Job/Unit: I20754 /KAP1 Date: 13-09-12 16:52:57 Pages: 7 FULL PAPER DOI: 10.1002/ejic.201200754 Dynamic Constitutional Hybrid Materials – Confined Guanosine Ribbons within Mesoporous Silica Simona Mihai, [a] Justine Dauthier, [a] Yann Le Duc, [a] Abdelsalam El Mansouri, [a] Ahmad Mehdi, [b] and Mihail Barboiu* [a] Keywords: Supramolecular chemistry / Self-assembly / Nucleobases / Hydrogen bonds / Hybrid materials / Mesoporous materials Hydrogen-bonded guanosine (G) dynamic supramolecular architectures exchange between different polymorphs such as G-ribbons, G-quartets and G-quadruplexes. Oriented mesoporous silica can be used as a scaffolding matrix to ori- ent and to stabilize lipophilic guanosine-ribbons in confined conditions. The interface between the lipophilic G-ribbons and the functionalized silica mesopores is based on revers- Introduction Convergent molecular self-assembly in functional supra- molecular architectures can be “frozen” in hybrid materials by using the sol–gel process, which transcribes their specific self-organization into solid hybrids. [1–4] The classical organo- silsesquioxane precursors, in which the organic and inor- ganic components are covalently bonded, require that the complementarity between the self-assembly and the sol–gel polymerization processes be considered as a key point for the design of hybrid supramolecular materials. [2,3] Non- covalent interactions (H-bonds, coordination, van der Waals bonding, etc.) are typically less robust than the cova- lent siloxane bonds formed during the sol–gel process. One solution to overcome these difficulties uses robust or- ganogel templates during the hydrolysis and polycondensa- tion of alkoxysilanes. [4] A second strategy uses a hydro- phobic noncovalent interface between the molecular or- ganic components and the siloxane matrix, which generates dense [5a] and mesoporous hybrids. [5b] On the other hand, dynamically exchanging supramolec- ular guanosine (G) H-bonded architectures that form G- ribbons, G-quartets or G-quadruplexes have been proposed as powerful scaffolds for the construction of synthetic sup- ramolecular devices and materials. [6,7] Moreover, G-quar- [a] Adaptative Supramolecular Nanosystems, Institut Européen des Membranes - IEM-UMII-ENSCM-CNRS 5635, Place Eugène Bataillon, CC 047, 34095 Montpellier, France E-mail: barboiu@iemm.univ-montp2.fr Homepage: http://nsa-systems-chemistry.fr [b] Chimie Moléculaire et Organisation du Solide, CMOS, Institut Charles Gerhardt, UMR 5253 Place Eugène Bataillon, CC 1701, 34095 Montpellier, France Eur. J. Inorg. Chem. 0000, 0–0 © 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1 ible hydrophobic interactions. This contributes to the high level of adaptability and correlativity of the self-organization of the supramolecular G-ribbons and the oriented mesopo- rous silica systems. Biomimetic-type hybrids, in which such structures are extremely stable and robust, can be generated by using this strategy. tets, which are stabilized in the presence of cations, play a very important role in biology, in particular in nucleic acid telomeres of potential interest to cancer therapy. [6] In the absence of metal templates, the substituted guanosine molecules self-assemble into ribbon-like architec- tures, which form lyotropic phases. [6] However, these sys- tems are in general polymorphic and oriented sheetlike architectures are generally difficult to isolate. [7] Within this context, we have recently reported H-bonded macrocyclic systems that lead to columnar architectures, so as to enable ion-transport in lipid bilayers and hybrid membranes. [2a–2d] Such dynamic systems have been set up within the pores of mesoporous silica and evidence was presented that the Scheme 1. Synthesis of the alkylguanosine derivatives 6 and 7.