Juliana A. Vale

Knoevenagel Condensation of Aldehydes and Ketones with Malononitrile Catalyzed by Amine Compounds-Tethered Fe3O4@SiO2 Nanoparticles

A new magnetic nanoparticle supported-catalyst was developed for the Knoevenagel condensation between malononitrile and several aldehydes. The Fe3O4@SiO2-3N (where 3N = N1-(3-trimethoxysilylpropyl)diethylenetriamine) catalyst was characterized by XRD, infrared spectroscopy, and thermogravimetric analysis. The reactions provide excellent yields in a shorter reaction time in relation to others reported in the literature. The catalyst was easily recovered and reused until six times without significant loss of its catalytic capacity.Graphical Abstract

Rapid conversion of cyclohexenone, cyclohexanone and cyclohexanol to ε-caprolactone by whole cells of Geotrichum candidum CCT 1205

Abstract ɛ-Caprolactone (ɛ-CL) was obtained with excellent conversion and short reaction times from the substrates cyclohexenone, cyclohexanone and cyclohexanol using whole cells of Brazilian Geotrichum candidum (CCT 1205). The reactions were monitored over time by gas chromatography, and the intermediates of the one-pot cascade biotransformation involving reductions of C=C and C=O bonds as well as the Baeyer–Villiger oxidation were identified and quantified. The Baeyer–Villiger monooxygenase (BVMO) enzyme was predominant, and all three substrates were completely converted into ɛ-CL. Furthermore, the whole cells of Geotrichum candidum were recycled and reutilized in the biotransformation of cyclohexanone, producing ɛ-CL at least six consecutive times without a significant loss of activity, reaction yields or product purity.

Rare Earth-Indomethacinate Complexes with Heterocyclic Ligands: Synthesis and Photoluminescence Properties

In this work, synthesis, characterization and photophysical properties of trivalent rare earth complexes with a nonsteroidal anti-inflammatory drug [the indomethacinate (indo), presenting formulas RE(indo)3(H2O)x (x = 3, for Eu and Gd, and x = 4 for Tb), RE(indo)3(bipy) and RE(indo)3(phen) (bipy: 2,2’-bipyridine, and phen: 1,10-phenanthroline)] were investigated. Based on photoluminescent results, the intramolecular energy transfer process from T1 triplet states of indo, phen and bipy ligands to the D0 emitting level of the Eu ion in the coordination compounds is discussed. Accordingly, it is proposed two possible intramolecular energy transfer mechanisms between indomethacinate ligand and rare earth ions, which involve the participation of excited electronic states of the heterocyclic ligands as intermediate ones.

Novel luminescent Eu3+-indandionate complexes containing heterobiaryl ligands

Novel Ln3+-indandionate complexes of formulas [Ln(aind)3L(H2O)] and [Ln(bind)3L]∙H2O (L: 1,10-phenanthroline (phen) or 4,7-dimethyl-1,10-phenanthroline (dmphen), Ln3+: Eu3+ or Gd3+, aind: 2-acetyl-1,3-indandionate and bind: 2-benzoyl-1,3-indandionate) were synthesized and characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analyses. The characterization data are consistent with the presence of a water lattice molecule in the [Ln(bind)3L]∙H2O compounds. However, the data also suggest that the water acts as a coordinated molecule in the [Ln(aind)3L(H2O)] ones. Theoretical geometries of the Eu3+-complexes have been optimized via the SPARKLE/AM1 Model for lanthanide complexes that are consistent with their luminescence experimental data. The photoluminescence properties of the Eu3+-compounds have been discussed in terms of experimental intensity parameters (Ω2 and Ω4), radiative (Arad), and non-radiative (Anrad) spontaneous emission coefficients. The higher values of emission quantum efficiency (η) of the [Eu(bind)3L]∙H2O compounds reflect the absence of luminescence-quenching water molecule in their first coordination spheres.

Lanthanide nitrates as Lewis acids in the one-pot synthesis of 1,2,4-oxadiazole derivatives

In this work we report the use of lanthanide nitrates [Ln(NO3)3] acting as catalyst in direct one-pot synthesis of 3-benzoyl- and 3-acetyl-1,2,4-oxadiazoles derivatives from ketones, nitriles and nitric acid. This is the first example of one-pot synthesis of benzoyl- and acetyl 1,2,4-oxadiazoles derivatives preparation using acetophenones derivates with electron-donator groups.