One-Pot Synthesis of Oligo-Ladder Phenylsilsesquioxanes via Pyridine–Silicon Adduct Formation at Aqueous–Organic Liquid Boundary

Abstract

Three kinds of oligo-ladder polyphenylsilsesquioxanes were synthesized by two unique methods through the aqueous–organic boundary reaction via octahedrally-coordinated pyridine–silicon adduct PhSiCl3(Py)2, which is formed from trichlorophenylsilane (TCP) monomer and pyridine in n-propyl acetate. When two equivalent pyridines to TCP were used, SQ polymer-1 was formed as a viscous solid, which was recrystallized in n-hexane to obtain SQ polymer-2B. When an excess pyridine was used (pyridine/Si = 10), SQ polymer-2A was directly obtained as a white solid. MALDI–TOF/TOF–MS, FT-IR and 29SiNMR clearly shows that the “Ladder” structure of SQ polymers is dominant in both methods. It was shown that in this one-pot synthesis, SQ polymer structure was controlled by pyridine amount. Furthermore, MO simulation of pyridine adduct formation (PhSiCl3(Py)2) supports the hydrolysis pathway for synthesis as well as the “Ladder” structure formation. Finally, it was also suggested that the hydrolysis reaction occurred in a stepwise manner.