Organogels derived from tetranitrated crown ethers

Organic Letters

Volumn 8, Issue 7, 2006, Pages 1371-1373

  Langford, Steven J ^a   Latter, Melissa J ^a   Lau, Vei Lin ^a   Martin, Lisandra L ^a   Mechler, Adam ^a  

^a MONASH UNIVERSITY   (Australia)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33645940614     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol060142j     Document Type: Article

References (30)

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23. Tetranitrodibenzo-18-crown-6 was found to be an inefficient gelator because of its low solubility in the solvents tested.
24. 3 showed no significant differences between liquid and gel states for both proton and carbon spectra in the presence of an external standard apart from an expected broadening.
25. DSC was conducted on a TA Q100 instrument using a ramping method starting at 40 °C with 10 °C/minute.
26. The application of AFM to measure gel structures is rare, likely because of the complexity of such measurements; however, the visualization of fibrous structures has been reported in ref 11.
27. Samples were imaged in ultrapure water. This technique was employed to overcome the problem associated with the collapse of the gel once the solvent was removed.
28. We used an NT-MDT "NTEGRA" AFM with a 100 μn 3D closed-loop scanner to obtain topography images of gels 3 and 4. Mikromasch NSC 36 B probes (tip apex radius of ∼10 nm. tip height of ∼15 μm, cantilever length of 90 μm. spring constant of ∼1.75 N/m) were used in low-amplitude (∼20 nm) tapping modes. These conditions allow imaging with tapping forces in the nanonewton range, which is essential to minimize the deformation of the gel upon interaction with the probe. Image processing was performed with WsXM 4.0 (www.nanotec.es) and Gwyddion 1.13 (www.gwyddion.net) freewares.
29. Images were recorded using a Hitachi S570 SEM operating at 15 kV. Samples prepared by freeze-drying were transferred to a carbon tab which was gold-sputter coated prior to imaging.
30. Without inviting speculation on the structure of the gel, we have recently described the X-ray structure of 4 from acetonitrile solution. See: Belousoff, M.; Langford, S. J.; Lau, V.-L.; Latter, M. J. Acta Crystallogr., Sect. E 2005, E61, 3284-3285.