Water-soluble Eu(III) and Tb(III) complexes with N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N'-diacetic acid (Hbpcd) have been synthesized and characterized in their racemic and enantiopure forms. The ligand has been designed to bind Ln(III) ions, providing a dissymmetric environment able to solicit strong chiroptical features while at the same time leaving a few coordination sites available for engaging further ancillary ligands. Potentiometric studies show that Ln(III) complexes have a relatively good stability and that at pH 7 the [Ln(bpcd)] species is largely dominant. DFT calculations carried out on the (S,S)-[Y(bpcd)(HO)] complexes (the closed-shell equivalents of [Eu(bpcd)(HO)] and [Tb(bpcd)(HO)]) indicate that the two trans-O,O and trans-N,N configurations are equally stable in solution and present two coordinated water molecules. This is in agreement with the hydration number ∼2.6 determined by luminescence lifetime measurements on Tb(III) and Eu(III) complexes. A detailed optical and chiroptical spectroscopic characterization has been carried out and reveals that the complexes display an efficient luminescence in the visible spectral range accompanied by a strong CPL activity. A value for g (around 0.1 on the top of the 546 nm band) for the Tb-based complex has been found. This is one of the highest g values measured up to now for chiral Tb complexes. These results suggest that in principle Tb(bpcd)Cl is suitable to be employed as a CPL bioprobe for relevant analytes in aqueous media.

Lactate anion signaling by a chiral Tb(iii) complex based on total and circularly polarized luminescence.

Alkynyl(triphenylphosphine)gold(i) complexes carrying variously substituted propargylic amines have been synthesized and fully characterized in solution and solid state. High levels of toxicity (i.e. micromolar range) were recognized for a series of cancer cell lines with particular emphasis on HT29, IGROV1, HL60 and I407. In particular the lead compound 3ab was identified as the most active compound in all cell lines (IC50: 1.7-7.9 μM).

A new chiral complex {[EuL(tta)(HO)]CFSO; L = N, N'-bis(2-pyridylmethylidene)-1,2-( R, R + S, S)-cyclohexanediamine; tta = 2-thenoyltrifluoroacetyl-acetonate} has been synthesized and characterized from a structural and spectroscopic point of view. The molecular structure in the solid state shows the presence of one chiral L, two tta, and one water molecules bound to the metal center. L and tta molecules can efficiently harvest and transfer to Eu(III) the UV light absorbed in the 250-400 nm range. The forced electric-dipole D → F emission band dominates the Eu(III) emission spectra recorded in the solid state and in solution of acetonitrile or methanol and the calculated intrinsic quantum yield of the metal ion is around 40-50%. The light emitted by the enantiopure complex shows a sizable degree of polarization with a maximum value of the emission dissymmetry factor ( g) equal to 0.2 in methanol solution. If compared with the complex in the solid state or in acetonitrile solution, then the first coordination sphere of Eu(III) when the complex is dissolved in methanol is characterized by the presence of one CHOH molecule instead of water. This fact is related to different Eu(III) CPL signatures in the two solvents.