Diamantane clusters formed inside superfluid helium nanodroplets were analyzed by time-of-flight mass spectrometry. Distinct cluster sizes were identified as “magic numbers” and the corresponding feasible structures for clusters consisting of...
On-surface self-assemblies of aromatic organic molecules have been widely investigated, but the characterization of analogous self-assemblies consisting of fully sp3-hybridized molecules remains challenging. The possible on-surface orientations of alkyl molecules not exclusively comprised of long alkyl chains are difficult to distinguish because of their inherently low symmetry and non-planar nature. Here, we present a detailed study of diamondoid ethers, structurally rigid and fully saturated molecules, which form uniform 2D monolayers on a highly oriented pyrolytic graphite (HOPG) surface. Using scanning tunneling microscopy (STM), various computational tools, and X-ray structural analysis, we identified the most favorable on-surface orientations of these rigid ethers and accounted for the forces driving the self-organization process. The influence of the oxygen atom and London dispersion interactions were found to be responsible for the formation of the observed highly ordered 2D ether assemblies. Our findings provide insight into the on-surface properties and behavior of non-aromatic organic compounds and broaden our understanding of the phenomena characteristic of monolayers consisting of non-planar molecules.
Diamondoids
have emerged as promising carbon-based nanomaterial
building blocks because of their unique combination of exceptional
properties and availability for selective functionalization. Until
now, the chemical functionalization of diamondoids was primarily based
on solution methods. However, the limited solubility of diamondoid
derivatives and their tendency to sublimate at even slightly elevated
temperatures made it difficult to prepare more extensive diamondoid
scaffolds. Here, we present the first mechanochemical synthesis of
several diamondoid ethers differing in the type, size, and number
of their hydrocarbon cage subunits. We found that the efficient preparation
of these ethers is enabled solely by high-temperature ball milling
conditions and does not proceed under ambient conditions. When compared
to the conventional synthesis of the same ether derivatives, the calculated
green chemistry metrics showed the enormous sustainability benefits
of the mechanochemical synthesis. The mechanochemical approach includes
shorter reaction times, a green inorganic base, a simplified workup
procedure, comparable or superior reaction yields, and the elimination
of solvents in the synthesis. Furthermore, crystal structures obtained
from single-crystal X-ray diffraction experiments confirmed the molecular
structures of the target products and gave insight into their intermolecular
interactions in the solid state. From the perspective of the future
applicability of these materials in nanotechnology, the cost and sustainability
of their preparation are paramount. We demonstrated herein that mechanochemistry
is a viable option for this challenge.
Diamondoid ethers were introduced into superfluid helium nanodroplets and the resulting clusters were analyzed by time-of-flight mass spectrometry. Clusters of higher abundances (magic number clusters) were identified and the corresponding...
Benzimidazo[1,2-a]quinolines substituted with amide chains have been evaluated for their antiproliferative, antibacterial and antiviral activity in vitro.
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