Metal-Free Regioselective Monocyanation of Hydroxy-, Alkoxy-, and Benzyloxyarenes by Potassium Thiocyanate and Silica Sulfuric Acid as a Cyanating Agent.

A novel and efficient metal- and solvent-free regioselective para-C-H cyanation of hydroxy-, alkoxy-, and benzyloxyarene derivatives has been introduced, using nontoxic potassium thiocyanate as a cyanating reagent in the presence of silica sulfuric acid (SSA). The desired products are obtained in good to high yields without any toxic byproducts.

The 1,6,7,12-Tetraazaperylene Bridging Ligand as an Electron Reservoir and Its Disulfonato Derivative as Redox Mediator in an Enzyme-Electrode Process.

The homodinuclear ruthenium(II) complex [{Ru(l-N4 Me2 )}2 (µ-tape)](PF6 )4 {[1](PF6 )4 } (l-N4 Me2 =N,N'-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane, tape=1,6,7,12-tetraazaperylene) can store one or two electrons in the energetically low-lying π* orbital of the bridging ligand tape. The corresponding singly and doubly reduced complexes [{Ru(l-N4 Me2 )}2 (µ-tape.- )](PF6 )3 {[2](PF6 )3 } and [{Ru(l-N4 Me2 )}2 (µ-tape2- )](PF6 )2 {[3](PF6 )2 }, respectively, were electrochemically generated, successfully isolated and fully characterized by single-crystal X-ray crystallography, spectroscopic methods and magnetic susceptibility measurements. The singly reduced complex [2](PF6 )3 contains the π-radical tape.- and the doubly reduced [3](PF6 )2 the diamagnetic dianion tape2- as bridging ligand, respectively. Nucleophilic aromatic substitution at the bridging tape in [1]4+ by two sulfite units gave the complex [{Ru(l-N4 Me2 )}2 {µ-tape-(SO3 )2 }]2+ ([4]2+ ). Complex dication [4]2+ was exploited as a redox mediator between an anaerobic homogenous reaction solution of an enzyme system (sulfite/sulfite oxidase) and the electrode via participation of the low-energy π*-orbital of the disulfonato-substituted bridging ligand tape-(SO3 )22- (Ered1 =-0.1 V versus Ag/AgCl/1 m KCl in water).

Study of the Discrepancies between Crystallographic Porosity and Guest Access into Cadmium-Imidazolate Frameworks and Tunable Luminescence Properties by Incorporation of Lanthanides.

An extended member of the isoreticular family of metal-imidazolate framework structures, IFP-6 (IFP=imidazolate framework Potsdam), based on cadmium metal and an in situ functionalized 2-methylimidazolate-4-amide-5-imidate linker is reported. A porous 3D framework with 1D hexagonal channels with accessible pore windows of 0.52 nm has been synthesized by using an ionic liquid (IL) linker precursor. IFP-6 shows significant gas uptake capacity only for CO2 and CH4 at elevated pressure, whereas it does not adsorb N2 , H2 , and CH4 under atmospheric conditions. IFP-6 is assumed to deteriorate at the outside of the material during the activation process. This closing of the metal-organic framework (MOF) pores is proven by positron annihilation lifetime spectroscopy (PALS), which revealed inherent crystal defects. PALS results support the conservation of the inner pores of IFP-6. IFP-6 has also been successfully loaded with luminescent trivalent lanthanide ions (Ln(III) =Tb, Eu, and Sm) in a bottom-up one-pot reaction through the in situ generation of the linker ligand and in situ incorporation of photoluminescent Ln ions into the constituting network. The results of photoluminescence investigations and powder XRD provide evidence that the Ln ions are not doped as connectivity centers into the frameworks, but are instead located within the pores of the MOFs. Under UV light irradiation, Tb@IFP-6 and Eu@IFP-6 (λexc =365 nm) exhibit observable emission changes to a greenish and reddish color, respectively, as a result of strong Ln 4 f emissions.

Photochemical Synthesis of Both Strained and Macrocyclic (1,7)Naphthalenophanes.

Naphthalenophanes are a special type of cyclophanes. While in the past (1,5)-, (1,6)-, and (1,8)naphthalenophanes were successfully prepared by using the photo-dehydro-Diels-Alder (DDA) reaction, access to (1,7)naphthalenophanes by this method was hitherto unknown. After numerous unsuccessful attempts to prepare these compounds by thermal DDA, we found that the photoinitiated variant (PDDA) represents a very efficient method to [k](1,7)naphthalenophanes 13. The scope ranged from highly strained (k = 11, 12) to macrocyclic products (k = 22, 24). The extraordinary reactivity could be explained by folded ground-state geometries of diketones 12 used as reactants of the PDDA. Furthermore, we calculated the ring-strain energies with the help of an isodesmic reaction and evaluated structural and spectroscopic (NMR) consequences of ring strain.

