Bera Sayan, Bhattacharya Santanu
School of Applied and Interdisciplinary Sciences, Indian Association for the Cultivation of Science Kolkata 700032 India
Department of Organic Chemistry, Indian Institute of Science Bangalore 560012 India.
Chem Sci. 2024 Aug 12;15(34):13987-97. doi: 10.1039/d4sc01631a.
Circularly polarized luminescence (CPL) is gaining interest across various disciplines, including materials science, pharmaceuticals, and sensing technologies. Organic molecules, due to their ease of synthesis and reduced toxicity, are a focus for achieving high dissymmetry values ( ) in CPL. Here, we present a low molecular weight molecule (1), a dipeptide (Ala-Phe) covalently linked with tetraphenyl-ethylene (TPE), an Aggregation-Induced Emission luminophore (AIE-gen). Varying the stereochemistry of amino acid chiral centers, we synthesized homochiral 1-(l, l) & 1-(d, d) and heterochiral 1-(l, d) and 1-(d, l). In aqueous media, these molecules exhibit aggregation-induced chirality at the TPE chromophore. Heterochiral systems form sheet-like structures, displaying a bisignate induced circular dichroism signal and a good value for CPL [7.5 (±0.04) × 10]. Conversely, homochiral systems adopt fibrillar morphology, exhibiting a monosignate induced circular dichroism signal with a lower dissymmetry value for CPL [1.3 (±0.05) × 10]. This study introduces the concept of chiroptical amplification, emphasizing enhanced CPL through heterochiral peptide-induced CPL compared to its homochiral counterpart, with an ON and OFF CPL signal at low and high temperature respectively.
圆偏振发光（CPL）在包括材料科学、制药和传感技术在内的各个学科中都越来越受到关注。有机分子由于易于合成且毒性降低，成为在CPL中实现高不对称值（ ）的研究重点。在此，我们展示了一种低分子量分子（1），它是一种二肽（丙氨酸-苯丙氨酸）与四苯基乙烯（TPE）共价连接而成，TPE是一种聚集诱导发光体（AIE-发光团）。通过改变氨基酸手性中心的立体化学，我们合成了同手性的1-(l, l)和1-(d, d)以及异手性的1-(l, d)和1-(d, l)。在水性介质中，这些分子在TPE发色团处表现出聚集诱导的手性。异手性体系形成片状结构，显示出双信号诱导圆二色性信号和良好的CPL值[7.5（±0.04）×10]。相反，同手性体系呈现纤维状形态，表现出单信号诱导圆二色性信号，CPL的不对称值较低[1.3（±0.05）×10]。本研究引入了手性光学放大的概念，强调与同手性对应物相比，通过异手性肽诱导的CPL增强CPL，分别在低温和高温下具有开和关的CPL信号。
