Chiral photonics deals with enantioselective polarization control of linear and nonlinear optical functions and holds a great promise for a wide range of applications including optical signal processing, biosensing, and chiral bioimaging. Development of chiral materials with optical activity exceeding that of natural materials therefore becomes a prerequisite to realizing the full potential of this field. Herein, we report on a study of structure−property relations of two chiral polymers with ester functional groups in lateral branch. To enhance rotational strength, the macroscopic measure of chirality, we employ a fluorene−quinoxaline motif in the monomer unit. To the best of our knowledge, we find the optical activity of one of the studied polymers to be the highest reported so far. Theoretical calculations reveal a correlation between the topological conformations and the simulated CD spectra in agreement with the experimental measurements and help clarify the mechanism of optical activity enhancement that could create insight for further enhancement of chirality.

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The thermochromism of a polyfluorene derivative complexed with a europium ion was interpreted using the photophysical properties of the noncomplexed polymer and a low molecular mass model compound having the same structure of the complexed site in the polymer. To the naked eye, the thermochromism was characterized by a strong red at low temperatures (170− 260 K, due to Eu 3+ ion) and a blue color at higher ones (280−330 K, due to fluorene). Absorption and emission spectra, time-resolved measurements, and theoretical simulations showed that the polymer chain does not affect the europium photophysical properties, but the opposite occurred: the ion insertion precluded interchain aggregation, and the backbone emission did not vary with temperature variation, in the range of 170−330 K. To the best of our knowledge, this effect is reported for the first time and opened a new avenue for the design of nanothermometers, since the polymer can act as a "built-in standard", thus allowing the construction of much simpler devices.