Reversible ferroelectric phase transition of 1,4-diazabicyclo [2,2,2]octane N,N′-dioxide di(perchlorate)

Properties of Aliphatic Ligand-Based Metal-Organic Frameworks

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.

Diverse Hydrogen-Bonded Structural Motifs in 1,4-Diazabicyclo[2.2.2]octane N,N’-Dioxide Salts with Oxoanions

Four new hybrid inorganic–organic salts of 1,4-diazabicyclo[2.2.2]octane N,N’-dioxide (odabco) with the formulae odabco·2HNO3 (1), odabco·HClO4 (2), odabco·H2SO4 (3) and odabco·2H2SO4 (4) were synthesized and characterized by single-crystal x-ray diffraction (XRD), powder XRD and infrared spectroscopy. Compound 1 is based on the isolated (H2odabco)2+ fragments, representing 0D structure. 2 is based on cationic 1D {Hodabco}nn+ hydrogen-bonded chains. Compound 3 comprising a strongly coordinated sulfate anion consists of two-component hydrogen-bonded {-H2odabco-SO4−} fragments forming uncharged 1D helical chains. 4 contains both {-HSO4-}nn– and {-HSO4-H2odabco-HSO4−} hydrogen bonding motifs, resulting in a 3D polymeric network. A comparative structural analysis of both the obtained and the previously reported cognate structures was performed to rationalize the impact of the degree of odabco protonation and the anion donor ability on the structural features and dimensionalities of odabco-based hydrogen-bonded lattices.