Promoting and Tuning Porosity of Flexible Ether-Linked Phthalazinone-Based Covalent Triazine Frameworks Utilizing Substitution Effect for Effective CO₂ Capture

Abstract

Five porous ether-linked phthalazinone-based covalent triazine frameworks (PHCTFs) were successfully constructed via ionothermal polymerizations from flexible dicyano monomers containing asymmetric, twisted, and N-heterocyclic phthalazinone structure. All the building blocks could be easily prepared by simple and low-cost aromatic nucleophilic substitution reactions, showing the large-scale application potential of thermal stable phthalazinone structure in constructing porous materials. Generally, the flexible building blocks are avoided to prevent the networks from collapsing in constructing high surface area porous materials. Our experimental results revealed that the introduction of the substituents can effectively decrease the probability of the network interpenetration from the longer struts and the intermolecular/intramolecular intercalation from the increased degree of conformation freedom in the flexible ether-linkage, the BET surface areas of PHCTFs increasing from 676 to 1270 m g. Meanwhile, the effects of introducing different sizes (methyl or phenyl group) and amounts (one or two) of substituents on the porosities of the target polymer networks were also investigated in detail. The high CO adsorption capacity of 10.3 wt % (273 K, 1 bar) can be ascribed to the strong affinity of the electron-rich N,O-containing networks with CO. Excitingly, PHCTF-5 demonstrates the high CO/N selectivity up to 138 (273 K, 1 bar), according to the ideal adsorbed solution theory (IAST) for the higher proportion of V accompanied the electron-rich heteroatoms characteristic. Such high CO adsorption capacity and good separation properties are superior to those of many other microporous organic polymers. These properties along with easily up-scalable synthesis make porous PHCTFs promising candidates applied in gas sorption and separation field.

Playing with covalent triazine framework tiles for improved CO2 adsorption properties and catalytic performance

“…A comparative analysis with the current literature data (according to samples analyzed under similar pressure and temperature conditions, see Table 2) reveals that CTF1 and CTF4 rank among the samples with the highest CO 2 uptake capacity reported up to now in the literature both at T = 273 and 298 K. With the exception of the CFT-py HT sample [30] (featured by a markedly higher specific surface area of 3040 m 2 ·g −1 ; Table 2, entry 9), the highly N/O co-doped HAT-CTF material [51] (1090 m 2 ·g −1 ; Table 2, entry 15) and the perfluorinated df -TzCTF600 [52] (1720 m 2 ·g −1 ; Table 2, entry 28), CTF4 outperforms the CO 2 adsorption capacity of many benchmark systems from this class of porous organic polymers. With 1.23 mmol·g −1 and 3.83 mmol·g −1 of adsorbed CO 2 at room temperature and 0.1 bar and 1 bar pressure, respectively (Table 2, entry 4), CTF4 surpasses the adsorption ability of samples such as bipy-CTFs (3.07–2.95 mmol·g −1 ; Table 2, entries 10, 11) [33], F-CTF (3.21–3.41 mmol·g −1 ; Table 2, entries 13, 14) [53], PHCTFs (1.57–1.34 mmol·g −1 ; Table 2, entries 17, 18) [54], bpim-CTFs (2.46–2.77 mmol·g −1 ; Table 2, entries 22, 23) [55] CTF-CSU41 (1.80 mmol·g −1 ; Table 2, entry 24) [56], PHCTF-8(650) (2.54 mmol·g −1 ; Table 2, entry 25) [57] and acac-CTF-5-500 (1.97 mmol·g −1 ; Table 2, entry 27) [58].…”

“…However, the Q st values and the CO 2 adsorption capacity on porous samples do not always coherently correlate [64]. Indeed, the literature presents several examples of materials featuring very high Q st values but only moderate CO 2 uptake [54,56]. The Q st value of CTF3 is relatively high because of its exceptionally high N content.…”

Gas Storage in Porous Molecular Materials

“…The use of organic functionalization to tune porosity has been demonstrated across all advanced porous materials including MOFs, COFs, porous polymers, PCCs, and porous organic molecules [104–108] . Studies focused on tuning and optimizing permanent porosity for intrinsically porous molecular organic materials have recently garnered increased attention [42] .…”

Covalent Triazine‐based Frameworks—Tailor‐made Catalysts and Catalyst Supports for Molecular and Nanoparticulate Species

“…[25,39,44,45,47,48] Ag eneral trend shows that increasing porosity and especially the accessibility of (ultra-)micropore volumee nhance gas adsorption properties, while specific surface area alone does play am inor but not negligible role. Additionally, N-, O-, and S-heteroatoms, [48,49] fluorinated buildingu nits, [44,50] cationic viologen or imidazolium motifs [51,52] as well as metal dopants [53] have been reported to positively influence the adsorption and separation performance of the resultingC TFs. This knowledge is crucial for the tailoredd esign of active and selective catalysts applied in gas-phase reactions,a sw ill be highlighted later within this review.…”