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45137-B4
The Design and Study of Molecular-Scale Photonic Devices and Green Chemistry Approaches Towards Their Synthesis

Saliya A. De Silva, Montclair State University

Our research is focused on designing chromophore-spacer-receptor assemblies that can function as fluorescent sensors or switches towards various cations.  The fluorescent signaling of these assemblies depend upon photoinduced electron transfer (PET) between the chromophore and the receptor(s), which in turn, depend upon cation binding within the receptor. First generation PET sensors have one receptor and can function as an "Off-On" or an "On-Off" fluorescent switch towards a single cation due to a single PET process.  Second generation PET sensors have two receptors and can show more complicated fluorescence modulation with cation binding due to two PET processes.  We have been successful in developing one of the first examples of a second generation PET sensor that is capable of behaving as an "Off-On-Off" fluorescence switch for protons by combining the proton receptors of the two first generation sensors.¹  Our studies on higher generation PET sensors has also led to the first example of a third generation PET sensor that functions as a fluorescent "off-on-off" proton switch with an overriding "enable-disable" sodium ion switch.²

During the past year, we have developed a new PET sensor (1) that is capable of generating an "Off-On" signal for Zn(II) ions in the presence of protons.  The new sensor is based on the cation receptor of our second generation PET sensor and an electron reservoir that is analogous to the one utilized in our third generation PET sensor. 

The fluorescence modulation of all cation sensors that are based on a chromophore-spacer-receptor architecture and utilize a tertiary nitrogen to quench the fluorescence of an anthracene chromophore is also dependant on protons.  This is the first example of a PET sensor that is designed to utilize a separate PET channel to quench a fluorescence signal generated due to the protonation of a tertiary nitrogen.  We are currently in the process of preparing a manuscript based on senor 1.

Support from this PRF grant has allowed us to develop sensor 1 at Montclair State University.  This grant provided summer stipends for two undergraduate research students and a SRF supplement also allowed a faculty member from a primarily undergraduate institution to work in the PI's lab during the summer.  

1.              de Silva, S. A.; Zavaleta, A.; Baron, D. E.; Allam, O.; Isidor, E. V.; Kashimura, N.; Percarpio, J. M.  Tetrahedron Lett. 1997, 38, 2237.

2.              de Silva, S. A.; Amorelli, B.; Isidor, D. C.; Loo, K. C.; Crooker, K. E.; Pena, Y. E.  Chem. Commun. 2002, 1360.

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