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Supramolecular Nanowires from an Acceptor–Donor–Acceptor Conjugated Chromophore
Author(s) -
Chakraborty Saptarshi,
Varghese Shinto,
Ghosh Suhrit
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904463
Subject(s) - chromophore , acceptor , bathochromic shift , photochemistry , supramolecular chemistry , materials science , triptycene , conjugated system , crystallography , delocalized electron , band gap , chemistry , fluorescence , polymer chemistry , crystal structure , organic chemistry , polymer , optoelectronics , physics , quantum mechanics , composite material , condensed matter physics
Oligothiophene derivatives have been extensively studied as p‐type semiconducting materials in organic electronics applications. This work reports the synthesis, self‐assembly and photophysical properties of acceptor–donor–acceptor (A–D–A)‐type oligothiophene derivatives by end‐group engineering of quaterthiophene (QT) with naphthalene monoimide (NMI) chromophores that are further connected to a trialkoxy benzamide wedge. Conjugation to the NMI units reduces the HOMO–LUMO gap significantly, and consequently the absorption spectrum exhibits a bathochromic shift of about 50 nm compared with QT. Furthermore, extended H‐bonding interactions among the amido groups of the peripheral wedges produce entangled fibrillar nanostructures and gelation in hydrocarbon solvents such as methylcyclohexane, wherein the A–D–A chromophore exhibits typical H‐aggregation. On the contrary, the fact that the same chromophore, lacking only the amido units, does not produce gels or H‐aggregates indicates strong impact of H‐bonding on the self‐assembly. Computational studies revealed the electronic properties of the chromophore and predicted the geometry of a dimer in the H‐aggregate that reasonably matches with the experimental results. Bulk electrical conductivity measurements determined an excellent conductivity of 2.3×10 −2 S cm −1 for the H‐aggregated system (OT‐1), which is two orders of magnitude higher than that of the same chromophore lacking the amido groups (OT‐2).