A new unsymmetric tripodal ligand bis(2-benzimidazolylmethyl)(2-pyridylmethyl)amine (L) bearing two kinds of chromophores benzimidazole and pyridine has been synthesized, and two series of lanthanidecomplexes [LnL(NO3)3] C2H5OH (Ln = La, Sm, Eu, Gd, Tb or Tm) and [LnLCl3(H2O)] C2H5OH (Ln = La, Sm, Eu, Tb or Ho) have been characterized by elemental analyses, FAB mass spectra, 1H NMR, conductivity measurements, and IR spectra. The crystal and molecular structures of the three complexes [SmL(NO3)3] C2H5OH 1, [GdL(NO3)3] C2H5OH 2, and [SmLCl3(H2O)] C2H5OH 3 have been determined by X-ray diffraction analysis. 1 and 2 are isomorphous with the central metal ion co-ordinated by the four nitrogen atoms of the ligand and six oxygen atoms of three chelating nitrate groups. In complex 3, besides the four nitrogen atoms of the ligand and three chlorine atoms, there is one H2O molecule co-ordinated. Conductivity studies on the [LnL(NO3)3] C2H5OH complexes in methanol showed that two of the nitrate anions dissociate to give 2 : 1 electrolytes. Comparison of the emission lifetimes of the Eu3 and Tb3 complexes in CH3OH and CD3OD gives the average value for q, the number of co-ordinated methanol molecules, of 3.4, suggesting the formation of species [LnL(NO3)(CH3OH)3][NO3]2. The emission quantum yields of the nitrate-coordinated series are substantially higher than those of the chloride series, as shown by luminescence studies in MeCN.

The flexible linear multidentate ligands 1,5-bis(8-quinolylsulfanyl)-3-oxapentane (OESQ) and 1,8-bis(8-quinolylsulfanyl)- 3,6-dioxaoctane (ODSQ) reacted with silverperchlorate affording the simple mononuclear complexes [Ag(OESQ)]ClO4 1 and [Ag(ODSQ)]ClO4 2, respectively. However, with silver nitrate, novel metallosupramolecular complexes [Ag4(ODSQ)2(η1-NO3)2(η2-NO3)2] 3 and [Ag4(OESQ)(ODSQ)(η1-NO3)2(η2-NO3)2] H2O 4 were obtained, in which the co-ordination motifs [Ag(OESQ)] and [Ag(ODSQ)] are spontaneously self-assembled by sulfurbridged silver ions into tetrametallotricyclic molecules containing the same or mixed building blocks. All four complexes have been characterized by elemental analyses, IR and 1H NMR spectroscopy, and single crystal X-ray diffraction methods. The possible self-assembly process has been discussed with the aid of electrospray mass spectrometry.