Nine mostly novel aromatic Schiff bases containing from two to four terminal ethynyl groups and one or two methanimine groups per one molecule are reported. The spectral and DFT characteristics and the extent of conjugation are discussed in connection with the structure and architecture of prepared compounds. The applicability of compounds as building blocks for conjugated polymers is shown in TaCl5-catalysed polycyclotrimerization (proceeding in ethynyl groups) yielding either soluble luminescence or insoluble microporous polymers.

We report the synthesis of conjugated highly cross-linked polyacetylene-type networks with a high content of functional groups (-CH2OH, -NO2, -Ph2N, content up to 3.9 mmol/g) via a chain-growth copolymerization of either 1,4-diethynylbenzene or 4,4´-diethynylbiphenyl with functionalized mono- and diethynylbenzenes. The backbone of the networks consists of substituted polyene main chains that are cross-linked by arylene links. The optimised combinations of comonomers in the feed provide functionalized networks with a Brunauer-Emmett-Teller specific surface area up to 667 m2/g and enhanced affinity for CO2 adsorption (compared to the non-functionalized hydrocarbon networks of the same type). The dependence of the specific surface area of the networks on the size and architecture of the comonomers used for the synthesis is discussed in the paper. The reported networks can be classified into the group of conjugated microporous polymers (CMPs). Contrary to the CMPs synthesized by step-growth couplings, significantly lower average comonomer functionality in the feed (f = 1.5 - 2.0) is sufficient for the high specific surface area to be achieved in the reported polyacetylene-type CMPs.

Spontaneous catalyst-free polymerizations of 4-ethynylpyridine (4EPy) and 2-ethynylpyridine with bifunctional quaternizing agents (QAs) of bis(bromomethyl)arenes provide highly crosslinked polymer networks in high yields. 13C cross-polarization magic-angle spinning (CP/MAS) NMR, Fourier transform IR (FTIR) and diffuse reflectance vis spectroscopy confirm that these networks consist of polyacetylene main chains substituted with pyridyl and pyridiniumyl groups, the latter interconnected with -CH2(arylene)CH2- linkers. Variation of the 4EPy/QA ratio in the polymerization feed results in networks with different extents of crosslinking and pyridyl/pyridiniumyl ratio (N/N+ from 0 to 1.32). Networks exhibit photoluminescence and are also moderately active in CO2 capture (the highest uptake is 16.4 cm3 (STP)/g at 293 K and equilibrium CO2 pressure of 750 Torr).