| Cyanine dyes have broad application prospects in the biomedical field because of their structural characteristics and spectral properties,such as for the determination of nucleic acid,protein analysis,labelling of bio-macromolecules,living cells staining,tumor detection,etc.Complex merocyanine dyes,as an important branch of cyanine dyes,have not been researched too much in recent years.In this paper,a series of benzo[c,d]indole rhodanine complex dyes were designed and synthesized.Furthermore,their spectral properties in various solvents and the nature as photosensitizer in the photodynamic therapy were also investigated.This dissertation included four aspects which are as follows:1.The structure features and properties of cyanine dyes have been summarized,and the structural characteristics of the merocyanine dyes and complex merocyanine dyes have been introduced.Meanwhile,the synthesis and application progress of rhodanine complex dyes were also reviewed in recent years.2.Two merocyanine dyes and five rhodanine complex dyes(seven novel compounds)were synthesized using 3-ethyl rhodanine and 2-methylthiobenzo[c,d]indole iodide as starting material.The products were identified by UV-Vis,1H NMR,IR and I IRMS.At the same time,the stable structures of seven dyes were determined in quantum chemistry level.3.The UV-Vis and fluorescent spectra of seven dyes in various solvents were investigated.The results showed that in the same kinds of common organic solvents,the order of λmax is:complex merocyanine(D2-D6)>dimethine merocyanine(D7)>zero methine merocyanine(D1).And for complex merocyanine(D2-D6),they are in this order:D3(containing acridine nucleus)>D6(containing 4-methyl quinoline nucleus)>D5(containing 2-methyl quinoline nucleus)>D4(containing benzo[c,d]indole nucleus)>D2(containing benzothiazole nucleus).The influence of different solvents for the same dye on the absorption spectra was not large.D1 and D7 could emit fluorescence in methanol,and the fluorescence maxima were 590.6 nm and 634.4 nm,and the Stokes shifts were 60.6 nm 65.4 run,respectively.They were no fluorescence in other solvents.D2 and D4 emitted fluorescence in methanol,ethanol,acetone,chloroform and DMSO,and their fluorescence maxima and Stokes shifts were in the range of 591.0-667.2 nm and 16.0-70.5 nm in different solvents,respectively.D3 and D5 didn’t emit fluorescence in the six solvents.D6 emitted fluorescence only in chloroform and DMSO,and the fluorescence maxima were 658.6 nm and 665.2 nm,while the Stokes shifts were 37.1 nm 45.7 nm,respectively.Cytotoxicity of D2-D6 for SMMC-7721 and their application as photosensitizers in photodynamic therapy were investigated.The results showed that when the concentration of D2-D6 reached 1.00×10-5 mol/L,the cell viability was above 50%,which indicated that D2-D6 showed slight toxic on SMMC-7721 cells,meaning dyes exhibited low dark toxicity.Pure irradiated blank had no damage to SMMC-7721 cells and D2-D6 under nonirradiated were the same result,however,after xenon lamp irradiated,D2-D6 on SMMC-7721 cells showed significantly phototoxicity.Under the concentration of 5.00×10-6 mol/L,the cell survival rate of D2 under nonirradiated was 92%,while the cell inhibition rate of D2 under irradiated was 72%.It indicated the PDT activity of D2 was excellent under this concentration.For the same reason,the PDT activities of D3-D6 were excellent under the concentration of 2.50×10-6 mol/L.4.The geometric structure,molecular orbital,UV-Vis,1H NMR,IR and fluorescence emission spectrum of one trinucleus dimethine cyanine dye D9 were studied by theoretical method(DFT).The calculated values of UV-Vis,IR and 1H NMR are in good agreement with the experimental data.The clear excitation and emission spectra of D9 were given in the experimental and theoretical levels.Molecular orbital coefficient analysis showed that λmax generated by π→π*electronic transitions and fluorescence emission peak generated by S1→S0 transition was caused by the π*→π transitions. |
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