Structural changes at the active site of an enzyme induced by binding to a substrate molecule can result in enhanced activity in biological systems. Herein, we report that the new hybrid ultramicroporous material sql‐SIFSIX‐bpe‐Zn exhibits an induced fit binding mechanism when exposed to acetylene, C2H2. The resulting phase change affords exceptionally strong C2H2 binding that in turn enables highly selective C2H2/C2H4 and C2H2/CO2 separation demonstrated by dynamic breakthrough experiments. sql‐SIFSIX‐bpe‐Zn was observed to exhibit at least four phases: as‐synthesised (α); activated (β); and C2H2 induced phases (β′ and γ). sql‐SIFSIX‐bpe‐Zn‐β exhibited strong affinity for C2H2 at ambient conditions as demonstrated by benchmark isosteric heat of adsorption (Qst) of 67.5 kJ mol−1 validated through in situ pressure gradient differential scanning calorimetry (PG‐DSC). Further, in situ characterisation and DFT calculations provide insight into the mechanism of the C2H2 induced fit transformation, binding positions and the nature of host‐guest and guest‐guest interactions.
Closed-to-open structural transformations
in flexible coordination
networks are of potential utility in gas storage and separation. Herein,
we report the first example of a flexible SiF6
2–-pillared square grid material, [Cu(SiF6)(L)2]
n
(L = 1,4-bis(1-imidazolyl)benzene), SIFSIX-23-Cu. SIFSIX-23-Cu exhibits reversible
switching between nonporous (β1) and several porous
(α, γ1, γ2, and γ3) phases triggered by exposure to N2, CO2, or H2O. In addition, heating β1 to 433 K resulted in irreversible transformation
to a closed polymorph, β2. Single-crystal X-ray
diffraction studies revealed that the phase transformations are enabled
by rotation and geometrical contortion of L. Density functional theory
calculations indicated that L exhibits a low barrier to rotation (as
low as 8 kJmol–1) and a rather flat energy surface.
In situ neutron powder diffraction studies provided further insight
into these sorbate-induced phase changes. SIFSIX-23-Cu combines stability in water for over a year, high CO2 uptake (ca. 216 cm3/g at 195 K), and good thermal stability.
Two new ionic dinuclear Ir(III) Schiff base complexes which are straightforward to synthesise have luminescence quantum yields as high as 37% in neat films. These are the first examples of dinuclear ionic Ir(III) complexes that display aggregation-induced phosphorescent emission (AIPE).
Unprecedented Anderson-like alkoxo-polyoxovanadate [V6O6(OCH3)9(μ6-SO4)(COO)3](2-) polyanions can serve as 3-connected second building units (SBUs) that assemble with dicarboxylate or tricarboxylate ligands to form a new family of metal organic tetrahedrons of V4E6 and V4F4 type (V = vertex, E = edge, and F = face). To our knowledge, this alkoxo-polyoxovanadate-based SBU is the first ever reported.
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