroscopic and molecular docking methods under physiological conditions. Results of UV–Vis and fluorescence spectroscopy showed that the fluorescence quenching of HSA was a result of the formation of HSA–TGC complex. The binding constants (Ka), binding sites (n), and the corresponding thermodynamic parameters (∆H, ∆S, and ∆G) of the interaction system were calculated. Thermodynamic parameters revealed that the binding process is spontaneous and the hydrophobic interactions were the main force to stabilize the complex. The distance r between the donor (HSA) and acceptor (TGC) molecules was obtained according to Förster’s theory of non-radiation energy transfer. Furthermore, the effect of some metal ions (Ca2+, Cu2+, and Fe3+) on the binding constants between TGC and HSA was examined. Finally, the binding of tigecycline to HSA was modeled using the molecular docking method.Graphical abstract