Although many monometallic active sites have been installed in metal–organic frameworks (MOFs) for catalytic reactions, there are no effective strategies to generate bimetallic catalysts in MOFs. ...Here we report the synthesis of a robust, efficient, and reusable MOF catalyst, MOF‐NiH, by adaptively generating and stabilizing dinickel active sites using the bipyridine groups in MOF‐253 with the formula of Al(OH)(2,2′‐bipyridine‐5,5′‐dicarboxylate) for Z‐selective semihydrogenation of alkynes and selective hydrogenation of C=C bonds in α,β‐unsaturated aldehydes and ketones. Spectroscopic studies established the dinickel complex (bpy⋅−)NiII(μ2‐H)2NiII(bpy⋅−) as the active catalyst. MOF‐NiH efficiently catalyzed selective hydrogenation reactions with turnover numbers of up to 192 and could be used in five cycles of hydrogenation reactions without catalyst leaching or significant decrease of catalytic activities. The present work uncovers a synthetic strategy toward solution‐inaccessible Earth‐abundant bimetallic MOF catalysts for sustainable catalysis.
The synthesis of a robust, efficient, and reusable metal–organic framework (MOF) catalyst is described. Adaptive generation and stabilization of solution‐inaccessible dinickel active sites, (bpy.−)NiII(μ2‐H)2NiII(bpy.−) (bipyridine (bpy)), on MOF‐253 yield a catalyst that efficiently semihydrogenates alkynes to afford (Z)‐stilbenes and selectively hydrogenates C=C bonds in α,β‐unsaturated aldehydes and ketones.
Polyhedral oligomeric silsesquioxanes (POSS) are of considerable interest as building blocks for preparing low‐k materials. To date T8 POSS has been extensively investigated while the potential of ...larger POSS cages remain an unexplored area. Herein, the first known contribution to map the role of POSS cage size on the dielectric and other comprehensive properties of hybrid materials with identical chemical compositions is described. First, three vinyl POSS (T8, T10, and T12) species are isolated from a commercial POSS mixture. Then, they are converted to benzocyclobutene functionalized and thermo‐crosslinked hybrid materials. It is found that the cage size can strongly affect their k values, more importantly, showing a linear decrease while increasing the cage volumes (k = 2.24, 2.02, and 1.83 for c‐T8B8, c‐T10B10, and c‐T12B12, respectively). This finding highlights a profound influence of POSS cage changes on dielectric properties and could be used to predict ultralow‐k (1.5–1.1) materials by extrapolating to larger T14, T16, and T18 POSS cages. Meanwhile, varying the cage size has no obvious effect on the materials’ other properties, and all of them exhibit good comprehensive properties. Moreover, such low‐k values can persist at high temperature and high humidity conditions, which affords some promising (ultra)low‐k dielectrics for modern integrated circuit development.
A series of hybrid (ultra) low‐k materials are achieved based on T8, T10, and T12 polyhedral oligomeric silsesquioxanes (POSS). The results show that the POSS cage can strongly affect the materials’ k values, more importantly, showing a linear decrease with increasing the cage volumes. Moreover, varying the cage size has no obvious effect on the materials’ other properties and all of them show excellent thermal stability and mechanical performance, low surface roughness, high transparency, and hydrophobicity.
Organoborane compounds are among the most commonly employed intermediates in organic synthesis and serve as crucial precursors to alcohols, amines, and various functionalized molecules. A simple ...palladium‐based system catalyzes the conversion of primary C(sp3)H bonds in functionalized complex organic molecules into alkyl boronate esters. Amino acids, amino alcohols, alkyl amines, and a series of bioactive molecules can be functionalized with the use of readily available and removable directing groups in the presence of commercially available additives, simple ligands, and oxygen (O2) as the terminal oxidant. This approach represents an economic and environmentally friendly method that could find broad applications.
Crucial additives: A simple palladium‐based system catalyzes the conversion of primary C(sp3)H bonds in complex organic molecules into alkyl boronate esters. Amino acids, amino alcohols, alkyl amines, and a series of bioactive molecules that are modified with readily available directing groups are functionalized in the presence of commercially available additives, simple ligands, and oxygen as the terminal oxidant.
