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Handedness is an essential attribute of chiral nanocrystals, having a major influence on their properties. During chemical growth, the handedness of nanocrystals is usually tuned by selecting the corresponding enantiomer of chiral molecules involved in asymmetric growth, often known as chiral inducers. We report that, even using the same chiral inducer enantiomer, the handedness of chiral gold nanocrystals can be reversed by using Au nanorod seeds with either single crystalline or pentatwinned structure. This effect holds for chiral growth induced both by amino acids and by chiral micelles. Although it was challenging to discern the morphological handedness for L‐cystine‐directed particles, even using electron tomography, both cases showed circular dichroism bands of opposite sign, with nearly mirrored chiroptical signatures for chiral micelle‐directed growth, along with quasi‐helical wrinkles of inverted handedness. These results expand the chiral growth toolbox with an effect that might be exploited to yield a host of interesting morphologies with tunable optical properties. [ABSTRACT FROM AUTHOR]

Phase equilibria in the 1/2Y2O3–SrO–1/2Fe2O3 system were systematically studied at 1373 K in air. The homogeneity ranges and crystal structure of the solid solutions Sr1−xYxFeO3−δ with 0.875 ≤ x ≤ 1 (sp. gr. Pnma) and 0.05 ≤ x ≤ 0.25 (sp. gr. Pm3 m) and Sr3−zYzFe2O7−δ with 0 ≤ z ≤ 0.25 (sp. gr. I4/mmm) were determined by X‐ray diffraction analysis of quenched samples. The structural parameters of the single‐phase oxides were refined by the Rietveld profile method. The isothermal‐isobaric phase diagram for the 1/2Y2O3–SrO–1/2Fe2O3 system at 1373 K in air is presented. The changes of oxygen content in the solid solutions Sr1−xYxFeO3−δ (0.05 ≤ x ≤ 0.25) and Sr3−zYzFe2O7−δ with 0 ≤ z ≤ 0.25 vs temperature in air were determined by the thermogravimetric analysis. Oxygen content was also calculated from the iodometric titration results. The gradual substitution of strontium by yttrium in Sr1−xYxFeO3−δ (0.05 ≤ x ≤ 0.25) leads to a decrease in the oxygen content and the mean oxidation state of iron. The average thermal expansion coefficients for Sr1−xYxFeO3−δ (0.875 ≤ x ≤ 1 and 0.05 ≤ x ≤ 0.25) and Sr3−zYzFe2O7−δ (0 ≤ z ≤ 0.25) were calculated within the temperature range 298‐1373 K in air. The phase diagram of the 1/2Y2O3 ‐ SrO ‐ 1/2Fe2O3 system (T=1373 K, Po2=0.21 atm). [ABSTRACT FROM AUTHOR]

Handedness is an essential attribute of chiral nanocrystals, having a major influence on their properties. During chemical growth, the handedness of nanocrystals is usually tuned by selecting the corresponding enantiomer of chiral molecules involved in asymmetric growth, often known as chiral inducers. We report that, even using the same chiral inducer enantiomer, the handedness of chiral gold nanocrystals can be reversed by using Au nanorod seeds with either single crystalline or pentatwinned structure. This effect holds for chiral growth induced both by amino acids and by chiral micelles. Although it was challenging to discern the morphological handedness for L-cystine-directed particles, even using electron tomography, both cases showed circular dichroism bands of opposite sign, with nearly mirrored chiroptical signatures for chiral micelle-directed growth, along with quasi-helical wrinkles of inverted handedness. These results expand the chiral growth toolbox with an effect that might be exploited to yield a host of interesting morphologies with tunable optical properties., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The development of optical nanothermometers operating in the near-infrared (NIR) is of high relevance toward temperature measurements in biological systems. We propose herein the use of Nd 3+ -doped lanthanum oxychloride nanocrystals as an efficient system with intense photoluminescence under NIR irradiation in the first biological transparency window and emission in the second biological window with excellent emission stability over time under 808 nm excitation, regardless of Nd 3+ concentration, which can be considered as a particular strength of our system. Additionally, surface passivation through overgrowth of an inert LaOCl shell around optically active LaOCl/Nd 3+ cores was found to further enhance the photoluminescence intensity and also the lifetime of the 1066 nm, 4 F 3/2 to 4 I 11/2 transition, without affecting its (ratiometric) sensitivity toward temperature changes. As required for biological applications, we show that the obtained (initially hydrophobic) nanocrystals can be readily transferred into aqueous solvents with high, long-term stability, through either ligand exchange or encapsulation with an amphiphilic polymer., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)