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1.  Copper β-trinitrocorrolates 
Journal of porphyrins and phthalocyanines  2013;17(6-7):10.1142/S1088424613500120.
The β-nitration reaction carried out on the corrole macrocycle has been shown to be extremely regioselective, although the reduced symmetry of the macrocycle could potentially lead to a huge number of possible regioisomers. We recently reported that the careful use of AgNO2/NaNO2 as a nitrating system enabled the achievement in good yields of mono- and dinitro-derivatives on both corrole free base and its copper complex, proving to be an efficient and cost-effective method. In this work, we present a detailed study of the scope of this method using TtBuCorrH3 as a model corrole. A further increase of the oxidant pushes the nitration up to the functionalization of three β-pyrrolic positions, although concomitant decomposition of the macrocycle is also observed. The application of the proven nitration method with a five-fold excess of both silver and sodium nitrites with respect to corrole, afforded the 2,3,17-(NO2)3-TtBuPCorrCu as the main product, in 25% yield, together with traces of another compound identified by X-ray crystallographic analysis as the 3,8,17-(NO2)3-TtBuPCorrCu isomer. In light of these recent results, we also reinvestigated the characterization of the nitration products obtained from bis-substitution reactions, allowing among others the identification of the copper 3,8-(NO2)2 corrolate.
PMCID: PMC3811046  PMID: 24179331
corrole; β-functionalization; nitration; AgNO2
2.  Tris(4-formyl­phen­yl)phosphane oxide tetra­hydro­furan hemisolvate 
The title compound, C21H15O4P·0.5C4H8O, contains an ordered phosphane oxide in a general position and a tetra­hydro­furan solvent mol­ecule disordered about a twofold axis. All three aldehyde substituents are nearly coplanar with their attached benzene rings, with C—C—C—O torsion angles in the range 1.64 (17)–4.24 (19)°. All three have different conformations with respect to the P=O group, one syn, one anti, and one gauche. Two of the aldehyde substituents form inter­molecular C—H⋯O contacts.
PMCID: PMC3793837  PMID: 24109424
3.  Synthesis, characterization, and preliminary in vitro studies of vanadium(IV) complexes with a Schiff base and thiosemicarbazones as mixed-ligands 
[VO(Sal-L-tryp)(H2O)] 1 (where sal-L-tryp = N-salicylidene-L-tryptophanate) was used as a precursor to produce the novel complexes, [VO(Sal-L-tryp)(MeATSC)].1.5C2H5OH 2 (where MeATSC = 9-Anthraldehyde-N(4)-methylthiosemicarbazone), [VO(Sal-L-tryp)(N-Ethhymethohcarbthio)].H2O 3 (where N-Ethhymethohcarbthio = (E)-N-ethyl-2-(4-hydroxy-3-methoxybenzylidene)hydrazinecarbothioamide), and [VO(Sal-L-tryp)(acetylethTSC)].C2H5OH 4 (where acetylethTSC = (E)-N-ethyl-2-(1-(thiazol-2-yl)ethylidene)hydrazinecarbothioamide), by reaction with the respective thiosemicarbazone. The chemical and structural properties of these ligands and complexes were characterised by elemental analysis, ESI MS, FT-IR, UV-visible, ESR, 1H and 13C NMR spectroscopy, and X-ray crystallography. DMSO and DMSO-d6 solutions of compounds 1-4 were oxidised in air to produce vanadium(V) species which were verified by ESI MS and 51V NMR spectroscopy. Anti-cancer properties of compounds 2-4 were examined with three colon cancer cell lines, HTC-116, Caco-2, and HT-29, and also with non-cancerous colonic myofibroblasts, CCD18-Co. Compounds 2-3 exhibited less inhibitory effects in the CCD-18Co cells, indicating a possible cytotoxic selectivity towards colon cancer cells. In general, those compounds which exhibited anti-proliferative activity on cancer cells, but did not affect non-cancerous cells, may have a potential in chemotherapy.
PMCID: PMC3725831  PMID: 23904789
vanadium(IV); vanadium(V); 51V NMR; ESR spectroscopy; thiosemicarbazone; colorectal cancer
4.  Field effects induce bathochromic shifts in xanthene dyes 
Journal of the American Chemical Society  2012;134(25):10502-10508.
There is ongoing interest in near infrared (NIR) absorbing and emitting dyes for a variety of biomedical and materials applications. Simple and efficient synthetic procedures enable the judicious tuning of through-space polar (field) effects as well as low barrier hydrogen bonding to modulate the HOMO-LUMO gap in xanthene dyes. This affords unique NIR-absorbing xanthene chromophores.
