Molecular light switches

Molecular electronics, class II mixed-valence complexes, 41 303-304 Molecular light switch effect, 43 148 Molecular mechanisms, cobalt(III) hexaamines, 35 119-120 Molecular orbital calculations... 

Figure 19-17 also indicates that flat, aromatic molecules can be inserted between the flat, hydrogen-bonded nucleotide base pairs of DNA. We say that the flat molecule is intercalated between the base pairs. One of many analytical applications of aptamers utilizes a molecular light switch intercalated in the aptamer. 

Figure 19-18 Response of "molecular light switch" to immunoglobulin E (IgE). Aptamer concentration is 5 nM and ruthenium complex concentration is 40 nM. Addition of IgE displaces the ruthenium complex from the aptamer and decreases luminescence at 610 nm. Excitation wavelength = 450 nm.

From Y. Jiang, X. Fang, and C. Bai, Signaling Aptamer/Protein Binding by a Molecular Light Switch Complex." Anal. Chem. 2004, 76, 5230.]... 

Jiang, Y. Fang, X. Bai, C., Signaling aptamer/protein binding by a molecular light switch complex, Anal. Chem. 2004, 76, 5230-5235... 

The data concerning [Ru(phen)2 (dppz)] + nicely illustrate the concept of molecular light switch (dppz for 28). When the complex is bound to DNA, the excited-state lifetime is approximately 200 ns, whereas without bounding, it is only 200 ps. This light-switch effect provides the basis for a valuable photophysical probe of nucleic acids. Luminescent characteristics of the complexes bound to DNA can also be used to illustrate the chiral discrimination associated with binding to the right-handed helix. Direct oxidation of... 

Friedman AE, Chambron JC, Sauvage J-P, Turro NJ, Barton JK (1990) Molecular light switch for DNA Ru(bipy)2(dppz). J Am Chem Soc 112 4960... 

---