2,5-Bis-(3,4-dicarboxyphenylcarboxyethoxy)-4'-nitrostilbene dianhydride was prepared and reacted with 1,4-phenylenediamine, 4,4'-oxydianiline, 4,4'-diaminobenzanilide, and 4,4'-(hexafluoroisopropylidene)dianiline to yield unprecedented novel T-type polyimides (4-7) containing 2,5-dioxynitrostilbenyl groups as nonlinear optical chromophores, which constituted parts of the polymer backbones. 4-7 were soluble in polar solvents such as acetone and NN-dimethylformamide. They showed thermal stability up to 300 degreesC in thermogravimetric analysis thermograms; the glass-transition temperatures obtained from differential scanning calorimetry thermograms were around 153 degreesC. The second harmonic generation (SHG) coefficients (d(33)) of poled polymer films at the 1064-cm(-1) fundamental wavelength were around 4.35 x 10(-9) esu. The dipole alignment exhibited exceptionally high thermal stability even at 45 degreesC higher than the glass-transition temperature, and there was no SHG decay below 200 degreesC because of the partial main-chain character of the polymer structure, which was acceptable for nonlinear optical device applications. (C) 2004 Wiley Periodicals, Inc.