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Organoindium-Modified Monodisperse Ellipsoid-/Platelet-Like Periodic Mesoporous Silicas

Abstract

In this study, indium(III) silylamide complex was respectively grafted onto monodisperse ellipsoid-like (E) and platelet-like (P) large-pore hexagonal periodic mesoporous silicas (PMSs) SBA-15 to afford hybrid materials In[N(SiMe3)]3@SBA-15E and In[N(SiMe3)]3@SBA-15P with well-defined surface species (≡SiO)2In[N(SiMe3)2], ≡SiOIn[N(SiMe3)2]2, and ≡SiOSiMe3. Surface silylamido/alkyl alcohol ligand exchange performed the conversion of surface species (≡SiO)2In[N(SiMe3)2] and ≡SiOIn[N(SiMe3)2]2 into (≡SiO)2In(OR) and ≡SiOIn(OR)2 (R = Me, Et, iPr) with donor ligands thf or NH3, respectively, revealing that silylamido coordinated to indium centre could be completely exchanged by alkoxyl groups (-OMe, OEt or OiPr). Solid-state 1H, 13C and 29Si nuclear magnetic resonance spectra and elemental analyses confirmed that surface species ≡SiOIn[N(SiMe3)2]2 are dominant in comparison to bipodal (≡SiO)2In[N(SiMe3)2] and ≡SiOSiMe3. The diffuse reflectance infrared Fourier-transform spectroscopy of In-modified hybrid materials directly evidenced the alteration of surface species before and after grafting of In[N(SiMe3)]3 and surface ligand exchange. In addition, the change of pore parameters (pore diameter, specific surface area and pore volume) monitored by nitrogen physisorption also indirectly corroborated the immobilization of indium complex and the occurrence of ligand exchanges between -N(SiMe3)2]2 and -OR (R = Me, Et, iPr) on the surface of SBA-15. Note that the calcinations of In-modified hybrid materials at 540°C led to the formation of crystalline In2O3 nanoparticles with different sizes which respectively located in internal pore and on the external surface of SBA-15 due to pore confinement effect, migration effect and shape effect of parent support, but the long-range ordered mesopore arrays still preserved and the crystalline structures of In2O3 were verified by powder X-ray diffraction and transmission electron microscopy.

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Publication details

The article was received on 29 Mar 2017, accepted on 07 May 2017 and first published on 08 May 2017


Article type: Paper
DOI: 10.1039/C7DT01132F
Citation: Dalton Trans., 2017, Accepted Manuscript
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    Organoindium-Modified Monodisperse Ellipsoid-/Platelet-Like Periodic Mesoporous Silicas

    Y. Liang and M. Meixner, Dalton Trans., 2017, Accepted Manuscript , DOI: 10.1039/C7DT01132F

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