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We report the first example of very efficient NIR Circularly Polarized Luminescence (CPL) (around 970 nm) in water, obtained thanks to the combined use of a chiral Yb complex and of poly lactic-co-glycolic acid (PLGA) nanoparticles. [YbL(tta) 2 ]CH 3 COO (L=N, N'-bis(2-pyridylmethylidene)-1,2-(R,R+S,S) cyclohexanediamine and tta=2-thenoyltrifluoroacetonate) shows good CPL in organic solvents, because the tta ligands efficiently sensitize Yb NIR luminescence and the readily prepared chiral ligand L endows the complex with the necessary dissymmetry. PLGA nanoparticles incorporate the complex and protect the metal ion from the intrusion of solvent molecules, while ensuring biocompatibility, water solubility and stability to the complex. Hydrophilic NIR-CPL optical probes can find applications in the field of NIR-CPL bio-assays., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The synthesis of hexagonal NaBiF4 co‐doped with Tb3+ and Eu3+(NaBi0.75−xTb0.25EuxF4; with x=0, 5, 10, 20 and 30) was achieved via a facile and fast precipitation route at 35 °C. Powder X‐ray diffraction (PXRD) and luminescence spectroscopy have been employed to characterize and investigate the materials. The study of luminescence spectroscopy and decay kinetics of the 5D4 excited state of Tb3+ provides the evidence of a Tb3+→Eu3+ energy transfer process. Sodium citrate has been adopted as capping agent to promote a homogeneous dispersion of the materials into water and to protect the inorganic host, which is water sensitive, from direct contact with this molecule. The comparison of luminescence properties between bare and citrate‐capped samples of NaBiF4 co‐doped with Tb3+ and Eu3+ reveals a marked difference in the Tb3+→Eu3+ energy transfer efficiency, which has been tentatively explained on the basis of a different environment surrounding the lanthanide ions in the two families of compounds. [ABSTRACT FROM AUTHOR]

Two cationic enantiomeric complexes [(R,R)-[YbL]Cl and (S,S)-[YbL]Cl with L = N,N0-bis(2-pyridylmethyl)- 1,2-(R,R or S,S)-cyclohexanediamine functionalized at sp³ N with picolinate antennae] have been synthesized and spectroscopically characterized in polar protic solvents, such as water and methanol. The Yb(III) luminescence at about 980 nm is efficiently sensitized upon excitation of the picolinate antenna in the UV spectral region around 330 nm. The complexes exhibit good CPL activity for the ²F5/2 - ²F7/2 magnetic dipole (MD) allowed transition (glum values of |0.02| and |0.04| at 984 nm and 1021 nm, respectively) and high solubility in aqueous solution. The YbL species is largely predominant at physiological pH (7.4), given its high thermodynamic stability (log bYbL = 20.98). As elucidated by DFT calculations, among the possible isomeric species the one characterized by the cis-O, O-N, N geometry was found to be dominant. Furthermore, one solvent molecule is bound to Ln(III) in water, giving rise to 9-fold coordination at the metal ion. The enantiomeric (R,R)-[YbL]Cl and (S,S)-[YbL]Cl complexes can be considered promising candidates as NIR-to-NIR chiroptical bioprobes also for in vivo experiments. [ABSTRACT FROM AUTHOR]

We report the first example of very efficient NIR Circularly Polarized Luminescence (CPL) (around 970 nm) in water, obtained thanks to the combined use of a chiral Yb complex and of poly lactic‐co‐glycolic acid (PLGA) nanoparticles. [YbL(tta)2]CH3COO (L=N, N'‐bis(2‐pyridylmethylidene)‐1,2‐(R,R+S,S) cyclohexanediamine and tta=2‐thenoyltrifluoroacetonate) shows good CPL in organic solvents, because the tta ligands efficiently sensitize Yb NIR luminescence and the readily prepared chiral ligand L endows the complex with the necessary dissymmetry. PLGA nanoparticles incorporate the complex and protect the metal ion from the intrusion of solvent molecules, while ensuring biocompatibility, water solubility and stability to the complex. Hydrophilic NIR‐CPL optical probes can find applications in the field of NIR‐CPL bio‐assays. [ABSTRACT FROM AUTHOR]