Kinetic Control of Metal-Organic Framework Crystallization Investigated by Time-Resolved In Situ X-Ray Scattering

A synthetic route to ultralight hierarchically micro/mesoporous Al(III)-carboxylate metal-organic aerogels

Developing a synthetic methodology for the fabrication of hierarchically porous metal-organic monoliths that feature high surface area, low density and tunable porosity is imperative for mass transfer applications, including bulky molecule capture, heterogeneous catalysis and drug delivery. Here we report a versatile and facile synthetic route towards ultralight micro/mesoporous metal-organic aerogels based on the two-step gelation of metal-organic framework nanoparticles. Heating represents a key factor in the control of gelation versus crystallization of Al(III)-multicarboxylate systems. The porosity of the resulting metal-organic aerogels can be readily tuned, leading to the formation of well-ordered intraparticle micropores and aerogel-specific interparticle mesopores, thereby integrating the merits of both crystalline metal-organic frameworks and light aerogels. The hierarchical micro/mesoporosity of the Al-metal-organic aerogels is thoroughly evaluated by N₂ sorption. The good accessibility of the micro/mesopores is verified by vapour/dye uptake, and their potential for utilization as effective fibre-coating absorbents is tested in solid-phase microextraction analyses.

Hierarchically porous metal-organic monoliths are potential materials for mass transfer applications. Here, the authors synthesize metal-organic aerogels via the gelation of metal-organic frameworks, and are able to tune their porosity exploiting the properties of both crystalline and aerogel materials.

A highly selective fluorescent chemosensor for Al(III) ion and fluorescent species formed in the solution

A chemosensor for the Al(3+) ion, 1-[(3-hydroxypyridin-2-ylamino)methylene]naphthalen-2(1H)-one (H2L), based on inhibited excited-state intramolecular proton transfer was synthesized. The experimental and theoretical calculations at B3LYP+PCM/6-31G(d) revealed that Al(3+) and H2L form a 1:1 complex, [AlL(OH)(H2O)]2, in dimethyl sulfoxide that exhibits two remarkably enhanced fluorescent emissions at 523 and 553 nm. It is confirmed that H2L could be used to detect Al(3+) ions in cells by bioimaging.

Three-dimensional visualization of defects formed during the synthesis of metal-organic frameworks: a fluorescence microscopy study

Imperfections in the spotlight: fluorescence microscopy was used to detect defects in metal-organic frameworks formed during synthesis. In contrast to currently available techniques, confocal fluorescence microscopy offers the advantage of three-dimensional imaging at the single-crystal level combined with the sensitivity required to study the start of defect formation.

Alkylaminopyridine-modified aluminum aminoterephthalate metal-organic frameworks as components of reactive self-detoxifying materials

Aluminum aminoterephthalate MOF particulate materials (NH(2)-MIL-101(Al) and NH(2)-MIL-53(Al)), studied here as components of self-detoxifying surfaces, retained their reactivity following their covalent attachment to protective surfaces utilizing a newly developed strategy in which the MOF particles were deposited on a reactive adhesive composed of polyisobutylene/toluene diisocyanate (PIB/TDI) blends. Following MOF attachment and curing, the MOF primary amino groups were functionalized with highly nucleophilic 4-methylaminopyridine (4-MAP) by disuccinimidyl suberate-activated conjugation. The resulting MOF-4-MAP modified PIB/TDI elastomeric films were mechanically flexible and capable of degrading diisopropyl fluorophosphate (DFP), a chemical threat simulant.

Crystal growth of nanoporous metal organic frameworks

Nanoporous metal organic frameworks (MOFs) form one of the newest families of crystalline nanoporous material that is receiving worldwide attention. Successful use of MOFs for application requires not only development of new materials but also a need to control their crystal properties such as size, morphology, and defect concentration. An understanding of the crystal growth processes is necessary in order to aid development of routes to control such properties of the crystallites. In this Perspective article we aim to provide a short overview of the current work and understanding concerning the nucleation and growth processes of nanoporous MOFs and how this work may be expanded upon to further our comprehension of this subject. We also focus heavily on in situ studies that provide real time information on the developing materials and generally provide the most conclusive findings on the processes under investigation.