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Macromolecular self-assembly has made explosive development in the last several decades, are being extensively explored in the fields of drug delivery, lithography, catalysis, ...molecular electronics, sensors, and so many others. In this review, we summarize the self-assembly of macromolecules such as polymers, dendrimers, molecular nanoparticles, colloids, DNA and proteins, from the aspect of architectural engineering and mainly focus on the periodic and quasi-periodic assembled structures. In particular, simple building blocks can be conjugated together to construct complex macromolecular motifs with different architectures and physical interactions. We first introduce the concept of architectural engineering, then present a brief overview of supramolecular interactions and five main categories of building blocks, including polymer coils, dendrons, rods, discs, and polyhedra. We further discuss the detailed self-assembly behaviors of fifteen types of specific macromolecular motifs involving different building blocks. Special attention is paid to the architectural effect of macromolecular self-assembly. In the end, future perspective on architectural engineering is briefly mentioned.
Granular materials, composed of densely packed particles, are known to possess unique mechanical properties that are highly dependent on the surface structure of the particles. A microscopic ...understanding of the structure‐property relationship in these systems remains unclear. Here, supra‐nanoparticle clusters (SNPCs) with precise structures are developed as model systems to elucidate the unexpected elastic behaviors. SNPCs are prepared by coordination‐driven assembly of polyhedral oligomeric silsesquioxane (POSS) with metal‐organic polyhedron (MOP). Due to the disparity in sizes, the POSS‐MOP assemblies, like their classic nanoparticles counterparts, ordering is suppressed, and the POSS‐MOP mixtures will vitrify or jam as a function of decreasing temperature. An unexpected elasticity is observed for the SNPC assemblies with a high modulus that is maintained at temperatures far beyond the glass transition temperature. From studies on the dynamics of the hierarchical structures of SNPCs and molecular dynamic simulation, the elasticity has its origins in the interpenetration of POSS‐ended arms. The physical molecular interpenetration and inter‐locking phenomenon favors the convenient solution or pressing processing of the novel cluster‐based elastomers.
Supra‐nanoparticle clusters (SNPCs) were synthesized by convergence of metal–organic polyhedron scaffolds with precise giant building blocks. The mechanical properties and structural dynamics can be regulated by fine‐tuning the surface functionalization of the terminal POSS moieties. Unexpected elasticity with high Young's modulus of the OPOSS‐ended SNPCs was found to be highly correlated with the interpenetration of the neighboring GLs.
The hierarchical self‐assembly process opens up great potential for the construction of nanostructural superlattices. Precise regulation of self‐assembled superlattices, however, remains a challenge. ...Even when the primary molecules are precise, the supramolecular motifs (or secondary building blocks) can vary dramatically. In the present work, we propose the concept of unimolecular nanoparticles (UMNPs). The UMNPs act as the supramolecular motif and directly pack into the superlattices. A highly branched giant molecule is presented. We systematically explore its conformations and the superlattice of this giant molecule. Moreover, intriguing complex phases are discovered when blending this UMNP with other conventional giant molecules. These binary mixtures provide direct evidence to support our previously proposed self‐sorting process in the self‐assembly of “soft alloys”. The concept of UMNPs offers a unique approach toward more precise regulation of self‐assembled superlattices in soft matter.
With the precisely synthesized giant molecule βCD‐O21 the concept of soft unimolecular nanoparticles (UMNPs) has been realized. Upon self‐assembly or assembly with other giant molecules, βCD‐O21 directly participates in superlattice formation, giving rise to various complex superlattices with fast dynamics and enhanced ordering.
The packing structures of spherical motifs affect the properties of resultant condensed materials such as in metal alloys. Inspired by the classic metallurgy, developing complex alloy‐like packing ...phases in soft matter (also called “soft alloys”) is promising for the next‐generation superlattice engineering. Nevertheless, the formation of many alloy‐like phases in single‐component soft matter is usually thermodynamically unfavourable and technically challenging. Here, we utilize a novel self‐sorting assembly approach to tackle this challenge in binary blends of soft matter. Two types of giant shape amphiphiles self‐sort to form their discrete spherical motifs, which further simultaneously pack into alloy‐like phases. Three unconventional spherical packing phases have been observed in these binary systems, including MgZn2, NaZn13, and CaCu5 phases. It's the first time that the CaCu5 phase is experimentally observed in soft matter. This work demonstrates a general approach to constructing unconventional spherical packing phases and other complex superlattices in soft matter.
