Distinctly Different Chemical Functionalities on the Internal and the External Surfaces of Silica Nanotubes, and Their Applications as Multi‐Chemosensors

Abstract

Size matters: The frustrated Lewis pair derived from B(C6F5)3 and the sterically encumbered N‐heterocyclic carbene N,N′‐tBu2C3H2N2 (1) cleaves dihydrogen heterolytically to give a imidazolium borate (see scheme, left), and cleaves amine NH bonds to form aminoborate salts (right) or aminoboranes.

Selective Functionalization of the Internal and the External Surfaces of Mesoporous Silicon by Liquid Masking

“…Mesoporous materials with engineered surface properties are of interest for molecular separations, catalysis, drug delivery, and chemical sensing. , One of the longstanding chemical challenges in the engineering of nanomaterials is to control the placement of different chemistries in spatially distinct regions on a nanoscale object. Examples include Janus particles, where different chemical species are placed on the opposite sides of a nanoparticle, − and core–shell nanoparticles, where the interior and the surface of a nanoparticle contain distinct materials. − Selective suface modification has been achieved with mesoporous silica nanoparticles either by co-condensation during the sol–gel synthesis or by postsynthetic grafting of commercially available substituted trialkoxy- or trichloro-silanes . In addition, differential chemistries can be placed in or on porous nanostructures by using the inherent ability of the pores to exclude molecules larger than a certain size. , …”

“…esoporous materials with engineered surface properties are of interest for molecular separations, 1 catalysis, 2 drug delivery, 3 and chemical sensing. 4,5 One of the longstanding chemical challenges in the engineering of nanomaterials is to control the placement of different chemistries in spatially distinct regions on a nanoscale object. Examples include Janus particles, where different chemical species are placed on the opposite sides of a nanoparticle, 6À8 and coreÀshell nanoparticles, where the interior and the surface of a nanoparticle contain distinct materials.…”

“…9À12 Selective suface modification has been achieved with mesoporous silica nanoparticles either by co-condensation during the solÀgel synthesis or by postsynthetic grafting of commercially available substituted trialkoxy-or trichloro-silanes. 5 In addition, differential chemistries can be placed in or on porous nanostructures by using the inherent ability of the pores to exclude molecules larger than a certain size. 13,14 In the case of porous Si, chemical modification is usually performed either after, 15 or in tandem 16 with the electrochemical etching procedure employed in its synthesis.…”