Synthesis, Structural Characterization and Biological Evaluation of Rhenium(I) Tricarbonyl Complexes with β-Carboline Ligands

Abstract

Two β-carboline rhenium(I) complexes, fac-[Re(CO)3(dppz)(nHo)]O3SCF3 and fac-[Re(CO)3(nHo)2Cl] where dppz=dipyrido[3, 2-a:2′,3′-c] phenazine and nHo=9H-pyrido[3, 4-b]indole (norharmane), have been synthesized. These complexes were fully characterized by structural X-ray diffraction, 1H and 13C NMR, UV-vis absorption and FT-IR spectroscopy and mass spectrometry. Ground state geometry optimization was carried out in vacuo with the PBE0 hybrid functional using the LanL2DZ basis set. The characterization was complemented with TD-DFT calculations using several hybrid functionals. Cellular uptake and cytotoxic effect of both complexes against human lung carcinoma (A549) cells were evaluated. For comparative purpose, two related fac-[Re(CO)3(L)(nHo)]+ complexes (L=bpy and phen) were included in the biological studies. The anti-proliferative effect of the compounds was rationalized in terms of the different extension of the ligands π-system.