Melt-Phase Synthesis and Properties of Triptycene-Containing Copolyesters

Triptycene-like naphthopleiadene as a readily accessible scaffold for supramolecular and materials chemistry

Triptycene derivatives are used extensively in supramolecular and materials chemistry, however, most are prepared using a multi-step synthesis involving the generation of a benzyne intermediate, which hinders production on a large scale. Inspired by the ease of the synthesis of resorcinarenes, we report the rapid and efficient preparation of triptycene-like 1,6,2',7'-tetrahydroxynaphthopleiadene directly from 2,7-dihydroxynaphthalene and phthalaldehyde. Structural characterisation confirms the novel bridged bicyclic framework, within which the planes of the single benzene ring and two naphthalene units are fixed at an angle of ∼120° relative to each other. Other combinations of aromatic 1,2-dialdehydes and 2,7-disubstituted naphthalenes also provided similar triptycene-like products. The low cost of the precursors and undemanding reaction conditions allow for rapid multigram synthesis of 1,6,2',7'-tetrahydroxynaphthopleiadene, which is shown to be a useful precursor for making the parent naphthopleiadene hydrocarbon. The great potential for the use of the naphthopleiadene scaffold in supramolecular and polymer chemistry is demonstrated by the preparation of a rigid novel cavitand, a microporous network polymer, and a solution-processable polymer of intrinsic microporosity.

Introduction of Triptycene with a Particular Substitution Pattern into Polymer Chains Can Dramatically Improve the Structural and Rheological Properties

Although a large number of polymers that contain triptycene units in the main chains have been developed, no polymer design using 1,8-substituted triptycene has been reported to date. In this study, we investigated the properties of linear homo- and copolymers obtained by ring-opening polymerization of a triptycene monomer bearing a macrocyclic olefin linked at its 1,8-position and its copolymerization with cyclooctene, respectively. We found that the introduction of triptycene with this substitution pattern leads to nanoscale molecular ordering, thereby greatly improving the physical properties of the polymers. The key to this remarkable behavior of 1,8-substituted triptycene-containing polymers is the formation of a particular two-dimensional assembly of the triptycene units by nested hexagonal packing, which aligns one-dimensionally while folding the polymer chains into a well-defined layered structure. The polymer design using 1,8-substituted triptycene can be applied to other polymers, unless their main chain contains functional groups capable of a strong intermolecular interaction such as hydrogen bonding.

A novel column modification approach for capillary gas chromatography: combination with a triptycene-based stationary phase achieves high separation performance and inertness

Integration of the novel column modification approach with a triptycene-based stationary phase achieves high-resolution performance and inertness towards acids/bases and isomers for capillary GC analysis.

Separation performance of a new triptycene-based stationary phase with polyethylene glycol units and its application to analysis of the essential oil of Osmanthus fragrans Lour

This work presents a new triptycene-based stationary phase (TP-PEG) combining the three-dimensional (3D) triptycene (TP) framework with polyethylene glycol (PEG) moieties for gas chromatographic (GC) separations. Its statically coated capillary column showed high column efficiency of 5263 plates/m determined by naphthalene at 120 °C. Its Rohrschneider-McReynolds constants and Abraham solvation system constants were measured to characterize its polarity and molecular interactions with analytes of different types. As evidenced, the TP-PEG column showed high-resolution performance for the isomers of anilines, phenols, halobenzenes and alkanes with distinct advantages over the PEG columns, particularly those critical isomers such as 3,5-/2,3-xylidine (R = 2.94), m-/p-chlorotoluene (R = 1.92), p-/m-cresol (R = 1.89), 2,2-dimethylbutane/2-methylpentane (R = 1.51), 2,2,3-trimethylbutane /2,3-dimethyl pentane (R = 1.74) and 2,3-dimethylpentane/n-heptane (R = 1.92). In addition, it exhibited good column repeatability and reproducibility with the relative standard deviation (RSD) values of 0.02%-0.09% for run-to-run, 0.13%-0.22% for day-to-day and 2.7%-4.1% for column-to-column, respectively, and a wide operational temperature range (30 °C-280 °C) . Its application to GC-MS analysis of the essential oil of Osmanthus fragrans has proven its good potential for practical analysis of complex samples.

