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Copper complexes have long been considered as a promising class of anticancer or antibacterial therapeutics. In this paper, two novel copper(II) complexes containing a β-carboline derivative and amino acids, namely [Cu(1-Im-βc)(L-Val)]ClO 4 ·0.5H 2 O (Cu1) and [Cu(1-Im-βc)(L-Phe)]ClO 4 ·0.5H 2 O (Cu2), where 1-Im-βc = 1-(2-imidazolyl)-β-carboline, L-Val = L-valine, and L-Phe = L-phenylalanine, were designed and synthesized. The complexes were characterized by elemental analysis, infrared spectroscopy, molar conductivity measurements, and mass spectrometry to determine their spatial structures and compositions. Both complexes bind to DNA by insertion. The complexes also show a good affinity for human serum albumin (HSA). In addition, the antitumor activity of the two complexes against lung cancer cells (A549), cervical cancer cells (HeLa), and breast cancer cells (MBA-MD-231) is significantly superior to that of the traditional antitumor drug, cisplatin. Finally, the anticancer mechanism results show that the complexes can induce apoptosis in HeLa cells, which is associated with mitochondrial damage, oxidative stress caused by reactive oxygen species (ROS) production, and activation of the caspase protein family. This study demonstrates that the introduction of aromatic heterocyclic alkaloid ligands with a broad spectrum of biological activities and water-soluble amino acid ligands into copper complexes can regulate their amphiphilic properties and biological activity, so as to obtain highly efficient copper-based therapeutics.

This paper describes the recognition process of tetrahedral [Cu II (tnz) 2 X 2 ] (X = Cl, Br) complexes by a DNA chain, analyzing the specific interaction between the DNA bases and backbone with the metal and the tinidazole (tnz) ligand. We identified the coordination of the copper metal center with one or two phosphates as the first recognition site for the tinidazole copper(II) complexes, while the ligands present partial intercalation into the minor groove. Also, we discuss a novel trigonal copper(I) tnz bromide complex, obtained by reducing the previously reported [Cu(tnz) 2 Br 2 ]. This complex sheds light on the mechanism of action of tnz metal complexes as one of the most stable DNA-complex adducts depicts a trigonal geometry around the copper ion.

In this article, a novel triphenylamine-modified salicylaldehyde Schiff base 2-(((4-(diphenylamino)phenyl)imino)methyl)-4-(pyridine-4-yl)phenol (HL) was synthesized and structurally characterized. HL possessed D-π-A structure and exhibited typical AIE property in THF/H 2 O. It was applied to selectively recognize Cu 2+ through an on-off mode in THF/H 2 O (1/9, v/v), and the fluorescence attenuation was attributed to a paramagnetic quenching effect of Cu 2+ together with the abatement of HL aggregates. Hence, the detection limit achieved was as low as 1.32 × 10 -7 M. The spectroscopic and ESI-HRMS results revealed a 1 : 2 complexation ratio of Cu 2+ with HL. The mechanism for sensing Cu 2+ was further confirmed by performing DFT calculations. Owing to the large affinity between Cu 2+ and His, the resultant CuL2 system was further used to detect His via the off-on method based on the displacement of ligands. The detection limit for His reached 5.14 × 10 -8 M. Furthermore, HL was available to prepare handy indicator papers for the on-site recognition of Cu 2+ and His. Confocal fluorescent imaging demonstrated that HL could sequentially respond to intracellular Cu 2+ and His.