Sample Originator: Michael B. Hursthouse, Simon J. Coles, J. -P. Desvergne, H. Bouas-Laurent, J. H. R. Tucker, G. McSkimming and Mark E. Light.



Identification Number:10.5258/ecrystals/91
Date Created:17 January 2001
Deposited On:21 Jan 2008 15:29
Deposited By:A.N. Admin

Depositor Comments

Aza-crown ethers 2 and 3 with anthracene-containing pendant arms have been synthesised and characterised. Both compounds bind Group 1 metal cations in solution, forming complexes of 1:1 stoichiometry. The properties of compound 2 and its complexes have been studied by a range of techniques, including NMR, UV and fluorescence spectroscopy and X-ray crystallography. The pendant arms can adopt either a cis or a trans geometry, the cis geometry favoured with larger cations. The geometry of the complex affects the fluorescence properties of the system, with larger cations giving higher excimer/monomer ratios. Upon irradiation at >300 nm, coronand 2 forms the cryptand 5 through a reversible intramolecular [4+4] cycloaddition reaction. The rates of the forward and reverse reactions of this photochromic process are cation dependent; in particular the rate of the thermal reverse reaction is decreased by smaller cations and increased by larger cations, especially Rb+. The metal binding constants in methanol for 2 and 5 have been determined, revealing that the cryptand 5 binds Na+ and Rb+ more weakly than crown ether 2 by over two orders of magnitude.

Data collection parameters

Chemical formulaC44 H50 N2 O6
Crystal morphology
Crystal systemMonoclinic
Space group symbolP2(1)/c
Cell length a10.579(2)
Cell length b17.772(4)
Cell length c10.1254(16)
Cell angle alpha90.00
Cell angle beta93.545(6)
Cell angle gamma90.00
Data collection temperature150(2)

Refinement results

Solution figure of merit0.2160
R Factor (Obs)0.0788
R Factor (All)0.3258
Weighted R Factor (Obs)0.1280
Weighted R Factor (All)0.1988

Citation: Hursthouse, Michael B. and Coles, Simon J. and Desvergne, J. -P. and Bouas-Laurent, H. and Tucker, J. H. R. and McSkimming, G. and Light, Mark E. (2001) University of Southampton, Crystal Structure Report Archive. (doi:10.5258/ecrystals/91)
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