Tetrabromidocuprates(II)-Synthesis, Structure and EPR.

Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several "onium" cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g‖ and g⊥) of the tensors could be determined and information on the structural changes in the [CuBr4](2-) anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids.

Ionogels Based on Poly(methyl methacrylate) and Metal-Containing Ionic Liquids: Correlation between Structure and Mechanical and Electrical Properties.

Ionogels (IGs) based on poly(methyl methacrylate) (PMMA) and the metal-containing ionic liquids (ILs) bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II), tetrachloride cobaltate(II), and tetrachlorido manganate(II) have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic) properties of IGs.

Dual Role of Acetanilides: Traceless Removal of a Directing Group through Deacetylation/Diazotation and Palladium-Catalyzed C-C-Coupling Reactions.

The acetamide group enables regioselective oxidative ortho-C-H activation reactions, such as Pd-catalyzed acylation. The synthetic utility of these transformations can be significantly enhanced by using the acetamide as a quasi-leaving group in a subsequent conventional Pd-catalyzed coupling or cross-coupling reaction. The concept is illustrated herein for the synthesis of o-alkenyl- and o-arylphenones, which have potential for the synthesis of arylated aromatic heterocycles.

Structure-property relationships of a biological mesocrystal in the adult sea urchin spine.

Structuring over many length scales is a design strategy widely used in Nature to create materials with unique functional properties. We here present a comprehensive analysis of an adult sea urchin spine, and in revealing a complex, hierarchical structure, show how Nature fabricates a material which diffracts as a single crystal of calcite and yet fractures as a glassy material. Each spine comprises a highly oriented array of Mg-calcite nanocrystals in which amorphous regions and macromolecules are embedded. It is postulated that this mesocrystalline structure forms via the crystallization of a dense array of amorphous calcium carbonate (ACC) precursor particles. A residual surface layer of ACC and/or macromolecules remains around the nanoparticle units which creates the mesocrystal structure and contributes to the conchoidal fracture behavior. Nature's demonstration of how crystallization of an amorphous precursor phase can create a crystalline material with remarkable properties therefore provides inspiration for a novel approach to the design and synthesis of synthetic composite materials.

Giant Zn14 molecular building block in hydrogen-bonded network with permanent porosity for gas uptake.

In situ imidazolate-4,5-diamide-2-olate linker generation leads to the formation of a [Zn14(L2)12(O)(OH)2(H2O)4] molecular building block (MBB) with a Zn6 octahedron inscribed in a Zn8 cube. The MBBs connect by amide-amide hydrogen bonds to a 3D robust supramolecular network which can be activated for N2, CO2, CH4, and H2 gas sorption.

Imidazolium 2-substituted 4,5-dicyanoimidazolate ionic liquids: synthesis, crystal structures and structure-thermal property relationships.

Thirty six novel ionic liquids (ILs) with 1-butyl-3-methylimidazolium and 3-methyl-1-octylimidazolium cations paired with 2-substitited 4,5-dicyanoimidazolate anions (substituent at C2 = chloro, bromo, methoxy, vinyl, amino, methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and phenyl) have been synthesized and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and single-crystal X-ray crystallography. The effects of cation and anion type and structure on the thermal properties of the resulting ionic liquids, including several room temperature ionic liquids (RTILs) are examined and discussed. ILs exhibited large liquid and crystallization ranges and formed glasses on cooling with glass transition temperatures in the range of -22 to -68 °C. The effects of alkyl substituents of the imidazolate anion reflected the crystallization, melting points and thermal decomposition of the ILs. The Coulombic packing force, van der Waals forces and size of the anions can be considered for altering the thermal transitions. Three crystal structures of the ILs were determined and the effects of changes to the cations and anions on the packing of the structure were investigated.

Crystal structure of (2,11-di-aza-[3.3](2,6)pyridino-phane-κ (4) N,N',N'',N''')(1,6,7,12-tetra-aza-perylene-κ (2) N (1),N (12))ruthenium(II) bis-(hexa-fluorido-phosphate) aceto-nitrile 1.422-solvate.

