Self-Complementary [2]Catenanes and Their Related [3]Catenanes

Abstract

Three [3]catenanes with cavities large enough to accommodate aromatic guests have been designed and synthesized (yields = 5-20 %) by means of kinetically controlled self-assembly processes. The X-ray structural analysis of one of three [3]catenanes confirmed the presence of a rectangular cavity (dimensions = 7 x 11 A) lined by pi-electron-rich recognition sites and hydrogen-bond acceptor groups. In spite of their apparently ideal recognition features, none of these [3]catenanes bind guests incorporating a pi-electron-deficient bipyridinium unit. However, the template-directed syntheses of the [3]catenanes also produce, in yields of 2-23%, [2]catenanes incorporating a 1,5-dioxynaphtho[38]crown-10 interlocked with a bipyridinium-based tetracationic cyclophane. The X-ray structural analyses of two of these [2]catenanes revealed that a combination of [pi...pi] and [C-H...pi] interactions is responsible for the formation of supramolecular homodimers in the solid state. 1H NMR spectroscopic investigations of the four [2]catenanes demonstrated that supramolecular homodimers are also formed (Ka= 17-31M(-1), T= 185 K) in (CD3)2CO solutions. Dynamic 1H NMR spectroscopy revealed that the 1,5-dioxynaphtho[38]crown-10 and tetracationic cyclophane components in the four [2]catenanes and in the three [3]catenanes circumrotate (deltaGc(not equal to) = 9-14 kcal mol(-1)) through each other's cavity in (CD3)2CO. Similarly, the 1,5-dioxynaphthalene and the bipyridinium ring systems rotate (deltaGc(not equal to) =10-14 kcal mol(-1)) about their [O...O] and [N...N] axes, respectively, in solution.

Chemical synthesis gets a fillip from molecular recognition and self-assembly processes

“…Although good circumstantial evidence has been presented above for the self organization of the same (2)catenanes in an analogously intermolecular manner at air-water interfaces in Langmuir troughs before their being transferred to different substrates, we have uncovered, during a quest to synthesize a (3)rotacatenane (24), some clearcut examples (25) of (2)catenanes, incorporating 1,5-dinaphtho (38)crown-10 interlocked with bipyridinium-based tetracationic cyclophanes that form supramolecular homodimers in solution as well as in the solid state. The (2)catenane 8⅐4PF 6 , shown in Fig.…”

Design, synthesis, crystallization and biological evaluation of new symmetrical biscationic compounds as selective inhibitors of human Choline Kinase α1 (ChoKα1)

“…The first is the treatment of the 4-methylphenol (6) in ethanol with NaOH (1.1 equiv) stirring at room temperature for 30 min, followed by the addition of 1,2-dibromoethane (0.5 equiv), under microwave irradiation (130 °C, 28 min) to provide the 1,2-bis( p -methylphenoy)ethane ( 7 ) 44 45 . Then, bromination in the methylene of 7 with NBS and dibenzoylperoxide in CCl 4 also under microwave irradiation (120 °C, 21 min), to give the 1,2-bis(4-bromomethylphenoy)ethane ( 8 ) 45 46 . In comparison with conventional (thermal) heating, the microwave heating reduced the reaction time in both reactions (30 min vs. 8 h and 21 min vs. 5 h, respectively), but we also noted some yield improvement (35% vs. 21% and 65% vs. 39%, respectively) 45 46 .…”

Synthesis of New [γ-(Aryl)pyridino]dibenzo-27,28-Diazacrownophanes Containing Two Pyridine Rings

“…The parent compound (3) was effectively prepared from 2'-hydroxyacetophenone and 2,6-bis(tosyloxymethyl) pyridine (2) by using a known procedure [6] (Scheme 1).…”

“…PASS [6] was used to evaluate the general bioactivity potential of an organic drug-like molecule. Therefore, computer-aided drug discovery program was applied to predict the biological activities of synthesized compounds before in vitro testing ( Table 2).…”

“…Compound 2,6-bis(tosyloxymethyl)pyridine (2) was synthesized based on the method described earlier. [6] Synthesis of 2,6-bis [(2-acetophenyl)oxymethyl]pyridine (3). A solution of 1.37 g (3.00 mmol) 2,6-bis(tosyloxymethyl)pyridine (2), 1.00 ml (8.30 mmol) 2'-hydroxyacetophenone and 2.00 g (14.50 mmol) K 2 CO 3 in 10.00 ml acetonitrile was heated to reflux for 16 h. After that the mixture was cooled at ambient temperature, 500 ml ice water (0-4 °C) was added, then a slightly pink precipitate appeared.…”