4-(4-Pyrid-yl)pyridinium penta-aqua(pyridazine-4,5-dicarboxyl-ato)praseodymate(III).

In the title complex, (C(10)H(9)N(2))[Pr(C(6)H(2)N(2)O(4))(2)(H(2)O)(5)], the Pr atom is nine-coordinated by nine O atoms from two pyridazine-4,5-dicarboxyl-ate anions and five water mol-ecules. It is noteworthy that there is a protonated bipyridine mol-ecule in the structure. Inter-molecular O-H⋯O, O-H⋯N and N-H⋯N hydrogen bonds are present, resulting in a three-dimensional network.

(R)-1,1'-Binaphthalene-2,2'-diyl dicinnamate.

In the title compound, C(38)H(26)O(4), two cinnamo-yloxy groups are linked in a trans fashion to the two O atoms of optically active (R)-1,10-bi-2-naphthol. The dihedral angle between the mean planes of the two naphthyl groups is 71.8 (1)°. The crystal structure contains inter-molecular C-H⋯O and C-H⋯π inter-actions.

Enantioseparation of amino acid derivatives on an immobilized network polymer derived from L-tartaric acid.

Seven structurally related amino acid derivatives were successfully enantioseparated by HPLC with a commercially available column containing a chiral immobilized network polymer derived from L-tartaric acid. The experiments were carried out under normal-phase conditions. All the solutes could be baseline separated using n-hexane/2-propanol (95/5) as eluent at a flow rate of 1 ml/min at 25 degrees C, with reasonable retention time (<12 min). The effects of the polar alcohol modifier (type and content) in the mobile phase and the column temperature on the enantioseparation were studied. Apparent thermodynamic parameters were also calculated from the plots of ln alpha or ln k' versus 1/T. Some mechanistic aspects of chiral recognition were discussed with respect to the structures of the solutes. It was found that the enantioseparations are all enthalpy driven, and the N-acyl groups of the solutes have significant influence on the chiral recognition.