Appended Aromatic Moieties Determine the Cytotoxicity of Neutral Cyclometalated Platinum(II) Complexes Derived from 2-(2-Pyridyl)benzimidazole

Abstract

A new family of neutral chiral cyclometalated platinum­(II) complexes with formula [Pt­(κ2-(C^N))­Cl­(κ1-(L))], where (C^N) = 2-phenylpyridinate and (L) = 2-(2-pyridyl)­benzimidazole (L1) or (N-(CH2)-Ar-(2-(2-pyridyl)­benzimidazole) ligands; (Ar = phenyl (L2), naphthyl (L3), pyrenyl (L4)), have been synthesized and completely characterized. The unexpected κ1 coordination mode of the 2-(2-pyridyl)­benzimidazole-derived ligands has been confirmed by spectroscopic techniques and X-ray diffraction. The aromatic moieties on the ligands in the new platinum­(II) complexes have a remarkable influence on the cytotoxicity and in the binding mode to DNA. [Pt-L1]–[Pt-L4] complexes internalized more than cisplatin in the SW480 cancer cells even though only [Pt-L1] and [Pt-L2] display high cytotoxicity. 1H NMR and 13P­{1H}­NMR pointed out that [Pt-L1] and [Pt-L2] complexes bind covalently to dGMP, while the electrophoresis assays and CD experiments indicate that only [Pt-L2] is able to covalently interact with DNA, inducing the same conformational changes in the plasmid DNA as cisplatin. Although the complex [Pt-L4] intercalates into DNA, probably through the pyrenyl moiety, no biological activity is observed.

Photocatalytic Aerobic Dehydrogenation of N-Heterocycles with Ir(III) Photosensitizers Bearing the 2(2′-Pyridyl)benzimidazole Scaffold

“…The ligand 2-(2′-pyridyl)­benzimidazole ( L1 ) is commercially available, and its N-functionalized derivatives ( L2 – L5 ) were prepared by reacting L1 with MeI, for L2 , or the appropriate alkyl bromide (R-Br), for L3 – L5 , at room temperature in the presence of K 2 CO 3 , using DMF as solvent (see Figure ). − The incorporation of diverse alkyl groups into the N^N′ ligand aimed to reduce intermolecular interactions and to assess different effects on the photophysical and photocatalytic properties of the resulting Ir derivatives. Thus, the methyl and benzyl groups ( L2 , L3 , and L4 ) were chosen to protect the respective complexes from either self-quenching or N–H reactivity.…”

Tunable Emissive Ir(III) Benzimidazole‐quinoline Hybrids as Promising Theranostic Lead Compounds

“…The synthesis begins with the preparation of ligands L1 and L2 , see Scheme 1. Both of them were prepared following a slightly modified procedure previously described by Shavaleev [34] and Vaquero [35] for similar compounds. Specifically, benzimidazole derivatives were mixed with an excess of base, (K 2 CO 3 in DMF in the case of L1 and KOH in CH 3 CN for L2 ) to assist the nucleophilic substitution reaction that takes places thereafter the addition of 2‐chloromethylquinoline.…”

Effect of 1-Substituted 2-(Pyridin-2-yl)-1H-Benzo[d]imidazole Ligand-Coordinated Copper and Cobalt Complex Redox Electrolytes on Performance of Ru(II) Dye-Based Dye-Sensitized Solar Cells

“…The 2-(2-pyridyl)­benzimidazole ligand (typically N , N ′-diimine chelating system) has an admirable history in coordination chemistry, which was generally used for biological, medicinal, and luminescence applications. ,− Simplistic alkylation of the 2-(2-pyridyl)­benzimidazole NH group can be able to attach a broad diversity of substituents to the metal–diimine core in an approach that was not so synthetically suitable for metal–bipyridine and phenanthroline complexes . This class of ligands was first introduced into DSSCs as one of the coordinated ligands with the ruthenium metal complex dyes, which obviously confirmed electron transport rigidity and electrochemical activity of the ligands .…”