XPush-pull indole-containing nonlinear optical chromophores with different acceptor and ð-conjugated moieties have been synthesized and characterized. Experimental measurements of the second-order nonlinear optical response demonstrated that the chromophores exhibit similar or superior optical nonlinearity compared with their analogues with an aniline moiety as the donor group, but the indole-based chromophores display blueshifted absorption, even up to 30 nm.

A series of nonlinear optical (NLO) chromophores were successfully prepared, in which pyrrole moieties were the conjugated bridge. In comparison with their analogues containing furan or thiophene groups as the bridge, these chromophores demonstrated similar or enhanced NLO effects (up to 3.3 times) and interesting optical behavior. While the acceptor groups were malononitrile (Mal), 3-phenyl-5-isoxazolone (Iso), and 1,3-diethylthiobarbituric acid (Bar), the chromophores exhibited much blue-shifted maximum absorption wavelengths (ìmax) (up to 36 nm); however, the ìmax of the chromophore containing tricyanovinyldihydrofuran (TCF) as acceptor became much longer than that of the analogue (up to 75 nm).

Three indole-based nonlinear optical (NLO) chromophores with changeable isolation groups were successfully introduced into the polymer backbone to yield a series of main-chain polyurethanes. Thanks to the mainchain structure and the advantages of the indole-based chromophores, all of the polymers show excellent transparency, good processability, thermal stability, and relatively good NLO effects. The obtained experimental results indicated that the polymer backbone, in addition to the linked isolation moieties, could act as isolation spacers in some special cases. The tested NLO results demonstrated that the isolation groups with apparent site-isolation effect might not benefit the macroscopic NLO effect of the resultant polymers.

Two new dendronized nonlinear optical (NLO) polyfluorenes were synthesized with high azochromophore loading density by the introduction of high generation chromophore dendrons on the side chains. Thanks to the advantages of Sharpless' click chemistry reaction, the dendrons were conveniently bonded to the backbone of polyfluorene with the conversion of 100%, although they were really very bulky. The new-formed triazole rings in the dendrons acted as suitable isolation groups to minimize the strong dipole-dipole interactions among the polar chromophore moieties to improveNLO effects, according to the results obtained from UV-vis spectra and order parameters. All the polymers were well characterized and exhibited good solubility, high thermal ability, wide optical window, and largeNLOeffects (up to 106.0 pm/V). In addition, the testedNLOresults of these dendronzied polymers demonstrated a deviation from the dipolar frustration that typically limits the NLO effect in conventional chromophore/polymer composite materials, indicating that the frequently observed asymptotic dependence of electro-optic activity on chromophore density may be overcome through rational design.