RESUMEN
A versatile Lewis acid catalyzed tandem cyclization of in situ generated alkynyl o-quinone methides ( o-AQMs) with electron-rich phenols has been developed on the basis of the mode involving an intermolecular 1,4-conjugate addition/6-endo cyclization/1,3-aryl shift/intramolecular 1,4-conjugate addition cascade. This reaction provides a new method for expeditious assembly of synthetically and biologically interesting tetracyclic bridged dioxabicyclo[3.3.1]nonane skeletons featuring a congested bridgehead oxa-quaternary stereocenter.
RESUMEN
Ranaconitine is an important diterpenoid alkaloid from Aconitum sinomontanum Nakai. The absolute configuration of natural ranaconitine was determined through an X-ray structure analysis of hydrated ranaconitine hydrobromide. The crystal presents a monoclinic system, space group P2(1) with Z = 2, unit cell dimensions: a = 10.6604(12) Å, b = 12.3674(14) Å, c = 12.2938(13) Å and ß = 91.056(2)°. The chirality of the asymmetric carbon atoms was as follows: C10(S), C13(S), C14(S), C15(S), C16(S), C17(R), C23(S), C25(R), C26(S), C27(S), C28(S) and C30(S). Moreover, a complex network of hydrogen bonds occurred between neighbouring molecules.
Asunto(s)
Aconitina/análogos & derivados , Cristalografía por Rayos X/métodos , Aconitina/química , Modelos MolecularesRESUMEN
In attempts to investigate whether the photoluminescence properties of the Zn-based heterometal-organic frameworks (MOFs) could be tuned by doping different Ln(3+) (Ln = Sm, Eu, Tb) and Mn(2+) ions, seven novel 3D homo- and hetero-MOFs with a rich variety of network topologies, namely, [Zn(mip)](n) (Zn-Zn), [Zn(2)Mn(OH)(2)(mip)(2)](n) (Zn-Mn), [Mn(2)Mn(OH)(2)(mip)(2)](n) (Mn-Mn), [ZnSm(OH)(mip)(2)](n) (Zn-Sm), [ZnEu(OH)(mip)(2)](n) (Zn-Eu1), [Zn(5)Eu(OH)(H(2)O)(3)(mip)(6)·(H(2)O)](n) (Zn-Eu2), and [Zn(5)Tb(OH)(H(2)O)(3)(mip)(6)](n) (Zn-Tb), (mip = 5-methylisophthalate dianion), have been synthesized hydrothermally based on a single 5-methylisophthalic acid ligand. All compounds are fully structurally characterized by elemental analysis, FT-IR spectroscopy, TG-DTA analysis, single-crystal X-ray diffraction, and X-ray powder diffraction (XRPD) techniques. The various connectivity modes of the mip linkers generate four types of different structures. Type I (Zn-Zn) is a 3D homo-MOF with helical channels composed of Zn(2)(COO)(4) SBUs (second building units). Type II (Zn-Mn and Mn-Mn) displays a nest-like 3D homo- or hetero-MOF featuring window-shaped helical channels composed of Zn(4)Mn(2)(OH)(4)(COO)(8) or Mn(4)Mn(2)(OH)(4)(COO)(8) SBUs. Type III (Zn-Sm and Zn-Eu1) presents a complicated corbeil-like 3D hetero-MOF with irregular helical channels composed of (SmZnO)(2)(COO)(8) or (EuZnO)(2)(COO)(8) heterometallic SBUs. Type IV (Zn-Eu2 and Zn-Tb) contains a heterometallic SBU Zn(5)Eu(OH)(COO)(12) or Zn(5)Tb(OH)(COO)(12), which results in a 3D hetero-MOF featuring irregular channels impregnated by parts of the free and coordinated water molecules. Photoluminescence properties indicate that all of the compounds exhibit photoluminescence in the solid state at room temperature. Compared with a broad emission band at ca. 475 nm (λ(ex) = 380 nm) for Zn-Zn, compound Zn-Mn exhibits a remarkably intense emission band centered at 737 nm (λ(ex) = 320 nm) due to the characteristic emission