Two different methods for the regioselective nitration of different meso-triarylcorroles leading to the corresponding β-substituted nitrocorrole iron complexes have been developed. A two-step procedure affords three Fe(III) nitrosyl products - the unsubstituted corrole, the 3-nitrocorrole and the 3,17-dinitrocorrole. In contrast, a one-pot synthetic approach drives the reaction almost exclusively to formation of the iron nitrosyl 3,17-dinitrocorrole. Electron-releasing substituents on the meso-aryl groups of the triarylcorroles induce higher yields and longer reaction times than what is observed for the synthesis of similar triarylcorroles with electron-withdrawing functionalities, and these results can be confidently attributed to the facile formation and stabilization of an intermediate iron corrole π-cation radical. Electron-withdrawing substituents on the meso-aryl groups of triarylcorrole also seem to labilize the axial nitrosyl group which, in the case of the pentafluorophenylcorrole derivative, results in the direct formation of a disubstituted iron μ-oxo dimer complex. The influence of meso-aryl substituents on the progress and products of the nitration reaction was investigated. In addition, to elucidate the most important factors which influence the redox reactivity of these different iron nitrosyl complexes, selected compounds were examined by cyclic voltammetry and thin-layer UV-visible or FTIR spectroelectrochemistry in CH2Cl2.
The title compound, [Ag(C9H13N5S)Cl(C18H15P)2], crystallizes with four independent molecules in the asymmetric unit, in each of which the Ag atom is in a distorted tetrahedral coordination, defined by the chloride ligand, the S atom of the neutral ligand and two P atoms derived from the triphenyl phosphine ligands. The thiosemicarbazone acts as a monodentate ligand through its thione S atom. An intramolecular N—H⋯Cl hydrogen bond occurs in two of the independent molecules. In the crystal, the molecules are assembled through N—H⋯Cl hydrogen bonds, forming chains along .
Structural characterization of a dihydrogen phosphate complex of triprotonated tris[2-(2-thienylmethylamino)ethyl] amine shows that eight dihydrogen phosphate anions are assembled around the host by strong interactions of H-bond donors and acceptors to form a new type of cyclic anion octamer as (H2PO4−)8, an analogy of cyclic water octamer. The presence of an anion cluster has also been identified by electrospray ionization mass spectrometry and 31P NMR experiments.
The title compound, C26H18, consists of a benzene ring with meta-substituted 1-naphthalene substituents, which are essentially planar (r.m.s. deviation = 0.039 and 0.027 Å). The conformation is mixed syn/anti, with equivalent torsion angles about the benzene–naphthalene bonds of 121.46 (11) and 51.58 (14)°.
The title compound, C26H18, consists of a benzene ring with meta-substituted 2-naphthalene substituents, which are essentially planar [r.m.s. deviations = 0.022 (1) and 0.003 (1) Å]. The conformation is syn, with equivalent torsion angles about the benzene–naphthalene bonds of −36.04 (13) and +34.14 (13)°. The molecule has quasi-C
s molecular symmetry.
Several procedures for the demetalation of silver(III) corrolates have been tested. Acidic conditions induce removal of the silver ion but they can also promote concomitant oxidation of the corrole nucleus to an isocorrole species, the degree of which will depend upon the specific acidic media. This oxidation cannot be completely avoided by addition of hydrazine, particularly in the case of 3-NO2 substituted complexes which are quantitatively converted into the corresponding 3-NO2, 5-hydroxy isocorroles upon silver ion removal. Several β-nitro isocorrole products were isolated, and one was structurally characterized. Electrochemical and chemical reductive methods for silver(III) corrolates demetalation were then tested with the aim to avoid the formation of isocorroles. While reaction with sodium borohydride was shown to be quite effective to demetalate unsubstituted silver corrolates this was not the case for the β-nitro derivatives where the peripheral nitro group is reduced by borohydride giving the corresponding 3-amino free base corrole species. For the β-nitro corrole silver complexes, a successful approach was obtained using DBU/THF solutions which afforded the 3-NO2 corrole free-base compound as a single reaction product in good yield. These conditions were also effective for unsubstituted corroles although longer reaction times were necessary in this case. To study in greater detail the corrole demetalation behavior, selected Ag(III) derivatives were characterized by cyclic voltammetry in pyridine, and the demetalation products spectrally characterized after controlled potential reduction in a thin-layer spectroelectrochemical cell.
