Iron-induced cyclodextrin self-assembly into size-controllable nanospheres.
Iron-induced self-assembly of beta-cyclodextrin, beta-CD, into size controllable nanospheres with a well-defined spherical morphology and a relatively narrow size distribution was formed when acetone was added to a solution of beta-CD with iron(II) acetate, Fe(OAc)(2), in DMF. Thermogravimetric analysis, inductively coupled plasma atomic emission spectroscopy, and high resolution transmission electron microscopy showed that the irons were present as a well-dispersed state in the beta-CD nanospheres. In the (1)H NMR spectrum of the beta-CD/Fe(OAc)(2), beta/Fe, solution before adding acetone, the peaks corresponding to beta-CD were broadened and their spin-spin splitting had disappeared. In particular, the beta/Fe solutions were found to remain in a clean solution state at 1 week after solution preparation. These findings indicate the isolation of individual iron ions caused by the surrounding of each ion with the beta-CD molecules in the solution before the addition of acetone. X-ray crystal structure analysis, morphological observations, and N(2) adsorption and desorption experiments showed that the beta-CD nanospheres were generated by the formation of iron-embedded beta-CD primary particles with disordered cage type structure and simultaneous spherical assembly of the primary particles during the addition of acetone to the beta/Fe solution with appropriate mole ratio between beta-CD and Fe(OAc)(2). Interestingly, the size of the beta-CD nanospheres could be simply controlled by changing the speed at which acetone was added to the solution, with higher acetone addition speeds yielding smaller particles.
Chung
Jae Woo
JW
Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-744, Korea.
Kwak
Seung-Yeop
SY
D005290:Ferric Compounds / Q000737:chemistry*; D054118:Nanospheres / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D047392:beta-Cyclodextrins / Q000737:chemistry*
D005290:Ferric Compounds; D047392:beta-Cyclodextrins; C047434:ferric acetate; C031215:betadex