Maria Cieślak-Golonka

Spectroscopy of chromium(VI) species

This review is concerned with recent developments in the spectroscopy of the chromium(VI) ion covering the literature published mostly in the last decade. The growing industrial importance of chromium(VI) compounds and ecological problems connected with environmental pollution prompted to devote this work entirely to the highest oxidation state of this metal. The chromium-oxygen species described here form discrete units which remain unchanged during various chemical reactions. Contrary to the tetrahedral oxyanion where the CrO 4 2− group is clearly established, the CrO 4+ and CrO 2 2+ species are often only formal as in CrO 2 Cl 2 where strong covalent bonds exist between the metal ion and chlorine

Silver(I) complexes with hydantoins and allantoin☆ Synthesis, crystal and molecular structure, cytotoxicity and pharmacokinetics

Coordination polymers [Ag(L(1,3))](n) (L(1)=hydantoin, L(3)=5,5-dimethylhydantoin), {[Ag(L(2))](.)0.5H(2)O}(n) (L(2)=1-methylhydantoin) and [Ag(NH(3))(L(4))](n) (L(4)=allantoin) were prepared and characterized by elemental analysis, spectroscopic (IR, FTIR and NMR), thermal and mass spectrometry methods. The crystal structure of {[Ag(1-methylhydantoin)]·0,5H(2)O}(n) was determined and analyzed. Three 1-methylhydantoinate ligands create a T-shape (CN=3) coordination sphere around the Ag(+) ion. Additionally, a short Ag⋯Ag distance of 2.997Å was found in the structure resulting in the expanded [3+2] environment of a distorted square shape. The [Ag(L(2))] entities are bound to each other by the bridging organic ligands. Thus a two-dimensional coordination polymer is created with water molecules located between the layers. In contrast to hydantoins, the allantoin complex contains an additional ammonia molecule in the coordination sphere. Moreover, in the Ag-alla complex the M-organic ligand binding site is shifted to the N-atom of the ureid chain. Free ligands are cytotoxically inactive against human MCF-7 and A549 cancer cell lines and mouse fibroblasts Balb/3T3. The silver hydantoin complexes exhibit a very strong activity against these lines. (The introduction of the methyl groups to the ring slightly increases resistance only against the A549 cell line.) In contrast, the silver complex of allantoin shows only a weak activity which may be related to the presence of the cytotoxic ammonia group in the composition of the compound and/or the different binding site of the ligand. Calculated in silico physiochemical parameters are promising for the future application of the complexes as drugs.

Systematic investigation of the [Ni2+–phen–CrO42−] system; dichromate species isolated from alkaline solutions

Abstract Nickel(II) dichromate and chromate complexes with 1,10-phenanthroline were isolated from basic (pH 8–9) solutions. [Ni(phen)3]Cr2O7·8H2O (1), NiCrO4 (2), [Ni(phen)3]Cr2O7·3H2O (3) and [Ni(phen)(OCrO3)(H2O)3]·H2O (4) were characterized with spectroscopic (UV–Vis, IR, FIR) methods and one (4), additionally, with X-ray data. In the complex (4) the chromate ion is monodentately coordinated to nickel ion. This complex crystallizes in the triclinic crystal system (space group P 1 ). The single crystal electronic spectrum of complex (4) at 4 K reveals a rare feature when the structured second d–d band (Oh symmetry) is unsplit in spite of lowering symmetry. The filtration process has revealed that this band is vibronically structured in the νs NiOCr quantum. A new broad low intensity band at approximately 14 000 cm−1 was assigned to the forbidden transition in the bridge. An attempt to explain precipitation of dichromates from alkaline solutions has been given.

Synthesis, crystal structure and spectroscopic characterisation of double salt [Zn(bpy)3](CrO4)0.5NO36.5H2O

Abstract A new Zn(II) complex with 2,2′bipyridine (bpy), chromate and nitrate groups, [Zn(bpy)3](CrO4)0.5NO36.5H2O has been prepared and characterised with crystallographic and spectroscopic methods. The orthorhombic complex crystallises in the space group Ccc2 with the lattice constants a=13.992(3) A , b=24.483(5) A , c=21.556(4) A and Z=8. The coordination environment about Zn(II) ion is nearly octahedral. The CrO42− and NO3− entities exhibit anionic position in the crystal. The electronic spectra enhanced with mathematical methods (filtration and deconvolution) exhibit the presence of vibrational fine structure in the CrO42− entity on the spin-forbidden 3T1 transition.

