Multimodular Wide-Band Capturing Nanohybrids: Role of Carbon Nanotubes in Slowing Charge Recombination in Supramolecular C<sub>60</sub>-BisstyrylBODIPY-(Zinc Porphyrin)<sub>2</sub> Donor–Acceptor Molecular Cleft
Shahrzad Kazemi, Ajyal Z. Alsaleh, Paul A. Karr, Francis D’Souza
Abstract
The importance of diameter-sorted single-wall carbon nanotubes (SWCNTs) noncovalently bound to a donor–acceptor molecular cleft, 1, in prolonging the lifetime of charge-separated states is successfully demonstrated. For this, using a multistep synthetic procedure, a wide-band capturing, multimodular, C 60 -bisstyrylBODIPY-(zinc porphyrin) 2, molecular cleft 1, was newly synthesized and shown to bind diameter-sorted SWCNTs. The molecular cleft and its supramolecular assemblies were characterized by a suite of physicochemical techniques. Free-energy calculations suggested that both the (6,5) and (7,6) SWCNTs bound to 1 act as hole acceptors during the photoinduced sequential electron transfer events. Consequently, selective excitation of 1 in 1:SWCNT hybrids revealed a two-step electron transfer, leading to the formation of charge-separated states. Due to the distant separation of the cation and anion radical species within the supramolecules, improved lifetimes of the charge-separated states could be achieved. The present supramolecular strategy of improving charge separation involving SWCNTs and donor–acceptor molecular clefts highlights the potential application of these hybrid materials for various light energy harvesting and optoelectronic applications.