118 research outputs found
Expanding Stereochemical and Skeletal Diversity Using Petasis Reactions and 1,3-Dipolar Cycloadditions
A short and modular synthetic pathway using intramolecular 1,3-dipolar cycloaddition reactions and yielding functionalized isoxazoles, isoxazolines, and isoxazolidines is described. The change in shape of previous compounds and those in this study is quantified and compared using principal moment-of-inertia shape analysis.Chemistry and Chemical Biolog
Mesoporous silica nanoparticles with tunable pore size for tailored gold nanoparticles
The aim of this paper was to verify a
possible correlation between the pore-size of meso-
porous silica nanoparticles (MSNs) and the sizes of
gold nanoparticles (AuNPs) obtained by an impreg-
nation of gold(III) chloride hydrate solution in the
MSNs, followed by a specific thermal treatment.
Mesoporous silica nanoparticles with tunable pore
diameter were synthesized via a surfactant-assisted
method. Tetraethoxysilane as silica precursor, cetyl-
trimethylammonium bromide (CTAB) as surfactant
and toluene as swelling agent were used. By varying
the CTABâtoluene molar ratio, the average dimension
of the pores could be tuned from 2.8 to 5.5 nm.
Successively, thiol groups were grafted on the surface
of the MSNs. Finally, the thermal evolution of the gold
salt, followed by ââin situââ X-ray powder diffraction
(XRPD) and thermogravimetric analysis (TGA),
revealed an evident correlation among the degradation
of the thiol groups, the pore dimension of the MSNs
and the size of the AuNPs. The samples were
characterized by means of nitrogen adsorptionâ
desorption, transmission electron microscopy, small-
angle X-ray scattering, XRPD ââin situââ by synchro-
tron radiation, and ââex situââ by conventional tech-
niques, diffuse reflectance infrared Fourier transform
spectroscopy, and TGA
- âŠ