Effects of methyl substitution of metal (II) bis(2-(2-hydroxyphenyl) benzothiazolate) chelates on optical properties

The influence of methyl substitution on three-position of metal (II) bis(2-(hydroxyphenyl)benzothiazolate) on thermal stability, photophysical, electronic structure, and electrochemical properties was investigated. Experimental results show that methylated complexes were more thermally stable and had 10–20nm red shift in emission wavelength. Quantum chemistry calculation indicated that the methyl substitution affects mostly the highest occupied molecular orbitals charge distribution. In addition, the introduction of electro-donating methyl group can produce a decrease in the energy of the lowest unoccupied molecular orbitals.