Fluorescent PET (photoinduced electron transfer) sensors selective for submicromolar calcium with quantitatively predictable spectral and ion-binding properties

The anthracene (QCa1) and pyrazoline (QCa2) derivatives display Ca2+- induced enhancements of fluorescence quantum yields (ϕF), by factors of 16 and 92, respectively; the binding selectivities (vs. Mg2+ and H+) and characteristics of the electronic (absorption and emission) spectra (except ϕFmax.) are reasonably predictable from simpler model compounds.