Electronic quantum dynamics approach sheds light on the photophysics of DNA silver quantum dots

MARTÍN I. TACCONE; MATÍAS BERDAKIN; CRISTIÁN G. SÁNCHEZ; GUSTAVO A. PINO

Mendoza

Congreso; 9th International Meeting on Photodynamics and Related Aspects; 2016

One interesting application of metal mediated base pairing is the production of highly fluorescent and tunable hybrid DNA-Agn clusters. An interesting property of these is the fact that they have two intense absorption bands, one in the visible range tunable with DNA base sequence and/or the number of Ag atoms and the other, in the UV spectral region, common to all of them regardless of the position of the visible band.1 Recent evidence indicate that the UV absorption band corresponds to excitation of the nucleobases.1 Interestingly, the excitation of the UV band leads to the same fluorescence spectrum as in the case of excitation of the tunable visible band. Nevertheless the detailed mechanism responsible for this coupling is still elusive. In this context, our work pretends to be a significant leap in this sense by providing a dynamical picture of excitation and the processes that take place upon light absorption in these systems using a time-dependent density functional tight binding approach. In the present work we explore the electronic coupling mechanism in a system composed by a double string of deoxy-polycytosine with 6 bases (hereafter dpC6) and a rod of 6 Ag atoms.