Improvement of the quadratic non-linear optical properties of pyrimidine chromophores by N-methylation and tungsten pentacarbonyl complexation

In this contribution, we report the synthesis of two series of compounds: 4-(arylvinyl)-1-methylpyrimidinium derivatives and tungsten pentacarbonyl complexes of 4-(arylvinyl)pyrimidines. Their second order non-linear properties, measured by Electric-Field Induced Second Harmonic generation (EFISH) method, and their photophysical behavior were thoroughly investigated and compared to the corresponding 4-(arylvinyl)pyrimidines. A strong enhancement of the NLO response was observed upon methylation or complexation by W(CO)5 of the pyrimidine ring. DFT theoretical calculations were performed to provide complementary insights on the structure-properties relationships in particular concerning the amplitude of the NLO response.