Actinium Chemical Research Institute, Via Casilina 1626a, 00133 Rome, Italy.
Int J Mol Sci. 2020 Dec 22;22(1):8. doi: 10.3390/ijms22010008.
Optical rotatory dispersion (ORD) is a beautiful analytical technique for the study of chiral molecules and polymers. In this study, ORD was applied successfully to follow the degree of polycondensation of -(+)-lactic acid toward the formation of poly(lactic acid) oligomers (PLAO) and high molecular weight poly(L-lactic acid) (PLLA) in a simple esterification reaction equipment. PLLA is a biodegradable polymer obtainable from renewable raw materials. The racemization of the intrinsically isotactic PLLA through thermal treatment can be easily followed through the use of ORD spectroscopy. Organic or molecular electronics is a hot topic dealing with the combination of π-conjugated organic compounds and polymers with specific properties (e.g., chirality) which can be exploited to construct optoelectronic devices, such as organic light-emitting diodes (OLEDs), organic photovoltaic (OPV) high efficiency cells, switchable chirality devices, organic field-effect transistors (OFETs), and so on. ORD spectroscopy was applied to study either the gigantic optical rotation of PLLA films, as well as to detect successfully the excitonic coupling, occurring in thin solid PLLA green film loaded with a combination of two dyes: SY96 (a pyrazolone dye) and PB16 (the metal-free phthalocyanine pigment). The latter compound PLLA loaded with SY96 and PB16 shows a really gigantic optical activity in addition to typical ORD signal due to exciton coupling and may be considered as a simple and easily accessible model composite of a chiral polymer matrix combined with π-conjugated dyes for molecular electronics studies.
旋光色散（ORD）是一种研究手性分子和聚合物的优美分析技术。在这项研究中，成功地将 ORD 应用于跟踪（+）-乳酸的缩聚程度，以在简单的酯化反应设备中形成聚（乳酸）低聚物（PLAO）和高分子量聚（L-乳酸）（PLLA）。PLLA 是一种可生物降解的聚合物，可从可再生原料中获得。通过热处理，内消旋 PLLA 的外消旋化可以通过 ORD 光谱学轻松跟踪。有机或分子电子学是一个热门话题，涉及与具有特定性质（例如手性）的π共轭有机化合物和聚合物的结合，这些性质可以用来构建光电设备，如有机发光二极管（OLED）、有机光伏（OPV）高效电池、可切换手性器件、有机场效应晶体管（OFET）等。ORD 光谱学用于研究 PLLA 薄膜的巨大旋光性，以及成功检测到在薄的固体 PLLA 绿光薄膜中负载两种染料：SY96（一种吡唑啉酮染料）和 PB16（无金属酞菁颜料）时发生的激子耦合。负载有 SY96 和 PB16 的 PLLA 除了由于激子耦合而产生的典型 ORD 信号外，还显示出非常巨大的光学活性，并且可以被认为是一种简单且易于获得的手性聚合物基质与π共轭染料相结合的模型复合材料，用于分子电子学研究。
