Synthesis and characterization of chiral azobenzene dye functionalized Janus dendrimers

Eight bischromophoric bisMPA based polyester Janus dendrimers emanating from a pentaerythritol core were synthesized and their properties evaluated. 4-((4-(Ethyl(2-(2-(6-methoxynaphthalen-2-yl)propanoyloxy)ethyl)amino)-phenyl)diazenyl)-benzoic acid and 4-((4-(ethyl(2-(2-(6-methoxynaphthalen-2-yl)propanoyloxy)-ethyl)-amino)phenyl)diazenyl)-3-nitrobenzoic acid were attached to the dendritic polyester skeleton to make chiral dendrimers up to the second generation. The structures and the purity of the molecules were verified with 1H NMR, 13C NMR, ESI TOF mass spectrometry, and elemental analysis. Spectral properties were evaluated with UV-vis and CD spectrometer. The compounds displayed broad absorption maxima in the visible region. The CD spectra confirmed the optical purity of the compounds. The thermal properties were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).