33S nuclear quadrupole coupling constants (χ ) and the principal component of the electric field gradient (qzz ) in 3- and 4-substituted benzenesulphonates are dependent on the electronic properties of substituents. Previously reported experimental results were interpreted with the support of theoretical calculations in vacuo and in aqueous solution. To obtain good reproducibility of the experimental data, the introduction of the solvent effect into the calculations was mandatory. The best results were obtained at the B3LYP/6-311++G(3d,p) level using the Integral Equation Formalism for the Polarisable Continuum Model (IEF-PCM) to reproduce the solvent effect. In vacuo, for neutral substituents, the substituent effect on sulphur qzz can be mainly ascribed to electronic interactions (i.e., inductive and mesomeric effects transmitted through the aromatic ring). For charged substituents () there is also a relevant contribution of coulomb origin, owed to the electric charge on the substituent itself, which polarises the S–O and C–S bonds. In aqueous solution, short-range solute–solvent interactions (i.e., hydrogen bonding) can be neglected, and the solvent effect can be adequately described considering the electrostatic interactions between the moiety and the electric charges on the surface of the cavity embedding the molecule within the solvent. These interactions amplify the electronic contribution transmitted through the aromatic ring and partially annihilate the coulomb contribution of the intrinsic charges of substituents. The results of the Natural Bond Orbital (NBO) analysis support these results and demonstrate that the polarisation of the S–O and S–C bonds and oxygen lone pairs due to solvent interactions produces only a redistribution of the electron density around the sulphur nucleus, thus inducing the variations of qzz.

We describe the synthesis of two novel poly(1,4-arylene-2,5-thienylene)s P1 and P2 containing benzo[c][2,1,3]thiadiazole monomeric units via Suzuki–Miyaura polymerization of a thiophene diboronic ester with aryl diiodides. The use of a catalyst complex consisting of Pd(OAc)2 in combination with the electron-rich biaryl phosphine S-Phos resulted in efficient polymerization reactions. The polymers synthesized, P1 and P2, were characterized by UV–vis spectroscopy and cyclic voltammetry. Theoretical calculations and electrochemical measurements on P1 suggested a favorable position of the molecular orbitals for employment in polymer solar cells in combination with PCBM. Devices containing P1:PCBM 1:2 in the active layer showed an efficiency of 1.2% by simple spin casting from chloroform.

The synthesis of two new dye families of croconic acid derivatives, semicroconaine and non-symmetric croconaine dyes, is reported for the first time. These compounds show strong absorption in the UV-visible and NIR, respectively. Semicrocon-aine dyes were obtained by a scalable and efficient condensation of croconic acid with aromatic heterocyclic methylene-active compounds. The subsequent reaction of the semicroconaine dyes with aromatic heterocyclic compounds affords non-symmetric croconaines. The structure and electronic properties of the synthesized compounds have been investigated by preliminary theoretical calculations at DFT level of approximation.

A general method to synthesize conjugated molecules with a benzofulvene core is reported. Up to four conjugated substituents have been introduced via a three-step sequence including (1) synthesis of 1,2-bis(arylethynyl)- benzenes; (2) exo-dig electrophilic cyclization promoted by iodine; and (3) cross-coupling reaction of the resulting bisiodobenzofulvenes with organoboron, organotin, or ethynyl derivatives under Pd catalysis. Structural aspects of the new compounds are discussed.

In a recent report (Eur. J. Org. Chem. 2014, 30, 6583) we emphasized the importance of addressing research efforts in OPV-active materials toward synthetic processes scalable up to industrial production. In this context, palladiumcatalyzed direct (hetero)arylation polymerization (DHAP) can be a suitable approach to reduce the number of reaction steps and to avoid the use of toxic reagents in the synthesis of donor polymers. Random donor−acceptor copolymers have been shown to be promising materials for bulk heterojunction (BHJ) solar cells with high efficiencies and increased thermal stability. We report here the synthesis by DHAP of a ternary double-acceptor/donor random copolymer including benzo[c][1,2,5]thiadiazole and benzo[d][1,2,3]triazole as the accepting units and benzo[1,2-b;4,5-b′]dithiophene as the donor moiety. The results are discussed in comparison with the synthesis of the same polymer via the Stille polymerization. The coupling products formed in the early stage of the polycondensation have been isolated and characterized by NMR spectroscopy to gain insight into the regiochemistry of DHAP. The polymers synthesized have been tested in BHJ solar cells with PC71BM as the electron acceptor material. Power conversion efficiencies (up to 2.8%) are comparable or lower (depending on the processing conditions) than those of the same polymer synthesized via the Stille coupling reaction; however, the DHAP protocol is more convenient in terms of synthetic complexity.