The syntheses and spectroscopic properties of a series of pegylated zinc(II)-phthalocyanines (Zn-Pcs) containing one, two or eight tri(ethylene glycol) chains are described. The single molecular structure of a phthalonitrile precursor containing one hydroxyl and one PEG group, and its unique intermolecular hydrogen bonding are presented. The pegylated Pcs are highly soluble in polar organic solvents and have fluorescence quantum yields in the range 0.08–0.28.
PDT; PEG; phthalocyanine; phthalonitrile; fluorescence
The title compound, C32H40N2O4, is a 1,10-diaza-18-crown-6 cryptand with an o-terphenyl bridge. In the polyether ring, two adjacent –CH2– groups are disordered with very nearly equal populations of two conformers. The ordered bond lengths are normal, with average C—C = 1.511 (3) Å, C—O = 1.421 (3) Å, and C—N = 1.466 (4) Å. The r.m.s. deviations of the three rings of the terphenyl bridge vary from 0.007 to 0.009 Å and the two rings ortho to one another are twisted by 50.75 (5) and 47.76 (4)° with respect to the third ring. The N⋯N distance is 5.408 (1) Å.
The dirhodium complex, [Rh2(C18H15P)4(CO)2]·2(CH3)2CO, has crystallographic twofold symmetry and the Rh—Rh distance is 2.6266 (8) Å. The four atoms proximate to each Rh atom [Rh—P = 2.3222 (7) and 2.3283 (8) Å, and Rh—C = 1.961 (3) and 2.045 (3) Å] form a distorted tetrahedron with large deviations from the putative tetrahedral angles [r.m.s. deviation = 23 (1)°]. The six angles more closely approximate those of a trigonal bipyramid [r.m.s. deviation = 14 (1)°] with one missing equatorial ligand. The two bridging carbonyl ligands are much more linearly coordinated to one Rh [Rh—C O = 151.0 (2)°] than to the other [127.0 (2)°], and the two Rh2CO planes form a dihedral angle of 45.43 (5)°. The two acetone solvent molecules are disordered, and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst.
The absolute configuration of 3-benzoyl-4-hydroxy-6,6-dimethyl-1,5,7-tris(3-methylbut-2-enyl)bicyclo[3.3.1]non-3-ene-2,9-dione, C33H42O4, isolated from Hypericum hypericoides, has been determined. The previous study [Xiao et al. (2007 ▶). J. Nat. Prod.
70, 1779–1782] gave only the established relative configuration. The three stereogenic centers are now established as 1R, 5R and 7S on the basis of the refinement of the Flack absolute structure parameter against Cu Kα data and correspond to a specific rotation of [α]D
20 = +66°. The enol–hydroxy group forms an intramolecular O—H⋯O hydrogen bond to close an S(6) ring.
The title compound, C34H30N4O2, lies on an inversion center and consists of two 3-substituted-1H-indole units linked by a 1,2-dimethylenehydrazine bridge. It is one of numerous examples in which two aromatic ring systems are joined by this 4-atom bridge. The geometry of the centrosymmetric bridge is: C(arom)—C = 1.444 (3), C=N = 1.284 (3), N—N = 1.414 (4) Å, C(arom)—C=N = 122.6 (2) and C=N—N = 111.9 (2)°. The nine non-H atoms of the indole unit lie in a plane (δr.m.s. = 0.0089 Å) which is twisted 6.0 (2)° with respect to the hydrazine bridge plane. The benzyloxymethyl substituents do not lie in the plane of the rest of the molecule and are in a folded rather than an extended conformation. This is described by the three torsion angles in the middle of the C=N—C—O—CBz group, viz. 98.5 (3), −62.1 (3), and −66.3 (2)°.
The title compound, C12H14O3, is a natural product derived from the medium-sized hawthorn Crataegus persimilis (’prunifolia’). The mean plane of the butene moiety is twisted by 13.27 (7)° with respect to the that of the dioxobenzaldehyde moiety. There is an intramolecular hydrogen bond between the hydroxyl group and the carbonyl O atom.
