Synthesis and characterization of a polyhedral oligomeric silsesquioxane-functionalized methyl red: A novel candidate for non-linear optical applications

摘要

A Polyhedral Oligomeric Silsesquioxane (POSS) functionalized with methyl red azo dye was synthesized using the Steglich Esterification. The resultant organic-inorganic colorant was characterized using FTIR， 1H NMR and elemental techniques. Change of acidic carbonyl groups to an esteric one was related to formation of functionalized dye. Differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) also confirmed that grafting was occurred, the result of which was observation of 12℃ increase in thermal stability of the functionalized nano-structured dye. A 5 nm bathochromic shift revealed in UV-Visible spectra of the grafted dye was attributed to the covalent bonding of POSS and dye. Characterization techniques indicated that more dye is covalently grafted to POSS when the molar ratio of methyl red to POSS was 4:1. Studies of induced birefringence showed promising results confirming that aggregation of dye was significantly reduced due tc incorporation of POSS to the dye chromophore.