Containing The Polar Substituted Phenyl Polysilane Synthesis, Characterization And Fluorescence Properties

Polysilanes is a class of δ-conjugated polymers that consist of a linear Si-Si main chain and two alkyl or aromatic substituents on each silicon atom. They have unique physical and chemical properties, and that give them many potential applications such as polymeric photoconductors, light-emitting diodes, materials with nonlinear optical properties, high resolution microlithography, ceramic precursors for Si-C ceramic or fibers et al.Several dichlorosilanes, such as (methyl) (phenyl) dichlorosilane, (methyl) (p-methoxyphenyl) dichlorosilane and (methyl) (p-methylphenyl) dichlorosilanes, were prepared by Grignard reagents method.Three series of polysilanes were synthesized by Wurtz-type reductive coupling of dichlorosilanes. The polysilanes were characterized by FT-IR, 1H-NMR and GPC. The fluorescence (FL) properties of the polysilanes in solid status and in dilute solution were investigated.First, some polysilanes with different molecular composition were synthesized from dimethyldichlorosilanes, diphenyldichlorosilanes, both of them can be bought from market easily, and methylphenyldichlorosilanes, which were self-prepared. The polysilanes are as follows.Poly(di-methyl-co-di-phenylsilane) (PS1, monomer ratio =1:1) Poly(methylphenylsilane) (PS2)Poly(di-methyl-co-di-phenylsilane) (PS3, monomer ration =1:2) Poly(di-methyl-co-di-phenylsilane) (PS4, monomer ratio = 2:1) Poly(di-methyl-co-methylphenylsilane) (PS5, monomer ratio =1:1) Poly(di-phenyl-co-methylphenylsilane), (PS6, monomer ratio = 1 : 1) The influence of molecular composition and structure of polysilanes with different phenyl contents on FL properties were studied. The conjugated substituents and conformation determine the FL properties of the polysilanes. Increasing the amount of conjugated phenyls will lead the maximum fluorescence emittingwavelength, λ max, of the polysilane to an Einstein shift.Second, the polysilanes as follows, with electron-donating para-methyl on the phenyl were prepared. Poly(methyl-p-methoxyphenylsilane) (PS 7)Poly(di-methyl-co-methyl-p-methoxyphenylsilane), (PS8 monomer ratio=1:1) Poly(methylphenyl-co-methyl-p-methoxyphenylsilane), (PS9 monomer ratio=1:1) Poly(di-phenyl-co-methyl-/?-methoxyphenylsilane) (PS 10 monomer ratio=l: 1)Third, the polysilanes as follows with electron-donating para-methoxy on the phenyl were prepared. Poly(methyl-p-methlphenylsilane) (PS11)Poly(di-methyl-co-methyl-p-methlphenylsilane) (PS 12 monomer ratio=1 :1) Poly(methyphenyl-co-methyl-p-methlphenylsilane) (PS13 monomer ratio=1:1) Poly(di-phenyl-co-methyl-p-methlphenylsilane) (P14 monomer ratio=1:1)The electron donating effect of the para groups caused the A max of the polysilane a little Einstein shift, but not notable. The delocalization of the side groups and the conformation of the polysilanes may also be the factors that obviously influence their fluorescence properties. A polysilane having longer chain length seems to have a higher fluorescence intensity.The primary conclusions were proposed as follows.First, the para methyl or methoxy substituents on the phenyl as a side group of polysilane influences the maximum fluorescence emission wavelength λmax of polysilane, but not very remarkable.Second, more aromatic side groups on the backbone of polysilane can change the λ max more remarkably.