V-Shaped Methylpyrimidinium Chromophores for Nonlinear Optics

A series of four V-shaped methylpyrimidinium salts bearing diphenylamino-electron-donating groups appended at various pyrimidine positions were designed. These chromophores were obtained by regioselective N(1) monomethylation by methyl methanesulfonate of the pyrimidine core. Linear optical properties were studied experimentally and electronic properties were further completed by (TD)-DFT calculations. The second-order nonlinear optical (NLO) properties were also studied using electric field induced second harmonic generation (EFISH) method in chloroform, and all pyrimidinium salts exhibited mu beta(0)>1000x10(-48) esu. The 2,4-disubstituted pyrimidinium core is preferred over 4,6-disubstitution as it enhances the NLO response and increases the dipole moment. (E,E)-2,4-Bis[4-(diphenylamino)styryl]-1-methylpyrimidin-1-ium methanesulfonate appears to be the best NLO-phore in chloroform in the series (mu beta(0)=2500x10(-48) esu) and a figure of merit mu beta(0)/MW=3.4 10(-48) esu mol g(-1).

Automated summary

A series of V-shaped methylpyrimidinium salts with diphenylamino-electron-donating groups were designed, showing good NLO properties in the study. The 2,4-disubstituted pyrimidinium core exhibited enhanced NLO response and increased dipole moment compared to 4,6-disubstitution. Among the series, (E,E)-2,4-Bis[4-(diphenylamino)styryl]-1-methylpyrimidin-1-ium methanesulfonate was identified as the best NLO-phore with a figure of merit of mu beta(0)/MW=3.4x10(-48) esu mol g(-1).