A Family of Hexacopper Phenylsilsesquioxane/Acetate Complexes: Synthesis, Solvent-Controlled Cage Structures, and Catalytic Activity.

Convenient self-assembly synthesis of copper(II) complexes via double (phenylsilsesquioxane and acetate) ligation allows to isolate a family of impressive sandwich-like cage compounds. An intriguing feature of these complexes is the difference in the structure of a pair of silsesquioxane ligands despite identical (Cu) nuclearity and number (four) of acetate fragments. Formation of particular combination of silsesquioxane ligands (cyclic/cyclic vs condensed/condensed vs cyclic/condensed) was found to be dependent on the synthesis/crystallization media.

Fe(III)-Based Phenylsilsesquioxane/Acetylacetonate Complexes: Synthesis, Cage-like Structure, and High Catalytic Activity.

Unprecedented iron-based silsesquioxane/acetylacetonate complexes were synthesized. The intriguing cage-like structure of compounds is alkaline metal-dependent: the FeLi complex includes condensed Si-silsesquioxane and four acetylacetonate ligands; the FeNa complex exhibits two cyclic Si-silsesquioxane and eight acetylacetonate ligands, while the FeK complex features two cyclic Si-silsesquioxane and six acetylacetonate ligands. The latter case is the very first observation of small trimeric silsesquioxane ligands in the composition of cage-like metallasilsesquioxanes.

Halogen Bonding in the Decoration of Secondary Coordination Sphere of Zinc(II) and Cadmium(II) Complexes: Catalytic Application in Cycloaddition Reaction of CO with Epoxides.

Three new zinc(II) complexes [Zn(HL)(HO)] (), [Zn(HL)(HO)] () (HL = 2,4-diiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2)-ylidene)hydrazineyl)isophthalate) and [Zn(HL)(DMF)(HO)] () were synthesized by the reaction of Zn(II) salts with 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl) isophthalic acid (HL), 2,4,6-triiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2)-ylidene)hydrazineyl) isophthalic acid (HL) (in the presence of NHOH·HCl) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)-2,4,6-triiodoisophthalic acid (HL), respectively. According to the X-ray structural analysis, the intramolecular resonance-assisted hydrogen bond ring remains intact, with NO distances of 2.562(5) and 2.

Design, synthesis and anticancer evaluation of novel arylhydrazones of active methylene compounds.

Nerve growth factor (NGF) and its receptor, tropomyosin kinase receptor kinase type A (TrkA) is emerging as an important target for Glioblastoma (GBM) treatment. TrkA is the cancer biomarker majorly involved in tumor invasion and migration into nearby normal tissue. However, currently, available Trk inhibitors exhibit many adverse effects in cancer patients, thus demanding a novel class of ligands to regulate Trk signaling.

A Family of Cagelike Mn-Silsesquioxane/Bathophenanthroline Complexes: Synthesis, Structure, and Catalytic and Antifungal Activity.

This study reports a novel family of cage manganesesilsesquioxanes prepared via complexation with bathophenanthroline (4,7-diphenyl-1,10-phenanthroline). The resulting Mn-, MnLi-, and MnNa-compounds exhibit several unprecedented cage metallasilsesquioxane structural features, including intriguing self-assembly of silsesquioxane ligands. Complexes were tested for fungicidal activity against seven classes of phytopathogenic fungi.

Cage-like CuCs-Phenylsilsesquioxanes: Synthesis, Supramolecular Structures, and Catalytic Activity.

A small family of nonanuclear CuCs-based phenylsilsesquioxanes - were prepared by a convenient self-assembly approach and characterized by X-ray diffraction studies. The compounds and show some unprecedented structural features such as the presence of a [PhSiO] silsesquioxane ligand and a CuCs nuclearity in which the metal cations occupy unusual positions within the cluster. Copper ions are "wrapped" into a silsesquioxane matrix, while cesium ions are located in external positions.

XXII International Symposium on Homogeneous Catalysis.

This special collection of reviews, minireviews, full papers and communications at Chemistry Europe journals (Chem. Eur. J.

