Self-assembly, structures, and photophysical properties of 4,4'-bipyrazolate-linked metallo-macrocycles with dimetal clips.

By employing functional diimine ligands coordinated dipalladium(II,II) or diplatinum(II,II) clips as corners and the coplanar 4,4'-bipyrazolate dianion (L(2-)) ligand as linker, a series of bipyrazolate-bridged metallo-macrocycles, namely, [M8L4](NO3)8 (M = Pd(dmbpy), 1; Pd(bpy), 2; Pt(bpy), 3a; Pd(phen), 4; Pt(phen), 5; Pd(15-crown-5-phen), 6; Pd(18-crown-6-phen), 8; Pd(benzo-24-crown-8-phen), 10a; Pt(15-crown-5-phen), 7a, Pt(18-crown-6-phen), 9a; Pt(benzo-24-crown-8-phen), 11a) and [M6L3](NO3)6 (M = Pt(bpy), 3b; Pt(15-crown-5-phen), 7b; Pt(18-crown-6-phen), 9b; Pd(benzo-24-crown-8-phen), 10b; Pt(benzo-24-crown-8-phen), 11b), have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the 1H-bipyrazolyl ligands in aqueous solution. All these compounds have a crown-shaped cavity that can serve as host to solvent molecules and anions. The structures are characterized by elemental analysis, (1)H and (13)C NMR, ESI-MS, and in the cases of 1a (the BF4(-) salt of 1), 2a (the BF4(-) salt of 2), and 3b by single-crystal X-ray diffraction analysis.

[Synthesis, characterization and relaxivity of dimeric DTPA-gadonium (III) complexes with long chain alkyl esters of L-lysine].

To look for new MRI (magnetic resonance imaging) contrast agents with higher relaxivity as well as liver-selecsivity, four novel ester-amino ligands were synthesized by bis-acylation of octadecanyl, hexadecanyl, tetradecanyl and dedecanyl L-lysine with diethylenetriaminepentaacetic acid mono-anhydride (DTPA-MA), respectively. The corresponding dimeric Gd(III) complexes were gained by the reaction of these ligands with GdCl3 x 6H2O. All ligands and complexes were characterized by FTIR, 1H NMR and elemental analysis.