Scintillators, materials that produce light pulses upon interaction with ionizing radiation, are widely employed in radiation detectors. In advanced medical-imaging technologies, fast scintillators enabling a time resolution of tens of picoseconds are required to achieve high-resolution imaging at the millimetre length scale. Here we demonstrate that composite materials based on fluorescent metal-organic framework (MOF) nanocrystals can work as fast scintillators. We present a prototype scintillator fabricated by embedding MOF nanocrystals in a polymer. The MOF comprises zirconium oxo-hydroxy clusters, high-Z linking nodes interacting with the ionizing radiation, arranged in an orderly fashion at a nanometric distance from 9,10-diphenylanthracene ligand emitters. Their incorporation in the framework enables fast sensitization of the ligand fluorescence, thus avoiding issues typically arising from the intimate mixing of complementary elements. This proof-of-concept prototype device shows an ultrafast scintillation rise time of ~50 ps, thus supporting the development of new scintillators based on engineered fluorescent MOF nanocrystals.

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In the organic matter dynamic and fluid phases cannot survive down to temperatures of a few kelvins, temperature at which only low-inertial-mass groups, such as methyls, may exhibit fast rotation. Here we fabricate 3D-architectures of spontaneous molecular rotors by engineering in metal organic frameworks full-fledged barrierless rotors with exceptionally-low activation energy of 6.2 small cal mol-1. The trigonal bipyramidal symmetry of the rotator in the struts was frustrated by its arrangement in the cubic crystal cell, generating high multiplicity of 12 shallow minima per turn, with a benchmark 10 10 Hertz frequency persistent even below 2K. The nearly degenerated energy landscape allows for continuous unidirectional hyper-fast rotation, which lasts for hundreds of turns, by 'overflying' several minima. Such an impressive dynamic performance in solid organic matter is only comparable to that of methyl rotation, opening new fields of application whenever hyper-fast dynamics at extremely-low temperatures and minimization of thermal-noise are needed.

Incorporation of photoswitchable molecules into solid state materials hold promise for fabrication of the responsive materials, the properties of which can be controlled ondemand. However, the possible applications of these materials are limited, due to the restrictions imposed by the solid state environment on the incorporated photoswitches, which render the photoisomerization inefficient. Here we present responsive porous switchable framework materials based on a bistable chiroptical overcrowded alkene incorporated in the backbone of the rigid aromatic framework. Due to the high intrinsic porosity, the resulting framework readily responds to a light stimulus as demonstrated by solid-state Raman and reflectance spectroscopies. Solid state 13 C NMR spectroscopy highlights efficient and quantitative bulk photoisomerization of the incorporated light-responsive overcrowded olefins in the solid material. Taking advantage of the quantitative photoisomerization, the porosity of the framework, and as a consequence gas adsorption, can be reversibly modulated in response to light and heat. Inspired by biological systems, a vast number of artificial molecular machines and switches, capable of elaborate structural dynamics, have been developed. 1-4 However, in solution stimulated molecular motion is inevitably overwhelmed by isotropic thermal noise which thereby precludes any form of collective action and the extraction of macroscopic work, since the molecules behave independently from one another. 5-7 On the contrary, solid state organization can translate stimuli-controlled nanoscopic changes into useful material properties and preludes to practical outputs. Thus, a challenging endeavour of current research is to organize molecular machines and switches in the solid state to impede random, thermal motion and amplify mechanical effects along multiple length scales: this effort requires reliable strategies, allowing for restricting random motion and limiting the degrees of freedom to selected modes, without impairment of the rotary or switching functions. 8-10 One strategy to achieve these goals is the use of solid porous materials 11-15 which can incorporate switchable moieties and provide the free volume essential for unhindered dynamics, thereby serving as a static scaffold for the flexible components. Indeed, it was demonstrated recently that molecular rotors 16-23 , shuttles 24 , switches 25 and motors 26 can display their designed motion while incorporated

Porous 3D polymers, fabricated using multidentate monomers, efficiently adsorb CO2 and CH4 up to 180 bar.