Synthesis And Optical Properties Of The First Generation Unsymmetrical Conjugate Dendrimers

Dendrimer, a new polymer developing in recently years, is consisted of center core,branched units and peripheral end functional groups, it possesses a “Core-Shell”structure that multibranched units that radiates out from a central core. With the increaseof generation, the number of functional groups grow exponentially. Compared with thetraditional polymers, its can be precisely modified at the molecular level at any portion.In recent years, dendrimers have been applied in plenty of aspects, such as photoelectricmaterials, catalysts, and applications in biological. The main work of this paper is asfollows:4,5-Di(3′,5′-di-tert-butylphenylethynyl)-2-methoxyphenol (G1) was synthesized,by coupling with different chromophores(biphenyl, azobenzene, anthracene, pyrene),the first generation unsymmetric conjugate dendrimers (PAD-biphenyl, PAD-azobenzene, PAD-anthracene, PAD-pyrene) were obtained via solution convergentprocess.Optical properties of G1and the first generation unsymmetric conjugatedendrimers were studied, it showed that the UV/Vis absorption and fluorescenceemission spectra of demdrimers were red-shifted as compared to G1, that is the result ofthe increasing of conjugation by coupling with different chromophores.Fluorescence quenching experiments showed that, this class of demdrimer canform ion pair with electron-defect compounds as well as electron-affluent compounds,hence, these dendrimers may act as either electron acceptors or donors, at the same time,introduction of the chromophore increased the steric hindrance, which can prevent thefluorescence concentration quenching of the small molecule result of forming excimer.