A donor–acceptor–donor (D–A–D) type naphthalene-diimide (NDI-H) chromophore exhibits highly cooperative J-aggregation leading to nanotubular self-assembly and gelation in n-decane.

Herein we reveal a straightforward supramolecular design for the H-bonding driven J-aggregation of an amine-substituted cNDI in aliphatic hydrocarbons. Transient absorption spectroscopy reveals sub-ps intramolecular electron transfer in isolated NDI molecules in a THF solution followed by a fast recombination process, while a remarkable extension of the excited state lifetime by more than one order of magnitude occurred in methylcyclohexane likely owing to an increased charge-separation as a result of better delocalization of the charge-separated states in J-aggregates. We also describe unique solvent-effects on the macroscopic structure and morphology. While J-aggregation with similar photophysical characteristics was noticed in all the tested aliphatic hydrocarbons, the morphology strongly depends on the "structure" of the solvents. In linear hydrocarbons (n-hexane, n-octane, n-decane or n-dodecane), formation of an entangled fibrillar network leads to macroscopic gelation while in cyclic hydrocarbons (methylcyclohexane or cyclohexane) although having a similar polarity, the cNDI exhibits nanoscale spherical particles. These unprecedented solvent effects were rationalized by establishing structure-dependent specific interactions of the solvent molecules with the cNDI which may serve as a general guideline for solvent-induced morphology-control of structurally related self-assembled materials.

The utility of an external structure-directing agent to induce orthogonal H-bonding-mediated programmed supramolecular-assembly and gelation of an n-type NDI chromophore is reported. Further, the effect of π-stacking and morphology on electrical conductivity of semiconducting NDI building blocks is revealed.

This communication reveals the H-bonding driven supramolecular assembly of a sulfur-substituted naphthalenediimide leading to the formation of very strong (Tg > 90 °C) organogel in aliphatic hydrocarbons. Mechanistic investigation reveals nucleation-elongation pathway for self-assembly. Photophysical studies show explicit features of classical J-aggregation which reduces the non-radiative fluorescence rate constant considerably and thus results in a remarkable fluorescence enhancement (ΦPL increases from 1% to 30%) which is unprecedented in the entire NDI literature.

Three component supramolecular assemblies from a mixture of an aromatic donor (D), acceptor (A) and external structure directing agent (ESDA) are achieved by orthogonal noncovalent interactions involving two different types of H-bonding and alternate D-A stacking. An ESDA containing amide or urea produces a charge-transfer gel and sol, respectively, owing to their contrasting morphology.