Synthesis and nonlinear optical properties of rod-like luminescent materials containing Schiff-base and naphthalimide unitsElectronic supplementary information (ESI) available: DSC of 2A and 3B, and a picture of the smectic F phase for 3B. See http://www.rsc.org/suppdata/jm/b1/b109384n/

Two series of novel rod-like compounds containing Schiff-base and naphthalimide units were synthesized. The liquid crystalline and amorphous phases of these compounds have been studied by differential scanning calorimetry (DSC), polarizing microscopy and X-ray diffraction. It was found that compounds 1A, 2A and 3A with a bridge of benzene show an amorphous glassy state, whereas compounds 1B, 2B and 3B with 2,5-dioctyloxy-1,4-bis(phenylenevinylene)benzene as a bridge exhibit smectic F and nematic mesomorphic phases. These rod-like compounds emit yellow–green light with the photoluminescent peak at about 505 nm and have relatively high quantum yields. The nonlinear optical properties of the compounds have been investigated by using a second harmonic generation (SHG) technique on a Langmuir–Blodgett monolayer. Compound 3B exhibits SHG properties with a susceptibility χ(2) of about 1.51 × 10−9 esu.