Covalent organic frameworks (COFs) mixed matrix membranes (MMMs) combining individual attributes of COFs and polymers are promising for gas separation. However, applying COF MMMs for propylene/propane (C3H6/C3H8) separation remains a big challenge due to COF inert pores and C3H6/C3H8 similar molecular sizes. Herein, the designed synthesis of a Cu(I) coordinated COF for membrane C3H6/C3H8 separation is reported. A platform COF is synthesized from 5,5′‐diamino‐2,2′‐bipyridine and 2‐hydroxybenzene‐1,3,5‐tricarbaldehyde. This COF possesses a porous 2D structure with high crystallinity. Cu(I) is coordinated to bipyridyl moieties in the COF framework, acting as recognizable sites for C3H6 gas, as shown by the adsorption measurements. Cu(I) COF is blended with 6FDA‐DAM polymer to yield MMMs. This COF MMM exhibits selective and permeable separation of C3H6 from C3H8 (C3H6 permeability of 44.7 barrer, C3H6/C3H8 selectivity of 28.1). The high porosity and Cu(I) species contribute to the great improvement of separation performance by virtue of 2.3‐fold increase in permeability and 2.2‐fold increase in selectivity compared to pure 6FDA‐DAM. The superior performance to those of most relevant reported MMMs demonstrates that the Cu(I) coordinated COF is an excellent candidate material for C3H6 separation membranes.

Gas separation efficiency of covalent organic framework (COF) membrane can be greatly elevated through precise functionalization. A pair-functionalized COF membrane of 1,3,5-triformylphloroglucinol (TP) and isoquinoline-5,8-diamine (IQD) monomers in two and three nodes is designed and synthesized. TP-IQD is crystallized in a two-dimensional structure with a pore size of 6.5 Å and a surface area of 289 m 2 g À 1 . This COF possesses NÀ O paired groups which cooperatively interact with C 2 H 2 instead of C 2 H 4 . TP-IQD nanosheets of � 10 μm in width and � 4 nm in thickness are prepared by mechanical exfoliation; they are further processed with 6FDA-ODA polymer into a hybrid membrane. High porosity and functionality pair of TP-IQD offer the membrane with significantly increased C 2 H 2 permeability and C 2 H 2 /C 2 H 4 selectivity which are 160 % and 430 % higher of pure 6FDA-ODA. The boosted performance demonstrates high efficiency of the pairfunctionality strategy for the synthesis of separation-led COFs.

Gas separation efficiency of covalent organic framework (COF) membrane can be greatly elevated through precise functionalization. A pair-functionalized COF membrane of 1,3,5-triformylphloroglucinol (TP) and isoquinoline-5,8-diamine (IQD) monomers in two and three nodes is designed and synthesized. TP-IQD is crystallized in a two-dimensional structure with a pore size of 6.5 Å and a surface area of 289 m 2 g À 1 . This COF possesses NÀ O paired groups which cooperatively interact with C 2 H 2 instead of C 2 H 4 . TP-IQD nanosheets of � 10 μm in width and � 4 nm in thickness are prepared by mechanical exfoliation; they are further processed with 6FDA-ODA polymer into a hybrid membrane. High porosity and functionality pair of TP-IQD offer the membrane with significantly increased C 2 H 2 permeability and C 2 H 2 /C 2 H 4 selectivity which are 160 % and 430 % higher of pure 6FDA-ODA. The boosted performance demonstrates high efficiency of the pairfunctionality strategy for the synthesis of separation-led COFs.

We report the design, synthesis, and physicochemical properties of an array of phenanthro[2,1-b:7,8-b’]dithiophene (PDT-2) derivatives by introducing five types of alkyl (CnH2n+1; n = 8, 10, 12, 13, and 14) or two types of decylthienyl groups at 2,7-positions of the PDT-2 core. Systematic investigation revealed that the alkyl length and the type of side chains have a great effect on the physicochemical properties. For alkylated PDT-2, the solubility was gradually decreased as the chain length was increased. For instance, C8-PDT-2 exhibited the highest solubility (5.0 g/L) in chloroform. Additionally, substitution with 5-decylthienyl groups showed poor solubility in both chloroform and toluene, whereas PDT-2 with 4-decylthienyl groups resulted in higher solubility. Furthermore, UV-vis absorption of PDT-2 derivatives substituted by decylthienyl groups showed a redshift, indicating the extension of their π-conjugation length. This work reveals that modification of the conjugated core by alkyl or decylthienyl side chains may be an efficient strategy by which to change the physicochemical properties, which might lead to the development of high-performance organic semiconductors.

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