This work reports on a synthetic strategy to generate poly(3-alkylthiophene)s (P3ATs) with jointsimultaneous control of the molar mass and the regioregularity. A series of chiral P3ATswith different regioregularities is synthesized using a Pd(RuPhos)-catalyzed chain-growth polymerisation. All polymers have molar masses and polydispersities (PDI) that lie within a narrow region. Furthermore, it is shown that the Pd-catalyst forms all kinds of couplings [head-to-tail (HT), tail-to-tail (TT) and head-to-head (HH)] to a similar extent, which allows to insert predictable amounts of regio-irregularities into the polymer chain. This enables a thorough study of the influence of the regioregularity on the properties of P3AT, which was performed using UV-vis and circular dichroïsm (CD) spectroscopy, differential scanning calorimetry (DSC) and atomic force microscopy (AFM) measurements. Unexpectedly, it is found that in "kinetic" conditions the highest crystallinity, π-stacking, supramolecular organisation and chiral expression are not obtained for fully regioregular P3AT with 100% HT couplings, but that a small amount of regio-irregularity increases these properties and the chiral expression. In "thermodynamical" conditions (after annealing, very slow solvent evaporation or very slow cooling from the melt), this effect is less pronounced or not found. This behaviour can be explained by a higher degree of motional freedom within the non-perfect polymer chains due to the increased steric repulsion from the HH-couplings, which leads to a more easy stacking in "kinetic" conditions.

Polythiophenes with alcohol, tosylate, azide, ethynylene, carboxylic acid and amine end groups were prepared by a combination of functionalized nickel initiators and post-polymerization reactions. The azide and ethynylene polymers were subsequently used in a click reaction to produce a conjugated block-copolymer. Finally, a conjugated triblock-copolymer was synthesized by means of a chain growth polymerization initiated by a binuclear nickel initiator.

k Cambridge ? Buffalo Faraday rotation, the rotation of the polarization of light due to a magnetic field in the direction of propagation of the light, is used in applications ranging from quantum memory to the detection of biomagnetic fields. For these applications large Faraday rotation is necessary, but absorption of light is detrimental. In search of these properties, we have characterized the Verdet constant of a so far unexplored class of mesogenic organic molecules. We report their spectra and provide an interpretation. A Verdet constant of almost 2.5• 10 5 deg T 1 m 1 is found around 520 nm. This Verdet constant is three orders of magnitude larger than the largest known for organic molecules in a region without spectral features. We attribute this enormous Faraday rotation to resonant enhancement by a triplet excitation which does not appear in the linear absorption spectrum, and near-resonant enhancement by low-energy singlet excitations. Furthermore we are able to switch the Faraday rotation by changing the liquid crystal phase of the compound. These results demonstrate a new class of Faraday rotating materials with great potential to replace current materials and improve existing applications. The inherent flexibility in the synthesis of this class of molecules opens a new field of research in Faraday rotation.

The performance of catalyst transfer polymerization (CTP) reactions which depend on catalyst association was studied on 3,6-dioctylthiothieno[3,2-b]thiophene (TT)-monomers. This monomer was selected because a strong association of the catalyst is expected, since the aromaticity of thienothiophene is largely maintained when the catalyst and thienothiophene associate. This study includes both reported and unreported Ni-and Pd-catalyst systems. It is found that no polymer formation can be observed using Ni-catalysts, whereas Pd-catalysts show a similar behavior as for other monomer systems. During the study of the Ni-catalyzed CTPs, the π-associated Ni 0 -complex has been isolated in situ and displayed a high stability in solution. It is shown that the associated complex interferes with the polymerization reaction and even prevents polymer formation. Furthermore, this complex prevented any Kumada-coupling reaction in the presence of the TT unit, as it serves as a "trapping site" for free Ni 0 -catalyst entities. Ni 0 -trapping does not occur during polymerization of 3-alkylthiophene, confirming the presence of the π-associated Ni 0 -complex in this polymerization. This introduces a new convenient method of probing Ni 0 -association during all Ni-catalyzed reactions. Furthermore, these results establish the presence of an upper limit to the catalyst association strengthabove which oxidative addition is prevented and the polymerization is inhibitedand they therefore add extra considerations for optimal catalyst design.

Abstract. In this manuscript, the Kumada catalyst transfer polymerization (KCTP) of cyclopenta [2,1-b;3,4-b']dithiophene (CPDT), a monomer consisting of two fused thiophene entities, is investigated. It is shown that this polymerization follows a controlled chain-growth mechanism. Furthermore, the formation of block-copolymers with poly(3-alkylthiophene)s is investigated, and it is shown that these block-copolymers can be formed if 3-alkylthiophene is used as the first block and CPDT as the second. The resulting all-conjugated block-copolymers consist of two blocks with substantially different electronic and physical properties and it is shown that the blocks influence each other, resulting in a unique material with different properties compared to a blend.2