Ligand-induced chirality in semiconducting nanocrystals has been the subject of extensive study in the past few years and shows potential applications in optics and biology. Yet, the origin of the chiroptical effect in semiconductor nanoparticles is still not fully understood. Here, we examine the effect of the interaction with amino acids on both the fluorescence and the optical activity of chiral semiconductor quantum dots (QDs). A significant fluorescence enhancement is observed for l/d -Cys-CdTe QDs upon interaction with all the tested amino acids, indicating suppression of nonradiative pathways as well as the passivation of surface trap sites brought via the interaction of the amino group with the CdTe QDs’ surface. Heterochiral amino acids are shown to weaken the circular dichroism (CD) signal, which may be attributed to a different binding configuration of cysteine molecules on the QDs’ surface. Furthermore, a red shift of both CD and fluorescence signals in l / d -Cys-CdTe QDs is only observed upon adding cysteine, while other tested amino acids do not exhibit such an effect. We speculate that the thiol group induces orbital hybridization of the highest occupied molecular orbital (HOMOs) of cysteine and the valence band of CdTe QDs, leading to the decrease of the energy band gap and a concomitant red shift of CD and fluorescence spectra. This is further verified by density functional theory calculations. Both the experimental and theoretical findings indicate that the addition of ligands that do not “directly” interact with the valence band (VB) of the QD (noncysteine moieties) changes the QD photophysical properties, as it probably modifies the way cysteine is bound to the surface. Hence, we conclude that it is not only the chemistry of the amino acid ligand that affects both CD and PL but also the exact geometry of binding that modifies these properties. Understanding the relationship between the QD’s surface and chiral amino acid thus provides an additional perspective on the fundamental origin of induced chiroptical effects in semiconductor nanoparticles, potentially enabling us to optimize the design of chiral semiconductor QDs for chiroptic applications.

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Using the luminescent properties of temperature-sensitive paints (TSPs) to monitor temperature is a new type of temperature measurement technology. Herein, Na 9 [EuW 10 O 36 ](EuW 10 ) molecules were doped with non-fluorescent rare earth metal ions (La 3 + and Gd 3 + ) to prepare Na 9 [Eu x La 1-x W 10 O 36 ](Eu x La 1-x W 10 ) and Na 9 [Eu x Gd 1-x W 10 O 36 ](Eu x Gd 1-x W 10 ) probe molecules. The doping of non-fluorescent rare earth metal ions (La 3 + and Gd 3 + ) will not change the structure of the parent EuW 10 . As the relative content of La 3 + ions increasing, the luminescent intensity of the Eu x La 1-x W 10 series decreases non-monotonically; as the relative content of Gd 3 + ions increasing, the luminescent intensity of Eu x Gd 1-x W 10 series decreases monotonically. Sub-sequently, Eu x La 1-x W 10 and Eu x Gd 1-x W 10 as probe molecules were added into methyl methacrylate (MMA) to obtain temperature-sensitive paints via polymerization process. In the range of 50°C to 100°C, the maximum relative sensitivity of temperature-sensitive paints EuW 10 /PMMA, Eu 0.9 La 0.1 W 10 /PMMA and Eu 0.7 Gd 0.3 W 10 /PMMA can reach 1.27 %°C À 1 , 1.43 %°C À 1 , 1.42 %°C À 1 , respectively. This study indicates that the temperature sensing characteristics can be enhanced by doping EuW 10 with non-fluorescent rare earth ions (La 3 + , Gd 3 + ), which can be promising materials used in more areas with high-precision temperature measurements.

Large area and mechanically stable temperature-sensitive paints (TSPs) with excellent temperature sensing properties are highly desirable by the industry for temperature measurement applications. Along these lines, a novel compound of...