With the objective to study the effect of alkoxy terminal chain length on mesomorphic properties of liquid crystals, we have synthesized two (Azo and Imine) different series of dimesogens by varying terminal alkoxy chain length (n=6-12) with a short spacer unit in between two mesogens. Transition temperatures and phase characterization were studied by DSC, POM and XRD analysis. It was found that all the dimers show mesomorphic properties and the change in terminal alkoxy chain length has pronounced effect on the smectic phase window. In the DSC cooling scan, the smectic phase window of azo compounds increased from 6.4 degrees C (2A(6)) to 16.0 degrees C(2A(12)), whereas in Schiff base compounds, it increased from 9.2 degrees C (2S(6)) to 31.0 degrees C(2S(12)). Further, the 2A(11) dimer was found to undergo photo induced configurational changes.