Monika Wałęsa-Chorab

A new polymeric complex of silver(I) with a hybrid pyrazine–bipyridine ligand – synthesis, crystal structure and its photocatalytic activity

The 2,3-bis(6′-methyl-2,2′-bipyridin-6-yl)pyrazine ligand L reacts with trifluoromethanesulfonate silver(I) to give a coordination polymer {[AgL](CF3SO3)}n in which metal ions are in a distorted tetragonal pyramidal coordination geometry. The complex has been characterized by spectroscopic techniques, elemental analysis, X-ray diffraction, and UV-Vis spectroscopy. The methylene blue (MB) degradation was studied using UV-Vis spectrophotometry. After 400 min of exposure to UV light MB was completely decomposed. Degradation of MB after exposure to sunlight was considerably slower: 34% after 400 min and 90% after 133 h. Photodegradation of the dye follows second-order kinetics. {[AgL](CF3SO3)}n is an active photocatalyst for MB degradation under UV-Vis and sunlight irradiation.

Self-assembly of quaterpyridine ligands and Cu + cation into helical complexes of 2:2 stoichiometry under ESI condition

Solutions containing the quaterpyridine ligand 1 and Cu2+ cation were analysed by electrospray ionisation mass spectrometry (ESI-MS). It was found that copper reduction under ESI conditions and self-assembly of 1 and Cu(I) led to the formation of the 2:2 stoichiometry complex. Such stoichiometry is characteristic of the helical complex of a quaterpyridine ligand with Cu(I). The isotope pattern characteristic of the [Cu212]2+ ion, which is different from that of [Cu1]+ ion, is observed. When using methanol as the solvent, only [Cu212]2+ ions are observed in the mass spectrum obtained at low cone voltage. At higher cone voltage, the [Cu212]2+ ion easily dissociates, producing a [Cu1]+ ion. When using other solvents studied, water and acetonitrile, the 2:2 stoichiometry complex is formed, but along with complexes of other stoichiometries. The helical complex was not observed for the silver cation for which only a 1:1 stoichiometry complex was observed (ion [Ag1]+).

Association of quaterpyridine complex cations with polyanionometallates

Reactions in CH3CN:CH2Cl2 (2:1) under Ar of the dimethyl-quaterpyridine ligand C22H18N4 (L) with Mn(ClO4)2, Fe(BF4)2, CoCl2, Co(NO3)2, Zn(NO3)2, Cd(CH3COO)2 and HgCl2 give complexes of the type [ML(H2O) m X n ]2[MX p ], where X denotes the initial counterions, with m = 1, n = 1, p = 4 or m = 2, n = 0, p = 6. The complexes have been characterised by spectroscopic techniques and elemental analysis. The solid-state structures of two forms of the CoCl2 complex have been established by X-ray crystallography, enabling an analysis of the interactions occurring in crystals of this type.

Novel self-assembled supramolecular architectures of Mn(II) ions with a hybrid pyrazine–bipyridine ligand

A new hybrid pyrazine-bipyridine ligand L (C26H20N6) and its complexes with Mn(NO3)2, Mn(ClO4)2, MnCl2 and MnBr2 have been synthesised. By the self-assembly of L and Mn(II) ions three different kinds of supramolecular complexes have been obtained: binuclear baguette complex [Mn2L(H2O)6](NO3)4·2.5H2O 1 and tetranuclear [2 × 2] grid-type complex [Mn4L4](ClO4)8·2.5(CH3CN)·2CH3OH 2 and mononuclear complexes [MnL2]X2 (where X = Cl(-)3 and X = Br(-)4). Crystal structures and magnetic properties of Mn(II) complexes 1 and 2 have been also investigated. The crystal structures reveal that in both 1 and 2 complexes the Mn(II) ions have coordination number 6 and distorted octahedral coordination geometry. In 2 four metal cations and four ligands have assembled into a grid-type [2 × 2] array, with a perchlorate anion occupying the central cavity, with clearly a good fit for the center of the cavity. The perchlorate anion, in contrast to the nitrate anion, probably acts as a template in the formation of tetranuclear grid-type complexes. Magnetic susceptibility measurements indicate that the Mn(II) ions are all high spin, and in both 1 and 2 complexes there are weak antiferromagnetic interactions between Mn(II) ions.

Association of a terpyridine ligand with lanthanide and copper(II) nitrates

Abstract Reactions between the 1,3-bis(6-methylpyridin-2-yl)pyridine ligand L, C17H15N3 and LnIII (1a, 1b, 1c, 1d) or a mixture of LnIII and CuII nitrates (2a, 2b, 2c, 2d) resulted in a series of respectively novel mono- and heterodinuclear complexes, where LnIII=Sm (a), Eu (b), Tb (c), Dy (d). The compounds were characterized by elemental analysis, ESI-MS and IR spectra, furthermore we obtained crystals of [H2L][Eu(NO3)5] (1b) and [CuL2][Eu(NO3)5] (2b) suitable for XRD characterization. In the crystal structures the Eu ions are 10-coordinated with quite a narrow range of Eu-O distances which are between 0.2436 and 0.2556 nm. In 1b the ligand molecule is protonated in both terminal rings, and the N-H groups are involved in the N-H···O hydrogen bonds with the same oxygen atom of one of the nitro groups. These hydrogen bonds connect the ions in 1b into the complex which is the principal building block of the structure. In 2b the [CuL2]2+ counterions are present; the Cu is octahedrally coordinated by all nitrogen iatoms of two L molecules which are therefore almost perpendicular to each other. The electrostatic interactions between the charged species are in both cases the main driving force of the crystal packing.

