We present a series of bisimidazole-based conjugated porous organic polymers (POPs) (BisImi-POP@1−6), which were formed by the CuI(I)−KOH/KOH-catalyzed cross-coupling reaction between the 2,2′-bisimidazole monomer and aryl halides. For iodine capture, the resultant POPs with a large number of imidazole N-heterocycle units in the skeletons can be used as effective adsorbents, which exhibit high iodine capture capacities

The second-order nonlinear optical (NLO) properties of porphyrin-metal-polyoxometalate (por-metal-POM) sandwich structures [(por)M(PW(11)O(39))](5-) (por = TPP, TPyP, TPPF(20), M = Hf; por = TPP, M = Zr) and [(TPP)Hf(XW(11)O(36))](6-) (X = Si, Ge) are investigated by time-dependent density functional theory (TDDFT). The character of charge-transfer transition indicates that the porphyrin ligand acts as an electron acceptor and the lacunary Keggin-type POM acts as an electron donor. Our results show that this kind of organic-inorganic hybrid compound possesses remarkably large molecular second-order NLO polarizability, approximately 100 x 10(-30) esu, and might be an excellent second-order NLO material. Furthermore, the NLO response can be tuned by the element substituents. The computed beta(0) values increase with the auxiliary electron-accepting group on the porphyrin ring (TPPF(20) > TPyP > TPP) and a heavy central heteroatom (Ge > Si > P). The present investigation provides important insight into the NLO properties of this class of por-metal-POM sandwich compound.

The donor-conjugated bridge-acceptor (D-A) model, as a simple molecular scheme, has been successfully used in the development of second-order organic compound, organometallic compound, and metal complex nonlinear optical (NLO) materials. However, for the totally inorganic molecules, the use of this model is still prohibitive. In the present paper, time-dependent density functional theory (TDDFT) was used to investigate the second-order NLO properties of vanadium- and molybdenum-trisubstituted Keggin and Wells-Dawson polyoxometalates (POMs). The results show that these POM clusters possess D-A structures. The oxygen atoms in the cap region and metal (vanadium and molybdenum) atoms in another cap region in these POM clusters can be viewed as the electron donor and acceptor, respectively. The vanadium ion derivatives possess larger second-order NLO responses and dipole moment than molybdenum ions derivatives; thus, the three vanadium atoms in the cap region act as a strong acceptor related to the three molybdenum atoms in cap region in our D-A scheme. The vanadomolybdate with Wells-Dawson structure displays the good second-order NLO response because of the relevant long conjugated bridge and strong acceptor. This D-A model may be an effective approach for optimizing the first hyperpolarizabilities of inorganic POM clusters.

The preparation and sorption properties of thiophene-based conjugated microporous polymers (CMPs) have been reported. The BET surface area of these porous polymers varied between 622 and 911 m 2 g −1 , and SCMP-COOH@1 showed an excellent CO 2 uptake capacity of 817 mg g −1 at 318 K under 60 bar pressure. In addition, SCMPs show good adsorption selectivity for CO 2 over N 2 and CH 4 .In recent years, excessive carbon dioxide (CO 2 ) emissions causing global climate change has attracted widespread public concern. 1 The development of viable CO 2 capture and storage (CCS) technology can effectively stabilize atmospheric carbon dioxide levels and prevent global warming. Porous materials 2,3 relying on physical adsorption are potential candidates for CO 2 capture because of their low regeneration energy consumption and high CO 2 sorption capacity. Conjugated microporous polymers (CMPs) are an important class of porous materials which are constructed from suitable aromatic building blocks via different reaction routes, which show high flexibility in the molecular design. 4-6 A combination of large specific surface areas, fully conjugated π-electron skeletons, synthetic diversification and better physicochemical stability makes CMPs excellent materials for gas storage/separation, 7,8 light emission, 9 supercapacitance, 10 heterogeneous catalysis, 11 and chemical sensing. 12 Noticeably, the knot and linker in the CMP skeleton are generally π-electron-rich aromatic molecules, and the extended conjugation in the polymer makes CMPs a promising platform for CO 2 capture. Thus, designing novel CMPs with a high surface area, high gas uptake capacity and high physiochemical stability toward CO 2 capture from the atmosphere is a continued interesting subject.The surface modification of porous polymers with polar groups can significantly enhance their CO 2 binding energy, † Electronic supplementary information (ESI) available: Details regarding the synthetic procedure, full methods, FT-IR spectra, 13 C NMR spectra, TGA curves, TEM images, PXRD profiles and corresponding data of gas adsorption capacity. See