Cyclopenta[hi]aceanthrylene Decorated with Multiple and Long Alkoxy Chains: Physicochemical Properties and Single-Walled Carbon Nanotubes’ Exfoliation Capability

Christoph Schierl,Giovanni Bottari,Dirk M Guldi,Virtudes Pardo,Tomas Torres

doi:10.1149/2162-8777/ab9a5a

Abstract

A rod-like cyclopenta[hi]aceanthrylene (CPA) derivative bearing three dodecyloxy chains at each of its two terminal positions was prepared. Spectroscopic (i.e., steady-state absorption and fluorescence) and electrochemical studies carried out with this polycyclic aromatic hydrocarbon (PAH) derivative showed an intense absorption through the entire UV–vis spectral range, weak fluorescence, small HOMO-LUMO gap, and excellent electron accepting capability. Transient absorption spectroscopy (TAS) revealed the formation of singlet and triplet excited states; the latter was, however, only observed in the presence of a triplet sensitizer. The exfoliation capability of this lipophilic CPA towards single-walled carbon nanotubes (SWCNTs) in THF was also investigated. On one hand, transmission electron microscopy (TEM) pointed to an efficient debundling of SWCNTs by the CPA derivative by means of non-covalent interactions. On the other hand, important differences in the ground and excited state features of the uncomplexed and SWCNT-complexed CPA were revealed by Raman and TAS.

Highlights

To date, several CPA derivatives have been synthesized,[22,23,24,25,26] in which the electron-accepting CP-polycyclic aromatic hydrocarbon (PAH) have been connected to electron-donating photo- and electroactive macrocycles,[27] incorporated into electron donor-acceptor (D-A) conjugated ladder polymers,[28] and copolymers,[29,30] or mixed with p-type polymers into D/A blends.[31]
In 1, the presence of a central planar π-surface and several peripheral long lipophilic chains makes it a perfect candidate to study the exfoliation of single-walled carbon nanotubes (SWCNTs)
Synthesis of CPA 1.—CPA derivative 1 was prepared in 33% yield by palladium catalyzed Sonogashira cross-coupling reaction between 2,7-diiodoCPA and 1,2,3-tris(dodecyloxy)-5-ethynylbenzene (Scheme 1).[35]

Summary

Introduction

Several CPA derivatives have been synthesized,[22,23,24,25,26] in which the electron-accepting CP-PAHs have been connected to electron-donating photo- and electroactive macrocycles,[27] incorporated into electron donor-acceptor (D-A) conjugated ladder polymers,[28] and copolymers,[29,30] or mixed with p-type polymers into D/A blends.[31]. The optoelectronic features of 1 were investigated by steady-state and time-resolved spectroscopic techniques, as well as electrochemical measurements, showing an intense and broad absorption, weak fluorescence, small HOMOLUMO gap, and excellent electron accepting capability. The formation of 1/SWCNTs gave rise to an important modification of the ground and excited state features of 1 compared to the uncomplexed derivative.

Results

Conclusion