PL 7 Calixarenes in Action: From Anion Recognition to DNA Condensation and RNA Cleavage Rocco Ungaro Dipartimento <strong>di</strong> Chimica Organica e Industriale, <strong>Università</strong> <strong>degli</strong> <strong>Stu<strong>di</strong></strong> <strong>di</strong> Parma and INSTM, Sezione <strong>di</strong> Parma, Viale G.P. Usberti 17/A, I-43100-Parma (Italy) Anion Recognition is an important topic in Supramolecular Chemistry and has been tackled using various strategies depen<strong>di</strong>ng on the particular application which one aims to. For many years we have been particularly interested in the synthesis of selective receptors for carboxylate anions, which are substrates of biological interest, using calixarenes as scaffolds and hydrogen bon<strong>di</strong>ng as the main supramolecular interaction. [1] More recently, we have adorned the upper rim of calix[n]arenes, having <strong>di</strong>fferent sizes and Figure Cl Cl Cl + H2N H N + + 2 NH2 H N Cl 2 NH + 2 NH HN NH2 HN H N HN 2 NH2 O O O O R R R R R = C 3 H 7 : 4G4Pr-cone R = C 6 H 13 : 4G4Hex-cone R = C 8 H 17 : 4G4Oct-cone Cl H2N + H N NH 2 + NH2 Cl H N NH 2 OMe MeO OMe HN Cl + NH2 shapes, with guani<strong>di</strong>nium groups and used the resulting water soluble multivalent ligands (Figure) in DNA bin<strong>di</strong>ng and cell transfection. By Atomic Force Microscopy (AFM) it has been possible to correlate the topology of the ligands with their DNA condensation and transfection ability. [2] In collaboration with Mandolini’s and Reinhoudt’s groups we have synthesized a series of calix[4]arenes bearing at the upper rim a variable number of metal ion chelating units such as aza macrocycles ([12]aneN3) or 2,6-bis[(<strong>di</strong>methylamino)methyl]pyri<strong>di</strong>ne (DMAP). The Zn(II) or Cu(II) complexes of these multivalent ligands are able to catalyze the methanolysis of aryl esters and the cleavage of phospho<strong>di</strong>ester bonds in oligoribonucleotides, showing substrate selectivity and cooperativity between the metal centers. [3] An overview of the most recent results obtained using anion receptors, multivalent ligands, and supramolecular catalysts based on calixarenes will be given in the lecture. [1] A. Casnati, F. Sansone, R. Ungaro, Acc. Chem. Res. 2003, 36, 246-254. A.V. Yakovenko,.I. Boyko, V. Kalchenko, L. Bal<strong>di</strong>ni, A. Casnati, F. Sansone, R. Ungaro, J. Org. Chem. <strong>2007</strong>, 72(9), 3223-3231. [2] F. Sansone, M. Du<strong>di</strong>, G. Donofrio, C. Rivetti, L. Bal<strong>di</strong>ni, A. Casnati, S. Cellai, R.Ungaro, J. Am. Chem. Soc. 2006, 128, 14528 – 14536. L. Bal<strong>di</strong>ni, A. Casnati, F. Sansone, R. Ungaro, Chem. Soc. Rev. <strong>2007</strong>, 34, 254-266. [3] R. Cacciapaglia, A. Casnati, L. Mandolini, D.N. Reinhoudt, R. Salvio, A. Sartori, R. Ungaro, J. Am. Chem. Soc. 2006, 128, 12322-12330 and references therein. OMe NH 2 N H 2 n-3 N H n = 4: 4G4Me-mobile n = 6: 6G6Me-mobile n = 8: 8G8Me-mobile Cl + NH2 + + Cl H Cl 2N NH2 N H 2 NH O O O HN O NH 2 NH HN Cl H2N + NH2 H2N 4G4Pr-alt Cl NH2 + PL 8 From Supramolecular Chemistry to Constitutional Dynamic Chemistry Jean-Marie Lehn ISIS, Université Louis Pasteur, Strasbourg and Collège de France, Paris Supramolecular chemistry is actively exploring the design of systems undergoing selforganization, i.e. systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components, on the basis of the molecular information stored in the covalent framework of the components and read out at the supramolecular level through specific interactional algorithms, thus behaving as programmed chemical systems. The implementation of such molecular information-controlled self-organizing processes for the generation of functional nanostructures provides a powerful approach to nanoscience and nanotechnology . Supramolecular chemistry is intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their constituents. The same holds for molecular chemistry when the molecular entity contains covalent bonds that may form and break reversibility, so as to allow a continuous change in constitution by reorganization and exchange of buil<strong>di</strong>ng blocks. These features define a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels. CDC introduces a para<strong>di</strong>gm shift with respect to constitutionally static chemistry. The latter relies on design for the generation of a target entity, while CDC takes advantage of dynamic <strong>di</strong>versity to allow variation and selection. The implementation of selection in chemistry introduces a fundamental change in outlook. Thus, self-organization by design strives to achieve full control over the output molecular or supramolecular entity by explicit programming, whereas self-organization with selection operates on dynamic constitutional <strong>di</strong>versity in response to either internal or external factors to achieve adaptation. Applications of this approach in biological systems as well as in materials science will be described. The merging of the features: - information and programmability, - dynamics and reversibility, -constitution and structural <strong>di</strong>versity, points towards the emergence of adaptive chemistry. Lehn, J.-M., Supramolecular Chemistry: Concepts and Perspectives, VCH Weinheim, 1995. Lehn, J.-M., Dynamic combinatorial chemistry and virtual combinatorial libraries, Chem. Eur. J., 1999, 5, 2455. Lehn, J.-M., Programmed chemical systems : Multiple subprograms and multiple processing/expression of molecular information, Chem. Eur. J., 2000, 6, 2097. Lehn, J.-M., Toward complex matter: Supramolecular chemistry and self-organization, Proc. Natl. Acad. Sci. USA, 2002, 99, 4763. Lehn, J.-M., Toward self-organization and complex matter, Science, 2002, 295, 2400. Lehn, J.-M., Dynamers : Dynamic molecular and supramolecular polymers, Prog. Polym. Sci., 2005, 30, 814. Lehn, J.-M., From supramolecular chemistry towards constitutional dynamic chemistry and adaptive chemistry, Chem. Soc. Rev., <strong>2007</strong>, 36, 151.
Exercising Demons: Synthetic Molecular Motors and Machines Dave Leigh School of Chemistry, University of E<strong>di</strong>nburgh, The King’s Buil<strong>di</strong>ngs, West Mains Road, E<strong>di</strong>nburgh EH9 3JJ, UK David.Leigh@ed.ac.uk; http//www.catenane.net or www.rotaxane.net An exciting contemporary area of chemistry is making molecules with moving parts, with the goal that they can function as nanoscopic machines capable of performing physical tasks. To do so for any molecular machine more sophisticated than a simple switch requires the introduction of ratchet principles into synthetic molecular structures. We will <strong>di</strong>scuss some of the latest developments from our group in this area, inclu<strong>di</strong>ng the experimental realisation of both energy ratchets and information ratchets. [1] [1] For some recent papers from the Leigh group see: Nature, 424, 174-179 (2003); Science, 299, 531 (2003); Science, 306, 1532-1537 (2004); Proc Natl Acad Sci USA, 102, 13378-13382 (2005); Nature Mater, 4, 704-710 (2005); Angew Chem Int Ed, 44, 3062-3067 (2005); Angew Chem Int Ed, 44, 4557-4564 (2005); J Am Chem Soc, 127, 12612-12619 (2005); Proc Natl Acad Sci USA, 103, 17650-17654 (2006); Nature, 440, 286-287 (2006); J Am Chem Soc, 128, 526-532 (2006); J Am Chem Soc, 128, 1784-1785 (2006); J Am Chem Soc, 128, 2186-2187 (2006); J Am Chem Soc, 128, 4058-4073 (2006); Angew Chem Int Ed, 45, 77-83 (2006); Angew Chem Int Ed, 45, 1385-1390 (2006); J Am Chem Soc, 129, 476-477 (<strong>2007</strong>); Angew Chem Int Ed, 46, 72-191 (<strong>2007</strong>); Nature, 445, 523-527 (<strong>2007</strong>). ICA
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