Synthesis and Gas Sorption Properties of Microporous Poly(arylene ethynylene) Frameworks

Abstract

Microporous organic polymers (MOPs) have drawn much attention because of their potential applications such as gas storage, separation and heterogeneous catalysis. There is great interest in the design, synthesis and property evaluation of poly(arylene ethynylenes) (PAEs) with intrinsic microporosity. In addition to Sonogashira coupling reaction between terminal alkynes and halides, the oxidative dimerization of terminal alkynes is an alternating strategy for the buildup of the microporous PAE frameworks. In this paper, a series of MOPs were synthesized by the oxidative dimerization of terminal alkynes using triethynyl monomers such as tris(4-ethynylphenyl)amine, tris(4-ethynylphenyl)methylsilane and polytris(4-ethynylphenyl)phenylsilane. The resulting MOPs were characterized by FT-IR spectra, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD) measurements. FT-IR spectra indicate the success of the homocoupling reaction for constructing the dialkyne-bridged polymer frameworks. These polymer frameworks exhibit high thermal stability with onset of decomposition temperature above 350 ℃ at 5% mass loss under nitrogen flow. PXRD and TEM measurements revealed that all the polymer frameworks are amorphous solid in nature. These dialkyne-bridged MOPs exhibit moderate surface areas ranging from 602 to 715 m 2 •g-1. The incorporation of triphenylamine moieties into the polymer skeleton increases the number of electron donating basic nitrogen sites in the porous frameworks. Thus, the triphenylamine-based polymer polytris(4-ethynylphenyl)amine (TE-PA-MOP) with the highest Brunauer-Emmett-Teller (BET) surface area shows the highest CO 2 uptake capacity of 1.59 mmol•g-1 at 273 K and 1.13 bar among the resulting polymer frameworks. In addition, TEPA-MOP showed the highest H 2 adsorption up to 1.04 wt% at 1.13 bar and 77 K and polytris(4-ethynylphenyl)phenylsilane (TEPP-MOP) displayed the lowest H 2 adsorption of 0.64 wt% at the same conditions. As for separation of CO 2 , both TEPA-MOP and TEPP-MOP exhibit relatively high CO 2-over-N 2 selectivities of 69.9 and 73.2 at 273 K, respectively. The above results show that TEPA-MOP might be the good candidate for the balanced CO 2 uptake capacity with impressive CO 2 /N 2 selectivity among the microporous PAE frameworks.

Recent Advances in the Z/E Isomers of Tetraphenylethene Derivatives: Stereoselective Synthesis, AIE Mechanism, Photophysical Properties, and Application as Chemical Probes

“…Accordingly,t he TPE isomers showedd ifferent photophysical properties in terms of, for example,t heir mechanochromism (MC), mechanoluminescence (ML), solvatochromism (SC), and meltingp oints. [47][48][49][50] In 2012, during their syntheses of polycyclic aromatic TPE derivatives, Hu et al obtained am ixture of (Z)-/(E)-BETPEb y using the McMurry couplingr eaction ( Figure 5a). [51] However, they could not separate the Z and E isomersb yu sing column chromatography, because of their similar polarities, which were derived from the weak polarity of the ethynyl group.…”

“…Reproduced with permission from Ref. [50]. 1 HNMR spectrao f(Z)-TPE-2OXE after heatinga t200 8C for 15 min (c), and as-prepared (Z)-TPE-2OXE (d).…”

“…Most of the pure Z / E isomers that have been reported have exhibited large polarity differences. Accordingly, the TPE isomers showed different photophysical properties in terms of, for example, their mechanochromism (MC), mechanoluminescence (ML), solvatochromism (SC), and melting points …”

Photoinduced E to Z isomerization of tetraphenylethylene derivatives within organometallic supramolecular assemblies

“…Therefore, the EZI process has been studied with unsymmetrically disubstituted TPE derivatives [6][7][8][9][10][11][12][13][14][15][16][17]. Apart from being ideal candidates for the study of the EZI process, pure E-and Z-isomers of disubstituted TPE and the investigation of their properties has recently attracted interest based on the differences in their optical properties, host-guest chemistry and related features [18][19][20][21][22][23][24][25][26][27][28]. Disubstituted TPE derivatives are conventionally synthesized by the McMurry coupling of unsymmetrically sybstituted ketones.…”