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 10-20 nm 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.