Maria Lalia-Kantouri

Kinetic analysis of thermogravimetric data on some nickel(II) N-alkyldithiocarbamates

Thermogravimetric and derivative thermogravimetric curves of some complexes [Ni(S2CNHR)2] (R=Me, Et, Pri, Bui, But, Bz,p-MePh,p-MeOPh,p-ClPh,p-NO2Ph) in a dynamic nitrogen atmosphere were studied to determine their modes of decomposition. All these complexes show similar TG profiles. The weight losses in the main decomposition stages indicate conversion of the nickel(II) dithiocarbamates to sulphide. Reaction orders were estimated via the shape characteristics of the corresponding derivative thermogravimetric curves and kinetic analysis of the thermogravimetric data was performed by using the Coats-Redfern and Horowitz-Metzger methods.ZusammenfassungIm Stickstoffstrom wurden TG- und DTG-Kurven einiger Komplexe [Ni(S2CNHR)2] mit R=Me, Et, Pri, Bui, But, Bz,p-MePh,p-MeOPh,p-ClPh undp-NO2Ph ermittelt, um Art und Weise ihrer Zersetzung zu bestimmen. Alle diese Komplexe zeigen ähnliche TG-Proflle. Die Gewichtsverluste der Hauptzersetzungsschritte weisen auf eine Umwandlung der Nickel(II)dithiokarbamate in Sulfide hin. Aus dem Verlauf der korrespondierenden DTG-Kurven wurde auf die Reaktionsordnung geschlossen und unter Anwendung der Coats-Redfern und Horowitz-Metzger Methoden wurde eine kinetische Analyse der TG-Daten durchgeführt.РезюмеС целью определения х арактера разложения комплексов [Ni(S2CNHR)2], где R=Me, Et, i-Pr, i-Вц, t-Bu, Bz, p-MePh, p-MeOPh, p-ClPh и p-NO2Ph, были изме рены в динамической атмосфере азота крив ые ТГ и ДТГ. Все комплек сы показали подобный ха рактер ТГ кривых. Потери веса на главны х стадиях разложения указывают на превращение дитио карбаматов никеля до его сульфид а. Порядок реакций был определен посредством модельн ых характеристик соответствующих ДТГ кривых и кинетическо го анализа данных ТГ, проведенно го методами Коутса-Рэдферна и Хор овиц-Мецгера.

Copper(II) complexes of salicylaldehydes and 2-hydroxyphenones: synthesis, structure, thermal decomposition study and interaction with calf-thymus DNA and albumins

The neutral mononuclear copper(II) complexes with substituted salicylaldehyde (X-saloH), or 2-hydroxyphenone (ketoH) ligands, having the formula [Cu(L)2(S)n] (where S = solvent CH3OH or H2O and n = 0, 1 or 2) have been prepared and characterized, and their interaction with DNA and albumins was studied. The ligands are chelated to the metal ion through the phenolate and carbonyl oxygen atoms. The crystal structures of [Cu(5-NO2-salo)2(CH3OH)2] (3), [Cu(5-Cl-salo)2] (4), [Cu(bpo)2] (6) and [Cu(mpo)2]·2H2O (7·2H2O) have been determined by X-ray crystallography. The thermal stability of the copper complexes has been investigated by a simultaneous TG/DTG-DTA technique. Spectroscopic (UV), electrochemical (cyclic voltammetry) and physicochemical (viscosity measurements) techniques have been employed in order to study the binding mode and strength of the complexes to calf-thymus (CT) DNA while competitive studies with ethidium bromide (EB) performed by fluorescence spectroscopy have revealed the ability of the complexes to displace the DNA-bound EB. In conclusion intercalation is the most possible mode of interaction of the complexes with CT DNA. The interaction of the complexes with serum albumin proteins has been studied by fluorescence emission spectroscopy and the determined binding constants exhibit relatively high values.

Synthesis and characterization of new addition compounds of bis(2-hydroxyaryloximato) nickel(II) with α-diimines: Crystal and molecular structure of [Ni(saox)2phen]·H2O

Abstract A series of new addition compounds of bis(2-hydroxyaryloximato) nickel(II), [Ni(ox)2], with an α-diimine (enR), under the general formula [Ni(ox)2enR], were synthesized and characterized. The IR and electronic excitation spectra indicate that the bidentate coordination mode of the ligands consists with the chromophore NiN4O2. The octahedral environment around nickel(II) was confirmed by an X-ray structure analysis of [1,10-phenanthroline-bis(2-hydroxy-benzaldoximato)nickel(II)], [Ni(saox)2phen]·H2O. The equatorial plane, which encompasses the nickel atom, is formed by four nitrogen atoms, two coming from the phenanthroline molecule and two from the two molecules of the 2-hydroxybenzaldoxime (salicylaldoxime). In the apical positions lie the two deprotonated phenolic oxygen atoms of the two salicylaldoxime ligands. The thermal stability and decomposition mode were studied in nitrogen using the technique of thermogravimetry (TG/DTG). Mass spectrometry was also used, and possible fragmentation patterns are given and discussed.

CRYSTAL STRUCTURE AND SPECTRA OF TRANS-BIS(PROPANONE, 1-2-HYDROXYPHENYL-OXIMATO)PALLADIUM(II)

Abstract The compound [Pd(ppox)2], (where ppox− denotes the anion of 2-hydroxypropiophenoneoxime, C9H10NO2−), was prepared and investigated by means of structural and spectroscopic (IR and electronic) measurements. The electronic excitation spectra are consistent with a square-planar PdN2O2 chromophore. The structure was determined by single-crystal X-ray diffraction and consists of discrete Pd(ppox)2 monomeric units. The Pd atom is in the equatorial plane bonded to two nitrogen atoms and two oxygen at distances of 1.979(3) and 1.970(2) A, respectively.

