A new chiral benzo[1,2-b:4,5-b′]dithiophene-based oligothiophene has been synthesized and spectroscopically characterized in solution and in the solid state. The electronic circular dichroism (ECD) spectra of the thin films revealed the occurrence of an uncommon phenomenon, consisting of the inversion of the circular dichroism sign by sample flipping. To the best of our knowledge, this is unprecedented in samples where no preferential orientation of the chromophores has been induced, and must be due to spontaneous local anisotropies. It reveals peculiar features upon the usual solvent annealing procedure, but finally results in stable and very strong signals, which are perfectly reproduced in sign, and relative and even absolute magnitude. Although the recorded signal cannot be considered as a true ECD spectrum, it corresponds to a very large discrimination of light circular polarization, which is well explained by means of the Mueller matrix analysis and does not depend on instrumental defects. It is a genuine property of this material, which correlates with polarized optical microscopy (POM) images and only depends on the self-assembling properties of this molecule. This phenomenon may have relevant implications, on account of its strength and of the interest of oligothiophenes in current optoelectronic devices.

Direct C–H bond arylation of (hetero)arenes is a very convenient approach for the synthesis of a wide variety of molecular targets, including compounds of pharmaceutical interest and π-conjugated small molecules and polymers. Compared to traditional transition metal-promoted cross-coupling reactions, direct C–H arylations best fit the Green Chemistry criteria, particularly in minimization of waste, use of less hazardous chemicals, atom economy, and reduction of unnecessary derivatization steps. Despite the advantages, these reactions still initially suffered from major limitations in terms of sustainable chemistry, i.e., toxic and expensive transition-metal catalysts, toxic and/or hazardous solvents, high temperatures and long reaction times. The increasing attention towards environmentally friendly reaction protocols has boosted studies directed towards the development of sustainable strategies for direct C–H bond arylation of (hetero)arenes. This review offers a critical overview of the research on this topic, focusing on three main aspects: (i) recoverable catalysts; (ii) sustainable solvents; (iii) non-conventional energy sources.

The study of chiroptical properties in thin films of chiral organic π‐conjugated dyes is more complex than isotropic solutions, due to the interference of macroscopic anisotropies often present in the solid state. The experimental circularly polarized (CP) absorption (electronic circular dichroism, ECD) and CP emission (circularly polarized luminescence, CPL) of a thin film can be expressed as the sum of several terms, some of which are non‐reciprocal upon film flipping. In this review, we shall discuss the fundamental theoretical concepts about reciprocal and non‐reciprocal chiroptical features in thin films of organic dyes, describing their correlation with the solid‐state structural organization and suggesting a practical toolbox to quantify their relative weight on an experimental ECD or CPL spectrum. Moreover, we shall also take into account the literature on thin films of organic π‐conjugated dyes showing strong non‐reciprocal CP absorption and/or CP emission, due to their potential high interest in the flourishing field of chiral photonics and electronics.