Advanced Surface Functionalization of Periodic Mesoporous Silica:  Kinetic Control by Trisilazane Reagents Clemens Zapilko Markus Widenmeyer Iris Nagl Frank Estler Reiner Anwander Gabriele Raudaschl-Sieber Olaf Groeger Günter Engelhardt 10.1021/ja065444v.s001 https://acs.figshare.com/articles/journal_contribution/Advanced_Surface_Functionalization_of_Periodic_Mesoporous_Silica_Kinetic_Control_by_Trisilazane_Reagents/3040576 The surface reactions of mesoporous silica MCM-41 with a series of new trisilylamines (trisilazanes) (SiHMe<sub>2</sub>)<sub>2</sub>NSiMe<sub>2</sub>R and (SiMe<sub>2</sub>Vin)<sub>2</sub>NSiMe<sub>2</sub>R (R = indenyl, norpinanyl, chloropropyl, 3-(<i>N</i>-morpholin)propyl; Vin = vinyl), disilylalkylamine (SiHMe<sub>2</sub>)<i>i</i>PrNSiMe<sub>2</sub>(CH<sub>2</sub>)<sub>3</sub>Cl, and monosilyldialkylamines Me<sub>2</sub>NSiMe<sub>2</sub>R (R = indenyl, chloropropyl, 3-(<i>N</i>-morpholin)propyl) were investigated. <sup>1</sup>H, <sup>13</sup>C, and <sup>29</sup>Si MAS NMR spectroscopy, nitrogen adsorption/desorption, infrared spectroscopy, and model reactions with calix[4]arene as a mimic for an oxo surface were used to clarify the chemical nature of surface-bonded silyl groups. The trisilylamines exhibited a comparatively slow surface reaction, which allowed for the adjustment of the amount of silylated and nonreacted SiOH groups and led to a stoichiometric distribution of surface functionalities. The 2:1 integral ratio of SiHMe<sub>2</sub> and SiMe<sub>2</sub>R moieties of such trisilazanes was found to be preserved on the silica surface as indicated by microanalytical as well as <sup>13</sup>C and <sup>29</sup>Si MAS NMR spectroscopic data of the hybrid materials. For example, the reaction of MCM-41 with (SiHMe<sub>2</sub>)<sub>2</sub>NSiMe<sub>2</sub>(CH<sub>2</sub>)<sub>3</sub>Cl, (SiHMe<sub>2</sub>)<i>i</i>PrNSiMe<sub>2</sub>(CH<sub>2</sub>)<sub>3</sub>Cl, and Me<sub>2</sub>NSiMe<sub>2</sub>(CH<sub>2</sub>)<sub>3</sub>Cl provided bi- and monofunctional hybrid materials with one-third, one-half, or all chemically accessible silanol groups derivatized by chloropropyl groups, respectively. Thus, a molecular precursor strategy was developed to efficiently control the relative amount of three different surface species, SiHMe<sub>2</sub> (or SiVinMe<sub>2</sub>), SiMe<sub>2</sub>R, and SiOH, in a single reaction step. The reaction behavior of indenyl-substituted monosilazanes and trisilazanes (R = Ind) with calix[4]arene proved that the indenyl substituent can act as a leaving group forming a dimethylsilyl species, which is anchored bipodally on the silica surface, that is, via two SiO bonds. 2006-12-20 00:00:00 29 Si MAS NMR spectroscopic data nonreacted SiOH groups 13 C Trisilazane ReagentsThe surface reactions SiMe 2R moieties SiHMe 2 indenyl trisilazane Advanced Surface Functionalization chloropropyl silanol groups derivatized silica surface MCM 29 Si MAS NMR spectroscopy