Designing an artificial light-harvesting system (LHS) with high energy transfer efficiency has been a challenging task. Herein, we report an atom-precise silver nanocluster (Ag NC) as a unique platform to...
Structural elucidation of the atom-precise thiolate-protected copper nanoclusters (Cu NCs) containing Cu(0) is quite challenging. Here, we report a new adamantane thiol protected [Cu18H3(S-Adm)12(PPh3)4Cl2] (Cu18) NC which reveals the first...
With the continuous development in nanoscience and nanotechnology, analytical techniques like surface-enhanced Raman spectroscopy (SERS) render structural and chemical information of a variety of analyte molecules in ultra-low concentration.
In metal nanoclusters (NCs), the kernel geometry and the nature of the surface protecting ligands are very crucial for their structural stability and properties. The synthesis and structural elucidation of Ag NCs is challenging because the zerovalent oxidation state of Ag is very reactive and prone to oxidization. Here, we report the NC [Ag 50 S 13 (S t Bu) 20 ][CF 3 COO] 4 with a hexagonal close-packed (hcp) cagelike Ag 14 kernel. A truncated cubic shell and an octahedral shell encapsulate the hcp-layered kernel via an interstitial S 2− anionic shell to form an Ag 36 Keplerian outer shell of the NC. A theoretical study indicates the stability of this NC in its 4+ charge state and the charge distribution between the kernel and Keplerian shell. The unprecedented electronic structure facilitates its application toward sustainable photoresponse properties. The new insights into this novel Ag NC kernel and Keplerian shell structure may pave the way to understanding the unique structure and developing electronic structure-based applications.
To acquire the atomic design of new functional Ag(I) clusters, a new synthetic approach of site-specific alloying has been unveiled, by which the neutral CO2 templated Ag20 core is confined...
We report an approach
for the online coupling of digital microfluidics
(DMF) with mass spectrometry (MS) using a chip-integrated microspray
hole (μSH). The technique uses an adapted electrostatic spray
ionization (ESTASI) method to spray a portion of a sample droplet
through a microhole in the cover plate, allowing its chemical content
to be analyzed by MS. This eliminates the need for chip disassembly
or the introduction of capillary emitters for MS analysis, as required
by state-of-the-art. For the first time, this allows the essential
advantage of a DMF devicefree droplet movementto be
retained during MS analysis. The broad applicability of the developed
seamless coupling of DMF and mass spectrometry was successfully applied
to the study of various on-chip organic syntheses as well as protein
and peptide analysis. In the case of a Hantzsch synthesis, we were
able to show that the method is very well suited for monitoring even
rapid chemical reactions that are completed in a few seconds. In addition,
the strength of the low resource consumption in such on-chip microsyntheses
was demonstrated by the example of enzymatic brominations, for which
only a minute amount of a special haloperoxidase is required in the
droplet. The unique selling point of this approach is that the analyzed
droplet remains completely movable after the MS measurement and is
available for subsequent on-DMF chip processes. This is illustrated
here for the example of MS analysis of the starting materials in the
corresponding droplets before they are combined to investigate the
reaction progress by DMF-MS further. This technology enables the ongoing
and almost unlimited tracking of multistep chemical processes in a
DMF chip and offers exciting prospects for transforming digital microfluidics
into automated synthesis platforms.
Changes in structural architecture via interlayer C–H⋯F interactions triggered by solvent molecules influence the dual (photon and phonon) emission mechanism of a two-dimensional cluster-assembled material, [Ag14(StBu)10(CF3COO)4(4,4′-azopyridine)2].
Ligand
protected atom-precise gold-based catalysts have been utilized
in many essential chemical processes, but their mechanism and the
fate of the catalyst during reaction are still unrevealed. Atom-precise
cluster without ligands are thus highly desirable to maximize atom
efficiency, but making these in solution phase is challenging. In
this scenario, catalysts with dispersion on oxide support are highly
desirable to understand the role of metal core during catalytic reaction.
Here, we report the synthesis of Au11(PPh3)7I3 cluster that consists of an incomplete icosahedron
core. During its impregnation process on CeO2 support,
all of the ligands were removed from the kernel and the Au11 kernel fits into the defects of ceria (embedded onto the oxygen
vacancy of ceria (111) plane). This Au11@CeO2 has high atom efficiency and catalytic activity for Ullmann-type
C–C homocoupling reactions for electron rich substrates. Density
functional theory calculations showed that hexagonal arrangements
of Au11 kernel on (111) plane of CeO2 is the
most stable one. Theoretical calculations also proved that the atop
gold atom has more favorable interaction with phenyl iodide than the
second layer gold atoms of the Au11@CeO2. This
demonstrated that the present catalyst mimics the single-atom catalyst-like
behavior in facilitating the coupling reactions.
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