Unconventional metal alloy‐originated superlattices with large volume asymmetry were successfully constructed in soft matter by blending binary giant shape amphiphiles, especially including a first experimentally observed CaCu5 phase in soft matter. Furthermore, the thermodynamic origin of these superlattices was also quantitatively analyzed by isoperimetric quotient.
Like other discotic molecules, self‐assembled supramolecular structures of perylene bisimides (PBIs) are commonly limited to columnar or lamellar structures due to their distinct π‐conjugated ...scaffolds and unique rectangular shape of perylene cores. The discovery of PBIs with supramolecular structures beyond layers and columns may expand the scope of PBI‐based materials. A series of unconventional spherical packing phases in PBIs, including A15 phase, σ phase, dodecagonal quasicrystalline (DQC) phase, and body‐centered cubic (BCC) phase, is reported. A strategy involving functionalization of perylene core with several polyhedral oligomeric silsesquioxane (POSS) cages achieved spherical assemblies of PBIs, instead of columnar assemblies, due to the significantly increased steric hindrance at the periphery. This strategy may also be employed for the discovery of unconventional spherical assemblies in other related discotic molecules by the introduction of similar bulky functional groups at their periphery. An unusual inverse phase transition sequence from a BCC phase to a σ phase was observed by increasing annealing temperature.
The unconventional spherical assembly of discotic perylene bisimides (PBIs), as opposed to common columnar assembly, was successfully achieved by the incorporation of bulky units at the periphery. The peripheric steric hindrance can be tuned by varying the linkage structures, resulting in diverse spherical supramolecular structures in PBIs.
Fabricating S-scheme photocatalysts to optimize their ability of using sunlight has gained great attention in environmental remediation. Herein, we designed a soluble hybrid, titanium oxide ...cluster-perylene diimide-polyhedral oligomeric silsesquioxane (TOC-PDI-POSS). Through π-π stacking interaction with the most commonly applied graphitic carbon nitride (g-C
3
N
4
), a new S-scheme heterostructure was successfully constructed. The combination of the near full visible light responsive TOC-PDI-POSS and g-C
3
N
4
enhanced the utilization of sunlight to achieve highly efficient charge-carrier separation. More importantly, the photo-Fenton reaction can be achieved without an extra oxidant. Owing to the enhanced oxidation capacity of holes, the obtained TOC-PDI-POSS/g-C
3
N
4
heterostructure displayed efficient photocatalytic degradation for phenol under an air atmosphere and the reaction rate constant reaches 5.6 h
−1
in five cycles under simulated sunlight.
We demonstrate that S-scheme photocatalysis of a hybrid system can promote the performance of photo-Fenton reaction under sunlight. Highly efficient charge-carrier separation can be achieved owing to a dispersion of TOC-PDI-POSS on the g-C
3
N
4
surface.
Achieving self‐assembled nanostructures with ultra‐small feature sizes (e. g., below 5 nm) is an important prerequisite for the development of block copolymer lithography. In this work, the ...preparation and self‐assembly of a series of giant molecules composed of vinyl polyhedral oligomeric silsesquioxane (VPOSS) tethered with monodispersed oligo(L‐lactide) chains are presented. Small‐angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM) results demonstrate that ultra‐small domain sizes (down to 3 nm) of phase separated lamellar morphology are achieved in bulk, driven by the strong tendency and fast kinetics for crystallization of VPOSS moieties. Moreover, upon gamma ray radiation, VPOSS cages in the lamellar structure can be crosslinked via polymerization of the vinyl groups. After pyrolysis at high temperature, ultra‐thin two‐dimensional nano‐silica sheets can be obtained.
Lamellar morphologies with ultra‐small domain sizes (down to 3 nm) are achieved by the self‐assembly of giant molecules. The driven force for the phase separation is attributed to the strong tendency and fast kinetics for crystallization of vinyl polyhedral oligomeric silsesquioxane (VPOSS) segment. Upon the gamma ray radiation followed pyrolysis, ultra‐thin two dimensional nano‐silica sheets are obtained due to polymerization of vinyl group in VPOSS.
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