Chalcogen bonding in copper(II)-mediated synthesis.

The chalcogen bond (ChB) is a noncovalent attraction between an electrophilic chalcogen atom and a nucleophilic (Nu) region in the same (intramolecular) or another (intermolecular) molecular entity: R-Ch⋯Nu (Ch = O, S, Se or Te; R = substituents; Nu = nucleophile). ChB is comparable to the hydrogen and halogen bonds both in terms of strengths and directionality. However, in contrast to the monovalent halogen atoms, usually the divalent or tetravalent chalcogen atoms are able to display more than one electrophilic centre (on account of the existence of two or three species bonded to the chalcogen atom), which provides an additional opportunity in the use of this type of noncovalent binding in synthetic operations.

Control of Selectivity in Homogeneous Catalysis through Noncovalent Interactions.

The regio-, site-, stereo- or chemoselective homogeneous catalytic transformations are extremely important for the growth/success of the current chemical industry. Based on empirical, theoretical or intuitive knowledge, several synthetic strategies, such as ligand design, transient directing group, metal node alternation, metal-ligand cooperation, pore decoration, biomimetic, have already been developed for the selective functionalization of organic substrates. In comparison to the other tactics, the use of noncovalent interactions for the control of selectivity in catalytic transformations of organic compounds may avoid multi-steps, reduce time of synthetic procedure, decrease cost of operation, and increase reactivity of catalyst.

Iron(III) Arylhydrazone Complexes Immobilized on Amine-Functionalized Mesoporous Silica: Catalysts for the Valorization of Biomass-Derived Furfuryl Alcohol.

The aquasoluble Fe complexes [Fe(H O) (L )] ⋅ 4H O (Fe1) and [Fe(H O) (L )] ⋅ 3H O (Fe2), bearing the basic forms of 5-chloro-3-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-2-hydroxy-benzenesulfonic acid (H L ) and 3-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonic acid (H L ), were incorporated for the first time into amine-functionalized SBA-15 support via an impregnation method. The successful preparation of the composites was confirmed by Fourier-Transform Infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscope (SEM/EDS), transmission electron microscopy (TEM), elemental analysis, and nitrogen adsorption-desorption isotherms. The resulting Fe1@aptesSBA-15 and Fe2@aptesSBA-15 composites were tested as the first SBA-15-based heterogeneous catalysts for the conversion of furfuryl alcohol under mild reaction conditions (80 to 100 °C) and with an environmentally friendly oxidant (TBHP, 70 % aq.

Halogen bonding in cadmium(II) MOFs: its influence on the structure and on the nitroaldol reaction in aqueous medium.

A solvothermal reaction of Cd(II) with the dicarboxyl-functionalized arylhydrazone pro-ligands, 5-(2-(2,4,6-trioxotetrahydro-pyrimidin-5(2)-ylidene)hydrazineyl)isophthalic acid (HL) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)isophthalic acid (HL), or their halogen bond donor centre(s) decorated analogs 2,4,6-triiodo-5-(2-(2,4,6-trioxotetrahydropyrimidin-5(2)-ylidene)hydrazineyl)isophthalic acid (HL) and 5-(2-(2,4-dioxopentan-3-ylidene)hydrazineyl)-2,4,6-triiodoisophthalic acid (HL), leads to the formation of known [Cd(HL)(HO)] (1) and new {[Cd(HL)(HO)(DMF)]·HO} (2), [Cd(HL)] (3) and {[Cd(μ-HO)(μ-HL)(HL)]·2HO} (4) coordination compounds, respectively. The aggregation of mononuclear units Cd-OC and Cd-OH coordination and C-I⋯I types of intramolecular halogen bonds lead to a dinuclear tecton 4. Both C-I⋯O and C-I⋯I types of intermolecular halogen bonds play a fundamental role in the supramolecular architectures of the obtained metal-organic frameworks 3 and 4.

Noncovalent Interactions at Lanthanide Complexes.

