Issue 18, 2013

On the role of singlet versus triplet excited states in the uncaging of ortho-nitrobenzyl caged compounds

Abstract

ortho-Nitrobenzylacetate (oNBA) is one of the smallest caged-compounds utilizing the famous ortho-nitrobenzyl caging group and thus serves here as a proto-typical example. Crucial for efficient uncaging of, here, acetate from oNBA is the formation of the aci-form of the nitro-group, which can be formed via excited-state intramolecular hydrogen transfer (ESIHT) in the lowest excited singlet S1 or the triplet T1 state. Using state-of-the-art quantum chemical methods, the efficiency of singlet and triplet ESIHT in aci-formation is investigated and the results are discussed in comparison to previous calculations on related caged-compounds as well as with respect to recent experimental findings. It is shown that the majority of the excited molecules undergo singlet ESIHT, which is generally inefficient with respect to aci-formation and subsequent uncaging, while only a minority of excited molecules undergo intersystem crossing and triplet ESIHT, which eventually leads to kinetically stable aci-isomers of oNBA resulting in final uncaging. Our computational results explain all existing experimental findings on ortho-nitrobenzylic caging groups conclusively and general synthetic strategies for their improvement are suggested.

Graphical abstract: On the role of singlet versus triplet excited states in the uncaging of ortho-nitrobenzyl caged compounds

Article information

Article type
Paper
Submitted
03 Dec 2012
Accepted
01 Mar 2013
First published
01 Mar 2013

Phys. Chem. Chem. Phys., 2013,15, 6691-6698

On the role of singlet versus triplet excited states in the uncaging of ortho-nitrobenzyl caged compounds

J. Mewes and A. Dreuw, Phys. Chem. Chem. Phys., 2013, 15, 6691 DOI: 10.1039/C3CP44338H

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.

Social activity

Spotlight

Advertisements