Signaling Recognition Events with Fluorescent Sensors and Switches.

▪ Abstract Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. We review several are...

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Proton-Coupled Electron Transfer

The origin of ions in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is currently a matter of active research A number of chemical and physical pathways have been suggested for MALDI ion formation, including gas-phase photoionization, ion–molecule reactions, disproportionation, excited-state proton transfer, energy pooling, thermal ionization, and desorption of preformed ions These pathways and others are critically reviewed, and their varying roles in the wide variety of MALDI experiments are discussed An understanding of ionization pathways should help to maximize ion yields, control analyte charge states and fragmentation, and gain access to new classes of analytes © 1999 John Wiley & Sons, Inc Mass Spec Rev 17: 337–366, 1998

Ion formation in MALDI mass spectrometry

We have used knowledge of the electronic structure of excited states of acids to design molecules that exhibit enhanced excited-state acidity. Such “super” photoacids are the strongest reversible photoacids known and allow the time evolution of proton transfer to be examined in a wide array of organic solvents. This includes breaking/formation of the hydrogen bonds in hundreds of femtoseconds, solvent reorientation and relaxation in picoseconds, proton dissociation, and, finally, diffusion and geminate recombination of the dissociated proton, observed in nanoseconds.

Excited-state proton transfer: from constrained systems to "super" photoacids to superfast proton transfer.

Molecular fluorescent signalling with ‘fluor–spacer–receptor’ systems: approaches to sensing and switching devices via supramolecular photophysics

Publisher Summary This chapter discusses acid–base properties of electronically excited states of organic molecules. Excited state pK-values are most easily accessible through the use of the Forster cycle. To perform this calculation for a particular molecule, it is necessary to know the ground state equilibrium constant for the reaction in question and to have some measure of the energy difference between the lowest vibrational level of the ground and the excited state in both the B and BH + forms. The effects of solvation on 0–0 energies are discussed. The changes in molecular fluorescence with acidity give information about the protolytic behavior of the excited singlet state of a compound. Two techniques, phase and pulse fluorometry, are used for the direct measurement of fluorescence decay rates. The excited state acid-base behavior of molecules has direct implications in the field of analytical fluorimetry and phosphorimetry.

J.F. Ireland

Papers

Acid-Base Properties of Electronically Excited States of Organic Molecules