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This study aimed to synthesize two ruthenium(II) complexes modified with aryl alkynes [Ru(phen)2(TMSEPIP)](ClO4)2 (1, phen = 1,10-phenanthrolin; TMSEPIP = 2-(2-trimethylsilylethylphenyl)imidazole[4,5f][1,10] phenanthroline) and [Ru(phen)2(BEPIP)](ClO4)2 (2, BEPIP = 2-(2-phenethylphenyl)imidazole[4,5f][1,10]phenanthroline) and evaluate their ability to act as luminescent probes of c-myc G-quadruplex DNA. It was discovered that the luminescence of 1 decreased in the presence of c-myc G-quadruplex DNA, while the luminescence of 2 clearly increased under the same conditions. Besides, in the presence of double-stranded DNA, the luminescence intensity of 1 and 2 showed little obvious change. It was interesting to find by atomic force microscopy that 1 could promote c-myc G-quadruplex DNA self-assembly to form a nano-network structure, while 2 could promote the formation of a nanowire structure. Further studies showed that 1 was inserted into the groove formed by base pairs A6-G8 and G21-T23 of c-myc G-quadruplex DNA, while 2 was inserted into the groove formed by G7-G9 and G22-A24. It is speculated that 2 can be developed as a potential luminescent switch-on probe through selectively recognizing and promoting self-assembly of c-myc G-quadruplex DNA.

Herein, a series of imidazo[4,5-f][1,10] phenanthroline derivatives RPIP (PIP = imidazo [4,5-f][1,10] phenanthroline, R = NO2, 1; CF3, 2; Cl, 3; OH, 4) have been synthesized in yields of 82.3–94.7% at 100 °C under the irradiation of microwave. MTT assay has been utilized to evaluate the inhibitory activity (IC50) of these compounds against the growth of various tumor cells, and the results revealed that these compounds, especially 1, exhibited excellent inhibitory activity against the growth of A549 cells with IC50 of 15.03 μM. Moreover, it’s also confirmed that 1 can penetrate into the membrane of tumor cells and distribute in mitochondria when observed under microscopy, resulting apoptosis of tumor cells. The further studies showed that 1 can bind to bcl-2 G-quadruplex DNA, which demonstrated by the increase of melting point of bcl-2 G4 DNA in the presence of 1, as well as electronic titration and emission spectra. In a word, this kind of compound may develop as a potential apoptosis inducer in cancer chemotherapy via binding and stabilizing to the bcl-2 G-quadruplex DNA.

A series of arene Ru(II) complexes coordinated with phenanthroimidazole derivatives, [(η⁶-C₆H₆)Ru(l)Cl]Cl(1b L = p-ClPIP = 2-(4-Chlorophenyl)imidazole[4,5f] 1,10-phenanthroline; 2b L = m-ClPIP = 2-(3-Chlorophenyl)imidazole[4,5f] 1,10-phenanthroline; 3b L = p-NPIP = 2-(4-Nitrophenyl)imidazole[4,5f] 1,10-phenanthroline; 4b L = m-NPIP = 2-(3-Nitrophenyl) imidazole [4,5f] 1,10-phenanthroline) were synthesized in yields of 89.9%-92.7% under conditions of microwave irradiation heating for 30 min to liberate four arene Ru(II) complexes (1b, 2b, 3b, 4b). The anti-tumor activity of 1b against various tumor cells was evaluated by MTT assay. The results indicated that this complex blocked the growth of human lung adenocarcinoma A549 cells with an IC50 of 16.59 μM. Flow cytometric analysis showed that apoptosis of A549 cells was observed following treatment with 1b. Furthermore, the in vitro DNA-binding behaviors that were confirmed by spectroscopy indicated that 1b could selectively bind and stabilize bcl-2 G-quadruplex DNA to induce apoptosis of A549 cells. Therefore, the synthesized 1b has impressive bcl-2 G-quadruplex DNA-binding and stabilizing activities with potential applications in cancer chemotherapy.