Self‐assembly of chiral diketopyrrolopyrrole chromophores giving supramolecular chains in monolayers and twisted microtapes

Abstract

Chiral diketopyrrolopyrroles appended with enantiomeric ethyl lactate functions through an ether linkage to the aryl backbone of the chromophore were synthesized via the Mitsunobu reaction. The molecules have good solubility and excellent optical properties, high molar absorption coefficients, and fluorescence quantum yields. Helical aggregates with circular dichroism arising from the supramolecular arrangement are seen in both solution and thin films, and the aggregates also display circularly polarized luminescence (glum ≈ ±0.1). The molecules assemble to give monolayers on graphite and precipitate from solution forming supramolecular twisted tapes hundreds of microns long.

Chiral diketopyrrolo[3,4‐c]pyrrole‐based oligothiophenes: Synthesis and characterization of aggregated states in solution and thin films

“…Similar to other DPPs previously reported in the literature, 70,[73][74][75][76][77][78][79] the three chiral compounds 1-3 are dark purple powders. All of them showed quite good solubility in chlorinated solvents such as CHCl 3 , whereas in highly polar solvents (in particular, MeOH) their solubility was low.…”

“…However, the study of the effects of chiral groups on the self‐assembly of DPP‐based systems at different hierarchical levels is far from being fully understood. DPP derivatives bearing helicene, 70–72 binaphthyl, 73 pyrido‐fused myrtanyl, 74 ethyl lactate, 75 or β‐citronellyl 76 groups on the terminal positions of the π‐conjugated backbone have been recently investigated in solution and/or thin films by ECD and related spectroscopies. Quite surprisingly, a similar chiroptical investigation is still at the beginning for DPPs functionalized with chiral appendages on the lactam moieties 77–81 .…”

Spatially Resolved Chiroptical Spectroscopies Emphasizing Recent Applications to Thin Films of Chiral Organic Dyes

“…[70] Amabilino and co-workers described a significant heterogeneity in the supramolecular arrangement of dropcasted thin films of a chiral diketopyrrolo[3,4-c]pyrrole dye, functionalized with enantiopure ethyl lactate groups through an ether linkage to the aryl backbone of the chromophore. [71] Finally, Siligardi's group has recently extended the application of SR-ECDi to a large number of thin films of achiral polyvinyl alcohol (PVA) doped with different amounts of enantiopure ddopa, to assess the chiral homogeneity of thin film preparation with potential antimicrobial property. [72] Very recently, our group proposed a new simple approach to ECDi of thin films of chiral organic dyes based on the CPM configuration.…”

“…have detected the formation of chiral and stable supramolecular assemblies with homogenous distribution in thin films of silicon phthalocyanines (SiPcs) bearing chiral lateral appendages (chiral naphthalenediimide derivatives or naproxen‐based structures) [70] . Amabilino and co‐workers described a significant heterogeneity in the supramolecular arrangement of drop‐casted thin films of a chiral diketopyrrolo[3,4‐ c ]pyrrole dye, functionalized with enantiopure ethyl lactate groups through an ether linkage to the aryl backbone of the chromophore [71] . Finally, Siligardi's group has recently extended the application of SR‐ECD i to a large number of thin films of achiral polyvinyl alcohol (PVA) doped with different amounts of enantiopure d ‐dopa, to assess the chiral homogeneity of thin film preparation with potential antimicrobial property [72] …”

Leveling up Organic Semiconductors with Crystal Twisting

“…91 Chiral diketopyrrolopyrroles were recently reported to form twisted single crystals from solution. 92 The twist sense was determined by the molecular chirality, with enantiomorphous twisting in opposite directions. These crystals exhibit circular dichroism and circularly polarized luminescence, making them promising candidates for chiroptoelectronics.…”