Effects of the substituting groups and proton abstraction on the nonlinear optical properties of heteroleptic bis-tridentate Ru(II) complexes

► βvec value increases with the increasing electron-donating ability of the group. ► Deprotonation affects βvec value and causes an efficient second-order NLO switching. ► Deprotonation has also an influence on the βvec sign from positive to negative.