Functional single-wall carbon nanotube nanohybrids-associating SWNTs with water-soluble enzyme model systems

We succeeded in integrating single-wall carbon nanotubes (SWNTs), several water-soluble pyrene derivatives (pyrene(-)), which bear negatively charged ionic headgroups, and a series of water-soluble metalloporphyrins (MP8+) into functional nanohybrids through a combination of associative van der Waals and electrostatic interactions. The resulting SWNT/pyrene(-) and SWNT/pyrene(-)/Mp(8+) were characterized by spectroscopic and microscopic means and were found to form stable nanohybrid structures in aqueous media. A crucial feature of our SWNT/pyrene- and SWNT/pyrene(-)/MP8+ is that an efficient exfoliation of the initial bundles brings about isolated nanohybrid structures. When the nanohybrid systems are photoexcited with visible light, a rapid intrahybrid charge separation causes the reduction of the electron-accepting SWNT and, simultaneously, the oxidation of the electron-donating MP8+. Transient absorption measurements confirm that the radical ion pairs are long-lived, with lifetimes in the microsecond range. Particularly beneficial are charge recombination dynamics that are located deep in the Marcus-inverted region. We include, for the first time, work devoted to exploring and testing FeP8+ and Cop(8+) in donoracceptor nanohybrids.