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

•Template synthesis of hydrazone lanthanide nitrate complexes.•The single X-ray diffraction analysis correlated with spectroscopic characterization.•The high and a relatively rare coordination number of 11.•The cleavage of 21-mer RNA in sequence-selective or non-selective manner.

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 (La3 +, Pr3 +, Nd3 +, Sm3 +, Eu3 +, Gd3 +, Tb3 +, Dy3 +, Ho3 +, Er3 +, Tm3 + or Yb3 +) nitrates as template agents. The analytical and spectral characterizations of all the compounds were correlated with the single crystal X-ray structural determination of Eu3 +, Gd3 +, Tb3 +, Dy3 + and Er3 + nitrate complexes. The Eu3 +, Gd3 +, Tb3 +and Dy3 + 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 Er3 + ion complex is 9-coordinated, which is consistent with the lanthanide contraction phenomenon. The scission of 21-mer RNA was assessed for Eu3 +, Gd3 + and Tb3 + 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.

Graphical abstractThe lanthanide 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) complexes are synthesized by template method. They extend the number of structurally documented lanthanide complexes displaying high and a relatively rare coordination number of 11. These complexes are able to cleave the phosphodiester bond in 21-mer RNA in a sequence-selective or non-selective manner.Figure optionsDownload full-size imageDownload as PowerPoint slide