A Successful Chemical Strategy To Induce Oligothiophene Self-Assembly into Fibers with Tunable Shape and Function

Abstract

Functional supramolecular architectures for bottom-up organic nano- and microtechnology are a high priority research topic. We discovered a new recognition algorithm, resulting from the combination of thioalkyl substituents and head-to-head regiochemistry of substitution, to induce the spontaneous self-assembly of sulfur overrich octathiophenes into supramolecular crystalline fibers combining high charge mobility and intense fluorescence. The fibers were grown on various types of surfaces either as superhelices or straight rods depending on molecular structure. Helical fibers directly grown on a field effect transistor displayed efficient charge mobility and intrinsic 'memory effect'. Despite the fact that the oligomers did not have chirality centers, one type of hand-helicity was always predominant in helical fibers, due to the interplay of molecular atropisomerism and supramolecular helicity induced by terminal substituents. Finally, we found that the new sulfur overrich oligothiophenes can easily be prepared in high yields through ultrasound and microwave assistance in green conditions.

Supramolecular Oligothiophene Microfibers Spontaneously Assembled on Surfaces or Coassembled with Proteins inside Live Cells

“…The singlecrystal X-ray structure of compound 2 showed that the inner quaterthiophene core is strictly planarwhich facilitates the stacking arrangement in the solid statewith short S···S intramolecular distances of 3.09 and 3.10 Å. 27,24 We found that only the quaterthiophene with this precise regiochemistry promotes the formation of microfibers, with any other arrangement of the S-hexyl groups leading invariably to amorphous morphologies. Also, the hexyl chains were needed for the formation of microfibers, as replacement with shorter chains resulted in star-shaped crystalline aggregates.…”

“…The microfibers, characterized by lengths of several micrometers, widths of a few micrometers, and submicrometric thickness, were reproducibly formed on glass, indium tin oxide (ITO), silicon, and gold, always with the same results. 24 Figure 1 shows optical microscopy images (without and with crossed polarizers) of representative microfibers formed by 1−4 on glass, together with fluorescence and scanning electron microscopy images. All of the microfibers displayed birefringence, being extinguished at four positions at intervals of 90°upon rotation of the polarized light, indicating their crystalline nature.…”

“…The microfibers were redox-active, fluorescent, and conductive. 24 Since aggregates formed on surfaces are the result of a balance between molecule−molecule and molecule−substrate interactions, in the case of 1−4 the molecule−molecule interactions always prevailed, leading to stable supramolecular systems with the same characteristics on every type of surface. Morphologically, the most interesting system was compound 3, which formed multihelical structures where superhelices (helices of helices) or even double helices of superhelices were present, displaying left-handed or right-handed helicity with the one or the other always predominating.…”

Redox‐Active Peptide‐Functionalized Quinquethiophene‐Based Electrochromic π‐Gel

“…The aggregated‐motifs further associated into higher ordered chiral supramolecular assemblies. The presence of chiral residual amino acid and molecular atropisomerism around thiophene residues induce chiral assemblies . A possible mechanism to determine the self‐assembling pattern of peptide‐quinquethiophene moieties in compound 1 is proposed (Figure ).…”

Optically active, regioregular, head-to-head/tail-to-tail poly(3-alkyl)thiophene by inherently regiospecific oxidative synthesis from 3,3′-dialkyl 2,2′-bithiophene monomer

“…10a and c). Due to the different deposition method (films electrochemically deposited or cast from the chloroform solution, respectively), the morphology of HH poly (DMBBT)-E appears to be rod-like, with sizes ranging from 6 to 150 mm by length and 2.5 to 10 mm by width, typical of oligothiophenes, as observed for a similar amorphous HH oligothiophene octamer bearing the 3-hexyl substituent in the side chain [15]. Prevalent platelets-like morphology mixed with some rod structures of smaller size with respect to the electrochemically obtained sample is displayed by HH poly (DMBBT).…”