Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.


Issue 12, 2004
Previous Article Next Article

Guest sorption and desorption in the metal–organic framework [Co(INA)2] (INA = isonicotinate) – evidence of intermediate phases during desorption

Author affiliations

Abstract

The metal–organic framework [Co(INA)2]·0.5EtOH (INA = isonicotinate, NC5H4-4-CO2), 1 was synthesised under solvothermal conditions. Its X-ray crystal structure shows channels containing ethanol guests which are hydrogen-bonded to carboxylate oxygens of the framework. The pyridyl rings of the framework alternate between ‘open’ and ‘closed’ positions along the channels resulting in large variation in the channel cross-sectional area from ca. 1.4 by 2.3 Å at the narrowest point to 4.9 by 5.3 Å at the widest. Despite the very small windows, the ethanol guests (of van der Waals diameter ca. 4.2–6.1 Å) may be reversibly desorbed and sorbed into the structure quantitatively, as shown by in situ variable-temperture IR spectroscopy and XRPD. The single-crystal structure of the desolvated form [Co(INA)2] 2 shows that there is no change in the overall connectivity on desolvation, but the rotational positions of the pyridine rings are altered. This suggests that pyridyl rotation may occur to allow guests to pass in and out. When the synthesis was conducted in 1-propanol solvent [Co(INA)2]·0.5PrnOH·H2O 3, was obtained, and a single-crystal X-ray structure revealed the same overall connectivity as in 1 but with pyridine rings disordered over closed and open positions. There was no evidence of included guests from X-ray crystallography, suggesting that they are also highly disordered. Variable-temperature XRPD performed on bulk samples showed peaks which were unsymmetrical and exhibited shoulders, suggesting that for each pattern obtained the material actually consisted of several closely-related phases. The movements of the peaks during desolvation showed the presence of intermediate phases before the final desolvated product was formed. The peak positions of the intermediate phases matched more closely with the calculated pattern for 3 than with 1 or 2, suggesting that they may have disordered structures similar to 3. The results also suggest that the intermediate phase represents an initial increase in volume before a larger decrease in volume occurs to give the final desolvated material.

Graphical abstract: Guest sorption and desorption in the metal–organic framework [Co(INA)2] (INA = isonicotinate) – evidence of intermediate phases during desorption

Back to tab navigation

Article information


Submitted
25 Mar 2004
Accepted
07 May 2004
First published
24 May 2004

Dalton Trans., 2004, 1807-1811
Article type
Paper

Guest sorption and desorption in the metal–organic framework [Co(INA)2] (INA = isonicotinate) – evidence of intermediate phases during desorption

Q. Wei, M. Nieuwenhuyzen, F. Meunier, C. Hardacre and S. L. James, Dalton Trans., 2004, 1807
DOI: 10.1039/B404485A

Social activity

Search articles by author

Spotlight

Advertisements