Despite its non-negligible 1 O2 quantum yield, the complexity evoked is also clearly present for CURC. Indeed, natural CURC may exist in two tautomeric forms, namely keto and enol, which coexist in nature including upon administration into the human body. Recently, we have also shown that the inclusion in liposome or membranes, is susceptible to displace the equilibrium between the two forms, hence posing important burdens on the possibility of drug delivering strategies. As shown in Scheme 1, the structural properties of keto and enol form are significantly different, which in turn leads to different optical and photophysical properties. Indeed, the enol tautomer is stabilized by an intermolecular hydrogen-bond (H-bond) between the OH and C=O groups. Such interaction confers rigidity to the global structure, and more importantly leads to a highly planar scaffold, which favours delocalization and p-conjugation. As a consequence, enol CURC presents a considerable red-shifted absorption spectrum, which is highly beneficial for biological applications. Conversely, and also due to the C=O lone pairs repulsion the keto tautomers shows a broken conjugation pattern and a twisted geometry, which correlates with a blue-shifted absorption. We have previously demonstrated, also through the proper exploration of the involved potential energy surfaces (PES), that both tautomers offer suitable, and energetically favourable, routes for ISC as well as possible fluorescence. However, the enol tautomer is usually regarded as unsuitable for PDT applications and ISC because of the opening of a relaxation pathways, based on the excited state transfer of the hydrogen involved in the intramolecular H-bond. Indeed, the lowest excited states of CURC having np* and pp* character they may lead to the weakening of the OH bond and hence favour the transfer. In this contribution, going beyond our previous modelling, we resort to non-adiabatic molecular dynamics (NAMD) in the state-hopping (SH) formalism, to assess the competition between H-transfer and ISC during the relaxation of the initially populated excited states. This is possible thanks to the inclusion of general coupling in the SH Hamiltonian, including spin orbit coupling (SOC) elements. Our SH simulations clearly confirm the occurrence of the Htransfer, already at a sub-ps timescale. However, we also show that ISC is not quenched and a significant, albeit non-dominant and non-ultrafast, population of the triplet state manifold is achieved.