Few hydrogen adsorbents balance high usable volumetric and gravimetric capacities. Although metal-organic frameworks (MOFs) have recently demonstrated progress in closing this gap, the large number of MOFs has hindered the identification of optimal materials. Here, a systematic assessment of published databases of real and hypothetical MOFs is presented. Nearly 500,000 compounds were screened computationally, and the most promising were assessed experimentally. Three MOFs with capacities surpassing that of IRMOF-20, the record-holder for balanced hydrogen capacity, are demonstrated: SNU-70, UMCM-9, and PCN-610/NU-100. Analysis of trends reveals the existence of a volumetric ceiling at ∼40 g H 2 L −1 . Surpassing this ceiling is proposed as a new capacity target for hydrogen adsorbents. Counter to earlier studies of total hydrogen uptake in MOFs, usable capacities in the highest-capacity materials are negatively correlated with density and volumetric surface area. Instead, capacity is maximized by increasing gravimetric surface area and porosity. This suggests that property/performance trends for total capacities may not translate to usable capacities.

Coordination polymers (CPs) have recently emerged as a promising class of high energy materials useful for the synthesis of tailored energetic materials. CPs have shown potential to improve energetic performance relative to conventional organic energetic materials with regard to density, oxygen balance, sensitivity, and heat of detonation. Thus far, a variety of energetic linkers have been applied, and success has been achieved across a number of structure classes including nitrogen-rich heterocycles and azides. Here, the current progress in the field of energetic CPs, both from the standpoint of structure and properties, is reviewed, and a perspective on current challenges and promising future directions for the field are delineated. Inasmuch as structure/function relationships have been elucidated for CPs with particular applications in mind, these are discussed as well as shortcomings in experimental work required to firmly establish predictive principles within the realm of energetic materials.

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All major classes of porous crystalline frameworks including zeolites, metal–organic frameworks, covalent organic frameworks and hydrogen-bonded organic frameworks exhibit structural flexibilities.

It is not unusual for advances in science to run ahead of nomenclature for the discovered phenomena. However, in the case of metal–organic frameworks (MOFs), research activity has been booming for more than a decade, and yet there is no agreed upon definition for the term. Different structural aspects of these materials are critically analyzed with examples and counterexamples to arrive at a definition of MOF that is both definite and consistent with common usage.