Dimethyl Derivatives of 2,2'-Bipyridine as Ligands in [W(CN)6(bpy)]2--Type Complexes.

The thermal decomposition of (XMebpyH)3(H3O)[W(CN)8]·3H2O (where XMebpy denotes 4Mebpy 4,4'-dimethyl-2,2'-bipyridine or 5Mebpy 5,5'-dimethyl-2,2'-bipyridine) in glycerol results in the coordination of XMebpy. Salts of the anion formula [W(CN)6(XMebpy)]2- were isolated for PPh4+ and/or AsPh4+ cations as well as for K+, Rb+, and Cs+ ones. X-ray single-crystal analyses for tetraphenyl-phosphonium and tetraphenyl-arsonium cations are described. IR, UV-Vis, and cyclic voltammetry data are presented. The results were compared with those for [W(CN)6(bpy)]2- (bpy = 2,2'-bipyridine) ion salts.

Covalent Modification by Click Mechanochemistry: Systematic Installation of Pendant OH Groups in a MOF for Rigidity Control and Luminescence-Based Water Detection.

Covalent linker transformations in metal-organic frameworks (MOFs) enable their functionalization but often suffer from low conversions or require harsh conditions, including heating, corrosive reactants and solvents, or catalysts. In this work, using solvent-free mechanochemistry for the first time for such conversions, we demonstrate the systematic MOF pore modification with pendant hydroxyl groups and the resulting effects on the network rigidity, its luminescent properties, as well as adsorption of CO2 and vapors of methanol, ethanol, isopropanol, D2O, and H2O. A new zinc-based heterolinker MOF (JUK-20) containing both protic luminescent units and reactive tetrazine cores was used as a model and subjected to an inverse electron-demand Diels-Alder (iEDDA) click reaction with a series of dienophiles (x) of different lengths having OH groups. From the obtained series of JUK-20(Zn)-x MOFs, a flexible material capable of luminescent humidity sensing was identified, and the influence of water on the luminescence of the material was explained by analogy with the excited-state intramolecular proton transfer (ESIPT) model. In general, our results provide guidance for designing and tuning MOFs for luminescence-based detection using a stepwise synthetic approach.

Ionic Dioxidovanadium(V) Complexes with Schiff-Base Ligands as Potential Insulin-Mimetic Agents-Substituent Effect on Structure and Stability.

Four dioxidovanadium(V) complexes with Schiff-base ligands based on 2-hydroxybenzhydrazide with four different substituted salicylaldehydes (5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde, 5-nitrosalicylaldehyde, 3-bromo-5-chlorosalicylaldehyde) were synthesized and described, by using V2O5 and triethylamine. The single crystal X-ray structure measurements as well as elemental analyses and IR spectra confirmed the formulas of the ionic complexes with a protonated triethylamine acting as counterion, HTEA[VO2(L)] (HL = Schiff-base ligand). The kinetic stability of the complexes at pH = 2 and 7 was discussed with respect to the neutral vanadium(V) complexes previously studied as potential insulin-mimetic agents. A correlation between the substituents in an aromatic ring of the Schiff-base ligands with crystal packing, and also with the stability of the compounds, was presented.

The High-Temperature Soft Ferromagnetic Molecular Materials Based on [W(CN)6(bpy)]2-/- System.

The synthesis of molecular materials with magnetic properties, in particular ferromagnetic properties, has been the subject of interest in coordination chemistry for decades. In the last three decades, research has accelerated, as it has emerged that creating bridging systems based on cyanido ligands is a good and relatively simple way to create complex polymer structures exhibiting magnetic properties. Based on many years of personal experience in the field of the synthesis of polycyanido systems, supported by comprehensive structural analysis, a simple method of transforming cyanido complexes into soft ferromagnetic materials with a Curie temperature (TC) higher than the thermal decomposition temperature, usually above 150 °C has been developed. Two soft ferromagnetic materials based on zinc and cadmium hexacyanido salts in the system with [W(CN)6(bpy)]2-/- anions are presented. The crystal structures (X-ray single crystal as well as XRD) of the precursors and the properties of the ferromagnetic materials are discussed. Most importantly, a patented method of synthesizing this type of material, based on which we obtain more than 80 soft, high-temperature ferromagnetic compounds, which proves the wide spectrum of this method, is also presented.

The Role of Prussian Blue-Thallium and Potassium Similarities and Differences in Crystal Structures of Selected Cyanido Complexes of W, Fe and Mo.

