Triptycene Moiety Research Articles

Analysis of governing factors controlling gas transport through fresh and aged triptycene-based polyimide films

The fundamental gas transport properties and physical aging behavior of a series of triptycene-based polyimides with various substitution groups were investigated. Wide-angle x-ray diffraction revealed that the 6FDA-1,4-triptycene polyimides exhibit two chain packing domains with d-spacing values of ~6.7Å and ~5.3Å, corresponding to triptycene-induced chain packing disruption and chain segments lacking the triptycene moiety, respectively. Positron annihilation lifetime spectroscopy (PALS) showed a bimodal distribution of microcavity size made up of triptycene cleft cavities that are ~3Å diameter and larger interchain cavities with an average diameter of ~7Å. Additionally, PALS confirmed 6FDA-1,4-trip_CH3 has the lowest fractional free volume, primarily due to smaller contributions from the interchain cavities, and 6FDA-1,4-trip_CF3 has the largest fractional free volume. It was also found that the addition of substituent groups had a unique and positive effect on the aging properties over nine months, in which the addition of CH3 and CF3 groups led to permeability increases of ~20% and ~40%, respectively. This is caused by the combination of the lowered driving force for physical aging, the substituent groups sterically hindering tighter packing with time, and the interconnectivity and/or unblocking of free volume over time through small-scale, local chain motion.

Triptycene-Roofed Quinoxaline Cavitands for the Supramolecular Detection of BTEX in Air.

Two novel triptycene quinoxaline cavitands (DiTriptyQxCav and MonoTriptyQxCav) have been designed, synthesized, and applied in the supramolecular detection of benzene, toluene, ethylbenzene, and xylenes (BTEX) in air. The complexation properties of the two cavitands towards aromatics in the solid state are strengthened by the presence of the triptycene moieties at the upper rim of the tetraquinoxaline walls, promoting the confinement of the aromatic hydrocarbons within the cavity. The two cavitands were used as fiber coatings for solid-phase microextraction (SPME) BTEX monitoring in air. The best performances in terms of enrichment factors, selectivity, and LOD (limit of detection) values were obtained by using the DiTriptyQxCav coating. The corresponding SPME fiber was successfully tested under real urban monitoring conditions, outperforming the commercial divinylbenzene-Carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fiber in BTEX adsorption.

Enhancing photophysical and photochemical properties of zinc(II) phthalocyanine dyes by substitution of triptycene moieties

The symmetrical zinc(II) phthalocyanines conjugated with 9,10-dioctyl-6,7-dimethoxy-2,3-dioxytriptycene or 9,10-diundecyl-6,7-dimethoxy-2,3-dioxytriptycene moieties were synthesized in this study. These novel phthalocyanines were characterized by standard characterization techniques such as 1H-NMR, FT-IR, UV–vis, Mass and Elemental Analysis. All these phthalocyanines showed highly solubility and formed non-aggregated monomeric species in most of the organic solvents. Their photochemical properties such as singlet oxygen, and photodegradation quantum yields, and photophysical properties including fluorescence quantum yields and lifetimes were investigated in toluene. The fluorescence quenching behavior of the studied zinc(II) phthalocyanines by the addition of 1,4-benzoquinone were also described in toluene.

Preparation of fluorinated polyimides with bulky structure and their gas separation performance correlated with microstructure

The fluorinated polyimides with high fractional free volume were prepared from 6FDA and aromatic diamines with bulky triptycene and pendent phenyl moieties. These polymers showed excellent solubility, high thermal stabilities and outstanding mechanical properties. The correlation of gas separation performance with the microstructure of these polyimide membranes was investigated. The results indicated that the GSPI-P membranes based on the diamines with pendent phenyl moieties exhibited higher fractional free volumes than GSPI-T membranes derived from diamines with triptycene moieties; as a result, the former gave the much higher permeability coefficients. The gas permeability of these membranes is strongly depended on their free volume and also affected by fluorine content. The GSPI-P membranes also provided good selectivity for CO2/CH4 and CO2/N2 gas pairs because their appropriate cavity size is favorable to separate the CO2 from the other gases.

