Binding energy emission process

The formation of these ternary luminescent lanthanide complexes was the result of displacement of the two labile metal-bound water molecules, which was necessary because the energy transfer process between the antenna and the Ln(III) metal centre is distance-dependent. This ternary complex formation was confirmed by analysis of the emission lifetimes in the presence of DMABA and showed the water molecules were displaced by a change in the hydration state q from 2 to 0, with binding constants of log fCa = 5.0. The Eu(III) complexes were not modulated in either water or buffered solutions at pH 7.4. Lifetime analysis of these complexes showed that the metal-bound water molecules had not been displaced and that the ternary complex was not formed. Of greater significance, both Tb -27 and Tb -28 could selectively detect salicylic acid while aspirin was not detected in buffered solutions at pH 7.4, using the principle as discussed for DMABA where excitation of the binding antenna resulted in a luminescent emission upon coordination of salicylic acid to the complex. 

Relaxation of the neutral excited complex towards the ground state with emission of fluorescence (process IV). The red shift in the absorption (excitation) spectra of the AH-B complex with respect to the absorption of the bare AH molecule will only measure the increase of the binding energy in the excited neutral form AH - B of the cluster. Then, the emission spectrum will be similar to the fluorescence of the free molecule. 

The IRMPD experiment has been developed into a quantitative tool for the estimation of activation barriers of fragmentation processes, the so-called FRAGMENT method [28]. The barriers correspond to binding energies for simple bond dissociation reactions, if the reverse reactions do not have significant barriers. Consequently, kinetic and thermodynamic data are accessible with this method despite the ill-definition of temperature. The experiment relies on the generation of a steady state of IR photon absorption and emission after a short induction period. 

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