The synthesis and single X-ray crystal structures of Tl2[W(CN)6(bpy)]·H2O, Tl[W(CN)6(bpy)], Tl57[{Fe(CN)6}12{NO3}9]·9H2O, Tl4[W(CN)8] and Tl4[Mo(CN)8] are described. Salts crystalize in the monoclinic or trigonal (Fe) space group. For all complexes, the very unusual "side-on" coordination of Tl to C and N of cyanido ligands is observed and compared to potassium cations. The very strong bonding to cyanido ligands with an 8-13 coordination number of thallium is described and discussed. The difference between potassium and thallium bonding is an indication of the biological activity of thallium and the role of Prussian blue in the thallium detoxification procedure.

Anion-cation interactions in a series of salts with substituted Hphen, Hbpy and H2bpy cations and [W(CN)8]4- anion: polymer with "super-short" N-H⋯N hydrogen bridges containing exclusively anions and H.

The 10 ion-pairs of [W(CN)8]4- with substituted Hphen and Hnbpyn+ (where phen = 1,10-phenantroline, bpy = 2,2'-bipyridine, n = 1 or 2) were isolated and the spectroscopic properties of these salts are discussed. Three salts with dimethyl-substituted Hnbpyn+ cation were structurally characterized. In the structure of the salt with H2bpy, one of the cyanido ligands of the anion is in the CNH form. This situation is very unique, as well as the formation of two water double bridges by water molecules in [W(CN)8]4-. The formulas of other compounds were determined based on the IR spectra, thermogravimetry, and elemental analyses. The ion-pair formation was accompanied not only by anion-cation charge-transfer bands in the visible part of the electronic spectra, but also low-energy bands above 1000 nm were found and are related to the thermal electron transfer; the amount of the paramagnetic WV was determined by EPR measurement. The thermal excitation of electrons may indicate the possibility of using these compounds as semiconductors. Finally, the improved method of K4[W(CN)8]·2H2O synthesis is also described.

Synthesis and Structure of Novel Copper(II) Complexes with N,O- or N,N-Donors as Radical Scavengers and a Functional Model of the Active Sites in Metalloenzymes.

To evaluate the antioxidant activity of potential synthetic enzyme mimetics, we prepared new five copper(II) complexes via a self-assembly method and named them [Cu(2-(HOCH2)py)3](ClO4)2 (1), [Cu(2-(HOCH2)py)2(H2O)2]SiF6 (2), [Cu2(2-(HOCH2CH2)py)2(2-(OCH2CH2)py)2](ClO4)2 (3), [Cu(pyBIm)3](BF4)2·1.5H2O (4) and [Cu(py2C(OH)2)2](ClO4)2 (5). The synthetic protocol involved N,O- or N,N-donors: 2-(hydroxymethyl)pyridine (2-(HOCH2)py), 2-(hydroxyethyl)pyridine (2-(HOCH2CH2)py), 2-(2-pyridyl)benzimidazole (pyBIm), di(2-pyridyl)ketone (py2CO). The obtained Cu(II) complexes were fully characterised by elemental analysis, FTIR, EPR, UV-Vis, single-crystal X-ray diffraction and Hirshfeld surface analysis. Crystallographic and spectroscopic analyses confirmed chromophores of both monomeric ({CuN3O3} (1), {CuN2O4} (2), {CuN6} (4), {CuN4O2} (5)) and dimeric complex ({CuN2O3} (3)). Most of the obtained species possessed a distorted octahedral environment, except dimer 3, which consisted of two copper centres with square pyramidal geometries. The water-soluble compounds (1, 3 and 5) were selected for biological testing. The results of the study revealed that complex 1 in solutions displayed better radical scavenging activity than complexes 3, 5 and free ligands. Therefore, complex 1 has been selected for further studies to test its activity as an enzyme mimetic. The chosen compound was tested on the erythrocyte lysate of two groups of patients after undergoing chemotherapy and chemoradiotherapy. The effect of the tested compound (1) on enzyme activity levels (TAS, SOD and CAT) suggests that the selected complex can be treated as a functional mimetic of the enzymes.

Tuning Anti-Biofilm Activity of Manganese(II) Complexes: Linking Biological Effectiveness of Heteroaromatic Complexes of Alcohol, Aldehyde, Ketone, and Carboxylic Acid with Structural Effects and Redox Activity.