Cadmium(II) complexes of 5-nitro-salicylaldehyde and α-diimines: synthesis, structure and interaction with calf-thymus DNA

Five Cd(II) complexes with the anion of 5-NO2-salicylaldehydeH (5-NO2-saloH) in the absence or presence of the α-diimine 1,10-phenanthroline (phen), 2,2′-dipyridylamine (dpamH), 2,2′-dipyridine (bipy), or 2,9-dimethyl-1,10-phenanthroline (neoc) were synthesized and characterized as [Cd(5-NO2-salo)2(CH3OH)2] (1), [Cd(5-NO2-salo)2(phen)]·2CH3OH·H2O (2), [Cd(5-NO2-salo)2(dpamΗ)] (3), [Cd3(5-NO2-salo)6(bipy)2] (4), and [Cd(5-NO2-salo)(neoc)(NO3)]2 (5). Based on spectroscopic results (IR, UV, NMR), elemental analysis and conductivity measurements an octahedral geometry around cadmium metal ion is suggested, with the 5-NO2-salicylaldehyde ligand having different coordination modes. The structures determined by X-ray crystallography verified neutral mononuclear 1–3 and trinuclear 4. Simultaneous TG/DTG–DTA technique was used to analyze the thermal behavior of 1, 2, and 3. The complexes bind tightly to calf-thymus DNA mainly by intercalation, as concluded by DNA viscosity measurements and exhibit significant displacement of EB from the EB-DNA complex.

Study of copper(I) heteroleptic compounds with 1-phenyl-1, 4-dihydro-tetrazole-5-thione and triphenylphosphine

The synthesis and structural investigation of three mononuclear heteroleptic copper(I) complexes of 1-phenyl-1,4-dihydro-tetrazole-5-thione (HL) with the stoichiometry [CuX(HL)(PPh3)2], where X represents a halide, are reported. The compounds were studied both in the solid state and in solution by a variety of spectroscopic methods. X-ray crystal structure determination of the three compounds revealed a distorted tetrahedral coordination environment around copper in every case. The thermal behavior of the complexes was investigated with respect to the thione ligand fragmentation. Complexation to copper(I) has a stabilizing effect on the nitrogen-rich thione as the TG studies on the free ligand reveal. **Dedicated to the memory of Professor Stefan I. Stoyanov.

Thermal decomposition kinetics of square-planar d8 bis(N-monosubstituted-dithlocarbamato)metal(II) complexes

Abstract Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies of [N(S 2 CN-HR) 2 ] complexes (M = Ni, Pd, Pt; R = Bu n , Cx, Ph) in dynamic nitrogen atmosphere have been performed, to determine their modes of decomposition. All of the complexes showed similar TG profiles. Mass loss considerations at the main decomposition stages indicate conversion of the metal(II) dithiocarbamates to sulphides. Reaction orders in each case were estimated by the shape characteristics of the corresponding DTG curves. Finally, kinetic parameters (energy, entropy of activation and pre-exponential factor) were determined from the TG curves.

trans-Dichloro(η 2-ethylene) (N-3-pyridinylmethanesulfonamide)platinum(II). Crystal structure, spectroscopic, and thermoanalytical characterization, and cytotoxicity assays

The organometallic complex, trans-[PtCl2(η 2-C2H4)(PMSA)] (1), where PMSA = N-3-pyridinylmethanesulfonamide, has been synthesized and characterized by elemental analysis, molar electric conductivity, IR, electronic, and NMR (1H, 13C, and 195Pt) spectroscopy, and thermal analysis. X-ray crystallography revealed that in 1 [monoclinic, P21 c, a = 5.1260(1), b = 19.1600(4), c = 12.7990(3) Å, β = 97.242(2)°, Z = 4] Pt(II) shows planar coordination geometry with PMSA coordinated via the pyridine. The ethylene is virtually perpendicular to the PtCl2N plane with the pyridine ring twisted relative to this plane by 47°. In in vitro assays, PMSA, K[PtCl3(η 2-C2H4)] · H2O, and 1 do not exhibit appreciable cytotoxic activity against human K562 and HepG2 tumor cell lines.

Thermal activities in Greece

The history of the Hellenic Society of Thermal Analysis (HSTA) is outlined. A review of thermal activities in Greece is presented, concentrating on polymeric and inorganic materials, minerals and pharmaceuticals. Some examples are given.

Copper(I) halide complexes of 2,2,5,5-tetramethyl-imidazolidine-4-thione: Synthesis, structures, luminescence, thermal stability and interaction with DNA.

Five neutral mononuclear copper(I) halide complexes containing 2,2,5,5-tetramethylimidazolidine-4-thione (tmimdtH) and triphenylphosphane (PPh3) or tri-o-tolylphosphane (totp) have been prepared and structurally characterized by X-ray single-crystal analysis. The complexes containing PPh3 adopt the usual distorted tetrahedral geometry, while the presence of the bulkier totp forces the formation of three-coordinated trigonal planar species. The interaction of the compounds with calf-thymus DNA was monitored directly via UV-vis spectroscopy, DNA-viscosity measurements and indirectly via its competition with ethidium bromide for DNA studied by fluorescence emission spectroscopy. Intercalation was revealed as the most possible mode of binding. Furthermore, luminescent properties and thermal stabilities of the complexes were investigated.