Department of Chemistry , Butler University , 4600 Sunset Avenue , Indianapolis , Indiana 46208 , United States.
J Phys Chem B. 2018 Sep 20;122(37):8730-8737. doi: 10.1021/acs.jpcb.8b06148. Epub 2018 Sep 5.
Materials that emit circularly polarized light have application in several important industries. Deep eutectic solvents (DES) with chiral components are attractive as solvents of luminescent lanthanides for the development of chiral light-emitting materials. Deep eutectic solvents are prepared with combinations of tetrabutylammonium (or tetrabutylphosphonium) chloride as hydrogen bond acceptor (HBA) and amino acids, l-and d-glutamic acid, l-proline, and l-arginine as hydrogen bond donor (HBD). A racemic mixture of dissymmetric lanthanide (europium, terbium, and samarium) complexes is dissolved in the DES to measure the induced circularly polarized luminescence (CPL). This resulted in green, orange, and red CPL with a sign that is dictated by the enantiomer of the amino acid in the DES. Thermodynamic measurements show that changing the salt from tetrabutylammonium to tetrabutylphosphonium leads to a 50% increase in the enthalpy and entropy of chiral discrimination. This study demonstrates the capability of chiral DES as a solvent for chiral light-emitting materials and the ability to control this capability through the choice of HBA and HBD.
具有圆偏振光发射性质的材料在一些重要的工业领域有着广泛的应用。具有手性组分的深共晶溶剂（DES）作为手性发光镧系元素的溶剂，在开发手性发光材料方面具有吸引力。深共晶溶剂是由四丁基氯化铵（或四丁基溴化膦）作为氢键受体（HBA）与氨基酸，l-和 d-谷氨酸、l-脯氨酸和 l-精氨酸作为氢键供体（HBD）组合而成。手性不对称镧系（铕、铽和钐）配合物的混合物溶解在 DES 中，以测量诱导的圆偏振发光（CPL）。这导致了绿色、橙色和红色 CPL，其符号由 DES 中氨基酸的对映异构体决定。热力学测量表明，将盐从四丁基铵变为四丁基膦，导致手性识别的焓和熵增加了 50%。这项研究展示了手性 DES 作为手性发光材料溶剂的能力，以及通过选择 HBA 和 HBD 来控制这种能力的能力。