The constantly growing resistance of bacteria to antibiotics and other antibacterial substances has led us to an era in which alternative antimicrobial therapies are urgently required. One promising approach is to target bacterial pathogens using metal complexes. Therefore, we investigated the possibility of utilizing series of manganese(II) complexes with heteroaromatic ligands: Alcohol, aldehyde, ketone, and carboxylic acid as inhibitors for biofilm formation of Pseudomonas aeruginosa. To complete the series mentioned above, Mn-dipyCO-NO3 with dipyridin-2-ylmethanone (dipyCO) was isolated, and then structurally (single-crystal X-ray analysis) and physicochemically characterized (FT-IR, TG, CV, magnetic susceptibility). The antibacterial activity of the compounds against representative Gram-negative and Gram-positive bacteria was also evaluated. It is worth highlighting that the results of the cytotoxicity assays performed (MTT, DHI HoloMonitorM4) indicate high cell viability of the human fibroblast (VH10) in the presence of the Mn(II) complexes. Additionally, the inhibition effect of catalase activity by the complexes was studied. This paper focused on such aspects as studying different types of intermolecular interactions in the crystals of the Mn(II) complexes as well as their possible effect on anti-biofilm activity, the structure-activity relationship of the Mn(II) complexes, and regularity between the electrochemical properties of the Mn(II) complexes and anti-biofilm activity.

A Vanadium-Catalyzed Synthesis of Fully Substituted Pyrroles.

We present a straightforward, fast, inexpensive, and environmentally friendly synthesis of 1,2,3,4,5-pentasubstituted derivatives of pyrrole, which were produced in one-pot reactions of 3-oxoanilides with hydrazides of carboxylic acids, catalyzed by 10 mol % VOSO4·H2O. The reactions were carried out in ethanol in contact with air as the oxidant. The 19 pyrroles obtained were usually crystalline and did not require purification. The reaction tolerates various substituents in both substrates. All products were characterized by infrared, nuclear magnetic resonance, and ultraviolet-visible spectroscopy and elemental analysis. The molecular structures of the products and the intermediates were unambiguously determined by X-ray single-crystal analysis.

Ruthenium(IV) Complexes as Potential Inhibitors of Bacterial Biofilm Formation.

With increasing antimicrobial resistance there is an urgent need for new strategies to control harmful biofilms. In this study, we have investigated the possibility of utilizing ruthenium(IV) complexes (H3O)2(HL1)2[RuCl6]·2Cl·2EtOH (1) and [RuCl4(CH3CN)2](L32)·H2O (2) (where L1-2-hydroxymethylbenzimadazole, L32-1,4-dihydroquinoxaline-2,3-dione) as effective inhibitors for biofilms formation. The biological activities of the compounds were explored using E. coli, S. aureus, P. aeruginosa PAO1, and P. aeruginosa LES B58. The new chloride ruthenium complexes were characterized by single-crystal X-ray diffraction analysis, Hirshfeld surface analysis, FT-IR, UV-Vis, magnetic and electrochemical (CV, DPV) measurements, and solution conductivity. In the obtained complexes, the ruthenium(IV) ions possess an octahedral environment. The intermolecular classical and rare weak hydrogen bonds, and π···π stacking interactions significantly contribute to structure stabilization, leading to the formation of a supramolecular assembly. The microbiological tests have shown complex 1 exhibited a slightly higher anti-biofilm activity than that of compound 2. Interestingly, electrochemical studies have allowed us to determine the relationship between the oxidizing properties of complexes and their biological activity. Probably the mechanism of action of 1 and 2 is associated with generating a cellular response similar to oxidative stress in bacterial cells.

Synthesis, Structural Characterization and Antimicrobial Evaluation of Ruthenium Complexes with Heteroaromatic Carboxylic Acids.

The antibacterial and antibiofilm activities of two new ruthenium complexes against E. coli, S. aureus, P. aeruginosa PAO1 (laboratory strain) and P. aeruginosa LES B58 (clinical strain) were evaluated. Complexes, mer-[RuIII (2-bimc)3 ] ⋅ H2 O (1) and cis-[RuIV Cl2 (2,3-pydcH)2 ] ⋅ 4H2 O (2), were obtained using aromatic carboxylic acid ligands, namely, 1H-benzimidazole-2-carboxylic acid (2-bimcH) and pyridine-2,3-dicarboxylic acid (2,3-pydcH2 ). Compounds were physicochemically characterized using X-ray diffraction, Hirshfeld surface analysis, IR and UV/VIS spectroscopies, as well as magnetic and electrochemical measurements. Structural characterization revealed that Ru(III) and Ru(IV) ions in the complexes adopt a distorted octahedral geometry. The intermolecular classical and weak hydrogen bonds, and π⋅⋅⋅π contacts significantly contribute to structure stabilization, leading to the formation of a supramolecular assembly. Biological studies have shown that the Ru complexes inhibit the growth of bacteria and biofilm formation by the tested strains and the complexes seem to be a potential as antimicrobial agents.

