2 research outputs found
Facile Large-Scale Synthesis of Monodisperse Mesoporous Silica Nanospheres with Tunable Pore Structure
Mesoporous silica nanoparticles (MSNs) are experiencing
rapid development
in the biomedical field for imaging and for use in heterogeneous catalysis.
Although the synthesis of MSNs with various morphologies and particle
sizes has been reported, synthesis of a pore network with monodispersion
control below 200 nm is still challenging. We achieved this goal using
mild conditions. The reaction occurred at atmospheric pressure with
a templating sol–gel technique using cetyltrimethylammonium
(CTA<sup>+</sup>) as the templating surfactant and small organic amines
(SOAs) as the mineralizing agent. Production of small pore sizes was
performed for the first time, using pure and redispersible monodispersed
porous nanophases with either stellate (ST) or raspberry-like (RB)
channel morphologies. Tosylate (Tos<sup>–</sup>) counterions
favored ST and bromide (Br<sup>–</sup>) RB morphologies at
ultralow SOA concentrations. Both anions yielded a worm-like (WO)
morphology at high SOA concentrations. A three-step formation mechanism
based on self-assembly and ion competition at the electrical palisade
of micelles is proposed. Facile recovery and redispersion using specific
SOAs allowed a high yield production at the kilogram scale. This novel
technique has practical applications in industry
Au<sub>10</sub>(SG)<sub>10</sub>: A Chiral Gold Catenane Nanocluster with Zero Confined Electrons. Optical Properties and First-Principles Theoretical Analysis
We
report facile synthesis of the Au<sub>10</sub>(SG)<sub>10</sub> nanoclusters,
where SG stands for glutathione, found to be promising
as a new class of radiosensitizers for cancer radiotherapy. The homoleptic
catenane structure with two Au<sub>5</sub>SG<sub>5</sub> interconnected
rings, among different isomer structures, gives the best agreement
between theoretical and experimental optical spectra and XRD patterns.
This catenane structure exhibits a centrosymmetry-broken structure,
resulting in enhanced second harmonic response and new characteristic
circular dichroism signals in the spectral region of 250–400
nm. This is the first determination of the nonlinear optical properties
of a ligated cluster with an equal Au-to-ligand ratio, thus without
a metallic core and therefore zero confined electrons. Insight into
the nonlinear and chiroptical efficiencies arising from interplay
between structural and electronic properties is provided by the TD-DFT
approach