Triptycene Research Articles

Two’s Company, Six is a Crowded Triptycene

Two’s Company, Six is a Crowded Triptycene

New Additions to the Triptycene Family

New Additions to the Triptycene Family

Application of structural principles to the design of triptycene-based molecular gears with parallel axes

This perspective discusses the important aspects of the design of molecular gear systems based on triptycene. Molecular systems are categorized into three classes according to the orientation of the gear axes: i) bent (bevel gears), ii) linear, and ii) parallel (spur gears). To date, no examples of molecular gears in which the axes of rotation lie in parallel have been reported; correspondingly, the bulk of this report focuses on the factors one must evaluate to construct such systems.

Synthesis of Extended Bifunctional Triptycenes

Extended triptycenes 5a,b and 7a-c have been designed to serve as convenient building blocks for a stepwise ramification of the parent triptycene structure by Diels-Alder oligomerization.

Enhancement to the rate-dependent mechanical behavior of polycarbonate by incorporation of triptycenes

The tensile and compressive properties of triptycene-polycarbonates were tested over 6 orders of magnitude in strain rate. Initially we studied a low molecular weight, low triptycene content PC blended with Iupilon® PC and then a series of higher molecular weight, higher triptycene content polymers. The PC blend with only 1.9wt% triptycene displayed up to 20% increase in modulus and up to 17% increase in yield strength with elongations over 80% as compared to the Iupilon® PC. The higher molecular weight T-PCs (up to 26wt% triptycene) exhibited improvements in modulus by over 20% and improvements in compressive strengths by nearly 50% at both low and high strain rates without any apparent sacrifice to ductility, as compared to Iupilon® PC. All samples containing triptycene units retained transparency and exhibited no signs of crystallinity or phase separation. Moreover, both the blends and triptycene-PC copolymers displayed significantly altered dynamic mechanical spectra, specifically, the emergence of a pronounced, new β′ relaxation approximately 75°C above the traditionally observed β relaxation in PC (approximately −100°C). The enhancement of the mechanical properties observed provides valuable insights into the unique packing and interactions during plastic flow induced by the presence of triptycene units.

Triptycenes

In contrast to their inactive parent compound triptycene (code name TT0), several triptycene (TT) analogs (code names TT1 to TT13), most of them new compounds, were synthesized and shown to prevent L1210 leukemic cells from synthesizing macromolecules and growing in vitro. The most potent rigid tetracyclic quinones synthesized so far are TT2 and its C2-brominated derivative, TT13. The antitumor activity of TT2 has been compared to that of daunomycin (DAU), a clinically valuable anthracycline antibiotic which is structurally different from TT2 but also contains a quinone moiety. TT2 inhibits the proliferation (IC50: 300 nM at day 2 and 150 nM at day 4) and viability (IC50: 250 nM at day 2 and 100 nM at day 4) of L1210 cells to the same maximal degree as DAU, suggesting that the cytostatic and cytotoxic activities of TT2 are a combination of drug concentration and duration of drug exposure. Since TT2 does not increase the mitotic index of L1210 cells at 24 h like vincristine, it is unlikely to be an antimitotic drug that disrupts microtubule dynamics. Like DAU, a 1.5-3 h pretreatment with TT2 is sufficient to inhibit the rates of DNA, RNA and protein syntheses determined over 30-60 min periods of pulse-labeling in L1210 cells in vitro (IC50: 6 microM). In contrast to DAU, which is inactive, a 15 min pretreatment with TT2 has the advantage of also inhibiting the cellular transport of nucleosides occuring over a 30 s period in vitro (IC50: 6 microM), suggesting that TT2 prevents the incorporation of [3H]thymidine into DNA because it rapidly blocks the uptake of [3H]thymidine by the tumor cells. After 24 h, TT2 induces as much DNA cleavage as camptothecin and DAU, two anti-cancer drugs producing DNA strand breaks and known to respectively inhibit DNA topoisomerase I and II activities. Interestingly, the abilities of TT2 to block nucleoside transport, inhibit DNA synthesis and induce DNA fragmentation are irreversible upon drug removal, suggesting that this compound may rapidly interact with various molecular targets in cell membranes and nuclei to disrupt the functions of nucleoside transporters and nucleic acids, and trigger long-lasting antitumor effects which persist after cessation of drug treatment. Because inhibition of nucleoside transport is highly unusual among DNA-damaging drugs, the use of bifunctional TTs with antileukemic activity in the nM range in vitro might provide a considerable advantage in polychemotherapy to potentiate the action of antimetabolites and sensitize multidrug-resistant tumor cells.

One-and two-photon fluorescence excitation spectra of multi-chromophoric molecules

The splittings in S 1 states of molecules containing weakly coupled π-chromophoric groups have been determined through one-and two-photon fluorescence excitation (OPF and TPF) spectroscopy. The 1B 2u state of benzene splits by about 140 cm -1 in the dimer, dihydroanthracene (DHA) and by about 2500 cm -1 in the strained trimer,triptycene (TR). While the exciton splitting in the trans-dimer of acenaphthylene (TDA), in which the two naphthalene moieties are linked by two ethylene bridges, is only 130 cm -1, no such near degeneracies are noticed in two-methylene-bridge-linked dihydrodibenzanthracene (DBA) or dihydropentacene (DHP).

Symmetrically trisubstituted triptycenes

Symmetrically trisubstituted triptycenes

The synthesis of perfluoro-1,6-disubstituted triptycenes containing group IV and group V elements

The step-wise syntheses, starting from 1,2-dibromotetrafluorobenzene, of eight fully-fluorinated 1,6-disubstituted triptycenes is described. In each case the intermediate tris(2-bromotetrafluorophenyl) compounds were isolated and characterized.

Optically Active Triptycenes, III. Synthesis of Optically Active 2-Methoxy-5-acyloxy- and 2-Acyloxy-5-methoxy-7-methoxycarbonyltriptycenes

Optically Active Triptycenes, III. Synthesis of Optically Active 2-Methoxy-5-acyloxy- and 2-Acyloxy-5-methoxy-7-methoxycarbonyltriptycenes

Nitration of triptycene

Nitration of triptycene