Aldo Taticchi

Conjugated anthracene derivatives as donor materials for bulk heterojunction solar cells: olefinic versus acetylenic spacers

Substituting olefinic for acetylenic pi-spacers in anthracene-based conjugated semiconductor donors leads to appreciable increases in the power conversion efficiencies of the resulting bulk heterojunction solar cells.

Molecular-Shape-Controlled Photovoltaic Performance Probed via Soluble π-Conjugated Arylacetylenic Semiconductors

The synthesis and characterization of a new series of anthracene-based derivatives and their use as donors in bulk-heterojunction solar cells is reported. It is found that when using well-defined building blocks in constructing the chromophore, the donor molecular shape dramatically affects organic photovoltaic (OPV) performance in a previously unrecognized way.

Conformational preferences and electronic effects in selenophene and tellurophene carbonyl derivatives investigated by lanthanide induced shifts

Computer simulation of the lanthanide induced shifts has been applied to study of the conformational preferences in the 2-formyl and 2-acetyl derivatives of furan, thiophene, selenophene and tellurophene. The results assign a nearly equipopulated mixture of s-cis and s-trans conformers to the furan, and a preponderance of the s-trans form to the thiophene, selenophene and tellurophene derivatives. This difference is interpreted as due to the interaction between the heteroatom and carbonyl oxygen lone pairs. The 2-N,N-dimethylcarboxyamide derivatives of furan, thiophene and selenophene are found to exist mainly in a quasi-planar s-cis form. The barriers to the rotation about the amide bond in these amides have been measured and related to the electronegativity of the heteroatom.

Ionization energies of selenophen, tellurophen and some of their derivatives

Abstract The ionization energies of selenophen, tellurophen and a number of derivatives have been determined by the electron impact technique. Comparison of the values obtained for tellurophen with those referring to the other 5-membered rings reveals two major differences: (1) the IP of the unsubstituted tellurophen is significantly lower than that of its congeners; (2) the sensitivity to substituent effects is much smaller. The peculiar behaviour of tellurophen with respect to the other congener systems can be explained by admitting that a different molecular orbital is involved in the first ionization process of this ring. This is confirmed by photoelectron spectroscopy measurements.

High Pressure Diels-Alder Reactions of 2-Vinyl-3,4-Dihydronaphthalene. Synthesis of Cyclopenta[c]- and Indeno[c]Phenanthrenones.

Abstract A new shorter synthesis of 2-vinyl-3,4-dihydro-naphthalene has been described. The Diels-Alder reactions of this diene with 4-acetoxy-2-cyclopenten-1-one, 3-bromoindan-1-one and inden-1-one under high pressure conditions are reported. A two step synthesis of cyclopenta[c]-and indeno[c]phenanthrenones is discussed. Structure analysis by 1 H and 13 C NMR spectroscopy is presented.

AN EFFICIENT SYNTHETIC APPROACH TO SUBSTITUTED PENTA- AND HEXAHELICENES

A two-step synthetic approach to penta- and hexahelicenes substituted at the terminal aromatic rings has been studied. This approach is based on the Diels–Alder reaction of 5,5′,8,8′-tetramethyl-3,3′,4,4′-tetrahydro-[1,1′]-binaphthalene (2b), 3-vinyl-1,2-dihydronaphthalene (5a), 5,8-dimethyl-3-vinyl-1,2-dihydronaphthalene (5b) and 3-vinyl-1,2-dihydrophenanthrene (15) followed by the aromatization of the cycloadducts. This method is flexible, efficient and of wide application to the synthesis of several benzenoid and nonbenzenoid penta- and hexahelicenes. The racemization energy barriers of helicenes 3, 9, 10, 13, 14, 17 and 18 were computed with the semiempirical quantum method AM1. The computed values show that, when methyl groups are introduced at the inner position of the terminal aromatic rings, the racemization barriers increase markedly. A structure analysis of the reaction products by 1H- and 13C-NMR spectroscopy is also presented.

A new short synthetic approach to cyclopentaphenanthrenones

Abstract The Diels-Alder reactions of 4-acetoxy-2-cyclopenten-1-one and 2-bromo-4-acetoxy-2-cyclopenten-1-one with vinylarenes are discussed. The aromatization of the reaction products opens a new two-step route for the synthesis of cyclopentaphenanthrenones. Structure analysis of reaction products by 1 H and 13 C-NMR spectroscopy is reported.

Photoelectron spectra of the α-substituted derivatives of furan, thiophen, selenophen, and tellurophen. A comparative study of the molecular orbital energies

Vertical ionization energies of the two highest molecular orbitals and of orbitals mainly localized on the substituent of 31 α-substituted derivatives of furan, thiophen, selenophen, and tellurophen are discussed. The substituent effects confirm the reversal in the energy sequence of the two highest occupied π-MOs of tellurophen with respect to other five-membered heteroaromatic congeners and permit the assignment of the ionization energy values of the and π2, π3 MOs in selenophen. Assignments for some of the bands other than the first two it :he photoelectron spectra of tellurophen and selenophen are proposed. The effect of the ring on the orbitals mainly localized on the substituent is briefly discussed.

[2.2]Paracyclophanes incorporated within poly(3-butylthiophene): synthesis and photoelectrical properties

The synthesis and photoelectrical properties of [2.2]paracyclophanes, containing conjugated acetylenic triple bonds in the linear side-chain, are described. These compounds were incorporated as an electroactive component within a conductive polymer, i.e. poly(3-butylthiophene). The blend showed a photoelectrical response higher than that of the neat polymer. Surprisingly, it was found that the application of an electric bias during the preparation of the blend led to an increase in the photocurrent.

High pressure and thermal Diels–Alder reaction of 2-vinyl-benzo[b]furan and 2-vinyl-benzo[b]thiophene. Synthesis of new condensed heterocycles

Abstract A new preparation of 2-vinyl-benzo[b]furan and 2-vinyl-benzo[b]thiophene is described. Diels–Alder reactions of these dienes with 3-nitro-2-cyclohexen-1-one and 2-inden-1-one was examined under thermal and high pressure conditions. The reaction products have been converted to multi-ring heteroaromatic compounds.