PMCID: PMC3384756  PMID: 22642754
xanthenes; near-infrared; large Stokes shift
5.  β-Nitro-5,10,15-tritolylcorroles 
Inorganic Chemistry  2012;51(12):6928-6942.
Functionalization of the β-pyrrolic positions of the corrole macrocycle with –NO2 groups is limited at present to metallocorrolates due to of the instability exhibited by corrole free bases under oxidizing conditions. A careful choice of the oxidant can limit the transformation of corroles into decomposition products or isocorrole species, preserving the corrole aromaticity, and thus allowing the insertion of nitro groups onto the corrole framework. Here we report results obtained by reacting 5,10,15-tritolylcorrole (TTCorrH3) with the AgNO2/NaNO2 system, to give mono- and di-nitrocorrole derivatives when stoichiometry is carefully controlled. Reactions were found to be regioselective, affording the 3-NO2TTCorrH3 and 3,17-(NO2)2TTCorrH3 isomers as the main products in the case of mono- and di-substitution, in 53 and 20% yields, respectively. In both cases, traces of other mono- and di-substituted isomers were detected, which were structurally characterized by X-ray crystallography. The influence of the β-nitro substituents on the corrole properties is studied in detail by UV-visible, electrochemical, and spectroelectrochemical characterization of these functionalized corroles. Density Functional Theory (DFT) and time-dependent DFT (TDDFT) calculations of the ground and excited state properties of these β-nitrocorrole derivatives also afforded significant information, closely matching the experimental observations. It is found that the β-NO2 substituents conjugate with the π-aromatic system of the macrocycle, which initiates significant changes in both the spectroscopic and redox properties of the so functionalized corroles. This effect is more pronounced when the nitro group is introduced at the 2-position, because in this case the conjugation is, for steric reasons, more efficient than in the 3-nitro isomer.
PMCID: PMC3381796  PMID: 22668242
6.  Bis-spirolabdane Diterpenoids from Leonotis nepetaefolia 
Journal of Natural Products  2012;75(4):728-734.
Ten new bis-spirolabdane diterpenoids, leonepetaefolins A–E (1, 3, 5, 7, 9) and 15-epi-leonepetaefolins A-E (2, 4, 6, 8, 10), together with eight known labdane diterpenoids (11–18) as well as two known flavonoids apigenin and cirsiliol, were isolated from the leaves of Leonotis nepetaefolia. The structures of the new compounds were determined on the basis of 1D-and 2D-NMR experiments including 1H, 13C, DEPT, 1H-1H COSY, HSQC, HMBC, and NOESY. The absolute configuration of an epimeric mixture of 1 and 2 was determined by X-ray crystallographic analysis. The compounds isolated were evaluated for their binding propensity in several CNS G protein-coupled receptor assays in vitro.
PMCID: PMC3338874  PMID: 22475308
7.  (Z)-1-(2-Hy­droxy­eth­yl)-4-(2-meth­oxy­benzyl­idene)-2-methyl-1H-imidazol-5(4H)-one 
In the title compound, C14H16N2O3, an analog of the chromophore in green fluorescent protein, the meth­oxy­phenyl substituent and the imidazole N adopt a Z conformation with respect to the C=C bond. Aside from the hy­droxy­ethyl group, the mol­ecule is approximately planar, with the five- and six-membered ring planes forming a dihedral angle of 9.3 (1)°. An intra­molecular C—H⋯N contact occurs. In the crystal, O—H⋯N hydrogen bonds link the mol­ecules, forming chains along the b-axis direction. C—H⋯O hydrogen bonds are also observed.
PMCID: PMC3629644  PMID: 23634131
8.  Bis(1,2,3-benzotriazolium) sulfate dihydrate 
In the asymmetric unit of the title hydrated salt, 2C6H6N3 +·SO4 2−·2H2O, there are two independent sulfate ions, one lying on a twofold axis, and the other in a general position. There are three independent benzotriazolium cations and three independent water mol­ecules. The sulfate ion in a general position forms hydrogen-bonded chains of stoichiometry SO4 2−·3H2O in the b-axis direction. The sulfate on the twofold axis is unhydrated and accepts hydrogen bonds from four surrounding benzotriazoles. The benzotriazolium cations form two types of stacks along b. One stack contains only one type of independent cation, related by inversion centers. The other stack contains two alternating independent cations and no symmetry. The two types of stacks have orientations which are rotated by about 79° in the ac plane. 12 symmetrically distinct hydrogen bonds of type N—H⋯O(sulfate), N—H⋯O(water), O—H⋯O(sulfate) and O—H⋯O(water), with donor–acceptor distances in the range 2.5490 (13)–2.7871 (12) Å, form a three-dimensional array.
