No abstract

Meso-macroporous hierarchical poly(ionic liquid)s are ionothermally synthesized through self-polymerization of the new divinylimidazole IL, exhibiting enhanced CO2 capture and excellent activity in the cycloaddition of CO2 to epoxides.

A new nitrile-tethered pyridinium polyoxometalate (POM) was prepared by anion-exchange of the ionic liquid precursor [N-butyronitrile pyridine]Cl ([C 3 CNpy]Cl) with the Keggin phosphovanadomolybdic acid H 5 PMo 10 V 2 O 40 (PMoV 2 ), and the obtained organic POM salt [C 3 CNpy] 4 HPMoV 2 was characterized by XRD, SEM, TG, 1 H NMR, 13 C NMR, ESI-MS, CHN elemental analysis, nitrogen sorption experiment, and melting point measure. When used as a catalyst, [C 3 CNpy] 4 HPMoV 2 causes the first example of reactioncontrolled phase-transfer hydroxylation of benzene with H 2 O 2 , showing high activity and stable reusability. Based on spectral characterizations and comparisons of reaction results, plus the reversible color change between fresh and recovered catalyst, a unique reaction mechanism is proposed for understanding the highly efficient [C 3 CNpy] 4 HPMoV 2 -catalyzed phase-transfer catalysis. The formation of dissolvable active species [VO(O 2 )] + is responsible for the phase-transfer behavior, while the intramolecular charge transfer and the protonated nitrile in cations accelerate the reaction and favor a better catalyst recovery rate.

In comparison with pigmentary colors, structural colors are with superior chemical stability and are resistant to photobleaching, making them promising candidates for color displays. What is more, the use of toxic dyes can be avoided by utilizing structural-colored materials to display various hues. Structural colors are widespread in nature and observed in opals, [3] beetles, [4] tropical fish, [5] peacock feathers, [6] chameleons, and similar iridescent materials. [7-9] Along with the growing understanding of the morphology and mechanism of natural structural-colored materials, their artificial counterparts have been manufactured with improved performance and functions consequently. Emerging structural-colored materials can be divided into three main categories according to their nanoscale architectures: photonic crystals (PCs), [10] liquid crystals (LCs), [11] and photonic glass. [12] Due to their ability to modulate visible light, the structural-colored materials have been applied in diverse domains such as optical waveguides, [13-16] luminescence enhancement, [17-19] photo electric devices, [20,21] photocatalysts, [22,23] anti-counterfeiting technologies, [24-26] and chemical and biological sensing. [27-29] With ingenious designs of nanostructures, a variety of responsiveness has been obtained on the structural-colored materials, corresponding to varying stimuli such as temperature, [30-32] solvent, [27] gases, [28] magnetic fields, [33] and external forces. [10-12] Among them, the mechanical responsive structural colors are able to visualize invisible stress in the materials, providing effective indicators for mechanical stimuli such as stretching, compression, or bending. Such mechanochromism can be directly achieved by the deformation-induced changes in periodic lattice constants of the structural-colored materials. [34,35] Recently developed mechanochromic structuralcolored materials have extended the responsive functions from conventional mechanical stimuli to complex signals such as electric stimuli. [10] In addition, although the color shift is a predominant method to achieve mechanochromic behavior, [34-36] increasing efforts have been made to develop mechanochromism based on polarization and transparence. [11,37,38] As one of the rapidly developing intelligent materials with multiresponse, [34,39,40] mechanochromic structural-colored materials have become promising in various applications, such as mechanical sensing, [11,41] colorful displays, [10,42] anti-counterfeiting, [26,37] and healthcare materials. [43,44] In this review, we summarize recent advances in mechanochromic structural-colored materials as shown in Figure 1.

In this work, we report a new family of viologen-based ionic porous hybrid polymers (V-iPHPs) with task-specific multiple catalytic active sites toward efficient catalytic fixation of carbon dioxide (CO2) to value-added cyclic carbonates. The targeted V-iPHPs were fabricated by the solvothermal Heck reaction between two newly designed viologen ionic linkers and octavinylsilsesquioxane (VPOSS). The obtained V-iPHPs possess tunable surface areas (150–562 m2 g–1) and pore volumes (0.41–1.82 cm3 g–1) along with adjustable ionic sites (0.92–1.47 mmol g–1). Especially, a plenty of silanol (Si–OH) groups are in situ formed via breaking polyhedral oligomeric silsesquioxane cages during the synthetic process. The typical catalyst V-iPHP-1 exhibits remarkable metal-free heterogeneous catalytic activities in the CO2 fixation with diverse epoxide substrates under very mild conditions. Besides, the heterogeneous catalyst V-iPHP-1 could be easily recovered with good reusability. The excellent catalytic performance could be assigned to the synergistic catalysis of hydrogen bond donors Si–OH groups and Br– anions, abundant mesoporosities, and the hydrophobic reaction microenvironment.