of Mn(2+). In addition, the fluorescence intensity of compound Zn-Mn is stronger than that of Mn-Mn as a result of Zn(2+) behaving as an activator for the Mn(2+) emission. Compound Zn-Sm displays a typical Sm(3+) emission spectrum, and the peak at 596 nm is the strongest one (λ(ex) = 310 nm). Both Zn-Eu1 and Zn-Eu2 give the characteristic emission transitions of the Eu(3+) ions (λ(ex) = 310 nm). Thanks to the ambient different crystal-field strengths, crystal field symmetries, and coordinated bonds of the Eu(3+) ions in compounds Zn-Eu1 and Zn-Eu2, the spectrum of the former compound is dominated by the (5)D(0) â (7)F(2) transition (612 nm), while the emission of the (5)D(0) â (7)F(4) transition (699 nm) for the latter one is the most intense. Compound Zn-Tb emits the characteristic Tb(3+) ion spectrum dominated by the (5)D(4) â (7)F(5) (544 nm) transition. Upon addition of the different activated ions, the luminescence lifetimes of the compounds are also changed from the nanosecond (Zn-Zn) to the microsecond (Zn-Mn, Mn-Mn, and Zn-Sm) and millisecond (Zn-Eu1, Zn-Eu2, and Zn-Tb) magnitude orders. The structure and photoluminescent property correlations suggest that the presence of Mn(2+) and Ln(3+) ions can activate the Zn-based hetero-MOFs to emit the tunable photoluminescence.
RESUMEN
The title compound, C(19)H(31)O(2)P, features a distorted tetra-hedral P atom that bonds to the phenyl ring, isopropyl and 2-isopropyl-5-methyl-cyclo-hexyl groups, and is determined as having an R(p) configuration. A chair conformation is observed for the cyclo-hexyl ring. In the crystal, mol-ecules are linked into chains running along the a axis by weak inter-molecular C-Hâ¯O hodrogen bonds.
RESUMEN
In the dinuclear title complex, [Sn(2)(CH(3))(4)(C(7)H(3)F(2)O(2))(4)], the Sn(IV) atom is chelated by two 3,5-difluoro-benzoate (dfb) anions and coordinated by two methyl groups while an O atom from the adjacent dfb anion bridges the Sb atom with a longer Sb-O bond distance of 2.793â (4)â Å. The complex mol-ecule has 2 symmetry and the Sn(IV) atom is in a distorted penta-gonal-bipyramidal coordination geometry. In the crystal, mol-ecules are connected by C-Hâ¯O and C-Hâ¯F hydrogen bonds.
RESUMEN
2-Aminopyridinium benzoate was synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were applied to characterize the composition and crystal structure of the compound. The lattice potential energy of the title compound was calculated to be UPOT = 284.297 kJ mol-1. Low-temperature heat capacities of the compound were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 K to 365 K. A polynomial equation of heat capacities against the temperature in the region of 78 K to 365 K was fitted by a least square method. Based on the fitted polynomial equation, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K. According to the synthesis reaction, the standard molar enthalpies of dissolution for the reactants and product in the selected solvent were measured by an isoperibol solution-reaction calorimeter, respectively. Accordingly, the enthalpy change of the synthesis reaction was calculated to be ΔrHom = -(20.016 ± 0.182) kJ mol-1. Finally, the standard molar enthalpy of formation of 2-aminopyridinium benzoate was determined to be ΔfHom = - (365.416 ± 0.961) kJ mol-1 in accordance with Hess law.