PMCID: PMC3629645  PMID: 23634132
9.  β-Nitro Derivatives of Iron Corrolates 
Inorganic Chemistry  2012;51(6):3910-3920.
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.
PMCID: PMC3307940  PMID: 22394192
10.  4-(1-Allyl-4,5-diphenyl-1H-imidazol-2-yl)-N,N-dimethyl­aniline 
The title compound, C26H25N3, crystallizes with four independent mol­ecules, 1–4, in the asymmetric unit of the triclinic unit cell. The allyl substituents on the imidazole rings adopt similar conformations in all four mol­ecules. The imadazole and the 4-and 5-substituted phenyl rings of two pairs of molecules in the asymmetric unit stack parallel to (110). In contrast, the dimethyl­aniline systems in these pairs of mol­ecules are almost normal to one another, with dihedral angles of 85.84 (10) and 85.65 (10)° between the benzene rings of the two dimethyl­aniline fragments of mol­ecules 1 and 2, and 3 and 4, respectively. The crystal structure features an extensive series of C—H⋯π inter­actions that link the mol­ecules into undulating rows along the c axis. The crystal studied was a pseudo-merohedral twin with twin law [-100, 0-10, 111] and the BASF parameter refined to 0.513 (3).
PMCID: PMC3629582  PMID: 23634069
11.  Chlorido{4-ethyl-1-[1-(pyrazin-2-yl)ethyl­idene]thio­semicabazidato-κS}bis­(triphenyl­phosphane-κP)silver(I) 
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 [101].
PMCID: PMC3588416  PMID: 23476487
12.  Anion Cluster: Assembly of Dihydrogen Phosphates for the Formation of a Cyclic Anion Octamer 
Crystal growth & design  2012;12(2):567-571.
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.
PMCID: PMC3306550  PMID: 22435043
13.  1-[3-(Naphthalen-1-yl)phen­yl]naphthal­ene1  
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)°.
PMCID: PMC3569826  PMID: 23424572
14.  2-[3-(Naphthalen-2-yl)phen­yl]naph­thal­ene1  
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.
PMCID: PMC3569827  PMID: 23424573
15.  Demetalation of Silver(III) Corrolates 
Inorganic chemistry  2009;48(14):6879-6887.
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.
PMCID: PMC3538369  PMID: 19548683
16.  Pegylated Phthalocyanines: Synthesis and Spectroscopic Properties 
Tetrahedron letters  2011;52(50):6675-6678.
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.
PMCID: PMC3322642  PMID: 22505781
PDT; PEG; phthalocyanine; phthalonitrile; fluorescence
17.  5,7,8,10,11,13,14,16-Octa­hydro-6,15-(ethanoxyethanoxyethano)-1,4:17,20-dietheno[9,12,6,15]benzodioxadiaza­cyclo­docosine1  
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.
PMCID: PMC3515318  PMID: 23284538
18.  Di-μ-carbonyl-bis­[bis­(triphenyl­phos­phane)rhodium(0)](Rh—Rh) acetone disolvate1  
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. D65, 148–155].
PMCID: PMC3515148  PMID: 23284375
19.  Redetermination and absolute configuration of (+)-7-epiclusianone 
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.
PMCID: PMC3515307  PMID: 23284527
20.  (1E,2E)-1,2-Bis[(1-benzyloxymethyl-1H-indol-3-yl)methylidene]hydrazine 
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)°.
PMCID: PMC3515253  PMID: 23284473
21.  1-(2-Hy­droxy-5-meth­oxy­phen­yl)-3-methyl­but-2-en-1-one1  
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.
PMCID: PMC3515231  PMID: 23284451
22.  Bis[2,3,4-trimethyl-5-[(3,4,5-trimethyl-2H-pyrrol-2-yl­idene-κN)meth­yl]-1H-pyrrolato-κN]copper(II)1  
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 [100].
PMCID: PMC3515100  PMID: 23284327
23.  μ2-m-Xylylenebis(salicylaldiminato)-bis­(η4-1,5-cyclo­octa­diene)dirhodium(I) dichloro­methane solvate 
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.
PMCID: PMC3470182  PMID: 23125626
24.  2-(3,4-Dimeth­oxy­phen­yl)-4,5-diphenyl-1-(prop-2-en-1-yl)-1H-imidazole 
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.
PMCID: PMC3470344  PMID: 23125757
25.  N-[2-(Phenyl­sulfon­yl)eth­yl]benzyl­amine1  
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)°.
PMCID: PMC3470312  PMID: 23125725

Results 1-25 (134)