Photophysical and Chiroptical Properties of the Enantiomers of ,'-Bis(1-phenylpropyl)-2,6-pyridinecarboxamide and their Chiral 9-Coordinate Ln Complexes.

The , and , enantiomers of ,'-bis(1-phenylpropyl)-2,6-pyridinedicarboxamide, , react with Ln ions (Ln = La, Eu, Gd, and Tb) to give stable [Ln((,)- and (,)-))] in anhydrous acetonitrile solution, as evidenced by various spectroscopic measurements, including NMR and luminescence titrations. In addition to the characteristic Eu and Tb luminescence bands, the steady-state and time-resolved luminescence spectra of the aforementioned complexes show the residual ligand-centered emission of the ππ* to ππ* states, indicating an incomplete intersystem crossing (ISC) transfer from the ππ* to ππ* and ligand-to-Ln energy transfer, respectively. The high circularly polarized luminescence (CPL) activity of [Eu()] confirms that using a single enantiomer of induces the preferential formation of one chiral [Eu()] complex, consistent with the [Eu ] complexes formed with other ligands derived from a 2,6-pyridine dicarboxamide moiety.

Physicochemical and Electronic Properties of Cationic [6]Helicenes: from Chemical and Electrochemical Stabilities to Far-Red (Polarized) Luminescence.

The physicochemical properties of cationic dioxa (1), azaoxa (2), and diaza (3) [6]helicenes demonstrate a much higher chemical stability of the diaza adduct 3 (pK =20.4, Ered1/2 =-0.72 V) compared to its azaoxa 2 (pK =15.

Synthesis of enantiomerically pure helicene like bis-oxazines from atropisomeric 7,7'-dihydroxy BINOL: Preliminary measurements of the circularly polarized luminescence.

Racemic sample of 2,2',7,7'-tetrahydroxy-1,1'-binaphthyl was resolved with ()-proline and the separated enantiomers were independently converted to atropisomeric bis-oxazines by aromatic Mannich reaction. These chirally pure oxazines were then converted to the helicene like cyclic ethers. The Circularly Polarized Luminescence (CPL) profile was consistent with the isolation of the targeted helical-like molecules in optically pure form, prepared from the achiral primary amines.