Controlling circularly polarized (CP) emission is key for both fundamental understanding and applications in the field of chiral photonics and electronics. Here, a completely new way to achieve this goal is presented. A luminescent thin film, made from a chiral conjugated phenylene bis‐thiophenylpropynone able to self‐assemble into ordered structures, emits highly circularly polarized light with opposite handedness from its two opposite faces. Such emergent nonreciprocal behavior in CP emission, so far unprecedented, represents a fundamental advance, opening new opportunities in design, preparation, and applications of CP emitting materials.

We introduce an optical microscopy technique, circularly polarized microscopy or CPM, able to afford spatially resolved electronic circular dichroism (ECD) of thin films of chiral organic semiconductors through a commercial microscope equipped with a camera and inexpensive optics. Provided the dichroic ratio is sufficiently large, the spatial resolution is on the order of the μm and is only limited by the magnification optics integrated in the microscope. We apply CPM to thin films of small chiral πconjugated molecules, which gave rise to ordered aggregates in the thin layer. Primarily, conventional ECD can reveal and characterize chiral supramolecular structures and possible interferences between anisotropic properties of solid samples; however, it cannot generally account for the spatial distribution of such properties. CPM offers a characterization of supramolecular chirality and of commingling polarization anisotropies of the material, describing their local distribution. To validate CPM, we demonstrated that it can be adopted to quantify the local ECD of samples characterized by intense signals, virtually on any standard optical microscope.

Supramolecular chirality is far from being determined only by local stereogenic elements. Three diketopyrrolo[3,4‐c]pyrrole–1,2,3‐1H‐triazole (DPP) dyes bearing the same chiral appendage R* but decorated with different achiral substituent groups Y showed profoundly different optical, chiroptical, electrochemical and thermal features in their aggregated form. More information can be found in the Research Article by A. Punzi, L. Di Bari and co‐workers (DOI: 10.1002/chem.202300291).

We studied the impact of achiral substituents on the chiral supramolecular architectures of diketopyrrolo [3,4-c]pyrrole-1,2,3-1H-triazole (DPP) dyes. The same chiral DPP motif was decorated with three different achiral substituents on the nitrogen atoms of the lactam moiety: the hydrophobic n-octyl alkyl chain, the hydrophilic tri(ethylene glycol) (TEG) chain and the thermocleavable tert-butoxycarbonyl (tBoc) carbamate group. In spite of identical p-conjugated chromophore and chiral appendage, in aggregated form these three purple dyes displayed profoundly different optical, chiroptical, electrochemical and thermal features.