ORGN 267 |
| We have recently shown that 4-chlororesorcinol can be utilized to direct the assembly of trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene (2,4'-bpe) in the solid state in a geometry suitable for an [2+2] photodimerization, which results in the quantitative formation of a head-to-tail isomer of rctt-1,2-bis(2-pyridyl)-3,4-bis(4-pyridyl)cyclobutane (2,4'-tpcb-hh) (where: hh = head-to-head). We have also demonstrated that that 2,4'-tpcb-hh can serve as a scaffold for metal-organic frameworks (MOFs) with cavities that are decorated with 2-pyridyl functionalities acting as free binding sites (Hamilton et al. J. Mol. Struct. 2006, 796, 58). Since the size of the cavities allows the binding of exclusively small molecules, we wish to synthesize analogues of 2,4'-tpcb-hh with extended monodentate units that are decorated with hydrogen-bond acceptor groups. Such ligands can serve as building block for MOFs with large functionalized cavities, which are able to accommodate bulky hydrogen-bonding molecules. Our synthetic approach is based on the design of a head-to-tail cyclobutane building-block with bromophenyl functionalities (2, scheme below), which can be further functionalized with various extended monodentate functionalities via palladium-catalyzed coupling reactions. Precursor 2 was synthesized via a template-directed [2+2] photodimerization of 1 in the solid state using 4,6-dibromo-resorcinol as linear template. Efforts to synthesize 3.1 and 3.2 are under way and will be reported later on.
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Molecular Recognition and Self Assembly
1:00 PM-4:40 PM, Monday, April 7, 2008 Morial Convention Center -- Rm. R04, Oral
Division of Organic Chemistry |
