Metal-promoted synthesis, characterization, crystal structure and RNA cleavage ability of 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) lanthanide complexes.

New 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) lanthanide complexes were formed in the metal-induced one-step [1+2] condensation reaction between 2,6-diacetylpyridine and 2-aminobenzoylhydrazide in the presence of lanthanide (La(3+), Pr(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), Ho(3+), Er(3+), Tm(3+) or Yb(3+)) nitrates as template agents. The analytical and spectral characterizations of all the compounds were correlated with the single crystal X-ray structural determination of Eu(3+), Gd(3+), Tb(3+), Dy(3+) and Er(3+) nitrate complexes. The Eu(3+), Gd(3+), Tb(3+)and Dy(3+) complexes of pentadentate 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) with the N3O2 set of donor atoms display a high and relatively rare coordination number of 11, whereas the Er(3+) ion complex is 9-coordinated, which is consistent with the lanthanide contraction phenomenon. The scission of 21-mer RNA was assessed for Eu(3+), Gd(3+) and Tb(3+) nitrate complexes. Lanthanide complexes not covalently attached to the oligonucleotide are able to cleave RNA at the target site in a sequence-selective or non-selective manner depending on the presence of protecting 12-mer 2'OMe RNA.