In the title complex, [Cu(C15H19N2)2] or [Cu(L
2)] (HL is 3,3′,4,4′,5,5′-hexamethylpyrromethene), the CuII atom is coordinated by four N atoms [Cu—N 1.939 (2)–1.976 (2) Å] from two L ligands in a distorted tetrahedral geometry. The mean planes of the CuN2C3 metallocyclic rings form a dihedral angle of 72.73 (6)°. In the L ligands, the pyrrole rings are inclined to each other at dihedral angles of 3.03 (7) and 9.83 (7)°. The crystal packing exhibits weak intermolecular C—H⋯π interactions, which form chains in .
In the title solvate, [Rh2(C22H18N2O2)(C8H12)2]·CH2Cl2, each organometallic molecule is composed of two RhI cations, the tetradentate dianion α,α′-bis(salicylaldiminato)-m-xylene and two 1,5-cyclooctadiene (COD) ligands. Each RhI atom is coordinated by one O atom [Rh—O = 2.044 (2) and 2.026 (2) Å], one N atom [Rh—N = 2.083 (2) and 2.090 (2) Å], and one COD ligand via two η2-bonds, each directed toward the mid-point of a C=C bond (Cg): Rh—Cg = 2.007 (2), 2.013 (2), 2.000 (2) and 2.021 (2) Å. Each RhI atom has a quasi-square-planar coordination geometry, with average r.m.s. deviations of 0.159 (1) and 0.204 (1) Å from the mean planes defined by Rh and the termini of its four coordinating bonds. The two COD ligands have quasi-C
2 symmetry, twisted from ideal C
2v symmetry by 30.0 (3) and −33.1 (3)°, and are quasi-enantiomers of one another. The intramolecular Rh⋯Rh distance of 5.9432 (3) Å suggests that there is no direct metal–metal interaction.
In the title compound, C26H24N2O2, the planar 1H-imidazole ring makes dihedral angles of 35.78 (4), 26.35 (5) and 69.75 (5)°, respectively, with the dimethoxyphenyl ring and the phenyl rings in the 4- and 5-positions. In the crystal, C—H⋯O hydrogen bonds connect neighbouring molecules, forming infinite chains running along the b axis. Furthermore, the crystal structure exhibits a C—H-⋯π interaction between a methyl H atom and a phenyl ring from an adjacent molecule.
The title compound, C15H17NO2S, exhibits intramolecular hydrogen bonding between the amine H atom and a sulfonyl O atom. The conformation of the molecule is described by the four PhCH2—NH—CH2—CH2—SO2Ph torsion angles of 79.6 (2), −166.21 (14), −70.29 (17) and −58.93 (13)°.
Copper and germanium complexes of β-substituted nitrocorroles were reacted with 4-amino-4H-1,2,4-triazole to give the corresponding β-amino-β-nitro derivatives, in moderate to good yields. This is the first successful example of a vicarious nucleophilic substitution performed on corrole derivatives, because the same reaction carried out on silver complexes afforded the corresponding 6-azahemiporphycenes by way of corrole ring expansion. The first step of this work is related to the modification of a synthetic protocol for preparation of the β-substituted nitro corroles. The nitration reaction was carried out on a copper corrole using NaNO2 as the primary source of NO2− coupled with AgNO2 used as oxidant. By variation of the molar ratio of the reagents it was possible to direct the product distribution towards mono- and di-nitro derivatives. The reaction between mono- and di-nitro derivatives of (TtBuCorrCu) with 4-amino-4H-1,2,4-triazole gave good results, leading to the isolation of 2,3-(NH2)(NO2)-TtBuCorrCu and 2,18-(NH2)2-3,17-(NO2)2-TtBuCorrCu in moderate yields. To elucidate factors that influence the reaction, and to highlight the different behavior observed for different metal complex substrates, the electrochemistry of three copper complexes, TtBuPCorrCu, (NO2)TtBuPCorrCu and (NO2)2TtBuPCorrCu, were studied by cyclic voltammetry and thin-layer UV-visible spectroelectrochemistry. The nitro groups on (NO2)xTtBuPCorrCu are highly electron-withdrawing, which leads not only to a substantial positive shift of all redox potentials, but also to a unique redox behavior and UV-vis spectrum of the singly reduced product as compared to the parent compound, TtBuPCorrCu. Finally, the amination reaction was carried out on a Ge(IV) nitrocorrolate, giving in good yield the 2-amino-3-nitroderivative, which was structurally characterized by single crystal X-ray crystallography.