Lanthanide complexes have attracted a widespread attention due to their structural diversity, as well as multifunctional and tunable properties. The development of lanthanide based functional materials has often relied on the design of the secondary coordination sphere of the corresponding lanthanide complexes. For instance, usually simple lanthanide salts (solvento complexes) do not catalyze effectively organic reactions or provide low yield of the expected product, whereas the presence of a suitable organic ligand with a noncovalent bond donor or acceptor centre (secondary coordination sphere) modifies the symmetry around the metal centre in lanthanide complexes which then successfully can act as catalysts in both homogenous and heterogenous catalysis.

Resonance Assisted Chalcogen Bonding as a New Synthon in the Design of Dyes.

Intramolecular chalcogen bonding in arylhydrazones of sulfamethizole is strengthened by conjugation in the π-system of a noncovalent five-membered ring. The S⋅⋅⋅O distance in the sulfamethizole moiety of these compounds ranges from 2.698(3) to 2.

Hydrogen and halogen bonding in the haloetherification products in chalcone.

Cooperative action of hydrogen and halogen bonding in the reaction of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-1-phenylprop-2-en-1-one with HCl or HBr in alcohol medium under microwave irradiation (20 W, 80 °C, 10 min) allows the isolation of the haloetherification products (2S,3S)-3-(3-tert-butyl-5-chloro-4-hydroxyphenyl)-2-chloro-3-ethoxy-1-phenylpropan-1-one, CHClO, (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-methoxy-1-phenylpropan-1-one, CHBrO, and (2S,3S)-2-bromo-3-(3-tert-butyl-5-bromo-4-hydroxyphenyl)-3-ethoxy-1-phenylpropan-1-one, CHBrO, in good yields. Both types of noncovalent interactions, e.g.

Arylhydrazone ligands as Cu-protectors and -catalysis promoters in the azide-alkyne cycloaddition reaction.

A series of water soluble copper(ii) complexes, [Cu(κOON-HL)(HO)]·2HO (2), [Cu(κO-HL)(HO)] (3), [Cu(κO-HL)(HO)] (5) and [Cu(HO)]·2HL·2(CH)NCHO (7), were prepared by the reaction of Cu(NO)·3HO with sodium (Z)-2-(2-(1-amino-1,3-dioxobutan-2-ylidene)hydrazineyl)benzenesulfonate, [Na(μ-1:2κO,2κO,3κO,4κO-HL)] (1; for 2 and 3), sodium (Z)-3-(2-(1-amino-1,3-dioxobutan-2-ylidene)hydrazineyl)-4-hydroxybenzene-sulfonate, [Na(μ-1κO,2κO-HL)] (4; for 5) or sodium (Z)-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazineyl)naphthalene-1-sulfonate, [Na(μ-1κOO,2κO-HL)(CHOH)] (6; for 7). Compounds 1-7 were fully characterized, also by single-crystal X-ray diffraction analysis, and applied as homogeneous catalysts for the azide-alkyne cycloaddition (AAC) reaction to afford 1,4-disubstituted 1,2,3-triazoles. A structure-catalytic activity relationship has been recognized for the first time on the basis of the occurrence of resonance- and charge-assisted hydrogen bond interactions (RAHB and CAHB), in charge and ligand binding modes, enabling the catalytic activity of the compounds to be ordered as follows: Cu(NO)≪7 (complex salt with RAHB and CAHB) < 3 (with RAHB and CAHB) < 5 (with RAHB) < 2 (neither RAHB nor CAHB).

characterization of arylhydrazones of active methylene derivatives.

Arylhydrazones of active methylene compounds (AHAMCs) are potent chemotherapy agents for the cancer treatment. AHAMCs enhance the apoptotic cell death and antiproliferation properties in cancer cells. In this study, a series of AHAMCs, 13 compounds, was assayed for cytotoxicity, apoptosis, externalization of phosphatidylserine, heterogeneity and cellular calcium level changes.

Chalcogen bonding in synthesis, catalysis and design of materials.

