Selective transportation of metal ions by photo-induced crown ether compounds

A novel photoresponsive system that we call a photo-induced crown ether (PI C) is described, in which excimers are used to fix the conformation of a mo lecule for relatively long periods. 1,n-bis(3-(1-pyrenyl)propylcarboxy)-oxa alkanes (DP3n: n = 3-6), linear oligooxyethylenes with pyrenyl groups at bo th ends, were prepared and investigated to determine whether they might wor k as PICs. DP35 molecules were found to capture and transport calcium ions more effectively when they were irradiated. This result is consistent with the finding that five-unit crown ether transported the greatest amount of c alcium ions. (C) 1999 Elsevier Science B.V. All rights reserved.