The analysis of porous materials and their interaction with guest molecules using neutron scattering is experimentally challenging. Even with advances in neutron sources and instrumentation, several hundred milligrams of material are usually required for successful neutron-scattering analysis of these systems. Evacuated materials prepared for guest sorption are air-sensitive, mandating their handling in specialist atmospheres such as a helium-filled glove box, where helium is necessary to avoid the heat-transfer medium freezing where the heat-transfer gas is not removed from activated samples prior to low-temperature (<10 K) measurement.

Obtaining a good neutron-scattering signal from the host or guest being studied can involve isotopic substitution, and often with complex ligands that require deuteration. The requirement of neutrons in this work is demonstrated by the recent synthesis of deuterated forms of complex ligands, such as 4, 4′, 4"-benzene-1, 3, 5- triyl-tribenzoic acid, through a technique developed at a specialist deuteration facility associated with a neutron-scattering centre. Such complex chemical syn­thetic routes are achievements in their own right [90].

The majority of neutron-scattering experiments exploring guest-host interactions in porous adsorbents are in situ in nature. The in situ approach, however, varies in accordance to the experimental need. Most commonly activated materials (porous materials with their pores empty) are analysed at low temperature first, before the introduction of guest molecules to the sample at a temperature where the guest will remain in the gaseous state, and the sample is then cooled slowly to where the guest molecules “lock in” to their equilibrium positions, before the measurement con­tinues. These measurements involve careful control of the temperature of the

sample as well as gas-delivery lines through the use of modified cryofurnaces. Advances in neutron instrumentation, particularly large area-detectors and higher — intensity sources, provide the opportunity to resolve in real-time details for such systems [91].