RESUMEN
The title compound, (C(2)H(10)N(2))(3)(C(2)H(9)N(2))(2)[Mo(5)(HPO(4))(2)O(15)]·10H(2)O, was prepared under hydro-thermal conditions at pH 5.0. The structure contains mono- and diprotonated ethyl-enediamine cations, [Mo(5)O(15)(HPO(4))(2)](4-) anions and uncoord-in-ated water mol-ecules. The [Mo(5)O(15)(HPO(4))(2)](4-) hetero-poly-oxometallate anion is made up of five MoO(6) octa-hedra sharing an edge and forming a ring, which is closed by common corners of the terminal MoO(6) octa-hedron. The ring is topped on both sides by two slightly distorted PO(4) tetra-hedra, sharing three corners with three MoO(6) octa-hedra. The terminal oxygen atoms of the PO(4) units are protonated. Together with the anions, the water mol-ecules and the ethyl-enediammonium cations are involved in N-Hâ¯O and O-Hâ¯O hydrogen bonding, forming a three-dimensional supra-molecular network.
RESUMEN
In the title compound, {[Zn(C(4)H(4)O(6))(H(2)O)]·2H(2)O}(n), the l-tartrate ligands adopt µ(4)- and µ(2)-coordination modes. The Zn(II) atom adopts an octa-hedral geometry and is chelated by two kinds of l-tartrate ligands through the hydr-oxy and carboxyl-ate groups and coordinated by one unchelating carboxyl-ate O atom and one water mol-ecule. In the crystal, the l-tartrate ligands link the Zn(II) atoms, forming a two-dimensional coordination layer; these layers are futher linked into a three-dimensional supra-molecular network by O-Hâ¯O hydrogen bonds between the two-dimensional coordin-ation layers and the uncoordinated water mol-ecules. The latter are equally disordered over two positions.
RESUMEN
In the title compound, C(13)H(9)NO(4), the two carb-oxy-lic groups and the benzene ring are approximately co-planar with a maximum atomic deviation 0.175â (4)â Å, while the pyridine ring is oriented at a dihedral angle of 31.07â (18)° with respect to the benzene ring. In the crystal, mol-ecules are linked by O-Hâ¯O, O-Hâ¯N and weak C-Hâ¯O hydrogen bonds, forming a three-dimensional supra-molecular framework.
RESUMEN
In the title compound, C(17)H(12)O(4)·H(2)O, the coumarin ring system is approximately planar with a maximum atomic deviation of 0.011â (2)â Å, and is nearly perpendicular to the phenyl ring at a dihedral angle of 86.63â (9)°. In the crystal, mol-ecules are linked by classical O-Hâ¯O and weak C-Hâ¯O hydrogen bonds. π-π stacking is also present [centroid-centroid distance = 3.6898â (12)â Å].
RESUMEN
The title complex, [Na(C(18)H(22)O(5))(H(2)O)](2)[Co(NCS)(4)], consists of two aqua-(2,3-naphtho-15-crown-5)sodium complex cations and one [Co(NCS)(4)](2-) complex anion, which has crystallographic symmetry. In the anion, the Co(II) centre is coordinated by the N atoms of four NCS(-) ligands in a distorted tetra-hedral geometry. In the complex cations, the Na(I) centre is coordinated by five O atoms of the 2,3-naphtho-15-crown-5 ligand and one water O atom. The complex mol-ecules form a two-dimensional network via weak O-Hâ¯S inter-actions between adjacent cations and anions.
RESUMEN
THE TITLE COMPOUND [SYSTEMATIC NAME: bis(2,5-dioxo-4,4-diphenylimidazolidin-1-ido-κN(1))bis(ethylenediamine-κ(2)N,N')cobalt(II)], [Co(C(15)H(11)N(2)O(2))(2)(C(2)H(8)N(2))(2)], has site symmetry . The Co(II) cation is located on an inversion center and coordinated by two phenytoin anions and two ethyl-enediamine ligands in a distorted octa-hedral geometry. In the phenytoin anion, the two phenyl rings are twisted with respect to the central hydantoin ring, making dihedral angles of 77.49â (16) and 64.55â (15)°. Intra-molecular and inter-molecular N-Hâ¯O hydrogen bonding is present in the crystal structure.