The title compound, C24H26O2Si2, has C
2 crystallographic symmetry. The dihedral angle between the aromatic rings is 84.5 (2)°. The acetylene group is slightly non-linear, with angles at the acetylene C atoms of 175.7 (2) and 177.0 (2)°. In the crystal structure, only van de Waals interactions occur.
The title compound, C13H15ClN2O6, was synthesized by hypochlorous acid-mediated chlorination of N-acetyl-3-nitro-l-tyrosine ethyl ester. The OH group forms an intramolecular O—H⋯O hydrogen bond to the nitro group and the N—H group forms an intermolecular N—H⋯O hydrogen bonds to an amide O atom, linking the molecules into chains along . The crystal studied was a non-merohedral twin, with a 0.907 (4):0.093 (4) domain ratio.
The title compound, C15H13N5, crystallizes with two independent molecules in the asymmetric unit. The molecular conformations are stabilized by C—H⋯N contacts forming S(6) ring motifs. In the crystal, pairs of molecules are connected into R
2(12) dimers by N—H⋯N hydrogen bonds. C—H⋯π interactions and π–π stacking interactions [centroid–centroid distances = 3.6085 (8), 3.6657 (8), 3.4745 (8) and 3.5059 (8) Å] also also observed.
In the title compound, C10H9N5, the phenyl ring is twisted with respect to the pyrazole ring, forming a dihedral angle of 24.00 (6)°. In the crystal, molecules are linked by N—H⋯N hydrogen bonds into chains running parallel to  containing alternating R
2(6) and R
2(12) rings. Further interactions are found in the crystal, viz. N—H⋯π(phenyl) interactions and weak face-to-face π–π stacking interactions [centroid–centroid distance = 3.8890 (6) Å] between the centroids of the pyrazole and phenyl rings are observed.
The title compound, C18H14O, is polymorphic at 123 K. The orthorhombic form reported herein has two independent molecules in the asymmetric unit, with molecular volume 313.5 Å3. The previously reported triclinic (P-1) form [Raston & Scott (2000 ▶). Green Chem., 2, 49–52] has molecular volume 309.6 Å3 at the same temperature. All three molecules deviate significantly and systematically from the putative Cs symmetry (δr.m.s. = 0.0265, 0.0256, 0.0497 Å). Comparison of the two molecules in the orthorhombic polymorph shows that 16 of the 19 equivalent pairs of framework atoms have a mirror-image pattern of deviations (above/below plane), suggesting that the two are quasi-enantiomorphs. The pattern of deviations in the triclinic form is nearly the same (13 of 19 atom pairs) as the orthorhombic form.
The title compound C20H20O4S, is polymorphic. In the tetragonal form, the molecule lies on a crystallographic twofold axis, while the monoclinic form has only approximate C
2 molecular symmetry. The greatest excursion from C
2 symmetry is in the orientation of the two phenyl rings; at 100 K, one of the rings is rotated −37.2 (3)° and the other by 46.9 (3)° from their symmetric (tetragonal) positions. There are only minor differences in the three-ring nucleus; the best molecular fit of the tetragonal and monoclinic forms, both at 100 K and excluding phenyl rings and H atoms, shows an r.m.s. deviation of 0.066 Å. Both forms have the same absolute configuration.
The title compound, C11H13NO2Si, is a low-temperature form of the previously reported room-temperature structure [Garcia et al. (1998 ▶). Acta Cryst. C54, 489–491]. At 298 K, the material crystallizes in the space group Pnma and occupies a crystallographic mirror plane, but at 100 K the space group changes to P212121, the volume decreases by 5% and the molecule distorts. The greatest molecular distortions from C
s symmetry are rotations of the trimethylsilyl and nitro groups by 10.56 (8) and 11.47 (9)°, respectively, to the benzene mean plane. At low temperature, the crystal also becomes an inversion twin, the refined ratio of the twin components being 0.35 (15):0.65 (15).
The title molecule, C20H24O2, is a chalconoid derivative in which the keto–enone group is slightly distorted from planarity; the O=C—C=C torsion angle is 12.24 (13)°.