Chiral nanocomposites based on thermally stable poly(amide–imide) having S-valine groups and α-Fe2O3 nanoparticles

A novel chiral poly(amide–imide) (PAI) containing triptycene and S-valine moieties was prepared from the polycondensation reaction of N,N′-(pyromellitoyl)-bis-S-valine diacid chloride with bis(4-aminophenoxy)phenyl triptycene. The new PAI/α-Fe2O3 nanocomposites were prepared via ultrasonic irradiation process by dispersing silane coupling agent modified α-Fe2O3 nanoparticles in the polymer matrix. The resulting nanocomposites were characterized by Fourier transform infrared, powder X-ray diffraction, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The TEM results indicated that the nanoparticles were dispersed homogeneously in PAI matrix on nanoscale. TGA confirmed that the thermal stability of the nanocomposite was improved in the presence of α-Fe2O3 nanoparticles.

Gas permeation and physical aging properties of iptycene diamine-based microporous polyimides

The synthesis and gas permeation properties of two 6FDA-dianhydride-based polyimides prepared from 2,6-diaminotriptycene (6FDA–DAT1) and its extended iptycene analog (6FDA–DAT2) are reported. The additional benzene ring on the extended triptycene moiety in 6FDA–DAT2 increases the free volume over 6FDA–DAT1 and reduces the chain packing efficiency. The BET surface area based on nitrogen adsorption in 6FDA–DAT2 (450m2g−1) is ~40% greater than that of 6FDA–DAT1 (320m2g−1). 6FDA–DAT1 shows a CO2 permeability of 120 Barrer and CO2/CH4 selectivity of 38, whereas 6FDA–DAT2 exhibits a 75% increase in CO2 permeability to 210 Barrer coupled with a moderate decrease in selectivity (CO2/CH4=30). Interestingly, minimal physical aging was observed over 150 days for both polymers and attributed to the high internal free volume of the shape-persistent iptycene geometries. The aged polyimides maintained CO2/CH4 selectivities of 25–35 along with high CO2 permeabilities of 90–120 Barrer up to CO2 partial pressures of 10bar in an aggressive 50:50 CO2:CH4 mixed-gas feed, suggesting potential application in membranes for natural gas sweetening.

Synthesis, photophysical and photochemical properties of novel phthalocyanines substituted with triptycene moieties

New metal-free and zinc(II) phthalocyanines containing four triptycene moieties were synthesized and characterized by 1H NMR, mass, IR, electronic spectroscopies and elemental analysis as well. The steady-state absorption spectra of the investigated compounds exhibited the main absorption bands in the visible region, at around 700nm. The fluorescence spectra and quantum yields were recorded by steady-state emission measurements. The powerful nanosecond laser flash photolysis technique was employed to record the transient absorption spectra of the long-lived triplet states of the investigated compounds. The singlet oxygen generation and photodegradation properties of the target phthalocyanines under light irradiation were also investigated in tetrahydrofuran solution.

Energy-efficient hydrogen separation by AB-type ladder-polymer molecular sieves.

Increases in hydrogen selectivity of more than 100% compared with the most selective ladder polymer of intrinsic microporosity (PIM) reported to date are achieved with self-polymerized A-B-type ladder monomers comprising rigid and three-dimensional 9,10-dialkyl-substituted triptycene moieties. The selectivities match those of materials commercially employed in hydrogen separation, but the gas permeabilities are 150-fold higher. This new polymer molecular sieve is also the most selective PIM for air separation.

Polyimide Membranes: Ultra‐Microporous Triptycene‐based Polyimide Membranes for High‐Performance Gas Separation (Adv. Mater. 22/2014)

Polymer membranes perform key industrial gas separations. Three-dimensional bridgehead-substituted triptycene moieties integrated into rigid polymer backbones are shown to yield highly permeable and exceptionally sieving membranes, as shown by I. Pinnau and co-workers on page 3688. These transparent, flexible, and robust materials are illustrated in this cover image by O. Kasimova.

