(E)-5,5'-bis(2-methylphenyl)- and (E)-5,5'-bis(2,4,6-trimethyphenyl)-3, 3'-bifuranylidene-2,2'-diones and their isomeric pyrano[4,3-c]pyran-1,5-diones were converted into the nitrogen analogs, in which the aryl groups were twisted relative to the parent skeletons, and had small conjugation effect. Another nitrogen analogs bearing coplanar aryl rings were prepared, and their UV-VIS and NMR spectral data were compared with those of the analogs having twisted aryl groups. Conjugation effect of the 2-alkylphenyl group is bathochromic shift by 24 nm. Steric compression due to coplanarity of the aryl rings causes a deshielding of a H-1 NMR signal by similar to 0.6 ppm, and a shielding of a C-13 NMR Signal by similar to 5 ppm.
(E)-5,5-二二
甲苯基二
羧酸酐和(E)-5,5-二印 oddly)-二
甲苯基-3, 3-
双烯基-
2,2-二酸酐的同系物,它们的亲本骨架中芳香环之间存在有过转。这些同系物的芳香环之间具有较小的共轭效应。另外制备了平面共轭芳香环的另一类含有异构性的
苯环双原子
环状物。并分别比较了它们的紫外-可见(UV-VIS)和核磁共振(NMR)光谱数据。结论表明,具有双烷基
苯环亲本骨架的共轭作用将使得双键的波长红移24 nm。平面共轭芳香环的立体压缩效应导致 Schiff碱N-1H之间类似0.6 ppm的
脱质,而
碳-13(C-13)NMR信号***类似5 ppm的平衡。