An approach is presented for the design of photoinduced electron-transfer-based sensors. The approach relies on the computational and theoretical prediction of electron-transfer kinetics based on Rehm-Weller and Marcus theories. The approach allows evaluation of the photophysical behavior of a prototype fluorescent probe/sensor prior to the synthesis of the molecule. As a proof of concept, a prototype sensor for divalent metal ions is evaluated computationally, synthesized, and then analyzed spectroscopically for its fluorescence response to zinc. Calculations predicted that the system would show a competition between electron transfer and fluorescence in the free state. In the zinc-bound state, the compound was predicted to be more highly fluorescent, due to the inhibition of electron transfer. Both predictions were confirmed experimentally. A nonzero fluorescence signal was observed in the absence of zinc and an enhancement was observed in the presence of zinc. Specifically, a 56-fold enhancement was observed over a 10-fold increase in zinc concentration.

This review covers the approximately two-year period since our last review (A1), roughly from January 2004 through December 2005. A computer search of Chemical Abstracts provided most of the references for this review. Other citations were found through individual searches by the various authors who wrote a particular section of this review. In an effort to more effectively accomplish this goal, we have included authors who are experts in the various subtopics of this review. Coverage is limited to articles that describe new developments in the theory and practice of molecular luminescence for chemical analysis in the ultraviolet, visible, and near-infrared region.Citations may be duplicated between sections due to articles with contents that span several topics. However, in an effort to reduce the length of this review, we have attempted to limit this kind of duplication. In general, citations are limited to journal articles and usually do not include patents, proceedings, reports, and dissertations.We have tried to focus on important advances of general interest and relevance to the field of analytical chemistry, rather than extensions of previous advances. This was done in an effort to continue our recent attempts to significantly reduce the length of this biennial review. In addition, we have also expanded our description of individual citations for better clarification of content where necessary.Although we are not able to provide extensive coverage of developments of relevance to broad areas such as chromatography and biological sciences, we have tried to include major review articles and chapters relevant to these topics. If you feel that we omitted an important article published during the above referenced time period, please forward the reference to one of us and we will be certain to consider it for the next review.