The spectroscopic and photophysical properties of fluorescent probes comprising donor-acceptor derivatives comprising the boric acid group or a derivative of boric acid, B(OH)3 (or borate ion, BO(OH)2−1), arsenious acid, H3 AsO3 (or arsenite ion, H2AsO3−1), telluric acid, H6TeO6 (or tellurate ion, H5 TeO6−1) or germanic acid, Ge(OH)6 (or germanate ion, GeO(OH)3−1) are described. Method of using said probes are also provided.