Study On Performances Of Films Of Novel Ruthenium (2,2'-bipyridine) Complexes

In this work, nano-films of a series of ruthenium (2,2'-bipyridine) complexes were prepared by Langmuir- Blodgett (LB) technique. Film formation of their films on ultrapure water as subphase and photoluminescence were investigated by UV-vis absorption spectra, fluorescence spectra, Fourier Transfer Infrared spectra (FT-IR), atomic force microscope (AFM) and NKD-8000v instrument for thickness of films.1. Three Ru(bpy)32+complexes with different length alkyl chain were synthesized, and then the performances of their LB films were studied. Although Ru-MV-Br complex posses hydrophilic Ru(bpy)32+and hydrophobic alkyl chain, Stable LB films could not be prepared because of the ratio of hydrophobic groups is much smaller compared with hydrophilic groups. LB films of Ru-MV-Nap1 and Ru-MV-Nap12 complexes were both made at pressure of 4.0mN/m due to appropriate proportion of hydrophilic groups and hydrophobic groups.The thicknesses of Ru-MV-Nap1 and Ru-MV-Nap12 complexes monolayer were calculated in theory and measured with polarity method, through which the angle between the molecules with the substrate was simulated. The result showed that the angle between Ru-MV-Nap1 complexes with the substrate is 33.5°and that of Ru-MV-Nap12 complex is 30°. Morphologies of their monolayer and LB films were also investigated by AFM. The results showed that Ru-MV-Nap1 molecules in LB film arranged helically and symmetrically, suggesting that LB films of Ru-MV-Nap1 complex might possess optical action.2. We investigated their properties irradiated with UV light preliminary in order to probe into the mechanism of these Ru(bpy)32+complexes with UV spectra and FT-IR. From FT-IR spectra, the peaks of aromatic rings in Ru-MV-Nap1 complex dramatically changed with extending UV light (248nm) irradiation time, but Ru-MV-Nap12 containing long alkyl chain was not clear. It is clear that Ru-MV-Nap12 complex was not sensitive to UV248nm light compared with Ru-MV-Nap1 complex. This indicates that electron conversion efficiency inter as well as intra molecules of Ru-MV-Nap12 complex was lower than that of Ru-MV-Nap1 complex, which may attribute to spatial hindrance of long alkyl chain between Ru-MV-Nap12 complex.Fluorescence spectra of three Ru(bpy)32+ complexes were studied in solution and films. They mainly emit blue purple light in CHCl3 solution, cyan light in spin-coated films and LB films. Fluorescence signal from spin-coated films of Ru-MV-Br complex with UV light irradiated (λ=248nm) for lmin extinguished. Extending UV light irradiated time, fluorescence signal renewed again with the width of half peak at 57nm, ranging from 371 nm to 428nm, which suggesting that Ru-MV-Br complex can be used as cyan fluorescence probe. The performance of fluorescence of Ru-MV-Nap1 complex with UV light irradiated (λ=248nm) was reversible, which can be used as a potential fluorescence probe or switch.