Growth of molecular designed crystal in alkane solvents: Self assembly of ionic liquid with alcohol
* DATE / TIME
2012-09-03, 4:00 PM
503 Conference room, APCTP Headquarters, Pohang
Dispersed 1-tetradecyl-3-methylimidazolium chloride ([C14MIM]Cl) ionic liquid (IL) into 97 weight % alkane solvents makes phase separation, but it starts to aggregate self-assembly by adding 1-octanol (molar ratio of IL/octanol is 1/3). When we observed with microscope, some of domain were selectively grows up to rod-like single crystals after several days. For the various solvents, 1-hexane, 1-octane, 1-decane, and 1-dodecane, 2- methyloctane, crystal growth was maximized in 1-octane solvent expecting to reduce the mismatch energy. Observed maximum length was 5.2 mm and analyzed growth rate was 7.0 (days)-1. Two different projection angles, 88 and 62 degrees were observed, but 62 degree was solely detected for IL/octanol > 1 and it was concluded as a crystal wedge angle. For IL/octanol < 1, identical crystal structure represented the composition ratio of IL:octanol is 1:1. By indexing XRD pattern of this crystal we found best solution of crystal structure having c = 24.8 Å which is comparable to the length of IL. Increased 4 Å of lattice parameter along the b-axis (normal to the imidazoliurm ring plane) distinguished itself against the triclinic structure of annealed [C14MIM]Cl powder (Chem. Mater. 2004 16, 43-48), and it well corresponded with interspaced octanol molecule.