Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS) and Departamento de Química Orgánica, Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain.
Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
Angew Chem Int Ed Engl. 2022 Aug 15;61(33):e202207623. doi: 10.1002/anie.202207623. Epub 2022 Jul 8.
Helical polymers such as poly(phenylacetylene)s (PPAs) are interesting materials due to the possibility of tuning their helical scaffold (sense and elongation) once they have been prepared and by the presence of external stimuli. The main limitation in the application of PPAs is their poor photostability. These polymers degrade under visible light exposure through a photochemical electrocyclization process. In this work, it was demonstrated, through a selected example, how the photochemical degradation in PPAs is directly related to their dynamic helical behavior. Thus, while PPAs with dynamic helical structures show poor photostability under UV/Vis light exposure, poly-(R)-1, bearing an enantiopure sulfoxide group as pendant group and designed to have a quasi-static helical behavior, shows a large photostability due to the restricted conformational composition at the polyene backbone, needed to orient the conjugated double bonds prior to the photochemical electrocyclization process and the subsequent degradation of the material.
螺旋聚合物，如聚（苯乙炔）（PPAs），是一类有趣的材料，因为一旦它们被制备出来，就有可能通过外部刺激来调整它们的螺旋支架（手性和伸长率）。PPAs 在应用中的主要限制是它们的光稳定性差。这些聚合物在可见光照射下通过光化学反应的电环化过程降解。在这项工作中，通过一个选择的例子，证明了 PPAs 中的光化学降解如何直接与其动态螺旋行为相关。因此，虽然具有动态螺旋结构的 PPAs 在 UV/Vis 光照射下表现出较差的光稳定性，但带有手性纯亚砜基团作为侧基的聚（R）-1 设计为具有准静态螺旋行为，由于聚烯主链上受限的构象组成，表现出较大的光稳定性，这对于在光化学反应的电环化过程和随后的材料降解之前定向共轭双键是必需的。