RESUMEN
In the title complex, [Cu(2)Cl(4)(C(17)H(22)N(2))(2)], the Cu(II) cation is coordinated by a N,N'-dibenzyl-propane-1,2-diamine ligand and two Cl(-) anions, and a Cl(-) anion from an adjacent mol-ecule further bridges to the Cu(II) cation in the apical position, with a longer Cu-Cl distance of 2.9858â (18)â Å, forming a centrosymmetric dimeric complex in which each Cu(II) cation is in a distorted square-pyramidal geometry. Intra-molecular N-Hâ¯Cl hydrogen bonding is observed in the dimeric complex.
RESUMEN
The title tetra-nuclear Sn(IV) compound, [Sn(4)(C(7)H(6)Cl)(8)Cl(2)O(2)(OH)(2)], has site symmetry . Two O(2-) and two OH(-) anions bridge four Sn(IV) cations to form the tetra-nuclear compound. The two independent Sn(IV) cations assume SnO(3)C(2) and SnO(2)C(2)Cl distorted trigonal-bipyramidal coordination geometries. Intra-molecular O-Hâ¯Cl hydrogen bonding is present in the structure. One Cl atom of a chloro-benzyl ligand is disordered over two sites with an occupancy ratio of 0.693â (2):0.307â (2).
RESUMEN
The asymmetric unit of the title complex, [Ni(C(16)H(20)N(2))(2)(H(2)O)(2)]Cl(2)·C(3)H(7)NO, consists of two Ni(II) atoms, each lying on an inversion center, two Cl anions, two N,N'-dibenzyl-ethane-1,2-diamine ligands, two coordinated water mol-ecules and one N,N-dimethyl-formamide solvent mol-ecule. Each Ni(II) atom is six-coordinated in a distorted octa-hedral coordination geometry, with the equatorial plane formed by four N atoms and the axial positions occupied by two water mol-ecules. The complex mol-ecules are linked into a chain along [001] by N-Hâ¯Cl, N-Hâ¯O and O-Hâ¯Cl hydrogen bonds. The C atoms and H atoms of the solvent mol-ecule are disordered over two sites in a ratio of 0.52â (2):0.48â (2).
RESUMEN
The mol-ecule of the title compound, C(28)H(42)N(6), has site symmetry with the centroid of the piperazine ring located on an inversion center. The piperazine ring adopts a chair conformation. The benzene ring and propyl-piperazine are on opposite sides of the C=N bond, showing an E configuration.
RESUMEN
In the title compound, C(27)H(26)N(2)O(6), the imidazolidine ring adopts an envelope conformation. The methyl group on the imidazolidine ring is disordered over two positions with occupancies of 0.517â (11) and 0.483â (11), and the 3,4-methyl-enedioxy-phenyl at the 3-position of imidazolidine ring is also disordered over two positions with occupancies of 0.60â (2) and 0.40â (2).
RESUMEN
In the title compound, [Er(C(18)H(22.5)N(2)O(4))(2)], the Er atom is located on a twofold rotation axis and is eight-coordinated by four O atoms and four N atoms from two symmetry-related 6,6'-dimethoxy-2,2'-(ethane-1,2-diyldiiminodimethylene)diphenolate(1.5-) ligands. Due to disorder of one phenolate H atom with half-occupation, the overall charge of one tetradentate ligand is -1.5. The ligand molecules are stabilised by intramolecular N-Hâ¯O and O-Hâ¯O hydrogen bonds and are linked into a chain parallel to the a axis by a C-Hâ¯O hydrogen bond. Neighbouring chains are connected by van der Waals forces, resulting in a three-dimensional network.
RESUMEN
The title compound, [Pr(C(18)H(22.5)N(2)O(4))(2)], is isotypic with its Er and Tb analogues. All interatomic distances, angles and the hydrogen bond geometry are very similar for the three structures..
RESUMEN
The title compound, [Tb(C(18)H(22.5)N(2)O(4))(2)], is isotypic with its Pr and Tb analogues. All interatomic distances, angles and the hydrogen bond geometry are very similar for the three structures.