Engineering Nanospaces: Iterative Synthesis of Melamine‐Based Dendrimers on Amine‐Functionalized SBA‐15 Leading to Complex Hybrids with Controllable Chemistry and Porosity

Abstract

TEM samples were prepared by dropping 10 lL of diluted solution in toluene onto 400-mesh carbon-coated copper grids by Finnpipette and slowly evaporating the solvent in air at room temperature. Many of these investigations have utilized ordered mesoporous silicas such as MCM-41 or SBA-15 as the inorganic component. These materials are in some regards ideally suited for this task, as they present the materials chemist with a highly ordered porous inorganic matrix, wherein well-developed silane chemistries can be exploited to build organic functionalities off the silica surface. In this vein there have been many investigations of the incorporation of organic functional groups into mesoporous silicas including the direct synthesis of hybrid materials, post-synthetic grafting, covalent versus non-covalent linkage, etc. [2,3,5] In general, a common theme of these investigations is that the organic moiety tethered to the surface is chemically ªsimpleº, often a single functional group. For hybrid materials to achieve their full potential the ability to synthesize complex/multifunctional organic moieties directly on the mesoporous substrate would be highly desirable.In the current report we describe the stepwise synthesis of a series of melamine-based dendrimers of various generations that are grown directly off the mesopore surface. While a few works have studied dendrimer±mesoporous silica hybrids formed via dendrimer physisorption, [6,7] and many works have studied the growth of dendrimers on nonporous silicas, [8±10] this is the first example we know of where complex organic macromolecules derived from multistep organic syntheses (e.g., six sequential reactions for the G3 (third-generation) dendrimer) have been grown using ordered mesoporous silica as a solid-phase support. As such we believe this work has important implications for organic±inorganic hybrid materials,

Functionalized magnetic MCM-48 nanoporous silica by cyanuric chloride for removal of chlorophenol and bromophenol from aqueous media

“…The MDA-magMCM-48 was synthesized using cyanuric chloride and EDA according to a procedure similar that described previously in literature [30]. Cyanuric chloride (5.5 g: 30 mmol) and DIPEA (7.1 mL: 46 mmol) were dissolved in dried tetrahydrofuran (300 mL) and stirred at 0°C for 3 h under argon atmosphere.…”

Adsorption of hydrogen peroxide on functionalized mesoporous silica surfaces

“…The use of grafting method usually preserves the mesostructure of the starting silica phase, but the distribution of organic moieties anchored to the silica surface is solvent dependent [29] and sometimes leads to pores blockage [30]. Another advantage of this method is that it can be applied to a diversity of organic molecules, from small ones like aminopropyltrimethoxysilane [29] or compounds used in our experiment, to large moieties as dendrimers [31] and fullerenes [32]. Co-condensation is a convenient direct method of synthesis when the total amount of the organic part is supposed to be rather small.…”

Identification of diamine linkers with differing reactivity and their application in the synthesis of melamine dendrimers

“…1 From these studies, aminomethylpiperidine emerged as a diamine linker of choice and was used extensively. 1,2,7,9,[15][16][17]19,20 Using competition experiments, the relative reactivity difference measured for the cyclic secondary amine and primary amine of aminomethylpiperidine is ~ 20 times. Theoretically, 5% of the product formed might derive from reaction of the monochlorotriazine dendron with the primary amine instead of the desired secondary amine.…”