In the title compound, [Ru(C14H16N4)(C16H8N4)](PF6)2·1.422CH3CN, discrete dimers of complex cations, [Ru(L-N4H2)tape](2+) are formed {L-N4H2 = 2,11-di-aza-[3.3](2,6)pyridino-phane; tape = 1,6,7,12-tetra-aza-perylene}, held together by π-π stacking inter-actions via the tape ligand moieties with a centroid-centroid distance of 3.49 (2) Å, assisted by hydrogen bonds between the non-coordinating tape ligand α,α'-di-imine unit and the amine proton of a 2,11-di-aza-[3.3](2,6)-pyridino-phane ligand of the opposite complex cation. The combination of these inter-actions leads to an unusual nearly face-to-face π-π stacking mode. Additional weak C-H⋯N, C-H⋯F, N-H⋯F and P-F⋯π-ring (tape, py) (with F⋯centroid distances of 2.925-3.984 Å) inter-actions are found, leading to a three-dimensional architecture. The Ru(II) atom is coordinated in a distorted octa-hedral geometry, particularly manifested by the Namine-Ru-Namine angle of 153.79 (10)°. The counter-charge is provided by two hexa-fluorido-phosphate anions and the asymmetric unit is completed by aceto-nitrile solvent mol-ecules of crystallization. Disorder was observed for both the hexa-fluorido-phosphate anions as well as the aceto-nitrile solvate mol-ecules, with occupancies for the major moieties of 0.801 (6) for one of the PF6 anions, and a shared occupancy of 0.9215 (17) for the second PF6 anion and a partially occupied aceto-nitrile mol-ecule. A second CH3CN mol-ecule is fully occupied, but 1:1 disordered across a crystallographic inversion center.

(1,6,7,12-Tetra-aza-perylene-κ(2) N,N')bis-(4,4',5,5'-tetra-methyl-2,2'-bipyridyl-κ(2) N,N')ruthenium(II) bis-(hexa-fluorido-phosphate) aceto-nitrile tris-olvate.

In the title compound, rac-[Ru(C14H16N2)2(C16H8N4)](PF6)2·3C2H3N, discrete dimers of complex cations, [Ru(tmbpy)2-tape](2+), of opposite chirality are formed (tmbpy = tetra-methyl-bipyridine; tape = tetraazaperylene), held together by π-π stacking inter-actions between the tetra-aza-perylene moieties with centroid-centroid distances in the range 3.563 (3)-3.837 (3) Å. These inter-actions exhibit a parallel displaced π-π stacking mode. Additional weak C-H⋯π-ring and C-H⋯N and C-H⋯F inter-actions are found, leading to a three-dimensional architecture. The Ru(II) atom is coordinated in a distorted octa-hedral geometry. The counter-charge is provided by two hexa-fluorido-phosphate anions and the asymmetric unit is completed by three aceto-nitrile solvent mol-ecules of crystallization. Four F atoms of one PF6 (-) anion are disordered over three sets of sites with occupancies of 0.517 (3):0.244 (3):0.239 (3). Two aceto-nitrile solvent mol-ecules are highly disordered and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE option in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155].

µ-1,6,7,12-Tetra-aza-perylene-κ(4) N (1),N (12):N (6),N (7)-bis-[chlorido-(η(6)-p-cymene)ruthenium(II)] bis-(hexa-fluorido-phosphate) acetone disolvate.

In the title compound, [Ru2(C10H14)2Cl2(C16H8N4)](PF6)2·2C3H6O, the binuclear Ru(II) complex dication, [{RuCl(η(6)-cym)}2(µ-tape)](2+), built up by a planar 1,6,7,12-tetra-aza-perylene (tape) bridge, two η(6)-bound cymene (cym) ligands and two chloride ligands, includes an inversion center. The Ru(II) atom shows the typical piano-stool motif for arene coordination. The counter-charge is provided by a hexa-fluorido-phosphate anion and the asymmetric unit is completed by an acetone mol-ecule of crystallization. The components of the structure are connected into a three-dimensional architecture by C-H⋯O/F/Cl inter-actions.

An isoreticular family of microporous metal-organic frameworks based on zinc and 2-substituted imidazolate-4-amide-5-imidate: syntheses, structures and properties.

