Microfluidic out-of-equilibrium control of molecular nanotubes

Abstract

The bottom-up fabrication of functional nanosystems for light-harvesting applications and excitonic devices often relies on molecular self-assembly. Gaining access to the intermediate species involved in self-assembly would provide valuable insights into the pathways via which the final architecture has evolved, yet difficult to achieve due to their intrinsically short-lived nature. Here, we employ a lab-on-a-chip approach as a means to obtain in situ control of the structural complexity of an artificial light-harvesting complex: molecular double-walled nanotubes. Rapid and stable dissolution of the outer wall was realized via microfluidic mixing thereby rendering the thermodynamically unstable inner tubes accessible to spectroscopy. By measurement of the linear dichroism and time-resolved photoluminescence of both double-walled nanotubes and isolated inner tubes we show that the optical (excitonic) properties of the inner tube are remarkably robust to such drastic perturbation of the system's supramolecular structure as removal of the outer wall. The developed platform is readily extendable to a broad range of practical applications such as e.g. self-assembling systems and molecular photonics devices.

Cryogenic TEM imaging of artificial light harvesting complexes outside equilibrium

“…The process of flash-dilution is carried out by mixing DWNT solution with a 1:1 (v/v) mixture of methanol and water in a microfluidic teardrop mixer 18 . The disappearance of the peak at ∼590 nm has been previously attributed to the dissolution of the outer NT 10 , 18 .…”

“…The process of flash-dilution is carried out by mixing DWNT solution with a 1:1 (v/v) mixture of methanol and water in a microfluidic teardrop mixer 18 . The disappearance of the peak at ∼590 nm has been previously attributed to the dissolution of the outer NT 10 , 18 . A broad peak at ∼574 nm corresponds to higher-energy excitonic transitions 10 , 16 ; the contribution from bundles can be ruled out as they were hardly observed in cryo-TEM images of the DWNT solution (Supplementary Information I).…”

Exciton localization in tubular molecular aggregates: Size effects and optical response

“…using cryo-TEM imaging, the tube's length was seen to grow while aging. 66 Next, we examine the overall line shape of the absorption spectra of large tubes in the presence of disorder. Figures 3(a) , Fig.…”

Structural characterization of supramolecular hollow nanotubes with atomistic simulations and SAXS

“…† A similar thickness (B2.4 nm) for C8S3 nanotubes is also suggested by recent results on modelling the inner and outer wall radii in flash-dilution experiments. 60…”