PHOTOINDUCED ELECTRON-TRANSFER VARIABLES - RIGIDITY OR ORIENTATION

The relative photoreactivities of bridged-ring systems 1, 3, 5-X and 6 -X (X = Cl or Br) have been studied at 254 nm in acetic acid. The form ation of photosolvolysis products was rationalized in terms of photoin duced intramolecular electron transfer (ET) processes. The relative ea se of ET in these donor-bridge-acceptor model systems was analyzed in terms of known ET variables including free-energy changes, orientation effects and rigidity effects. The observed relative photoreactivities agreed better with the calculated free-energy changes when relative r igidities of the electron acceptor termini were evaluated. In general, the more rigid systems were more photoreactive.