Two series of nonlinear optical chromophores G1–G4 and J1-J4 based on diethylaminophenyl or julolidinyl-based donor and tricyanovinyldihydrofuran acceptor have been synthesized. Compared to the unmodified isophorone bridge of chromophore G1 and J1, the bridges of chromophores G2/J2 and G3-G4/J3-J4 were modified with tert-butyldimethylsilyl (TBDMS) groups and fluorene group, respectively. In addition, we introduced bulky tert-butyldiphenylsilyl (TBDPS) groups to the donor of chromophore G4 and J4 to further increase poling efficiency. The results show that the chromophores G3-G4/J3-J4 modified with fluorene groups on the bridge have higher stability and larger electro-optic coefficient than chromophores G1-G2 and J1-J2. Electro-optical films doped with chromophore G1-G4 and J1-J4 have been poled to give r33 values of 69, 96, 118, 133, 143, 201, 240 and 261 pm/V at 1.31 μm, respectively. All these provide valuable insight into understanding of the impact of an isolation group on the performance of chromophores.