10.1080/10587259508038683
The research investigates the liquid crystal properties of non-chiral and racemic branched alkyl chain molecules, specifically focusing on their ability to exhibit alternating tilt smectic phases. The purpose of the study was to understand how variations in the molecular structure, particularly the branching of terminal alkyl chains and the nature of the linking groups, influence the phase behavior of these compounds. The findings indicate that increased branching enhances the stability of alternating tilt smectic phases while suppressing other smectic phases. The study utilized various chemicals, including methyl 4-hydroxycinnamate, alkyl bromides, 4-hydroxybiphenyl-4'-carboxylic acid, and diethylazodicarboxylate (DEAD), in the synthesis of the target compounds. The results suggest that the molecular geometry and steric factors significantly impact the phase behavior of non-chiral liquid crystals.
10.1039/c9sc06184c
The research focuses on the development of a redox-neutral photochemical Heck-type arylation of vinylphenols activated by visible light. The study discloses a method for the arylation of vinylphenols with non-activated aryl and heteroaryl halides under visible light irradiation, utilizing colored vinylphenolate anions as strong reducing photoactivators. These anions activate (hetero)aryl halides without the need for sacrificial reductants, leading to the formation of aryl radicals that couple with another molecule of vinylphenol to produce the desired arylation product in a regiospecific and stereoselective manner. The experiments involved the optimization of reaction conditions, evaluating the substrate scope with various (hetero)aryl halides, and conducting mechanistic investigations. Reactants included 4'-bromoacetophenone, methyl 4-hydroxycinnamate, and Cs2CO3 as the base, with DMSO as the solvent and blue LED light as the irradiation source. Analyses used to characterize the products and confirm the reaction mechanism included X-ray crystallography, UV-vis absorption spectra, Stern-Volmer quenching studies, and quantum yield determination.
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