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(+)) 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(-)) counterions favored ST and bromide (Br(-)) 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.

Using carboxylate-protected silver nanoclusters (Ag-carboxylate NCs) as a model, we separately investigated the contribution of the ligand shell and the metal core to understand the nature of photoluminescence of Ag NCs. A new Ag(0)NCs@Ag(I)-carboxylate complex core-shell structural model has been proposed. The emission from the Ag-carboxylate NCs could be attributed to ligand-to-metal-metal charge transfer from Ag(I)-carboxylate complexes (the oxygen atom in the carboxylate ligands to the Ag(I) ions) to the Ag atoms and subsequent radiative relaxation. Additionally, we found that the emission wavelength of the Ag NCs depends on the excitation wavelength implying a strong coupling between surface plasmon and emitter in Ag NCs. The strong coupling between the surface plasmon and the emitter determines the quantum yield and lifetime. The emission mechanism of Ag NCs and its relation to the organic templates and metal cores were clearly clarified. The results should stimulate additional experimental and theoretical research on the molecular-level design of luminescent metal probes for optoelectronics and other applications.

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Silver is an ideal candidate for surface plasmon resonance (SPR)-based applications because of its great optical cross-section in the visible region. However, the uses of Ag in plasmon-enhanced spectroscopies have been limited due to their interference via direct contact with analytes, the poor chemical stability, and the Ag(+) release phenomenon. Herein, we report a facile chemical method to prepare shell-isolated Ag nanoparticle/tip. The as-prepared nanostructures exhibit an excellent chemical stability and plasmonic property in plasmon-enhanced spectroscopies for more than one year. It also features an alternative plasmon-mediated photocatalysis pathway by smartly blocking "hot" electrons. Astonishingly, the shell-isolated Ag nanoparticles (Ag SHINs), as "smart plasmonic dusts", reveal a ∼1000-fold ensemble enhancement of rhodamine isothiocyanate (RITC) on a quartz substrate in surface-enhanced fluorescence. The presented "smart" Ag nanostructures offer a unique way for the promotion of ultrahigh sensitivity and reliability in plasmon-enhanced spectroscopies.