François X. Sauvage

A spectroscopic study of the complexation of phthalocyanines with water, ethanol and phenol

Abstract Assignments are collected for the i.r. spectra of solid films of phthalocyanines in their α and β modifications. On the basis of changes in these spectra the ability to form complexes with vapours of water, ethanol and phenol was investigated. All these species were found to be able to form hydrogen bonds to a nitrogen atom in the magnesium phthalocyanine molecule. Only phenol was found to adhere to zinc phthalocyanine but presenting a case of physisorption. There was, however, also signs of an interaction taking place between the zinc compound and water vapour. None of the vapours showed ability to interact with the iron, copper or metal-free phthalocyanine. The iron but not the metal-free compound proved capable of forming a complex, 1: 1, with water in a CCl 4 solution.

In situ time-resolved FTIR spectroelectrochemistry: study of the reduction of TCNQ

The efficiency and versatility of time-resolved FTIR spectroscopy has been used to follow concentration profiles of species produced during a cyclic voltammetric scan. It has been tested in situ and in resolved time, by probing the reduction of tetracyanoquinodimethane (TCNQ) on its first and second electrochemical wave. Besides the establishment of the method, the individual concentrations of TCNQ, of the monoanion and of the dianion were monitored at distinct infrared frequencies and the time derivatives of the concentration profiles were compared to the voltammograms.

A spectroscopic study of complexation of phthalocyanines with pyridine

Abstract The ability of solid films of phthalocyanines to form complexes when exposed to pyridine vapours was investigated on the basis of assignments of i.r. spectra. Pyridine was found to form a five-and a six-coordinated complex with iron and zinc phthalocyanines, respectively, but it did not interact with the copper or metalfree compound. It was, however, physisorbed to magnesium phthalocyanine. In solution iron phthalocyanine proved capable of forming a 1-1 as well as a 1–2 complex with pyridine, both equilibrium constants being 2.10 2 M −1 in CCl 4 . The 1-1 complex appeared instantaneously, whereas the 1–2 complex was formed in a reaction having a rate constant of 0.1 h −1 at room temperature.

First signals of electrochemically oxidized species of TTF and TTM-TTF: A study by in situ spectroelectrochemical FTIR and DFT calculations

A first study by in situ FTIR spectroelectrochemistry of TTF and TTM-TTF has been undertaken. The oxidation, in this case, is caused only by electrochemistry, which constitutes a clear advantage over chemical oxidation since no side products are present in the solution. In this context, we obtained the signals of neutral, radical cation, and dication species of TTF and TTM-TTF. The experimental conditions were chosen in order to avoid the possible formation of π-dimer species and to obtain a satisfactory signal-to-noise ratio. A weak signal was detected for TTF and a stronger one for TTM-TTF. The changes induced by the oxidation process in the IR spectra of TTF and TTM-TTF have been analyzed with the aid of B3P86/6-31G** density functional theory (DFT) calculations, which allows for a comprehensive assignment of the bands observed. DFT calculations show that the IR signal associated to the asymmetric stretching of the lateral CC bonds can be used as a structural signature to identify the different oxidation states of TTF and TTM-TTF. The frequency downshift and the intensity increase undergone by the νasym(CC) vibration upon oxidation are shown to be the key factors to understand the evolution of the IR spectra.

A spectroscopic study of the complexing ability of metal phthalocyanines with formic acid

Abstract The behavior of magnesium, iron and zinc phthalocyanines with formic acid has been studied in detail by i.r. spectroscopy. The results show that magnesium and zinc phthalocyanines adsorb formic acid vapors under a dissociated form, while only physisorption occurs with iron phthalocyanine. This latter phthalocyanine does not show any sign of interaction with formic acid in dilute CCl 4 solutions. The results are compared to previous studies and are discussed in terms of a valence bond model and a molecular orbital model.