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Four families of structurally related chiral π‐conjugated oligomers bearing a hydroquinone (HQ), 1,5‐dihydroxynaphthalene (Naph), benzo[1,2‐b:4,5‐b']dithiophene‐4,8‐diol (BDT) or 9H‐carbazole (CBZ) central core, for a total of 11 new compounds, have been synthesized by simple and versatile synthetic strategies involving Pd‐catalyzed cross‐coupling protocols: a Suzuki‐Miyaura reaction, a Sonogashira/desilylation/Sonogashira sequence or a Sonogashira/desilylation/acyl Sonogashira sequence. A systematic investigation of the optical and chiroptical features of the final chiral dyes was performed in chloroform solution and on spin‐coated thin films. The ECD investigation was crucial in revealing that, even within the same family of organic dyes, minor variations in the nature and length of the π‐conjugated backbone can result in very different solid‐state arrangements at different hierarchical scales. [ABSTRACT FROM AUTHOR]

Chiral materials formed by aggregated organic compounds play a fundamental role in chiral optoelectronics, photonics and spintronics. Nonetheless, a precise understanding of the molecular interactions involved remains an open problem. Here we introduce magnetic circular dichroism (MCD) as a new tool to elucidate molecular interactions and structural parameters of a supramolecular system. A detailed analysis of MCD together with electronic circular dichroism spectra combined to ab initio calculations unveils essential information on the geometry and energy levels of a self‐assembled thin film made of a carbazole di‐bithiophene chiral molecule. This approach can be extended to a generality of chiral organic materials and can help rationalizing the fundamental interactions leading to supramolecular order. This in turn could enable a better understanding of structure–property relationships, resulting in a more efficient material design. [ABSTRACT FROM AUTHOR]

In this work, we synthesized a family of three structurally related chiral oligothiophenes containing a 1,4‐diketo‐3,6‐diarylpyrrolo[3,4‐c]pyrrole (DPP) unit as the central core; functionalized with the same (S)‐3,7‐dimethyl‐1‐octyl chains on the nitrogen atoms of lactam moieties, they only differ in the number of lateral thiophene units. The aggregation modes of these π‐conjugated chiral systems were evaluated by means of UV–Vis absorption and ECD spectroscopies in conditions of solution aggregation (CHCl3/MeOH mixtures) and as thin films, describing in particular the impact of the π‐conjugation length on the chiroptical properties. Interestingly, we found that the variable number of thiophene units attached to the DPP core affects not only the propensity to aggregation but also the aggregates' helicity. ECD revealed information about the supramolecular arrangement of these molecules, that one would not obtain by using conventional optical spectroscopy and microscopy techniques. Thin film samples revealed very different aggregation modes with respect to solution aggregates, casting doubts on the common assumption that these latter may serve as simple models of the former ones. [ABSTRACT FROM AUTHOR]

The synthesis of chiral 3-atyl-1-alkynes via cross coupling of 3-alkyl- and 3,3-diaalkyl-1-bromo-1,2-dienes and arylbromocuprates (RCuBr)MgBr.LiBr was examined. The high 1,3-anti stereoselectivity of the coupling process helped in obtaining enantiomerically enriched 3-aryl-1-alkynes from optically active allenic substrates, thus indicating a simple pathway towards the synthesis of quaternary stereogenic centers characterized by an aryl group.

Research has been conducted on the rhodium-catalyzed intramolecular silylformylation of substituted omega-silylacetylenes. Results indicate its considerable organic synthesis potential.