Chirality-dependent interactions between molecular propeller structures in solution. Chiral recognition and discrimination processes modulated by temperature and incremental changes in structural chirality.

Time-resolved chiroptical luminescence (TR-CL) measurements are used to study chirality-dependent intermolecular interactions in dynamic excited-state quenching processes. The measurements are carried out on solution samples that contain a racemic mixture of chiral luminophore molecules (with enantiomeric structures denoted by LambdaL and DeltaL) and a small, optically resolved concentration of chiral quencher (CQ) molecules. The luminophores are excited with a pulse of linearly polarized laser radiation to produce an initially racemic excited-state population of LambdaL* and DeltaL* enantiomers, and TR-CL measurements are then used to monitor the differential decay kinetics of the LambdaL* and DeltaL* subpopulations.

Site-isolated luminescent europium complexes with polyester macroligands: metal-centered heteroarm stars and nanoscale assemblies with labile block junctions.

The synthesis of a series of polymeric Eu(III) complexes with polyester ligands, along with supporting emission spectra, luminescence lifetimes, and, for a Eu block copolymer film, atomic force microscopy (AFM) data, is presented. Dibenzoylmethane was derivatized with a hydroxyl initiator site (dbmOH, 1) for tin octoate catalyzed ring opening polymerization of dl-lactide. The resulting poly(lactic acid) macroligand, dbmPLA (2), was combined with EuCl3 to generate Eu(dbmPLA)3 (3).

Intermolecular chiral recognition probed by enantiodifferential excited-state quenching kinetics.

Time-resolved chiroptical luminescence (TR-CL) measurements are used to study the kinetics of chirality-dependent excited-state quenching processes in aqueous solution. Experiments are carried out on samples that contain a racemic mixture of chiral luminophore molecules (L) in solution with a small, optically active concentration of chiral quencher molecules (Q). The luminophores are excited with a pulse of unpolarized light to create an initially racemic excited-state population of lambda L* and delta L* enantiomers, and TR-CL measurements are then used to monitor the differential decay kinetics of the lambda L* and delta L* subpopulations.

Circularly polarized emission studies on Tb3+ and Eu3+ complexes with potentially terdentate amino acids in aqueous solution.

Circularly polarized emission (CPE) and total emission (TE) spectra are reported for Eu3+ and Tb3+ complexes of L-aspartic acid (L-asp), L-serine (L-ser), L-threonine (L-thr) and L-histidine (L-his) in D2O solution under various pH conditions. Variations in TE and CPE intensities and in CPE splittings and sign patterns as functions of solution pH are correlated with lanthanide ion/ligand binding characteristics and with structural changes in the coordination environment of the metal ion. In the Eu3+/amino acid systems, the emission bands associated with the 5D0 leads to 7F1 and 7F2 Eu3+ transitions are monitored, and in the Tb3+/amino acid systems the 5D4 leads to 7F5 Tb3+ emission is examined.