High-resolution performance of triptycene functionalized with polycaprolactones for gas chromatography

Developing highly selective stationary phases is essential to address the issues for separation of analytes with similar properties and various components in complex samples. Herein, we report a new triptycene-based material functionalized with polycaprolactone moieties (TP-PCL) as the stationary phase with high-resolution performance for gas chromatography (GC). The TP-PCL capillary column exhibited column efficiency of 5555 plates/m and moderate polarity. On the column, dozens of mixtures of positional and structural isomers can be well resolved, involving benzene derivatives with varying substituents (alkyl, halo, nitro, hydroxyl, amino), naphthalene derivatives, alkanes and alcohols. It exhibits advantageous performance for high resolution of the critical pairs of alkylbenzenes, phenols, anilines and alkanes over the PCL column and commercial DB-35 MS column with similar polarity. Moreover, the TP-PCL column showed excellent separation repeatability and reproducibility with RSD values of 0.02%-0.07% for run-to-run (n = 4), 0.11%-0.18% for day-to-day (n = 4) and 2.1%-4.7% for column-to-column (n = 4). In addition, it exhibited distinctly enhanced thermal stability in contrast to the PCL column. Its application to analysis of the essential oil from Artemisiae argyi proves its good potential for practical use.

Amphiphilic triptycene-based stationary phase for high-resolution gas chromatographic separations

This work reports a new type of triptycene-based amphiphilic stationary phase (TP-2IL) for gas chromatography (GC). It is an integration of the 3D π-rich triptycene framework with ionic liquids. Its capillary column showed the efficiency of 3880 plates/m determined by n-dodecane at 120 °C (k = 2.79) and exhibited good performance for analytes from apolar to polar nature. Particularly, it has outstanding capability for resolving critical pairs of anilines and phenols with good peak shapes and shows distinct advantages over its composing counterparts (TP-2BO and O-IL) and widely-used commercial columns, namely 35% phenyl methyl polysiloxane (DB-35) and polyethylene glycol (INNOWAX). Moreover, the TP-2IL column exhibited good repeatability and reproducibility with the values of relative standard deviation in the range of 0.02%-0.07% for run-to-run, 0.10%-0.35% for day-to-day and 2.9%-5.1% for column-to-column, respectively, and good thermal stability up to 300 °C. Furthermore, its applications for determining isomer impurities in real samples demonstrate its feasibility for practical GC analysis. This work presents a facile strategy for constructing triptycene-based stationary phases with amphiphilic selectivity and provides alternatives of highly selective stationary phases for chromatographic analysis.

Blurring the Lines between Host and Guest: A Chimeric Receptor Derived from Cucurbituril and Triptycene

We report the synthesis and X-ray crystal structure of a cucurbituril-triptycene chimeric receptor (1). Host 1 binds to guests typical of CB[6]-CB[8], but also binds to larger guests such as blue box (20) and the Fujita square (22). Intriguingly, the geometries of the 1⋅20 and 1⋅22 complexes blur the lines between host and guest in that both components fulfill both roles within each complex. The fluorescence output of 1 is fully quenched by the formation of complexes with pyridinium-derived guests.

Highly CO2-Selective Gas Separation Membranes Based on Segmented Copolymers of Poly(Ethylene oxide) Reinforced with Pentiptycene-Containing Polyimide Hard Segments

Poly(ethylene oxide) (PEO)-containing polymer membranes are attractive for CO2-related gas separations due to their high selectivity toward CO2. However, the development of PEO-rich membranes is frequently challenged by weak mechanical properties and a high crystallization tendency of PEO that hinders gas transport. Here we report a new series of highly CO2-selective, amorphous PEO-containing segmented copolymers prepared from commercial Jeffamine polyetheramines and pentiptycene-based polyimide. The copolymers are much more mechanically robust than the nonpentiptycene containing counterparts due to the molecular reinforcement mechanism of supramolecular chain threading and interlocking interactions induced by the pentiptycene structures, which also effectively suppresses PEO crystallization leading to a completely amorphous structure even at 60% PEO weight content. Membrane transport properties are sensitively affected by both PEO weight content and PEO chain length. A nonlinear correlation between CO2 permeability with PEO weight content was observed due to the competition between solubility and diffusivity contributions, whereby the copolymers change from being size-selective to solubility-selective when PEO content reaches 40%. CO2 selectivities over H2 and N2 increase monotonically with both PEO content and chain length, indicating strong CO2-philicity of the copolymers. The copolymer film with the longest PEO sequence (PEO2000) and highest PEO weight content (60%) showed a measured CO2 pure gas permeability of 39 Barrer, and ideal CO2/H2 and CO2/N2 selectivities of 4.1 and 46, respectively, at 35 °C and 3 atm, making them attractive for hydrogen purification and carbon capture.

Synthesis and characteristics of biobased copolyester for thermal shrinkage film

A series of poly(1,4-cyclohexanedimethyl-trimethylene glycol terephthalate), (PCTG), co-polyesters were synthesized using 1,3-propanediol (PDO) and 1,4-cyclohexanedimethanol (CHDM) via melt polymerization.