Water vapour induced reversible switching between a 1-D coordination polymer and a 0-D aqua complex

[Zn(3-tba)2], 1, a 1-D coordination polymer synthesised as 1 DMA, 1α, transformed to a nonporous form, 1β, upon activation. 1β underwent further transformation to the dimeric complex [Zn(3-tba)2(H2O)2], 2, above 40% RH. The reverse transformations, 2 to 1β and 1β to 1α, were accomplished by heating and exposure to DMA, respectively, and were single-crystal-to-single-crystal phase changes. Single crystal X-ray diffraction revealed that the second transformation resulted from Zn–carboxylate bond breakage and concomitant coordination of water molecules. Other solvent molecules did not induce a phase change</p

Tuning the gate-opening pressure in a switching pcu coordination network, X-pcu-5-Zn, by pillar ligand substitution

Coordination networks that reversibly switch between closed and open phases are of topical interest since their stepped isotherms can offer higher working capacities for gas‐storage applications than the related rigid porous coordination networks. To be of practical utility, the pressures at which switching occurs, the gate‐opening and gate‐closing pressures, must lie between the storage and delivery pressures. Here we study the effect of linker substitution to fine‐tune gate‐opening and gate‐closing pressure. Specifically, three variants of a previously reported pcu‐topology MOF, X‐pcu‐5‐Zn, have been prepared: X‐pcu‐6‐Zn, 6=1,2‐bis(4‐pyridyl)ethane (bpe), X‐pcu‐7‐Zn, 7=1,2‐bis(4‐pyridyl)acetylene (bpa), and X‐pcu‐8‐Zn, 8=4,4′‐azopyridine (apy). Each exhibited switching isotherms but at different gate‐opening pressures. The N2, CO2, C2H2, and C2H4 adsorption isotherms consistently indicated that the most flexible dipyridyl organic linker, 6, afforded lower gate‐opening and gate‐closing pressures. This simple design principle enables a rational control of the switching behavior in adsorbent materials

'Cultura plantarum'

Using a bis-triazolate ligand and tetrahedral Zn­(II) ion, we synthesized a flexible porous coordination polymer functionalized with pairs of uncoordinated triazolate N-donors that can be used as guest chelating sites to give very high CO₂ adsorption enthalpy and CO₂/N₂ selectivity. The dynamic CO₂ sorption behavior could be monitored well by single-crystal X-ray diffraction

Strong and Dynamic CO₂ Sorption in a Flexible Porous Framework Possessing Guest Chelating Claws

Using a bis-triazolate ligand and tetrahedral Zn­(II) ion, we synthesized a flexible porous coordination polymer functionalized with pairs of uncoordinated triazolate N-donors that can be used as guest chelating sites to give very high CO₂ adsorption enthalpy and CO₂/N₂ selectivity. The dynamic CO₂ sorption behavior could be monitored well by single-crystal X-ray diffraction

A coordination network that reversibly switches between two nonporous polymorphs and a high surface area porous phase

We report a 2-fold interpenetrated primitive cubic (pcu) network X-pcu-5-Zn, [Zn2(DMTDC)2(dpe)] (H2DMTDC = 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, dpe = 1,2-di(4-pyridyl)ethylene), that exhibits reversible switching between an as-synthesized “open” phase, X-pcu-5-Zn-α, and two nonporous or “closed” polymorphs, X-pcu-5-Zn-β and X-pcu-5-Zn-γ. There are two unusual features of X-pcu-5-Zn. The first relates to its sorption properties, which reveal that the α form exhibits high CO2 uptake (ca. 255 cm3/g at 195 K) via reversible closed-to-open switching (type F-IV isotherm) of the type desirable for gas and vapor storage; there are only three other reports of porous materials that combine these two features. Second, we could only isolate the β form by activation of the CO2 loaded α form and it persists through multiple CO2 adsorption/desorption cycles. We are unaware of a new polymorph having been isolated in such a manner. That the observed phase changes of X-pcu-5-Zn-α occur in single-crystal-to-single-crystal fashion enabled structural characterization of the three forms; γ is a coordination isomer of α and β, both of which are based upon “paddlewheel” clusters