The effect of high pressure on the twisted intramolecular charge transfer of 2-(4-dimethylaminonaphthalen-1-ylmethylene) malononitrile

The effect of pressure up to 65 kbar has been measured on the steady-state and time-dependent fluorescence of 2-(4-dimethylaminonaphthalen-1-ylmethylene)malononitrile (DMANMN) in four polymer matrixes [poly(methyl methacrylate), poly(acrylic acid), poly(vinyl chloride) and cellulose acetate]. The fluorescence intensity increases with pressure by a factor of 24-34 in different polymers. The formation of a twisted intramolecular charge transfer state is effectively retarded by pressure above 40 kbar. The abnormal photophysics of DMANMN in poly(acrylic acid) is the result of protonation of the dimethylamino group.