Isophthalate-Hydrazone 2D Zinc-Organic Framework: Crystal Structure, Selective Adsorption, and Tuning of Mechanochemical Synthetic Conditions.

A new layered mixed-linker metal-organic framework [Zn2(iso)2(pcih)2]n (MOF) built from isophthalate ions (iso2-) and 4-pyridinecarbaldehyde isonicotinoyl hydrazone (pcih) was prepared using both solution and mechanochemical methods. By use of the latter, the 2D MOF is obtained either in a one-mortar three-component grinding or on the way of a two-step mechanosynthesis. Tuning of mechanochemical synthetic conditions allowed us to identify both necessary and favorable factors for the solid-state formation of the MOF. Single-crystal X-ray diffraction reveals the presence of interdigitated layers in the ABAB arrangement and interlayer 0D cavities filled with guest molecules. Upon thermal activation, the dynamic framework exhibits stepwise and selective adsorption of CO2 over N2 as well as high-pressure H2 adsorption reaching maximum excess of 1.15 wt% at 77 K. The mechanochemical synthetic protocol is expanded to a few other interdigitated structures.

Synthesis and physicochemical characterization of two lead(II) complexes with O-, N-donor ligands. Lone pair functionality and crystal structure.

A dinuclear [Pb2(4-CHO-5-MeIm)6(NO3)2](NO3)2 (1) and a polynuclear [Pb(2-pzc)2(H2O)]n (2) complexes (where 5(4)-carbaldehyde-4(5)-methylimidazole (5(4)-CHO-4(5)-MeIm) and pyrazine-2-carboxylic acid (2-pzcH)) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. Structural determination for complex 1 reveals a cationic species [Pb(4-CHO-5-MeIm)3]2+ connected through bridging nitrate(V) ions. There are also an uncoordinated nitrate ions as counterions. Complex 2 is a three-dimensional architecture consisting of Pb6O12 building units. The pyrazine-2-carboxylato ligand behaves as a chelating agent and a bi-connective bridge. The coordination polyhedra around lead(II) ion could be described as a distorted docecahedron (1) or monocapped trigonal prism (2). The luminescent properties of 1 and 2 investigated in the solid state at room temperature indicate structure-dependent photoluminescent properties. The DFT calculations and the X-ray structural data point on rather hemidirected type of coordination around Pb(II) ions of 1 and 2.

Eight- and six-coordinated Mn(II) complexes of heteroaromatic alcohol and aldehyde: crystal structure, spectral, magnetic, thermal and antibacterial activity studies.

Crystal, molecular and electronic structure of new manganese(II) compounds: [Mn(2-CH2OHpy)2(NO3)2] (1), [Mn(4-CHO-5-MeIm)2(NO3)2] (2) and [Mn(4-CHO-5-MeIm)2Cl2] (3), where 2-hydroxymethylpyridine (2-CH2OHpy) and 5(4)-carbaldehyde-4(5)-methylimidazole (5(4)-CHO-4(5)-MeIm), have been characterised using X-ray, spectroscopic, magnetic and TG/DTG data. In compounds 1 and 2, the Mn(II) ion is eight-coordinated forming distorted pseudo-dodecahedron, that is rather unusual for the manganese(II) complexes, whereas in 3 the Mn(II) ion environment is a distorted octahedron. The high coordination number (CN=8) of 1 and 2 results from bidentate character of the nitrate ligands. The X-band EPR spectra of compounds 2 and 3 exhibit fine structure signals resulting from zero-field splitting (ZFS) of the spin states for high spin d(5) Mn(II), whereas for 1 the broad isotropic signals were observed. The estimation of ZFS for individual Mn(II) ions was carried out for all compounds using DFT calculations. The free ligands and their manganese(II) complexes have been tested in vitro against gram-positive and gram-negative bacteria in order to assess their antimicrobial properties.

A novel single-site manganese(II) complex of a pyridine derivative as a catalase mimetic for disproportionation of H2O2 in water.

A novel single site Mn(II) complex was successfully synthesized and tested in the aqueous disproportionation of hydrogen peroxide. The complex was found to be stable (HR-XAS) and exhibits catalase-like activity in neutral pH. Theoretical calculations suggested a reaction mechanism involving two complexes, changes in metal oxidation state and proton shuttling.

