Unique Ligand Exchange Dynamics of Metal–Organic Polyhedra for Vitrimer-like Gas Separation Membranes

Abstract

Metal-organic polyhedra (MOPs) possess micro-porous framework and impose hierarchical constraints on their surface ligands, leading to the long-ignored, logarithmic ligand exchange dynamics. Herein, the polymer networks with MOP as nanoscale crosslinkers (MOP-CNs) can integrate its unique ligand exchange dynamics and micro-porosity, affording the vitrimerlike gas separation membranes with promising mechanical performance and (re)processability. All the ligands on MOP surface are confined and correlated via the 3D coordination framework and their space neighboring, giving rise to high energy barrier for ligand exchange. Therefore, MOP-CNs demonstrate high mechanical strengths at room temperature due to their negligible ligand dynamics. The thermo-activated ligand exchange process with integrated network topology enables facile (re)processing and high solveresistance at high temperatures. This finally facilitates Arrhenius type temperature dependence of flowability and stress relaxation, giving rise to the simultaneous achievement of promising mechanical strengths and (re)processability. Finally, the cage topologies of MOPs endow the materials with bonusing micro-porous feature, and spur their applications as gas separation membranes.

Coordination Adaptable Networks: Zirconium(IV) Carboxylates

“…Reshapable metal‐containing 3D materials have previously been described, [9] with crosslinks generated by multiple (>2) valence either in the organic part, [10] or in the metallic ion/cluster, [11] or in both components [12] . Most of these materials function on the basis of coordinative bonds to polymer‐linked neutral (2‐electron, L‐type) donor ligands such as ethers, [12g] imines, [10d] pyridines, [10a,c] (benz)imidazoles [12e,f] and triazoles, [10b,12c] but a few also involve the exchange of anionic 2‐electron ligand (X‐type, 1‐electron donors in the neutral form), for instance carboxylates, [11,12d,h] β‐diketonates, [10e] catecholates [12a,b] and thiolates, [10f] with excess of the corresponding polymer‐anchored XH functions (i. e., carboxylic acids, β‐diketones, catechols, thiols). Whereas L‐type ligands can be exchanged dissociatively, associatively, or by an interchange mechanistic continuum, [13] anionic 2‐electron ligand strongly prefer the associative pathway in nonpolar media to avoid charge separation, except for the special case of weak bonds susceptible to homolytic cleavage.…”

Artificial intelligence-based gas chromatography-olfactometry for sensory evaluation of key compounds in food ingredients

“…A brief description of the process for the AINN is given in Figure 2c. Formally, given an odorant , where a i is the i -th atom type, c i ∈ ℝ 2 or ℝ 3 is the coordinate vector of the i -th atom, and N atom is the total number of atoms for the odorant. To obtain an atom embedding description for the odorant, , where v i ∈ ℝ d is the embedded vector for the i -th atom.…”

“…To obtain the sensory information of odor, gas chromatography/olfactometry (GC/O) has been widely applied as a powerful odor analytic strategy in various research areas, such as agriculture, food, and environmental science 1, 2 . In addition, gas separation membranes had been developed successfully forGC part 3, 4 . Although GC/O can be used to attain accurate sensory and chemical characteristics of odorants, this approach is expensive and time-consuming, which can limit its application.…”

A hierarchical system of covalent and dual non-covalent crosslinks promotes the toughness and self-healing properties of polymer hydrogels

“…30,31 For example, the fast dynamic nature of complexation bonds was utilized to construct supramolecular networks where a trade-off could be well achieved between stretchability and stiffness. 32,33 Besides, ionic bonds were combined with covalent bonds to construct a highly extensible and tough dual-network hydrogel that could also be recovered from large strains. 34 A dual physically crosslinked hydrogel based on hydrogen bonding and Fe 3+ coordination interactions was also reported with excellent toughness and self-healing properties.…”