We report on a new series of isoreticular frameworks based on zinc and 2-substituted imidazolate-4-amide-5-imidate (IFP-1-4, IFP = imidazolate framework Potsdam) that form one-dimensional, microporous hexagonal channels. Varying R in the 2-substitued linker (R = Me (IFP-1), Cl (IFP-2), Br (IFP-3), Et (IFP-4)) allowed the channel diameter (4.0-1.7 Å), the polarisability and functionality of the channel walls to be tuned. Frameworks IFP-2, IFP-3 and IFP-4 are isostructural to previously reported IFP-1. The structures of IFP-2 and IFP-3 were solved by X-ray crystallographic analyses. The structure of IFP-4 was determined by a combination of PXRD and structure modelling and was confirmed by IR spectroscopy and (1)H MAS and (13)C CP-MAS NMR spectroscopy. All IFPs showed high thermal stability (345-400 °C); IFP-1 and IFP-4 were stable in boiling water for 7 d. A detailed porosity analysis was performed on the basis of adsorption measurements by using various gases. The potential of the materials to undergo specific interactions with CO(2) was investigated by measuring the isosteric heats of adsorption. The capacity to adsorb CH(4) (at 298 K), CO(2) (at 298 K) and H(2) (at 77 K) at high pressure were also investigated. In situ IR spectroscopy showed that CO(2) is physisorbed on IFP-1-4 under dry conditions and that both CO(2) and H(2)O are physisorbed on IFP-1 under moist conditions.

Synthesis of 8-aryl-substituted coumarins based on ring-closing metathesis and Suzuki-Miyaura coupling: synthesis of a furyl coumarin natural product from Galipea panamensis.

The synthesis of 7-methoxy-8-(4-methyl-3-furyl)-2H-chromen-2-one, a natural product with antileishmanial activity recently isolated from the plant Galipea panamensis, is described. The key step is a Suzuki-Miyaura coupling of a furan-3-boronic acid and an 8-halocoumarin, which is advantageously synthesized using a ring-closing metathesis reaction. Several non-natural analogues are also available along these lines.

Synthesis, molecular structure, conformational analysis, and chemical properties of silicon-containing derivatives of quinolizidine.

A silicon analog of quinolizidine 3,3,7,7-tetramethylhexahydro-1H-[1,4,2]oxazasilino[4,5-d][1,4,2]oxazasilin-9a-yl)methanol 3 was synthesized. X-ray diffraction analysis confirmed the trans configuration and low temperature NMR spectroscopy both the flexibility (barrier of interconversion 5.8 kcal mol(-1)) and the conformational equilibrium (chair-chair and chair-twist conformers) of the compound. The relative stability of the different isomers/conformers of 3 was calculated also at the MP2/6-311G(d,p) level of theory. Intra- and intermolecular hydrogen bonding in 3 and the appropriate equilibrium between free and self-associated molecules was studied in solvents of different polarity. Both the N-methyl quaternary ammonium salt and the O-trimethylsilyl derivative of 3 could be obtained and their structure determined.

Cinerin C: a macrophyllin-type bicyclo[3.2.1]octane neolignan from Pleurothyrium cinereum (Lauraceae).

The structure of naturally-occurring cinerin C [systematic name: (7S,8R,3'R,4'S,5'R)-Δ(8')-4'-hydroxy-5,5',3'-trimethoxy-3,4-methylenedioxy-2',3',4',5'-tetrahydro-2'-oxo-7.3',8.5'-neolignan], isolated from the ethanol extract of leaves of Pleurothyrium cinereum (Lauraceae), has previously been established by NMR and HRMS spectroscopy, and its absolute configuration established by circular dichroism measurements. For the first time, its crystal structure has now been established by single-crystal X-ray analysis, as the monohydrate, C(22)H(26)O(7)·H(2)O. The bicyclooctane moiety comprises fused cyclopentane and cyclohexenone rings which are almost coplanar. An intermolecular O-H···O hydrogen bond links the 4'-OH and 5'-OCH(3) groups along the c axis.

Pd-catalyzed [2+2+1] coupling of alkynes and arenes: phenol diazonium salts as mechanistic trapdoors.

Alkynes and phenol diazonium salts undergo a Pd-catalyzed [2+2+1] cyclization reaction to spiro[4,5]decatetraene-7-ones. This structure was confirmed for one example by X-ray single-crystal structure analysis. The reaction is believed to proceed through oxidative addition of the phenol diazonium cation to Pd(0), subsequent insertion of two alkynes, followed by irreversible spirocyclization.

Pd-catalyzed arylation reactions with phenol diazonium salts: application in the synthesis of diarylheptanoids.

The first total synthesis of the natural product (3S,7R)-5,6-dehydro-de-O-methyl centrolobine and various analogues is reported, using a highly regio- and diastereoselective Mizoroki-Heck reaction of phenol diazonium salts and enantiopure dihydropyrans. The assigned relative configuration was confirmed by single-crystal X-ray structure analysis, but a revision of the absolute configuration is proposed based on polarimetric measurement.