Volume 13, Issue 29 p. 8277-8284
Full Paper

Self-Assembled Single-Walled Carbon Nanotube:Zinc–Porphyrin Hybrids through Ammonium Ion–Crown Ether Interaction: Construction and Electron Transfer

Francis D'Souza Prof.

Francis D'Souza Prof.

Department of Chemistry, Wichita State University, 1845 Fairmount, Wichita, Kansas 67260-0051, USA, Fax: (+1) 316-978-3431

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Raghu Chitta

Raghu Chitta

Department of Chemistry, Wichita State University, 1845 Fairmount, Wichita, Kansas 67260-0051, USA, Fax: (+1) 316-978-3431

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Atula S. D. Sandanayaka Dr.

Atula S. D. Sandanayaka Dr.

Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai, 980-8577, Japan, Fax: (+81) 22-217-5610

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Navaneetha K. Subbaiyan

Navaneetha K. Subbaiyan

Department of Chemistry, Wichita State University, 1845 Fairmount, Wichita, Kansas 67260-0051, USA, Fax: (+1) 316-978-3431

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Lawrence D'Souza Dr.

Lawrence D'Souza Dr.

Department of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton, Chicago 60607, USA

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Yasuyuki Araki Dr.

Yasuyuki Araki Dr.

Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai, 980-8577, Japan, Fax: (+81) 22-217-5610

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Osamu Ito Prof.

Osamu Ito Prof.

Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai, 980-8577, Japan, Fax: (+81) 22-217-5610

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First published: 25 September 2007
Citations: 71

Graphical Abstract

Nanohybrids: By adopting an alkyl ammonium ion–crown ether hydrogen-bonding motif, zinc–porphyrin–single-walled carbon nanotube (SWNT) donor–acceptor nanohybrids were constructed and characterized. Efficient photoinduced electron transfer from the singlet excited zinc–porphyrin to the SWNT was observed (see figure), and transient absorption spectral studies revealed charge stabilization in the self-assembled nanohybrids.

Abstract

An ammonium ion–crown ether interaction has been successfully used to construct porphyrin–single-walled carbon nanotube (SWNT) donor–acceptor hybrids. The [18]crown-6 to alkyl ammonium ion binding strategy resulted in porphyrin–SWNT nanohybrids that are stable and soluble in DMF. The porphyrin–SWNT hybrids were characterized by spectroscopic, TEM, and electrochemical techniques. Both steady-state and time-resolved emission studies revealed efficient quenching of the singlet excited state of the porphyrins and free-energy calculations suggested that electron-transfer quenching occurred. Nanosecond transient absorption spectral results supported the charge-separation quenching process. Charge-stabilization was also observed for the nanohybrids in which the lifetime of the radical ion pairs was around 100 ns. The present nanohybrids were also used to reduce the hexyl viologen dication (HV2+) and to oxidize 1-benzyl-1,4-dihydronicotinamide in solution in an electron-pooling experiment. Accumulation of the radical cation (HV.+) was observed in high yields, which provided additional proof for the occurrence of photoinduced charge separation. The present study demonstrates that a hydrogen-bonding motif is a successful self-assembly method to build SWNTs bearing donor–acceptor nanohybrids, which are useful for light-energy harvesting and photovoltaic applications.