Photoactive Platinum(II) Azopyridine Complexes^†

Abstract

Platinum(II) complexes containing the strong π‐acceptor N,N‐chelating ligand phenylazopyridine (Ph‐azpy) [Pt(p‐R‐Ph‐azpy)X2], R = H, NMe2 or OH, X = Cl or N3, have been synthesized and characterized to explore the effects of monodentate ligands and phenyl substituents on their absorption spectra and photoactivation. Time‐dependent density functional theory calculations showed that the complexes have a low‐lying unoccupied orbital with strong σ‐antibonding character toward the majority of the coordination bonds. The UV–visible absorption bands were assigned as mainly ligand‐centered or metal‐to‐ligand charge‐transfer transitions, with strong contributions from the chlorido and azido groups. In complexes with substituted Ph‐azpy ligands, σ‐donation from NMe2 and OH/O– groups results in a redshift of the main absorption bands compared with unsubstituted Ph‐azpy complexes. The diazido complexes are photoactive in solution upon irradiation with either UVA or visible light for R = H or NMe2, or UVA only when R = OH/O–. Intriguingly, the phenolate group of the latter complex undergoes very slow protonation in solution. Biological screening was limited by poor solubility; however, initial tests showed that the phenolato diazido complex is rapidly taken up into the nuclei of HaCaT keratinocytes, which are stained intensely blue, and its cytotoxicity is increased upon irradiation with UVA light.

Indole-containing arene-ruthenium complexes with broad spectrum activity against antibiotic-resistant bacteria

“…( Silva et al., 2021 ) Medicinal inorganic chemistry has been stimulated by the success of platinum anticancer drugs (used as a component of nearly 50% of all cancer chemotherapy treatments), by the use of gadolinium(III) complexes as MRI contrast agents (about 20 million doses administered per year), and of the radionuclide 99m-technetium radiopharmaceuticals for γ-ray imaging (used in about 20 million radio diagnostic procedures each year). ( Biancalana et al., 2020 , ( Farley et al., 2021 ), Hanif et al., 2020 , Rafols et al., 2021 ) However, the involvement of metals in many other diseases and conditions is of current interest in relation to their causes, their treatment or detection, including neurodegeneration, ( Anthony et al., 2020 ) fungal ( Golbaghi et al., 2020 ), parasitic, ( Minori et al., 2020 , Melis et al., 2021 ) viral ( Yuan et al., 2020 ) infections and inflammation. ( Zhang et al., 2017 ) In the last decades, a wide range of inorganic and organometallic compounds have been investigated for killing or inhibiting microbial growth.…”