Issue 11, 2012

Structural effects on the pH-dependent fluorescence of naphthalenic derivatives and consequences for sensing/switching

Abstract

Naphthalenic compounds are a rich resource for designers of fluorescent sensing/switching/logic systems. The degree of internal charge transfer (ICT) character in the fluorophore excited states can vary from negligible to substantial. Naphthalene-1,8;4,5-diimides (11–13), 1,8-naphthalimides (16) and 4-chloro-1,8-naphthalimides (15) are of the former type. The latter type is represented by the 4-alkylamino-1,8-naphthalimides (1). Whether ICT-based or not, these serve as the fluorophore in ‘fluorophore-spacer-receptor’ switching systems where PET holds sway until the receptor is bound to H+. On the other hand, 4-dialkylamino-1,8-naphthalimides (3–4) show modest H+-induced fluorescence switching unless the 4-dialkylamino group is a part of a small ring (5). Electrostatic destabilization of a non-emissive twisted internal charge transfer (ICT) excited state is the origin of this behaviour. An evolution to the non-emissive twisted ICT excited state is responsible for the weak emission of the model compound 6 (and related structures 7 and 8) across the pH range. Twisted ICT excited states are also implicated in the switch 9 and its model compound 10, which are based on the 6-dialkylamino-3H-benzimidazo[2,1-a]benz[d,e]isoquinolin-3-one fluorophore.

Graphical abstract: Structural effects on the pH-dependent fluorescence of naphthalenic derivatives and consequences for sensing/switching

Article information

Article type
Paper
Submitted
19 Mar 2012
Accepted
08 Jun 2012
First published
02 Jul 2012

Photochem. Photobiol. Sci., 2012,11, 1675-1681

Structural effects on the pH-dependent fluorescence of naphthalenic derivatives and consequences for sensing/switching

S. Zheng, P. L. M. Lynch, T. E. Rice, T. S. Moody, H. Q. N. Gunaratne and A. P. de Silva, Photochem. Photobiol. Sci., 2012, 11, 1675 DOI: 10.1039/C2PP25069A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements