J. Appl. Cryst.の発刊に際して

Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

https://www.pnas.org/content/pnas/90/5/1635.full.pdf

Supramolecular chemistry.

The literature on open-framework materials has shown numerous examples of porous solids with additional structural, chemical, or physical properties. These materials show promise for applications ranging from sensing, catalysis and separation to multifunctional materials. This critical review provides an up-to-date survey to this new generation of multifunctional open-framework solids. For this, a detailed revision of the different examples so far reported will be presented, classified into five different sections: magnetic, chiral, conducting, optical, and labile open-frameworks for sensing applications. (413 references.)

Old materials with new tricks: multifunctional open-framework materials.

Development of platinum group metal (PGM)-free catalysts for oxygen reduction reaction (ORR) is essential for affordable proton exchange membrane fuel cells. Herein, a new type of atomically dispersed Co doped carbon catalyst with a core–shell structure has been developed via a surfactant-assisted metal–organic framework approach. The cohesive interactions between the selected surfactant and the Co-doped zeolitic imidazolate framework (ZIF-8) nanocrystals lead to a unique confinement effect. During the thermal activation, this confinement effect suppressed the agglomeration of Co atomic sites and mitigated the collapse of internal microporous structures of ZIF-8. Among the studied surfactants, Pluronic F127 block copolymer led to the greatest performance gains with a doubling of the active site density relative to that of the surfactant-free catalyst. According to density functional theory calculations, unlike other Co catalysts, this new atomically dispersed Co–N–C@F127 catalyst is believed to contain substantial CoN2+2 sites, which are active and thermodynamically favorable for the four-electron ORR pathway. The Co–N–C@F127 catalyst exhibits an unprecedented ORR activity with a half-wave potential (E1/2) of 0.84 V (vs. RHE) as well as enhanced stability in the corrosive acidic media. It also demonstrated high initial performance with a power density of 0.87 W cm−2 along with encouraging durability in H2–O2 fuel cells. The atomically dispersed Co site catalyst approaches that of the Fe–N–C catalyst and represents the highest reported PGM-free and Fe-free catalyst performance.

Highly active atomically dispersed CoN 4 fuel cell cathode catalysts derived from surfactant-assisted MOFs: carbon-shell confinement strategy

Six new zinc-1,3,5-benzenetricarboxylate-based metal–organic frameworks (MOFs) have been successfully synthesized using three different surfactants (PEG 400, octanoic acid, and hexadecyltributylphosphonium bromide) as reaction media. These surfactants with different characteristics, such as being neutral, acidic, and cationic, have been demonstrated to show strong effects on directing the crystals’ growth and resulted in different secondary building units (SBUs) including an unusual SBU unit [Zn4(μ4-O)(CO2)7]. Our results clearly indicated that the surfactant–thermal method could offer exciting opportunities for preparing novel MOFs or other inorganic crystalline materials with diverse structures and interesting properties.

Growing crystalline zinc-1,3,5-benzenetricarboxylate metal-organic frameworks in different surfactants.

Four bimetallic Al or Zn complexes supported by anilido-aldimine ligands (o-C6H4(NHAr)–CHN)2CH2CH2 (Ar = 2,6-Me2C6H3, L11H2; Ar = 2,6-iPr2C6H3, L22H2) have been synthesized and characterized. Treatment of L11H2 or L22H2 with two equiv. of AlMe3 gives bimetallic complex L11(AlMe2)21 or L22(AlMe2)22, respectively. Reaction of L11H2 or L22H2 with two equiv. of ZnEt2 leads to bimetallic complex L11(ZnEt)23 or L22(ZnEt)24, respectively. All of the complexes 1–4 are efficient catalysts for ring-opening polymerization of e-caprolactone (CL) in the presence of benzyl alcohol and catalyze the polymerization of CL in living fashion yielding polymers with a narrow polydispersity index. The activity of bimetallic Zn complexes 3 and 4 is higher than bimetallic Al complexes 1 and 2.

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Bimetallic anilido-aldimine Al or Zn complexes for efficient ring-opening polymerization of epsilon-caprolactone.

Metal–oxo cluster-supported transition metal complexes: hydrothermal synthesis and characterization of [{M(phen)2}2(Mo8O26)] (M = Ni or Co)

Highly active half-metallocene type chromium(III) catalysts for ethylene polymerization have been developed. High molecular weight linear polyethylene (Mn > 1 000 000 g/mol) was produced by these catalysts in the presence of a relatively small amount of AlR3 (25 equiv).

Highly active half-metallocene chromium(III) catalysts for ethylene polymerization activated by trialkylaluminum.

Single crystals of gallium tris(8-hydroxyquinoline) (Gaq3) were obtained. The X-ray diffraction study showed that the Gaq3 solid is an extensive three-dimensional framework which is constructed fro...

Ling Ye

Papers

Growing crystalline zinc-1,3,5-benzenetricarboxylate metal-organic frameworks in different surfactants.

Bimetallic anilido-aldimine Al or Zn complexes for efficient ring-opening polymerization of epsilon-caprolactone.

Metal–oxo cluster-supported transition metal complexes: hydrothermal synthesis and characterization of [{M(phen)2}2(Mo8O26)] (M = Ni or Co)

Highly active half-metallocene chromium(III) catalysts for ethylene polymerization activated by trialkylaluminum.

X-ray Crystal Structure of Gallium Tris- (8-hydroxyquinoline): Intermolecular π−π Stacking Interactions in the Solid State