Convergent synthesis of near-infrared absorbing, "push-pull", bisthiophene-substituted, zinc(II) phthalocyanines and their application in dye-sensitized solar cells.

Zinc(II) phthalocyanine dyes that contain triarylamine-terminated bisthiophene and hexylbisthiophene groups have been synthesized by a convergent approach by using carboxytriiodo-ZnPc as a precursor. Further transformation of the iodo groups by a Pd-catalyzed reaction allowed easy preparation of further extended π-conjugated carboxy-ZnPcs. These dyes have been used as sensitizers in dye-sensitized solar cells, which exhibit a panchromatic response and moderate overall efficiencies.

Oxidation of 3-alkyl-substituted 2-pyrazolino[60]fullerenes: a new formyl-containing building block for fullerene chemistry.

A new building block for fullerene chemistry, endowed with a formyl group on C-3 of the 2-pyrazoline ring, has been prepared in a simple two-step synthesis by oxidation of readily available 3-alkyl-substituted 2-pyrazolino[60]fullerenes; the new building block paves the way for the preparation of new light-harvesting fullerenes.

On the thermal stability of [60]fullerene cycloadducts: retro-cycloaddition reaction of 2-pyrazolino[4,5:1,2][60]fullerenes.

2-Pyrazolino[4,5:1,2][60]fullerenes undergo a thermally induced retro-cycloaddition process whose efficiency is influenced by the nature of the C-substituent. C-Aryl-N-Aryl-2-pyrazolino[60]fullerenes (2a-d) poorly undergo a thermal retro-cycloaddition reaction even in the presence of a strong dipolarophile or a metal Lewis acid which, in contrast to other fullerene derivatives, shows their remarkable thermal stability. C-Alkyl-N-Aryl-2-pyrazolino[60]fullerenes (2e-f) show a different behavior, being more vulnerable to the presence of copper triflate and leading to the retro-cycloaddition product (pristine C60) in good yield.

A luminescent multicomponent species made of fullerene and Ir(III) cyclometallated subunits.

The first system containing a luminescent Ir(m) cyclometallated species and a functionalized C60 unit has been prepared; triplet-triplet energy transfer from the Ir-based MLCT state to the C60 triplet state occurs, leading to phosphorescence (lifetime, 4.8 ms) of the derivatized-C60 at 77 K.

Synthesis and excited state properties of a [60]fullerene derivative bearing a star-shaped multi-photon absorption chromophore.

The synthesis and excited state properties of a compound assembling C60 with a new multi-photon absorption chromophore are reported.

Synthesis of fullerodendrons with an ammonium unit at the focal point and their cooperative self-assembly on a fluorescent ditopic crown ether receptor.

Dendritic branches with 1, 2, or 4 peripheral fullerene subunits and an ammonium function at the focal point have been prepared. Their ability to form self-assembled dendritic structures with oligophenylenevinylene receptors bearing one or two crown ether moieties has been evidenced by ES-MS studies for the first time. These supramolecular complexes are multicomponent photoactive devices in which the emission of the central receptor is dramatically quenched by the fullerene units. This new property resulting from the association of the different molecular subunits allowed detailed investigations of the self-assembly process by means of fluorescence titrations. The binding studies have revealed positive cooperative effects for the assembly of the fullerodendrimers with the ditopic receptor. Interestingly, the stability of the supramolecular 2:1 structures increases as the size of the dendritic unit increases. This positive dendritic effect has been explained by the larger number of possible intramolecular fullerene-fullerene interactions between the two dendritic guests when the number of fullerene subunits is increased.

A highly directional fourfold hydrogen-bonding motif for supramolecular structures through self-assembly of fullerodendrimers.

Supramolecular dendrimers resulting from the dimerization of fullerene-functionalized dendrons through a quadruple hydrogen-bonding motif were prepared. The synthetic strategy is based on the esterification of a tert-butoxycarbonyl (Boc)-protected 2-ureido-4-[1H]pyrimidinone precursor possessing an alcohol function with fullerodendrons bearing a carboxylic acid unit at the focal point. Subsequent acidic treatment to cleave the protecting group and reaction of the resulting amine with octylisocyanate affords the targeted compounds. As demonstrated by the results of MALDI-TOF mass spectrometry and 1H NMR spectroscopy, both of the 2-ureido-4-[1H]pyrimidinone derivatives form self-assembled dimers spontaneously through hydrogen-bonding interactions, thus leading to supramolecular structures containing two or ten fullerene moieties.

Cooperative recognition of C60-ammonium substrates by a ditopic oligophenylenevinylene/crown ether host.

A new fullerene derivative with an ammonium subunit has been prepared. Its ability to form supramolecular complexes with oligophenylenevinylene derivatives bearing one or two crown ether moieties has been evidenced by electrospray mass spectrometry, and UV-visible and luminescence spectroscopy experiments. Interestingly, the assembly of the C60-ammonium cation with the oligophenylenevinylene derivative bearing two crown ether moieties leads to the cooperative formation of the 2:1 complex owing to intramolecular fullerene-fullerene interactions.

Fullerohelicates: a new class of fullerene-containing supermolecules.

A multicomponent array made of a bis-copper(I) helicate core and two peripheral fullerene subunits has been prepared and electron transfer from the photoexcited Cu(I)-complexed unit to C60 occurs.

Amphiphilic diblock dendrimers with a fullerene core.

Amphiphilic dendrimers with a C(60) core have been obtained by cyclization of dendritic 1,3-phenylenebis(methylene)-tethered bis-malonate derivatives at the carbon sphere. The relative position of the two cyclopropane rings in the resulting bis-methanofullerene derivatives has been determined based on the molecular symmetry (C(s)()) deduced from the (1)H and (13)C NMR spectra. The hydrophobic-hydrophilic balance of these dendrimers has been systematically modified by changing the size of the polar headgroup in order to investigate the role of the amphiphilicity both at the air-water interface and during deposition onto solid substrates. Langmuir studies have revealed a conformational change in the dendritic structure with the size of the polar headgroup. Because of a better anchoring onto the water surface, the compounds with the largest polar headgroup adopt a more compact structure and the dendritic branches are forced to wrap the fullerene core. This model is nicely confirmed by the amount of fullerene-fullerene interactions within the Langmuir-Blodgett films as deduced from their absorption spectra.