Ligand Chirality Transfer from Solution State to the Crystalline Self-Assemblies in Circularly Polarized Luminescence (CPL) Active Lanthanide Systems.

The synthesis of a family of chiral and enantiomerically pure pyridyl-diamide (pda) ligands that upon complexation with europium [Eu(CF3SO3)3] result in chiral complexes with metal centered luminescence is reported; the sets of enantiomers giving rise to both circular dichroism (CD) and circularly polarized luminescence (CPL) signatures. The solid-state structures of these chiral metallosupramolecular systems are determined using X-ray diffraction showing that the ligand chirality is transferred from solution to the solid state. This optically favorable helical packing arrangement is confirmed by recording the CPL spectra from the crystalline assembly by using steady state and enantioselective differential chiral contrast (EDCC) CPL Laser Scanning Confocal Microscopy (CPL-LSCM) where the two enantiomers can be clearly distinguished.

Lanthanide-directed synthesis of luminescent self-assembly supramolecular structures and mechanically bonded systems from acyclic coordinating organic ligands.

Herein some examples of the use of lanthanide ions (f-metal ions) to direct the synthesis of luminescent self-assembly systems (architectures) will be discussed. This area of lanthanide supramolecular chemistry is fast growing, thanks to the unique physical (magnetic and luminescent) and coordination properties of the lanthanides, which are often transferred to the resulting supermolecule. The emphasis herein will be on systems that are luminescent, and hence, generated by using either visibly emitting ions (such as Eu(III), Tb(III) and Sm(III)) or near infrared emitting ions (like Nd(III), Yb(III) and Er(III)), formed through the use of templating chemistry, by employing structurally simple ligands, possessing oxygen and nitrogen coordinating moieties. As the lanthanides have high coordination requirements, their use often allows for the formation of coordination compounds and supramolecular systems such as bundles, grids, helicates and interlocked molecules that are not synthetically accessible through the use of other commonly used templating ions such as transition metal ions. Hence, the use of the rare-earth metal ions can lead to the formation of unique and stable species in both solution and in the solid state, as well as functional and responsive structures.

Displacement assay detection by a dimeric lanthanide luminescent ternary Tb(III)-cyclen complex: high selectivity for phosphate and nitrate anions.

The luminescent dimeric ternary lanthanide­cyclen complexes (2-(Ln.1)2; Ln = Tb/Eu) were designed and both their self-assembly formation and their ability to detect anions via displacement assays were investigated using spectrophotometric titrations in MeOH solution. The formation of 2-(Tb.1)2 and 2-(Eu.1)2 was investigated in solution, and determination of the binding constants and stoichiometry showed that the former was formed almost exclusively over the 1:1 complex 2-(Tb.1) after the addition of two equivalents of 2; while for 2-(Eu.1)2 a mixture of both stoichiometries existed even after the addition of four equivalents of 2. Of these two systems, 2-(Tb.1)2 was studied in details as a probe for anions, where significant changes where observed in the photophysical properties of the complex; with the characteristic Tb(III)-centred emission being fully switched off upon the sensing of phosphates and nitrate, giving rise to the formation of a H2PO4(-):Tb.1 complex in a 1:2 stoichiometry upon sensing of H2PO4(-) by 2-(Tb.1)2, while NO3(-) gave 1:1 complex formation and two equivalents of NO3(-)·Tb.1.