TY - THES ID - 134514159 TI - Influence of position isomerism in chiral conjugated sequence-defined macromolecules AU - Erkens, Robin AU - Koeckelberghs, Guy AU - KU Leuven. Faculteit Wetenschappen. Opleiding Master in de chemie (Leuven) PY - 2023 PB - Leuven KU Leuven. Faculteit Wetenschappen DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:134514159 AB - The advancement of polymer science has given rise to the development of sequence-controlled polymers. Within this domain, sequence-defined polymers stand out as a remarkable subclass characterized by an unprecedented level of uniformity. These sequence-defined polymers exhibit precise positioning of each monomer, offering perfect control over their structural arrangement. While strategies using click chemistry and living polymerizations still face limitations of dispersity and positioning, the iterative synthesis approach proves to be the most suitable solution. The application of sequence definition in conjugated polymers holds great potential for advancing the field of polymer science. It offers the opportunity to synthesize novel materials with precisely controlled optoelectronic properties. However, limited research has been performed in this area thus far. Form initial investigations, it is evident that the AB+CD method, incorporating orthogonal reactions, represents the most efficient approach with minimal steps. Nevertheless, further exploration is needed for its applicability in sequence-defined conjugated polymers. In a previous study conducted in our group, a novel strategy was developed utilizing alternating Suzuki-Miyaura cross-coupling reactions and Horner-Wadsworth-Emmons reactions. This approach preserves conjugation, achieves high yields, and minimizes the formation of by-products. The aforementioned approach is employed to synthesize sequence-defined macromolecules, allowing for the investigation of the influence of chiral monomers. However, prior to conducting this investigation, it is necessary to synthesize the monomers that will serve as the building blocks. All monomers in this study are phenyl-based, with functional groups positioned at the 1 and 4 positions. One type contains a phosphonate and a bromide, while another consists of a boronate ester and an aldehyde. In total, 4 monomers are synthesized, including a chiral type with a (S)-2-methylbutyl sidechain and an achiral type with an octyl sidechain. Additionally, an achiral starting monomer with one active and one protected functional group is applied, featuring a bromide and a protected hydroxyl group. After the successful synthesis of the monomers, the oligomers are synthesized by employing the aforementioned strategy. Two distinct sequences are synthesized, wherein the position of the chiral monomers serves as the differentiating factor. This allows for the investigation of the influence of chiral monomer position. The oligomers are gradually expanded until they reach the size of hexamers, ensuring an adequate level of variability in the positioning of the chiral monomer. The characterization of both sequences, spanning from dimers to hexamers, is carried out extensively using various measurement techniques. The purity and structure of the oligomers are confirmed using 1H-NMR and 13C-NMR spectroscopy. The smaller chains are also characterized via mass spectroscopy. The determination of the number average molar mass and dispersity is achieved through GPC, which confirms the desired growth of the oligomers and their monodisperse nature. UV-VIS spectroscopy is employed to validate the preservation of the conjugated backbone by observing a red shift as the sequence expands. This technique also reveals the presence of a push-pull mechanism in specific structures. Insights into molecular dynamics and interactions are obtain through fluorescence spectroscopy ER -