Chalcogen bonding is a type of noncovalent interaction in which a covalently bonded chalcogen atom (O, S, Se or Te) acts as an electrophilic species towards a nucleophilic (negative) region(s) in another or in the same molecule. In general, this interaction is strengthened by the presence of an electron-withdrawing group on the electron-acceptor chalcogen atom and upon moving down in the periodic table of elements, from O to Te. Following a short discussion of the phenomenon of chalcogen bonding, this Perspective presents some demonstrative experimental observations in which this bonding is crucial for synthetic transformations, crystal engineering, catalysis and design of materials as synthons/tectons.

Lanthanide metal organic frameworks based on dicarboxyl-functionalized arylhydrazone of barbituric acid: syntheses, structures, luminescence and catalytic cyanosilylation of aldehydes.

Five isostructural lanthanide MOFs, [Ln(1κOO',2κO'',3κO''',4κO''''-μ-L)(NO)(DMF)]·n(DMF) {Ln = La (1), Ce (2), Nd (3), Sm (4) and Dy (5); L = 5-[2-{2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene}hydrazinyl]isophthalate; DMF = N,N'-dimethyl formamide}, based on dicarboxyl-functionalized arylhydrazone of barbituric acid were synthesized under solvothermal conditions. They were characterized by elemental analysis, FT-IR spectroscopy, thermogravimetric and X-ray diffraction analyses. Crystal structure analysis revealed that these frameworks possess a similar type of two dimensional (2D) structure with a dinuclear {Ln(COO)} unit acting as a secondary building block.

Resonance-Assisted Hydrogen Bonding as a Driving Force in Synthesis and a Synthon in the Design of Materials.

Resonance-assisted hydrogen bonding (RAHB), a concept introduced by Gilli and co-workers in 1989, concerns a kind of intramolecular H-bonding strengthened by a conjugated π-system, usually in 6-, 8-, or 10-membered rings. This Review highlights the involvement of RAHB as a driving force in the synthesis of organic, coordination, and organometallic compounds, as a handy tool in the activation of covalent bonds, and in starting moieties for synthetic transformations. The unique roles of RAHB in molecular recognition and switches, E/Z isomeric resolution, racemization and epimerization of amino acids and chiral amino alcohols, solvatochromism, liquid-crystalline compounds, and in synthons for crystal engineering and polymer materials are also discussed.

Water soluble heterometallic potassium-dioxidovanadium(V) complexes as potential antiproliferative agents.

Two water soluble heterometallic potassium–dioxidovanadium polymers, [KVO2(L1)]n (1) and [KVO2(L2)(H2O)]n (2) [H2L1= (2,3-dihydroxybenzylidene)-2-hydroxybenzohydrazide and H2L2=(2,3-dihydroxybenzylidene)benzohydrazide], have been synthesized and characterized by IR, NMR, elemental analysis and single crystal X-ray diffraction. The antiproliferative potentials of 1 and 2 were examined towards human colorectal carcinoma (HCT116), and lung (A549) and breast (MCF7) adenocarcinoma cell lines. 1 exhibits a high cytotoxic activity against colorectal carcinoma cells (HCT116), with IC50 lower than those for cisplatin.

Lanthanide derivatives comprising arylhydrazones of β-diketones: cooperative E/Z isomerization and catalytic activity in nitroaldol reaction.

Two complexes [KLa(HL(1))2{(CH3)2NCHO}2(H2O)3] (1) and [Sm(H2O)9](E-H2L(2))3·2H2O (2) were synthesized by the reaction of lanthanum(III) and samarium(III) nitrates with potassium 3-(2-(2,4-dioxopentan-3-ylidene)hydrazinyl)-2-hydroxy-5-nitrobenzenesulfonate (KH2L(1)) and potassium (E,Z)-5-chloro-3-(2-(1,3-dioxo-1-phenylbutan-2-ylidene)hydrazinyl)-2-hydroxybenzenesulfonate (KH2L(2)), respectively. Both complexes were fully characterized by elemental analysis, IR, (1)H and (13)C NMR spectroscopy, ESI-MS and single-crystal X-ray diffraction. Cooperative E,Z→E isomerization of KH2L(2), induced by resonance assisted hydrogen bonding and ionic interactions, occurs upon the interaction with Sm(III).