Spectroscopic properties of cyclophane/anthracene and cyclophane/9-fluorenone complexes in dichloromethane

摘要

Host/guest interactions of cyclophane/anthracene (C/A) and cyclophane/9-fluorenone (C/F) complexes in dichloromethane, where the cyclophane molecule is the host, are investigated. The stability constants, log K-a, for the C/A and C/F complexes are determined by absorption and fluorescence spectroscopy. For the C/A system, log K-a is 4.2 +/- 0.2 as determined from absorption (at 325 nm) and emission (at 382, 403 and 427 nm) spectroscopic data. The analogous measurements yield 3.6 +/- 0.2 from absorption (at 309 nm) and emission (at 505 nm) spectroscopic data for the C/F system. Heats of formation of these complexes were determined by measuring the complex association constants at 25, 29 and 32 degrees C. These results reveal that binding of the anthracene guest by this cyclophane molecule is thermodynamically favored over that for a 9-fluorenone guest. Excited state lifetimes of these systems are also determined. (c) 2004 Elsevier B.V. All rights reserved.