| Object: Design and synthesize thiosemicarbazone ligands and the relevant platinum complexes. Investigate their structural characteristics, the interaction modes between platinum complexes and HSA, and cytotoxicity, to select platinum complex with worthy biological activity. Synthesize a chain of zinc ion fluorescent complexes based on aminothiazolineone compounds, to study the factors influencing the fluorescence intensity, such as crystal structure, for development of novel fluorescent material and solid-state fluorescent probes.Methods: A series of thiosemicarbazone ligands, including TSC-1((E)-2-(1-(pyridin-2-yl)ethylidene)hydrazinecarbothioamide), TSC-2((E)-N-ethyl-2-(1-(pyridin-2-yl)ethylidene)hydrazinecarbothioamide) and TSC-3((Z)-2-(amino(pyridin-2-yl)methylene)hydrazinecarbothioamide), were synthesized using 2-acetylpyridine, 2-cyanopyridine, thiosemicarbazide, N(4)-ethylthiosemicarbazide. Then platinum complexes were synthesized with these ligands. All structures mentioned above were characterized by 1H-NMR, X-ray crystallography and element analysis, respectively. The interaction between the complexes and HSA was investigated by UV-vis, fluorescence emission spectrometry. MTT assay was applied to evaluate the cytotoxicity of ligands and complexes against HeLa, MCF-7, HepG-2 and NCI-H460 tumor cells. Zinc ion complexes based on aminothiazolineone compounds were synthesized, different spatial factors affecting the fluorescent properties were explored by density functional calculations and crystal structural analysis.Result: Three novel thiosemicarbazone-based platinum(II) complexes [Pt(MH-TSC)Cl](1), [Pt(ME-TSC)Cl](2) and [Pt(NH-TSC)2]Cl(3) were synthesized and structurally characterized. X-ray diffraction analyses revealed that 1 and 2 possessed very similar neutral mononuclear asymmetric units, and that complex 3 in a meridional arrangement, in which cationic nature was formed between two NH-TSC ligands and one Pt atom. A remarkable fluorescence decrease of HSA was observed with increasing concentration of 1–3. And the maximum emission wavelength showed no shift when Δλ was equal to 15 nm. However, the maximum emission wavelength displayed obviously red shift when Δλ was 60 nm. All complexes 1–3 and cisplatin displayed antitumor effect against four cancer cells. Meanwhile, monoclonal formation assay confirmed that 1-3 had a significant impact on cell proliferation. In the second part, the solid states of 4-6 emitted bright yellow, cyan, and spring green fluorescence, respectively, under 366 nm excitation. A large Stokes shift was observed, with the fluorescence quantum yield(Φ) in the order 4(0.12) < 6(0.15) < 5(0.45). The switching between fluorescence “OFF” and “ON” states of the complex solid, fuming by acid/base vapour, could be carried out repeatedly without obvious intensity decay. After a small amount of toluene being added, the luminescence of the powder was changed into cyan with fluorescence quantum yield increasing to 0.56 while the resulting fluorescence band was about 40 nm blue-shifted as compared to that of 4 alone.Conclusion: Results of the HSA interaction experiments suggested that the fluorescence quenching of HSA caused by 1–3 was a static quenching process. The environment around tryptophan had changed with the transformation of conformation when the quenching of fluorescence occurred. Meanwhile, complexes 1–3 showed higher cytotoxicity towards four tumor cell lines, than that of cisplatin. And the monoclonal formation assay indicated that 3 obviously inhibited cell proliferation. The complexes 4–6 exhibited high fluorescence emission, ON/OFF/ON fluorescence switching in solid state. Complex 5 displayed a 3–4 fold high fluorescence quantum yield(0.45) as that of complexes 4 and 6. Crystallographic analysis revealed that π-π stacking and intermolecular interactions were responsible for the unique fluorescence feature. And more, complex 4 might serve as a chemosensor to selectively detect toluene with naked eye. |
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