Abstract:Metal clusters (MCs) with dimensions between a single metal atom and nanoparticles of >2 nm usually possess distinct geometric and electronic structures, and their outstanding performance in catalysis applications have underpinned a broad research interest. However, smaller‐sized MCs are easily deactivated by migration coalescence during the catalysis process because of their high surface energy. Therefore, the search of an appropriate stabilizer for MCs is urgently demanded. In recent years, porous organic po… Show more
“…Among the reported porous matrixes, organic molecular cages, as newly developed microporous materials, have attracted increasing attention over the past few years . Such materials are composed of discrete molecules with intrinsic, guest-accessible cavities, which can be used to confine the MNPs and prevent aggregation. − Recently, the use of size-adjustable cavities of different kinds of organic cages to modulate MNP size and related catalytic activity has experienced rapid development. − Although great progress has been made, it remains a great challenge to compromise encapsulation and mass transfer in catalytic processes. In particular, the nanosized discrete pore once encapsulating the MNPs may block accessibility to some extent, which is detrimental to mass transfer, especially in the case of catalysis involving substrates of different sizes/geometries.…”
Incorporating metal nanoparticles (MNPs) into porous composites with controlled size and spatial distributions is beneficial for a broad range of applications, but it remains a synthetic challenge. Here, we present a method to immobilize a series of highly dispersed MNPs (Pd, Ir, Pt, Rh, and Ru) with controlled size (<2 nm) on hierarchically micro-and mesoporous organic cage supports. Specifically, the metal−ionic surfactant complexes serve as both metal precursors and mesopore-forming agents during self-assembly with a microporous imine cage CC3, resulting in a uniform distribution of metal precursors across the resultant supports. The functional heads on the ionic surfactants as binding sites, together with the nanoconfinement of pores, guide the nucleation and growth of MNPs and prevent their agglomeration after chemical reduction. Moreover, the as-synthesized Pd NPs exhibit remarkable activity and selectivity in the tandem reaction due to the advantages of ultrasmall particle size and improved mass diffusion facilitated by the hierarchical pores.
“…Among the reported porous matrixes, organic molecular cages, as newly developed microporous materials, have attracted increasing attention over the past few years . Such materials are composed of discrete molecules with intrinsic, guest-accessible cavities, which can be used to confine the MNPs and prevent aggregation. − Recently, the use of size-adjustable cavities of different kinds of organic cages to modulate MNP size and related catalytic activity has experienced rapid development. − Although great progress has been made, it remains a great challenge to compromise encapsulation and mass transfer in catalytic processes. In particular, the nanosized discrete pore once encapsulating the MNPs may block accessibility to some extent, which is detrimental to mass transfer, especially in the case of catalysis involving substrates of different sizes/geometries.…”
Incorporating metal nanoparticles (MNPs) into porous composites with controlled size and spatial distributions is beneficial for a broad range of applications, but it remains a synthetic challenge. Here, we present a method to immobilize a series of highly dispersed MNPs (Pd, Ir, Pt, Rh, and Ru) with controlled size (<2 nm) on hierarchically micro-and mesoporous organic cage supports. Specifically, the metal−ionic surfactant complexes serve as both metal precursors and mesopore-forming agents during self-assembly with a microporous imine cage CC3, resulting in a uniform distribution of metal precursors across the resultant supports. The functional heads on the ionic surfactants as binding sites, together with the nanoconfinement of pores, guide the nucleation and growth of MNPs and prevent their agglomeration after chemical reduction. Moreover, the as-synthesized Pd NPs exhibit remarkable activity and selectivity in the tandem reaction due to the advantages of ultrasmall particle size and improved mass diffusion facilitated by the hierarchical pores.
“…Functional organic materials retain their leading position in the evolution of chemistry and materials science. [1][2][3][4] Various organic compounds with different physicochemical properties and especially those bearing different states of aggregation are considered as promising functional materials. Recent investigations in this research area revealed that the incorporation of a nitrogen heteroaromatic motif into the molecular structure provides a substantial improvement of the materials' properties and broadens their application potential in comparison with the respective carbocyclic analogues.…”
Preparation of multipurpose high-energy materials for space technologies remains a challenging task and such materials usually require special precautions and fine tunability of their functional properties. To unveil new opportunities...
“…Organic materials constitute an important and enormous class of chemical substances with a wide set of practical applications in various areas of materials science. − Structurally diverse organic compounds with different physicochemical properties are considered promising functional materials. Keeping in mind a constant search for the “ideal” material with a desired set of functional properties, leading research groups focused their attention on the utilization of aromatic nitrogen heterocycles as a suitable platform for the design of next-generation organic materials. − This trend remains absolutely relevant in the creation of novel high-energy materials possessing balanced physicochemical and detonation properties. − …”
A majority of known and newly synthesized energetic materials comprise polynitrogen or nitrogen−oxygen heterocycles with various explosophores. However, available structural combinations of these organic scaffolds are finite and are about to reach their limits. Herein, we present the design and synthesis of a series of sulfurcontaining polyazole structures comprising 1,3,4-thiadiazole and furazan rings linked by C−C bonds and enriched with energetic nitro and azo functionalities. In terms of detonation performance, all synthesized 1,3,4thiadiazole-furazan assemblies (D = 7.7−7.9 km s −1 ; P = 26−28 GPa) lie between the powerful explosive TATB (D = 8.0 km s −1 ; P = 31 GPa) and melt-cast material TNT (D = 6.9 km s −1 ; P = 23 GPa). In the synthesized series, azo-bridged derivative 5 seems to be most practically interesting, as it combines a relatively high energetic performance (D = 7.9 km s −1 ; P = 28 GPa), a very high thermal stability (271 °C), and insensitivity to friction. By these functional properties, 5 outperforms the benchmark heat-resistant explosive hexanitrostilbene (HNS). To the best of our knowledge, this is the first example of an energetic alliance of furazan and 1,3,4-thiadiazole scaffolds and a rare case of sulfur-containing high-energy materials, which can certainly be considered as an evolutionary step in energetic materials science.
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