{Ru(CO)_x}-core terpyridine complexes: Lysozyme binding affinity, DNA and photoinduced carbon monoxide releasing properties

Reaction of 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine (L^PY) and 4′-(4-phenylmorpholine)-2,2′:6′,2″-terpyridine (L^morph) with {[RuCl₂(CO)₃]}₂ in methanol affords [RuCl₂(L^PY-κ²N¹N²)(CO)₂] (1) and a mixture of [RuCl₂(L^moph-κ²N¹N²)(CO)₂]/[RuCl₂(L^morph-κ³N¹N²N³)(CO)] (2), respectively. Their photoactivatable CO releasing properties are investigated upon the exposure to light source at 365 nm. One CO molecule is released from 1 at the excitation wavelength 365 nm, while the ligand changes its bidentate mode into the meridional tridentate one. The illumination profile and the influence of the uncoordinated pyridine arm on CO release are examined by solution ¹H and ¹³C NMR spectroscopy. The electronic transitions are studied by TDDFT. The DNA and hen white egg lysozyme binding affinity of the complexes are studied by UV/Vis. and electrospray ionization mass spectrometry. Stable lysozyme complexes, capable of photo induce CO, are formed via the loss of the labile chloride ligands or terpyridine moiety.