Triptycene-derived calixarenes, heterocalixarenes and analogues

With unique three-dimensional triptycene derivatives as the building blocks, several kinds of novel macrocyclic compounds including triptycene-derived calixarenes, heterocalixarenes, N(H)-bridged azacalixarenes, homooxacalixarene analogues, and tetralactam macrocycles could be conveniently synthesized with satisfactory yields by one-pot method or two-step fragment coupling reactions. With rigid triptycene moiety, these macrocyclic hosts not only have large enough cavities, but also show specific fixed conformations. These structural features made them exhibit well molecular recognition toward small organic molecules, fullerenes and organic dyes. Moreover, these macrocycles could also show interest self-assembly abilities in both solution and solid state, which will make them be broad application prospects.

Ultrafast Energy Transfer in Triptycene‐Grafted Bodipy Scaffoldings

A series of new compounds in which various Bodipy dyes are grafted logically on triptycene rigid structures are synthesized and characterized, and their absorption spectra and photophysical properties are studied, also by pump-probe transient absorption spectroscopy. The studied compounds are: the mono-Bodipy species TA, TB, and TC (where A, B, and C identify different Bodipy subunits absorbing and emitting at different wavelengths), the multichromophore species TA3 , which bears three identical A subunits, and the three multichromophoric species TAB, TBC, and TABC, all of them containing at least two different types of Bodipy subunits. The triptycene moiety plays the role of a rigid scaffold, keeping the various dyes at predetermined distances and allowing for a three-dimensional structural arrangement of the multichromophoric species. The absorption spectra of the multichromophoric Bodipy species are essentially additive, indicating that negligible inter-chromophoric interaction takes place at the ground state. Luminescence properties and transient absorption spectroscopy indicate that a very fast (on the picosecond time scale) and efficient photoinduced energy transfer occurs in all the multi-Bodipy species, with the lower-energy Bodipy subunits of each multi-Bodipy compounds playing the role of an electronic energy collector. In TAB, an energy transfer from the A-type Bodipy subunit to the B-type one takes place with a rate constant of 1.6×10(10) s(-1), whereas in TBC an energy transfer from the B-type Bodipy subunit to the C-type subunit is bi-exponential, exhibiting rate constants of 1.7×10(11) and 1.9×10(10) s(-1); the possible presence of different conformers with different donor-acceptor distances in this bichromophoric species is proposed to cause the bi-exponential energy-transfer process. Interpretation of the intricate energy-transfer pathways occurring in TABC is made with the help of the processes identified in the bichromophoric compounds. In all cases, the measured energy-transfer rate constants agree with a Förster mechanism for the energy-transfer processes.

Building large supramolecular nanocapsules with europium cations

A new tripodal ligand has been designed by connecting pyridine-based coordination units to a rigid triptycene moiety. Its reaction with europium(III) provides three-dimensional tetranuclear edifices, whose structural and photophysical characteristics as well as host-guest interactions are discussed in this contribution.

Triptycene poly(ether-imide)s with high solubility and optical transparency

A series of new poly(ether-imide)s containing three-dimensional triptycene moieties were prepared from 1,4-bis(3,4-dicarboxyphenoxy)triptycene dianhydride with various aromatic diamines via a conventional two-stage process. The inherent viscosities of the amic acid prepolymers were in the range of 0.44~0.91 dL/g. Most of the resulting poly(ether-imide)s presented good solubility in many organic solvents and could be solution-cast into transparent and strong films. They also showed good thermal stability with glass-transition temperatures of 238~302 °C and 10% weight loss temperatures in excess of 572 °C. These triptycene-based poly(ether-imide)s showed enhanced optical transparency, decreased color intensity and lowered dielectric constants as compared to conventional aromatic polyimides. The poly(ether-imide)s derived from trifluoromethyl-containing bis(ether amine)s could afford highly optically transparent and almost colorless films.

