1076237-92-7Relevant academic research and scientific papers
Controlled loadings in a mesoporous material: Click-on silica
Nakazawa, Jun,Stack, T. Daniel P.
, p. 14360 - 14361 (2008)
Hybrid mesoporous SBA-15 silicas were synthesized directly with variable alkylazide loading representing 2-50% surface coverage. These hybrid silica materials retain the favorable physical attributes of the parent SBA-15 materials and allow efficient covalent attachment of ethynylated organic moieties through a copper catalyzed 3 + 2 Huisgen cycloaddition reaction. Three distinctly different examples are provided demonstrating the efficiency and robust nature of this attachment synthetic strategy. The direct syntheses provide predefined loadings of randomly distributed organics within the materials, from site-dense to site-isolated. Such control over loadings along with simply implemented analytic procedures should facilitate the translation of homogeneous chemistries to heterogeneous supports. Copyright
Discrete complexes immobilized onto click-SBA-15 silica: Controllable loadings and the impact of surface coverage on catalysis
Nakazawa, Jun,Smith, Brian J.,Stack, T. Daniel P.
supporting information; experimental part, p. 2750 - 2759 (2012/03/22)
Azidopropyl functionalized mesoporous silica SBA-15 were prepared with variable azide loadings of 0.03-0.7 mmol g-1 (～2-50% of maximal surface coverage) through a direct synthesis, co-condensation approach. These materials are functionalized selectively with ethynylated organic moieties through a copper-catalyzed azide alkyne cycloaddition (CuAAC) or "click" reaction. Specific loading within a material can be regulated by either the azide loading or limiting the alkyne reagent relative to the azide loading. The immobilization of ferrocene, pyrene, tris(pyridylmethyl)amine (TPA), and iron porphyrin (FeTPP) demonstrates the robust nature and reproducibility of this two-step synthetic attachment strategy. Loading-sensitive pyrene fluorescence correlates with a theoretically random surface distribution, rather than a uniform one; site-isolation of tethered moieties ～15 A in length occurs at loadings less than 0.02 mmol g -1. The effect of surface loading on reactivity is observed in the oxygenation of SBA-15-[CuI(TPA)]. SBA-15-[MnII(TPA)]- catalyzed epoxidation exhibits a systematic dependence on surface loading. A comparison of homogeneous, site-isolated and site-dense complexes provides insight into catalyst speciation and ligand activity.
