Spectroscopy of Naphthalene Diimides and Their Anion Radicals*

Goja Andric; John F. Boas; Alan M. Bond; Gary D. Fallon; Kenneth P. Ghiggino; Conor F. Hogan; James A. Hutchison; Marcia A.-P. Lee; Steven J. Langford; John R. Pilbrow; Gordon J. Troup; Clint P. Woodward

doi:10.1071/CH04130

RESEARCH ARTICLE

Spectroscopy of Naphthalene Diimides and Their Anion Radicals*

Goja Andric ^A , John F. Boas ^B , Alan M. Bond ^A ^D , Gary D. Fallon ^A , Kenneth P. Ghiggino ^C , Conor F. Hogan ^A , James A. Hutchison ^C , Marcia A.-P. Lee ^A , Steven J. Langford ^A ^D , John R. Pilbrow ^B , Gordon J. Troup ^B and Clint P. Woodward ^A

+ Author Affiliations

- Author Affiliations

^A School of Chemistry, Monash University, Clayton VIC 3800, Australia.

^B School of Physics and Material Engineering, Monash University, Clayton VIC 3800, Australia.

^C School of Chemistry, University of Melbourne, Parkville VIC 3010, Australia.

^D Authors to whom correspondence should be addressed (e-mail: alan.bond@sci.monash.edu.au; steven.langford@sci.monash.edu.au).

Australian Journal of Chemistry 57(10) 1011-1019 https://doi.org/10.1071/CH04130
Submitted: 12 May 2004 Accepted: 4 August 2004 Published: 1 October 2004

Abstract

Naphthalene diimides 1–4 having different N,N-disubstitution undergo single electron reduction processes either chemically or electrochemically to yield the corresponding radical anion in high yield. This study concentrates on 1, bearing pentyl side chains connected through the diimide nitrogens, and compares the results obtained against those bearing isopropyl, propargyl, and phenylalanyl side chains. Compound 1 exhibits mirror image absorption and fluorescence in the near-UV region in CH₂Cl₂ and dimethylformamide that is typical of monomeric N,N-dialkyl-substituted naphthalene diimides. In toluene, excimer-like emission is observed, which suggests ground-state complexes involving 1 are formed. X-Ray crystallography has been used to characterize 1 in the solid state. Cyclic voltammetry enables the reversible potentials for [NDI]^0/– and [NDI]^−/2– type processes to be measured. Bulk one-electron reduction of 1–4 is characterized by dramatic changes in the absorption and emission spectra. Additionally, highly structured EPR (electron paramagnetic resonance) signals from dimethylformamide solutions of the radical anions of 1–3 have been obtained and are consistent with coupling between the unpaired electron and the naphthalene diimide nitrogens and hydrogens and the NCH hydrogens of the appropriate side chains. The overall structure of the EPR spectrum is substituent-dependent. These changes in spectroscopic output upon an electronic input may be described as a simple ‘on/off’ switching mechanism with which to apply a ‘bottom-up’ approach to molecular device manufacture.

^* Dedicated to the memory of T. M. Florence, a gentleman and a scholar.

Acknowledgments

This work was supported by the Australian Research Council Discovery Grants (awarded to S.J.L. and A.M.B.) and the School of Physics and Materials Engineering, Monash University (J.F.B., J.R.P., and G.J.T.). J.A.H. acknowledges an Australian Postgraduate Award.

References

Spectroscopy of Naphthalene Diimides and Their Anion Radicals*

Abstract

Acknowledgments

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