Magnetic field and methylene chain length effects on photochemistry of bichromophoric chain species containing 7-nitro-2-fluorenyloxy and anilino chromophores

The magnetic field effects (MFEs) and methylene chain length effects on photochemistry of [(7-nitro-2-fluorenyloxy)alkyl]aniline have been investigated by means of electronic absorption spectroscopy and high performance liquid chromatography (HPLC). When the number of methylene groups was 12, appreciable MFEs were detected on photoredox reaction yields, while when the chain length was short (three or six methylenes) almost no MFEs on photoproduct yield were observed. Photoinduced absorbance changes suggest that the photochemical reaction mechanism for the long-chain species is totally different from that for the short-chain compounds. MFEs on photoproduct yields observed for the long-chain species can be explained in terms of competition between cage and escape processes, spin-lattice relaxations and methylene chain dynamics which governs the interconversion between folded and extended conformers.