Ligands with a purely aliphatic backbone are receiving rising attention in the chemistry of coordination polymers and metal–organic frameworks. Such unique features inherent to the aliphatic bridges as increased conformational freedom, non-polarizable core, and low light absorption provide rare and valuable properties for their derived MOFs. Applications of such compounds in stimuli–responsive materials, gas, and vapor adsorbents with high and unusual selectivity, light-emitting, and optical materials have extensively emerged in recent years. These properties, as well as other specific features of aliphatic-based metal–organic frameworks are summarized and analyzed in this short critical review. Advanced characterization techniques, which have been applied in the reported works to obtain important data on the crystal and molecular structures, dynamics, and functionalities, are also reviewed within a general discussion. In total, 132 references are included.

A new metal–organic coordination polymer [Zn₂(sedc)₂(dabco)] (1se; sedc²⁻ = selepophene-2,5-dicarboxylate; dabco = 1,4-diazabicyclo[2.2.2]octane) was synthesized and characterized by single-crystal X-ray diffraction analysis. This MOF is based on {Zn₂(OOCR)₄N₂} paddle wheels and is isoreticular to the family of [Zn₂(bdc)₂(dabco)] derivatives (1b; bdc²⁻ = 1,4-benzenedicarboxylate) with pcu topology. The gas adsorption measurements revealed that 1se shows a 15% higher CO₂ volumetric uptake at 273 K and 28% higher CO₂ uptake at 298 K (both at 1 bar) compared to the prototypic framework 1b. Methane and nitrogen adsorption at 273 K was also investigated, and IAST calculations demonstrated a pronounced increase in CO₂/CH₄ and CO₂/N₂ selectivity for 1se, compared with 1b. For example, the selectivity factor for the equimolar CO₂/CH₄ gas mixture at 1 bar = 15.1 for 1se and 11.9 for 1b. The obtained results show a remarkable effect of the presence of selenium atom on the carbon dioxide affinity in the isoreticular metal–organic frameworks with very similar geometry and porosity.