7-Meth-oxy-2-phenyl-chroman-4-one.

In the title compound, C(16)H(14)O(3), the ring O atom and the two adjacent non-fused C atoms, as well as the attached phenyl ring, exhibit static disorder [occupancy ratio 0.559 (12):0.441 (12)]. The crystal packing features π-π [centroid-centroid distance = 3.912 (1) Å] and C-H⋯π inter-actions.

Ruthenium complexes in different oxidation states: synthesis, crystal structure, spectra and redox properties.

The reactions of a mother solution of RuCl(3) with benzimidazole derivatives 2-(2'-pyridyl)benzimidazole (2,2'-PyBIm, L(1)) and 2-hydroxymethylbenzimidazole (2-CH(2)OHBIm, L(2)) yielded three novel ruthenium complexes: (H(2)L(1))(2)[Ru(III)Cl(4)(CH(3)CN)(2)](2)[Ru(IV)Cl(4)(CH(3)CN)(2)]·2Cl·6H(2)O (1), mer-[Ru(III)Cl(3)L(1)(CH(3)CN)]·L(1)·3H(2)O (2), and (HL(2))(4)[Ru(IV)Cl(6)]·2Cl·4H(2)O (3). The isolated compounds were characterised by elemental analyses, UV-Vis and IR spectroscopy, and magnetic measurements. The nature of the ligands bound to the metal ions of these compounds and the experimental conditions significantly influenced the ruthenium complexes in different oxidation states. The N,N-donor ligand bound to the metal centre is a recognised stabiliser of the +III state of ruthenium, whereas the lack of ligand coordination promotes the formation of a mixed (Ru(III)/Ru(IV)) complex. In the case of complex 3, the absence of a N,O-donor ligand in the coordinate sphere facilitates the formation of the compound in a higher oxidation state. X-ray single crystal analyses revealed an octahedral geometry in each of the complexes. The crystal structure of ruthenium complexes is formed by a network of intermolecular classical and unconventional (C-H···π) hydrogen bonds. The most interesting feature of the supramolecular architecture of complexes is the existence of a very rare Cl(-)···π interaction and π···π stacking, which also contribute to structural stabilisation. Ruthenium compounds 2 and 3 behave as paramagnets with an octahedral geometry, corresponding to the presence of one or two unpaired electrons, respectively. The cyclic voltammetric data of complex 2 show three one-electron redox processes. The first redox couple is reversible, whereas the two other couples have a quasi-reversible nature. In the case of complex 3, two redox couples are reversible and the electrode processes are connected with exchange of one electron.

Self-assembly of long-chain quaternary ammonium cations in a hybrid inorganic-organic material with one-dimensional polymeric tribromidoplumbate(II).

catena-Poly[benzyldecyldimethylammonium [plumbate(II)-tri-µ-bromido]], {(C(19)H(34)N)[PbBr(3)]}(n), crystallizes as an inorganic-organic hybrid following monoclinic space-group symmetry P2(1)/c. The structure consists of extended chains running along the [001] direction and built of [PbBr(3)](-) units. These inorganic chains are separated by interdigitated ammonium cations which form hydrophilic layers through weak C-H···Br interactions. The architecture is essentialy the same as found for n-alkylbenzyldimethylammonium bromides.

(2Z)-2-Anilino-2-[oxido(phen-yl)iminio]-N-(2-pyrid-yl)acetamide methanol 0.425-solvate.

The title compound, C(19)H(16)N(4)O(2)·0.425CH(4)O, crystallizes with two formula units per asymmetric unit. Researching its crystal structure constitutes part of a study of the nature of inter-actions between the N(+)-O(-) group and the vicinal NH group. The nitrone group and methanol solvent mol-ecules are linked via four N-H⋯O and one O-H⋯O hydrogen bonds, with donor-acceptor distances of 2.603 (3)-2.730 (3) and 2.770 (3) Å, respectively. The crystal structure also involves two intermolecular N-H⋯N hydrogen bonds.

Benzyl-ethyl-dimethyl-ammonium bromide.

The crystal structure of the title compound, C(11)H(18)N(+)·Br(-), has been determined as part of an ongoing study of the influence of the alkyl chain length on amphiphilic activity of quaternary ammonium salts. The title salt forms a three-dimensional network of ionic contacts through weak C-H⋯Br hydrogen bonds, with donor-acceptor distances in the range 3.757 (2)-3.959 (2) Å, in which methyl groups serve as donors.