Jack Cousseau

Chemical generation and reactivity of C602−. High-yield and regioselective alkylation of [60, Ih] fullerene

Chemical generation of the dianion of C60 followed by the reaction of monoiodo- or α,ω-diiodo-alkanes leads to the high-yield and regioselective formation of 1,2- and 1,4- dialkyl C60 or 1,2-fused ring C60 adducts. 13C NMR studies including protoncarbon correlations were used to ascertain the geometry of the products while the new closed adducts were also characterized by MS, UV-vis and voltammetric measurements.

The synthesis of 4,4'(5')-diformyltetrathiafulvalene

The synthesis of the title compound 9, by three different routes, is described for the first time.

Tuning the Raman resonance behavior of single-walled carbon nanotubes via covalent functionalization.

We present a systematic Raman study over a range of excitation energies of arc discharge single-walled carbon nanotubes (SWCNTs) covalently functionalized according to two processes, esterification and reductive alkylation. The SWCNTs are characterized by resonance Raman spectroscopy at each step of the functionalization process, showing changes in radial breathing mode frequencies and transition energies for both semiconducting and metallic tubes. Particular attention is given to a family of tubes clearly identified in the Kataura plot for which we continuously tune the excitation energy from 704 to 752 nm. This allows us to quantify the energy shift occurring in the spacing of the van Hove singularities. We demonstrate that, independently of the functionalization technique, the type of chain covalently bound to the tubes plays an important role, notably when oxygen atoms lie close to the tubes, inducing a larger shift in transition energy as compared to that of other carbonaceous chains. The study shows the complexity of interpreting Raman data and suggests many interpretations in the literature may need to be revisited.

Photoinduced electron-transfer processes in C60-tetrathiafulvalene dyads containing a short or long flexible spacer

Intramolecular photoinduced charge-separation and charge-recombination processes in two C60-spacer-TTF dyads, in which C60 and TTF (tetrathiafulvalene) are connected through a flexible spacer of different lengths, have been investigated in polar solvents by time-resolved absorption and fluorescence techniques. Weak interaction between the C60-moiety and TTF-moiety in the ground state was suggested by the steady-state absorption spectra; the dyad with the shorter spacer shows slightly stronger interaction than that with the longer spacer. The observed short fluorescence lifetimes of these dyads, compared with that of their precursor fullerene derivative in THF and benzonitrile indicate that the charge separation takes place via the singlet excited state of the C60-moiety, producing the ion pairs (C60˙−-spacer-TTF˙+) as shown from the transient absorption spectra in the 800–1100 nm region. In polar benzonitrile solvent, the ion-pair state with the long flexible chain shows longer lifetime than that with the short chain, suggesting that weaker interaction between C60 and TTF moieties is preferred to the long ion-pair lifetime. These observations were compared with other reported data for C60-TTF dyads.

2,5-bis(1,4-dithiafulven-6-yl) substituted furans, thiophenes and N-methyl pyrroles as precursors for organic metals

Abstract New heterocyclic π-electron donors are synthetized by Wittig or Wittig-Horner reactions between the corresponding furan, thiophen and N-methyl pyrrole 2,5-dicarbaldehydes and the P-reagents W or P bearing the 1,3-dithiol-2-ylidene moiety adequately substituted at the 4,5-positions; thanks to usual and thin layer cyclic voltammetry, they are shown to possess good π-donor abilities.

Synthesis and electrochemical properties of fused [3,4]furano-tetrathiafulvalenes

Abstract The synthesis of the first fused [3,4]furano-TTFs has been accomplished starting from the 4-formyl-5-diethoxymethyl-2-thioxo-1,3-dithiole. Two routes have been explored involving either the furan ring or the TTF core. In particular, the first proceeds via the new [3,4]furano-2-thioxo-1,3-dithiole.

Mono-hydrofluorination of electrophilic alkynes by the liquid biphasic CsF–H2O–DMF system (DMF = N,N-dimethylformamide)

CsF induces the addition of HF in fair yields to activated acetylenic triple bonds in a DMF–water biphasic medium (DMF = N,N-dimethylformamide); in a homogeneous DMF–water mixture, no addition is observed.

Easy access to unprecedented mixed functionalized dihydrofullerenes C60RH and C60RR′: the C602− anion route

Functionalized mixed dihydrofullerenes C60RH and C60RR′ are easily obtained from reactions between C602− anion and halo derivatives RX and R′X. The key step consists in the selective reaction of the intermediate [C60R]− ion, as soon as it is formed, with either CF3CO2H or R′X. This process is made possible thanks to the very fast single electron transfer (SET) reaction between C602− and RX. Functionalized dihydrofullerenes C60RH thus prepared are also shown to be very good starting compounds for obtaining various C60RR′ derivatives.

Electronic and nuclear contributions to the third-order nonlinear optical properties of new polyfluroalkysulfanyl-substituted tetrathiafulvalene derivatives

From DFWM efficiency measurements, we deduce third-order susceptibility of polyfluroalkylsulfanyl-substituted TTF derivatives. To know the physical nature of the optical non-linearities, we separate the electronic and nuclear contributions in w h3i . The electronic contribution of these molecules turned out dominant. We also deduce the values of the second-order hyperpolarisabilities g which are about 10 3 greater than the g value of CS2 at the same wavelength 532 nm As the absorption of the studied compounds is very weak at 532 nm, their merit factors in term of relation between the third-order susceptibility and linear absorption coefficient are better than the ones obtained for ethylenic TTF derivatives studied previously. # 2000 Elsevier Science S.A. All rights reserved.

An expedient stereoselective access to (Z)-2-fluoroalkenoates

The reaction between an aldehyde R-CHO and diethyl 2-oxo-3-fluorobutan-1,4-dioate as its sodium salt EtO2C-CO-CF-CO2Et−, Na+ mainly leads in THF to (Z)-2-fluoroalkenoates R-CHCF-CO2Et (Z/E& > -80/20), the Z-stereoselectivity depending on the bulk of the R group.