Electrochromism and electrochemical properties of complexes of transition metal ions with benzimidazole-based ligand

Six new mononuclear complexes of transition metal ions (1–6) with (E)-2-(1-methyl-2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)-1H-benzoimidazole L were synthesized and characterized by spectroscopic methods as well as X-ray diffraction analysis. Structures of these complexes can be divided into three groups depending on the coordination number and environment of the metallic center: the first one of general formula [ML2]X2, the second one - [MLX3] and the third one - [MLX2], where X is anion or solvent molecule. Electrochemical and electrochromic properties of complexes were investigated. Complexes Fe(II) 1, Cu(II) 2–4 and Co(II) 5 were found to be electroactive and their colors depend on the oxidation state of metal center and ligand molecule. Fe(II) complex 1 exhibits purple color in the neutral state and its color changes to yellow after Fe(II) → Fe(III) oxidation, followed by pale-yellow after further oxidation of ligand molecule and to green when the metal center is reduced to Fe(I). The original color can be restored after electrochemical oxidation Fe(I) to Fe(II). It was found that this complex exhibits high color stability in solution during multiple oxidation/reduction cycles. This complex can be therefore regarded as very interesting material for the construction of multielectrochromic devices.

Generation of Low-Dimensional Architectures through the Self-Assembly of Pyromellitic Diimide Derivatives

Small π-conjugated molecules can be designed and synthesized to undergo controlled self-assembly forming low-dimensional architectures, with programmed order at the supramolecular level. Such order is of paramount importance because it defines the property of the obtained material. Here, we have focused our attention to four pyromellitic diimide derivatives exposing different types of side chains. The joint effect of different noncovalent interactions including π–π stacking, H-bonding, and van der Waals forces on the four derivatives yielded different self-assembled architectures. Atomic force microscopy studies, corroborated with infrared and nuclear magnetic resonance spectroscopic measurements, provided complementary multiscale insight into these assemblies.

Supramolecular complexes of cobalt(II), manganese(II) and cadmium(II) with bis(terpyridine) ligand as novel luminescent materials

Abstract Self-assembly of N6-donor bis(terpyridine) ligand L with transition metal ions: Co(II), Mn(II) and Cd(II) leads to a formation of three kinds of supramolecular complexes. In the electronic absorption and emission spectra of supramolecular complexes additional bands were observed what was ascribed to the coordination of ligand molecules to metal ions. Luminescence properties of these complexes strongly depend on the kind of metal ions and counter ions. The effective blue luminescence was observed in the case of Mn(II) and Cd(II) complexes in which all N-donor atoms of ligand molecules coordinate with the metal center

Coordination properties of N,N′-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine with d- and f-electron ions: crystal structure, stability in solution, spectroscopic and spectroelectrochemical studies

Template reaction between 5-methylsalicylaldehyde and 2-hydroxy-1,3-propanediamine in the presence of copper ion led to dinuclear and mononuclear copper(II) complexes [Cu2L(CH3COO)(CH3OH)](CH3OH) (1) and [CuHL](CH3OH) (2), where H3L is N,N′-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine. The result of the reactions between 5-methylsalicylaldehyde and 2-hydroxy-1,3-propanediamine in the presence of lanthanide ions and/or copper(II) ion was N,N′-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine (H3L B) or [CuHL](CH3OH) (2), respectively. Structures of the compounds were determined by single-crystal X-ray diffraction and physicochemical methods. The microstructures and phase compositions of crystals were studied by scanning electron microscopy (SEM). In dinuclear complex [Cu2L(CH3COO)(CH3OH)](CH3OH) (1), two copper(II) ions are bond to one H3L ligand and one acetate ion. Coordination modes of the two copper centers are different: the geometry of copper 1 is almost ideal square-planar, while that for copper 2 can be described as tetragonal pyramidal. In complex [CuHL](CH3OH) (2), the copper(II) ion is four coordinated and the coordination, rather than square-planar, can be described as flattened tetrahedral. Formation of complexes between copper(II) or lanthanide ions with N,N′-bis(5-methylsalicylidene)-2-hydroxy-1,3-propanediamine (H3L) was also studied in solution by pH potentiometry. It should be mentioned that the complexes of lanthanide ions exist only in solution. Additionally, the salen-type ligand H3L and its dinuclear and mononuclear copper(II) complexes were studied by cyclic voltammetry, and their spectroelectrochemical properties were examined.

CCDC 1564775: Experimental Crystal Structure Determination

Related Article: Monika Walesa-Chorab, Radoslaw Banasz, Maciej Kubicki, Violetta Patroniak||Electrochimica Acta|||doi:10.1016/j.electacta.2017.11.100