Supramolecular modification of single-walled carbon nanotubes with a water-soluble triptycene derivative

Supramolecular surface modification of single-walled carbon nanotubes (SWCNTs) using an amphiphilic molecule containing a bent triptycene moiety and a hydrophilic oligo(ethylene glycol) chain is described. The surface modification was realized through the binding of the triptycene moiety onto the sidewall of SWCNTs through a π–π stacking interaction, and the oligo(ethylene glycol) chains extend into the water and act as dispersing agents, thus yielding an aqueous SWCNT dispersion. This dispersion is stable for more than six months and contains a high concentration of SWCNTs. The dispersion was characterized by absorption, fluorescence, and Raman spectroscopy. Based on shape-fitting of SWCNTs and the triptycene moiety, the stacking of triptycene moieties on the SWCNT sidewall shows a nice selectivity for SWCNTs with a diameter of 1.0 nm.

ChemInform Abstract: Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C60 and C70.

Two pairs of novel triptycene-derived calix[6]arenes 4a,b and 5a,b have been efficiently synthesized through both one-pot and two-step fragment-coupling strategies starting from 2,7-bis(hydroxymethyl)-1,8-dimethoxytriptycene 1. Subsequent demethylation of 4a,b and 5a,b with BBr(3) in dry dichloromethane gave the macrocyclic compounds 6a,b and 7a,b. Treatment of either 4a or 6a with AlCl(3) resulted in the same debutylated product 8, while 9 was similarly obtained from either 5a or 7a. Structural studies revealed that all of the macrocycles have well-defined structures with fixed conformations both in solution and in the solid state owing to the introduction of the triptycene moiety with a rigid three-dimensional (3D) structure, making them very different from their classical calix[6]arene counterparts. As a consequence, it was found that all of these the triptycene-derived calix[6]arenes could encapsulate small neutral molecules in their cavities in the solid state. Moreover, it was also found that the macrocycles 4b and 5b showed highly efficient complexation abilities toward fullerenes C(60) and C(70), forming 1:1 complexes with association constants ranging from (5.22+/-0.20) x 10(4) to (8.68+/-0.30) x 10(4) M(-1).

Synthesis and Characterization of Polystyrene Possessing Triptycene Units in the Main Chain by Combination of ATRP and Click Chemistry Processes

Polystyrene with triptcyene units were synthesized by combination of Atom Transfer Radical Polymerization (ATRP) and “Click” chemistry processes and characterized. Well-defined precursor polystyrene with predetermined molecular weight and narrow polydispersity was prepared by ATRP in the presence of Cu(I)/pentamethyldiethylenetriamine (PMDETA) catalyst system and terminal bromine groups of the obtained polymer were converted to azide group by using NaN3. The click reaction between diazido compounds, namely diazido polystyrene (N3-PSt-N3) and diazidodecane (DAD) and dialkyne compounds, dipropargyloxytriptycene (DPT) and dipropargyloxydecane (DPD) resulted in the formation polystyrene with triptycene units in the main chain. Dialkyne compound without triptycene unit such as dipropargyloxybenzene (DPB) was used under the same click conditions for comparison. Characterization of the intermediates and the resulting polymers was performed by means of FT-IR and 1H-NMR spectral analysis, and GPC, DSC and TGA studies. The effect of the triptycene moiety on the thermal properties was evaluated.

Triptycene-Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C60and C70

Two pairs of novel triptycene-derived calix[6]arenes 4a,b and 5a,b have been efficiently synthesized through both one-pot and two-step fragment-coupling strategies starting from 2,7-bis(hydroxymethyl)-1,8-dimethoxytriptycene 1. Subsequent demethylation of 4a,b and 5a,b with BBr(3) in dry dichloromethane gave the macrocyclic compounds 6a,b and 7a,b. Treatment of either 4a or 6a with AlCl(3) resulted in the same debutylated product 8, while 9 was similarly obtained from either 5a or 7a. Structural studies revealed that all of the macrocycles have well-defined structures with fixed conformations both in solution and in the solid state owing to the introduction of the triptycene moiety with a rigid three-dimensional (3D) structure, making them very different from their classical calix[6]arene counterparts. As a consequence, it was found that all of these the triptycene-derived calix[6]arenes could encapsulate small neutral molecules in their cavities in the solid state. Moreover, it was also found that the macrocycles 4b and 5b showed highly efficient complexation abilities toward fullerenes C(60) and C(70), forming 1:1 complexes with association constants ranging from (5.22+/-0.20) x 10(4) to (8.68+/-0.30) x 10(4) M(-1).

