Introduction

For many areas of a science and engineering a problem of creation effective fluorophores for visible and, especially, blue-green region of a spectrum is important. In case of fluorescent probes, or biological labels the sensitive response of fluorophores on slightest changes of properties of an environment is determining. Derivatives of hydroxycoumarins satisfy to such requirements. Reaction in an excited states (interruption, transfer, connection of proton) results in formation of the several protolytic forms hydroxycoumarins: neutral, anionic, cationic, phototautomer, that allows to get a wide region of laser tuning, using hydroxycoumarins as active media.

In the present work the analysis of the possible ways of energy degradation of electron excited states of 4-methyl-7-hydxycoumarin (4-methyl-umbelliferone, 4MU) and its protolytic forms is presented; a ratio of radiative and nonradiative channels of deactivation of energy of electronic excitation is established; constants of photophysical processes (internal and intercrossing conversion), proceeding after act of absorption of light are designed (Fig.1).