Reflectance Spectra and Color of Potassium and Silver Chromates in Various Matrices

The matrix influence on the diffuse reflectance spectra of K2CrO4 and Ag2CrO4 has been studied spectroscopically and colorimetrically. Oxide matrices (MgO, BaO, Li2CO3) were found to be inert towards the studied compounds. In halide matrices, the symmetry decrease of the tetrahedral CrO42− ion was observed through the appearance of the symmetry-forbidden transitions and intensity reversal. A bathochromic shift of the bands, in comparison to the results for K2CrO4, was found in the Ag2CrO4/Ag2SO4 system. It is explained under the assumption of strong cationanion interaction in the latter. On the basis of the color parameters, the halide matrices can be ordered according to their inertness towards K2CrO4. The quantitative relationship between the matrix effect and the molecular size of the host lattice components is given for K2CrO4.

Atypical calcium coordination number: Physicochemical study, cytotoxicity, DFT calculations and in silico pharmacokinetic characteristics of calcium caffeates.

Two complexes of calcium ions containing monodeprotonated caffeate ligands were synthesized and physicochemically (IR, FIR, NMR, thermal analysis) and theoretically (DFT and pharmacokinetical parameters) characterized. [Ca(C(9)H(7)O(4))(2)].2H(2)O 1a and [Ca(C(9)H(7)O(4))(2)].2H(2)O KNO(3)1b are compounds with unusual four coordinate calcium ion containing the ligand coordinated to the metal ion through two carboxylic groups arranged with tetrahedrally-like mode (CaO(4)). Two water molecules are outside the first coordination sphere bound non-equivalently to the ligand through a net of hydrogen bonding. The compounds were found to be cytotoxically inactive. Finally, in silico parameters predict the potential application of the compound as a supplement and/or drug.

Application of the Digital Filter Method to Analysis of the d—d Absorption Bands in the Spectra of Cr(III) Complexes

Abstract A variable digital filter method was used to obtained well resolved solid state electronic spectra of Cr(III) complexes with ascorbic acid, cysteine and glutathione. Details of the filtered spectra such as symmetry lowering of the systems and fine structure were analyzed in terms of tetragonal distortions in the coordination sphere of the Cr(III) ion. Crystal field: Dq, Ds, Dt as well as Racah parameters B have been calculated.

Spectral studies on silver chromate and nitrate complexes with heterocyclic amines

Abstract Silver chromate and nitrate complexes of the general formulae [Ag2(L)x(CrO4)] and [Ag(L)x(NO3)] (L—heterocyclic amine) were synthesized and spectrally investigated. The coordination of the anion in [Ag2(4,′4bipy)(CrO4)] and [Ag2(HMTA)(CrO4)] was proposed from the IR data. A prominent matrix effect on the electronic spectra has been observed.

Homo- and hetero-nuclear chromium(III) complexes with natural ligands. Part 1. Spectroscopic and mass spectra studies on ternary [M–L1–L2] systems

Seven new ternary mono- and poly-nuclear CrIII complexes with natural ligands: glycine, glutaminic, nicotinic and asparginic acids, cysteine and glutathione, have been isolated and physicochemically characterized. Four of them have been tested and appear to be non-toxic. The complexes have been analysed using spectroscopic (diffuse reflectance U.v–vis., i.r., f.i.r.), magnetic methods, and (some) by FAB mass spectra. Spectral analyses with the digital filter and band deconvolution methods have been also presented.

The reactivity of cis-platin. Spectroscopic properties of products isolated from the [cis-Pt(NH3)2Cl2–quercetin] and [cis-Pt(NH3)2Cl2–CrVI–quercetin] systems

New coordination compounds: [PtIIQ] and [PtIV–CrIIIQ2], where Q = quercetin, were isolated from the [Pt(NH3)2Cl2–quercetin] and [Pt(NH3)2Cl2–CrVI–quercetin] systems, respectively. Structures are proposed on the basis of i.r., n.m.r. and deconvoluted electronic spectra.