Synthesis and characterization of triptycene type cross-linker and its use in photoinduced curing applications

A novel triptycene type diacrylate cross-linker, triptycene hydroquinone diacrylate (THDA) was synthesized from the reaction of triptycene hydroquinone with acryloyl chloride and characterized. The photocuring behaviour and the reaction kinetics of the synthesized cross-linker were investigated by means of photo-differential scanning calorimetry (photo-DSC) experiments. Formulations containing monofunctional (meth)acrylate monomers, namely glycidyl methacrylate (GMA), 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), and 2-ethylhexyl methacrylate (EHMA), cross-linker, THDA and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator were irradiated. A conventional cross-linker without triptycene unit such as hydroquinone diacrylate (HDA) was used under the same conditions for comparison. The effects of the structure of the monofunctional monomer and triptycene moiety on the photopolymerization kinetics were evaluated and discussed.

Supramolecular Surface Modification and Solubilization of Single‐Walled Carbon Nanotubes with Cyclodextrin Complexation

A novel approach to solubilize single-walled carbon nanotubes (SWCNTs) in the aqueous phase is described by employing supramolecular surface modification. We use cyclodextrin complexes of synthetic molecules that contain a planar pyrene moiety or a bent, shape-fitted triptycene moiety as a binding group connected through a spacer to an adamantane moiety that is accommodated in the cyclodextrin cavity. The binding groups attach to the sidewalls of SWCNTs through a pi-pi stacking interaction to yield a supramolecular system that allows the SWCNTs to dissolve in the aqueous phase through the formed hydrophilic cyclodextrin shell. The black aqueous SWCNT solutions obtained are stable over a period of months. They are characterized through absorbance, static, and time-resolved fluorescence spectroscopy as well as Raman spectroscopy, TEM, and fluorescence-decay measurements. Furthermore, the shape-fitted triptycene-based system shows a pronounced selectivity for SWCNTs with a diameter of 1.0 nm.

Synthesis and properties of novel organosoluble polyimides derived from 1,4-bis[4-(3,4-dicarboxylphenoxy)]triptycene dianhydride and various aromatic diamines

A novel triptycene-based dianhydride, 1,4-bis[4-(3,4-dicarboxylphenoxy)]triptycene dianhydride, was prepared from 4-nitro-N-methylphthalimide and potassium phenolate of 1,4-dihydroxytriptycene (1). The aromatic nucleophilic substitution reaction between 4-nitro-N-methylphthalimide and 1 afforded triptycene-based bis(N-methylphthalimide) (2), which hydrolyzed and subsequently dehydrated to give the corresponding dianhydride (3). A series of new polyimides containing triptycene moieties were prepared from the dianhydride monomer (3) and various diamines in m-cresol via conventional one-step polycondensation method. Most of the resulting polyimides were soluble in common organic solvents, such as chloroform, THF, DMAc and DMSO. The polyimides exhibited excellent thermal and thermo-oxidative stabilities with the onset decomposition temperature and 10% weight loss temperature ranging from 448 to 486°C and 526 to 565°C in nitrogen atmosphere, respectively. The glass transition temperatures of the polyimides were in the range of 221–296°C. The polyimide films were found to be transparent, flexible, and tough. The films had tensile strengths, elongations at break, and tensile moduli in the ranges 95–118MPa, 5.3–16.2%, and 1.03–1.38GPa, respectively. Wide-angle X-ray diffraction measurements revealed that these polyimides were amorphous.