| Ruthenium (Ru) complexes play a very important role in some research fields, such as solar energy conversion, nonlinear optical materials, electron transfer, photocatalysis, molecular recoginition, because of their rich photophysical and photochemical properties as well as ground state and excited state reactivity. Among them, ruthenium complexes have attracted much attention because of their favorable photophysical properties, stable thermodynamic properties, high reactivity and long lifetime of the excited state. Therefore, these complexes are widely applied in research fields such as dye-sensitized solar cell, special photoelectric materials, biological imaging and detection, photodynamic therapy and chemical luminescence.Photo-induced isomerization of nitrosylruthenium complexes is one kind of important photo reaction for ruthenium complexes. It is of great significance to study the reaction characteristics and dynamic mechanism for ruthenium complexes to design special photoelectric materials, new type photo catalyst, novel information storage medium, molecular switches and molecular motors as well as nanometer molecular machines. However, its reaction mechanism is very complicated and need to be further elucidated.In this degree thesis, electronic absorption spectrum, infrared spectrum and nuclear magnetic resonance spectrum of two types of nitrosylruthenium complexes are calculated with density functional theory (DFT), and compared with results of experimental measurement. At the same time, their absorption spectra were analyzed and the molecular vibrational modes were assigned reasonably.Using the nuclear magnetic resonance spectroscopy (NMR) and time-resolved IR spectroscopy technique, dynamic process of photo isomerization for two types of nitrosylruthenium complexes were investigated at different wavelengths upon photoirradiation, and the basic experimental method to regulate the process of isomerization for these ruthenium complexes was developed. The stretching vibrational dynamics of nitrosyl group of two nitrosylruthenium complex isomers were studied using 2DIR spectroscopy and IR pump detection technologies.The main content of this paper are as follows:First, the research progress for photo reactions of ruthenium complexes and photo-induced isomerization of nitrosylruthenium complexes are summarized and introduced.Secondly, two [Ru(OAc)(2cqn)2NO] (H2cqn=2-methyl-8-quinolinol) isomers and three [Ru(OAc)(2mqn)2NO] (H2mqn=2-methyl-8-quinolinol) isomers were successfully synthesized and purified. Structures, electronic spectra, infrared and NMR spectra of two [Ru(OAc)(2mqn)2NO] (H2cqn=2-methyl-8-quinolinol) isomers were calculated at the B3LYP level with 6-311++G(d,p) and Lanl2dz as the basis set, and were also calculated at the B3LYP level with 6-311++G(d,p) and Aug-cc-pVDZ-PP as the basis set. Good agreement between experimental and theoretical values of structural parameters was achieved. Density functional theory calculations provided rational analyses for molecular orbital, UV-vis, IR and NMR spectroscopy of these complexes. The study provided characteristic spectra signal to trace and investigate the photo-induced isomerization.Thirdly, the photo-induced isomerization of [Ru(OAc)(2cqn)2NO] and [Ru(OAc)(2mqn)2NO] were monitored by nuclear magnetic resonance (NMR) spectroscopy technique with 1H NMR signal of ligand in isomer as a labeling probe. We selected 254 nm,420 nm,475 nm and 550 nm as the excitation wavelength according to the absorption spectrum of isomers, the rate constant and quantum yields of photo-induced isomerization reaction under different excitation wavelength were calculated quantitatively. Rate constant and quantum yields of these two types of nitrosylruthenium complexes are in the order:k254nm> K:420nm> k475nm>k550nm,Φ254 nm>Φ420 nm>Φ475 nm>Φ550 nm, respectively. The results show that rate constant and quantum yields of photo-induced isomerization are greater upon irradiation with light around the absorption peak; on the other hand, rate constant and quantum yields of photo-induced isomerization become smaller upon irradiation with light around the lower-absorption region. The study provides the experimental basis for the regulation of photo-induced isomerization process through the different wavelengths of light.Fourthly, the dynamic of the isomerization of [Ru(OAc)(2cqn)2NO] and [Ru(OAc)(2mqn)2NO] complexes upon irradiation with white light and 420 nm light was studied by time-resolved Fourier infrared spectroscopy. Using the nitrosyl stretching (vNO) as vibrational probe, the structural dynamics and structural distributions of [Ru(OAc)(2cqn)2NO] isomers in different solution are examined by steady-state linear infrared and ultrafast two-dimensional infrared (2DIR) spectroscopy. The results show that NO plays an important role in the process of photoisomerization reaction. The vibrational relaxations of the nitrosyl stretch in different solvents were also studied using the magic-angle pump-probe IR spectroscopy. Center-line-slope (CLS) method was used to characterize the spectral diffusion process. Different geometric configurations show different kinetic characteristics of spectral diffusion.Finally, we made a summary and gave a outlook to the next step work. |
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