Paolo Bruni

Fourier transform infrared spectroscopy Part V. Vibrational studies on phenanthroline-perchloric acid complexes

Abstract Infrared spectra of phenanthrolines-perchloric acid hydrogen-bonded complexes are discussed together with x-ray results and theoretical calculations in order to verify the participation of ortho-hydrogens or ortho-methyls of phenanthroline in the complex formation. The role of through-bond and through-space contributions to hydrogen bonding is considered.

The reaction of 1,1,2,2-ethenetetracarbonitrile (TCNE) with aminopyridines: Salts and charge transfer complex formation☆

Abstract Aminopyridines form molecular complexes in solution with 1,1,2,2-ethenetetracarbonitrile (TCNE). Depending on the donor, the formation of pyridinium salts of the pentacyanopropenide anion may be competitive, or, in some cases, the sole reaction. This behaviour is discussed in terms of the basicity and geometry of aminopyridines. Formation constant and thermodynamic parameters were determined for the most stable complex with 2-dibenzoylaminopyridine-1-oxide.

3-phenyl-2H-1,4-benzoxazine-4-oxides—I : Synthesis and reduction

Abstract The title compounds were prepared by reductive cyclisation of o-nitro-phenoxy-acetophenones and characterized through a cycloadduct with acrylonitrile. Reduction of the N-oxides leads to the corresponding hydroxylamines that are highly unstable and can be transformed into the corresponding nitroxides by a variety of oxidation agents, including air. Previously unknown o-nitro-phenoxy-acetophenones were synthesized as starting materials for cyclisation reactions.

Trace element determination—I Use of 2,9-dimethyl-1,10-phenanthroline in determination of copper in heavy matrices by carbon furnace atomic-absorption spectrometry

A method for the determination of copper in complex matrices by electrothermal atomic-absorption spectrometry has been developed. It uses neocuproine as complexing agent. The detection limit is 0.2 ng/ml, and interferences are minimized.

Damaged polyethylene acetabular cups microscopy FT-IR and mechanical determinations

Attenuated total reflectance (ATR) microscopy FT-IR and micro-hardness determinations have been used to study defects in polyethylene acetabular cups for hip prosthesis. The morphology of polymer chains and the distribution of crystalline zones can cause anomalous wear, granulomatosis and, consequently, the failure of the implant. The results have been corroborated by applying a structural analysis by means of the finite element method (FEM).

Molecular complexes of hydrazones—VIII. Nitrofluorenes and arylhydrazones

Abstract Nitrofluorenes form π-π complexes with a series of hydrazones both in solution and in the solid state. The properties of the complexes, discussed on the basis of u.v.-vis and FT-i.r. data, suggest the presence of weak interactions, as confirmed by the formation constants and X-ray analysis. The presence of some degree of charge transfer is confirmed by ESR determinations. The X-ray analysis of the complex of benzaldehydediphenylhydrazone with 2,4,7-trinitrofluorenone is also reported.

Molecular Interactions Between Arylazopyridines and N-Hydroxyindoles

SummaryThe reaction of isomeric arylazopyridines with 1-hydroxy-2-phenylindole leads to molecular associations between the pyridine derivative and the 1-hydroxy-2-phenylindole itself or its dimer. The role of hydrogen bonding in the formation of the complex is also discussed in the light of conductivity measurements.ZusammenfassungDie Reaktion isomerer Arylazopyridine mit 1-Hydroxy-2-phenylindol führt zu molekularen Associaten zwischen den Pyridin-Derivaten und 1-Hydroxy-2-phenylindol oder seinem Dimer. Die Rolle der Hydrogenbindung bei der Bildung der Komplexverbindung wird mittels Leitfähigkeitsmessungen geprüft.

Molecular associations by Fourier transform infrared spectrometry. Part IV. Complexes of indoles with π*-organic acceptors

Abstract Molecular complexes of substituted indoles with π*-acceptors were investigated by means of Fourier transform infrared spectrometry under the conditions [D] 0 ⪢ [A] 0 , where [D] 0 and [A] 0 are the initial concentrations of the donor and acceptor, respectively. The formation constants of the complexes, evaluated on characteristic vibrational modes of the acceptors, are in substantial agreement with those determined by optical and nuclear magnetic resonance spectrometry.

Molecular associations of [2.2]paracyclophanearylhydrazones with organic acceptors, VIII

SummaryMolecular complexes of mono and disubstituted [2.2]paracyclophanehydrazones with organic acceptors have been studied by means of thermodynamic and spectroscopic properties. Furthermore, the enhancement of the donor strength, induced by the hydrazono group, is viewed in the light of substituent as well as transannular effects.ZusammenfassungEs wurden Molekülkomplexe von mono- und disubstituierten [2.2]Paracyclophanarylhydrazonen mit organischen Akzeptoren mittels thermodynamischer und spektroskopischer Methoden untersucht. Zusätzlich wird der Anstieg in der Donorstärke, der von der Hydrazonogruppe induziert wird, im Hinblick auf Substituenten- und auch transannulare Effekte diskutiert.

Fourier transform infrared spectroscopy: complexes of aromatic amines with organic acceptors. Part III

Abstract Determinations of formation constants in complexes of anilines with tetracyanoethylene and fluoranil by Fourier transform IR spectrometry are reported. The kinetics of the disappearance complexes are in agreement with the literature. Results of attempts to follow the reaction in the solid state are reported.