Defect engineering has developed over the last decade to become an inimitable tool with which to shape Metal-Organic Framework (MOF) chemistry; part of an evolution in the perception of MOFs from perfect, rigid matrices to dynamic materials whose chemistry is shaped as much by imperfections as it is by their molecular components. However, challenges in defect characterisation and reproducibility persist and, coupled with an as-yet opaque role for synthetic parameters in defect formation, deny chemists the full potential of reticular synthesis. Herein we map the broad implications defects have on MOF properties, highlight key challenges and explore the remarkable ways imperfection enriches MOF chemistry.

InOF-1 confirms a significant 2-fold increase (∼11 wt%) in CO ₂ capture under 20% relative humidity of water vapour.

Metal–organic frameworks (MOFs) are crystalline organic–inorganic hybrid materials, which are promising candidates for SO ₂ detection, due to their chemically mutable periodic structure.

Water adsorption was investigated in the hydrostable Sc(iii) coordination polymer NOTT-400. This material performed CO₂ capture under relative humidity (RH) conditions (20 and 10% RH). The maximum CO₂ capture was obtained at 20% RH and 30 °C with a total amount of ∼10.2 wt%, representing a 2.5-fold increase in comparison with anhydrous conditions.

NH ₂ -MIL-53(Al) exhibited a considerable stronger affinity to water than MIL-53(Al). Thus, the hydrophobicity (shown by in situ FTIR) of the pores within MIL-53(Al) enhanced the CO ₂ adsorption.