Hemi-Synthesis of Chiral Imine, Benzimidazole and Benzodiazepines from Essential Oil of Ammodaucus leucotrichus subsp. leucotrichus.

The hemi-synthesis of chiral imine, benzimidazole and benzodiazepine structures is reported by the condensation of (S)-(-)-perillaldehyde, the major phytochemical of Ammodaucus leucotrichus subsp. leucotrichus essential oil, with different amine derivatives of 2,3-diaminomaleonitrile, o-phenylenediamine and 3-[(2-aminoaryl)amino]dimedone. The reaction proceeds in situ at ambient temperature without prior isolation of the natural (S)-(-)-perillaldehyde. Final products precipitate in the ethanolic reaction medium. 2D NMR and single-crystal X-ray diffraction studies were used to unequivocally characterize the structures in solution and in the solid state, respectively. Chiral HPLC analysis confirms the formation of unique enantiomers and diastereomeric mixtures.

A Suitable Functionalization of Nitroindazoles with Triazolyl and Pyrazolyl Moieties via Cycloaddition Reactions.

The alkylation of a series of nitroindazole derivatives with 1,2-dibromoethane afforded the corresponding N-(2-bromoethyl)- and N-vinyl-nitro-1H-indazoles. The Cu(I)-catalysed azide- alkyne 1,3-dipolar cycloaddition was selected to substitute the nitroindazole core with 1,4-disubstituted triazole units after converting one of the N-(2-bromoethyl)nitroindazoles into the corresponding azide. The reactivity in 1,3-dipolar cycloaddition reactions with nitrile imines generated in situ from ethyl hydrazono-α-bromoglyoxylates was studied with nitroindazoles bearing a vinyl unit. The corresponding nitroindazole-pyrazoline derivatives were obtained in good to excellent yields.

Molecule-like Eu3+-dimers embedded in an extended system exhibit unique photoluminescence properties.

Much is known about the photoluminescence of lanthanide-containing systems, particularly amorphous silicates or organic-inorganic hybrids and crystalline metal-organic frameworks. Comparatively, stoichiometric microporous Ln-silicates are poorly studied. Here, we report the exceptional photoluminescence of microporous AV-24, K(7)[Ln(3)Si(12)O(32)] x xH(2)O (Ln(3+) = Sm(3+), Eu(3+), Gd(3+), Tb(3+)), the first silicate possessing Ln(3+)-O-Ln(3+) dimers (inter-Ln distance ca. 3.9 A), i.e., two edge-sharing {LnO(6)} octahedra embedded in a crystalline matrix. It is totally unprecedented that in AV-24 Eu(3+)-O-Eu(3+) dimers behave like discrete entities, i.e., molecules: they (i) have a unique emission signature, with pseudopoint group symmetry (C(i)), different from the symmetry (C(1)) of each individual constituent Eu(3+) ion, and (ii) exhibit the unusually long (5)D(0) lifetime of 10.29 ms (12 K). In accord with the experimental evidence, a molecular orbital model shows that the Eu(3+)-O-Eu(3+) dimers are energetically more stable than the individual metal ions.

1D to 3D NMR study of microporous alumino-phosphate AlPO(4)-40.

From one- to two- and three-dimensional MAS NMR solid-state experiments involving (31)P and (27)Al, we show that the structure of microporous alumino-phosphate AlPO(4)-40 contains at least four times more sites than expected, and we attribute two types of Al(IV) sites. The newly described (27)Al-(31)P MQ-HMQC opens new possibilities of describing details of three-dimensional bounded networks.

A new synthetic approach to N-arylquinolino[2,3,4-at]porphyrins from beta-arylaminoporphyrins.

A new reaction leading to porphyrins bearing fused rings is described. Novel N-arylquinolino[2,3,4-at]porphyrins 2 were obtained by thermal oxidative cyclization of beta-arylaminoporphyrins 1. The starting beta-arylaminoporphyrins were prepared by two routes: (i) nucleophilic displacement of the nitro group from 2-nitro-5,10,15,20-tetraphenylporphyrin by anilines and (ii) palladium-catalyzed amination of bromobenzene derivatives with (2-amino-5,10,15,20-tetraphenylporphyrinato)nickel(II). The N-arylquinolino[2,3,4-at]porphyrins show interesting UV-vis spectra with strong absorption bands in the red region.

An easy synthetic approach to pyridoporphyrins by domino reactions.

Beta-amino-meso-tetraarylporphyrins react with cyclic enol ethers to yield pyrido[2,3-b]porphyrins bearing two vicinal hydroxyalkyl groups. These reactions are catalyzed by lanthanum triflate and occur under mild conditions. Esterification of the hydroxyalkyl groups with succinic anhydride and dodecanoyl chloride afforded the corresponding esters in almost quantitative yields. The crystal structure of the most hydrophobic derivative 7 was determined, and it shows that these porphyrinic macrocycles form one-dimensional supramolecular tapes in the solid state.

Photoluminescent microporous lanthanide silicate AV-21 frameworks.

The hydrothermal synthesis and structural characterization of the lanthanide silicate system [Na(6)Ln(2)Si(12)O(30).x H(2)O] (Ln=La(3+), Sm(3+), Eu(3+), Gd(3+), and Tb(3+)), named AV-21, has been reported. Structural elucidation of the Sm(3+) analogue (isomorphous with the Eu(3+), Gd(3+), and Tb(3+) frameworks) using single-crystal synchrotron X-ray diffraction and solid-state NMR spectroscopy reveal disorder in the Si(1) second coordination sphere. La-AV-21 presents a distinct framework. These materials combine microporosity and interesting photoluminescence features with structural flexibility that allows the introduction of a second or third type of lanthanide center. Room-temperature lifetime decay dynamics have been used to estimate the Ln(3+)-Ln(3+) distances and the maximum distance over which energy transfer is active. Though the majority of Ln(3+) centers occupy regular framework positions, the Ln(2) defect centers are disordered over the Na(1) sites in the pores and greatly influence the energy-transfer process, providing a unique opportunity for studying the relationship between structural disorder and photoluminescence properties in framework solids.