Direct inclusion of triphenylmethane and triphenylsilane into the pores of zeolite Y

Abstract

A mixture of triphenylmethane (CHPh3, 1) and zeolite Y was heated to 423 K. The treatment resulted in the inclusion of 1 in the supercages of zeolite Y, up to 18 wt% (1.2 molecules of 1 per supercage). Similar phenomena were observed not only for 1 but also for the derivatives of 1 and for triphenylsilane (7). The inclusion of 1 was completed in less than 0.5 h, while the inclusion of 7 proceeded slowly (∼12 h), probably due to the bulk of 7. The included amounts of 1 and 7 tended to increase with a decreasing concentration of Al in zeolite Y. The Fourier-transform infrared spectra of 7-Y reveal the presence of three types of guest molecules, based on the appearance of three Si–H peaks in the Si–H stretching region. Calculations using molecular dynamics revealed that each of the three phenyl groups of 1 was inserted into the 12-membered rings of zeolite Y to form inclusion compounds. The catalytic activity of leucomalachite green and leucocrystal violet for the Knoevenagel reaction was significantly enhanced by the inclusion of these molecules into the SCs.