TY - JOUR AU - Grilj, Jakob AU - Buchgraber, Philipp AU - Vauthey, Eric TI - Excited-State Dynamics of Wurster's Salts PY - 2012 JF - Journal of Physical Chemistry A JA - J. Phys. Chem. A SN - 1089-5639 VL - 116 IS - 28 SP - 7516 EP - 7522 L1 - http://pubs.acs.org/doi/pdf/10.1021/jp3045548 L2 - http://pubs.acs.org/doi/full/10.1021/jp3045548 L3 - http://pubs.acs.org/doi/abs/10.1021/jp3045548 L4 - http://www.unige.ch/sciences/chifi/publis/pics/double/ref01303.png M3 - 10.1021/jp3045548 UR - http://dx.doi.org/10.1021/jp3045548 N2 - The excited-state dynamics of a series of Wurster’s salts (p-phenylenediamine radical cations) with different subtituents on the nitrogen atoms was investigated under a variety of experimental conditions using a combination of ultrafast spectroscopic techniques. At room temperature, the lifetime of the lowest excited state of all radical cations is on the order of 200 fs, independently of the solvent, that is, water, nitriles, alcohols, and room-temperature ionic liquid. On the other hand, all cations, except that with the bulky nitrogen substituents, become fluorescent below 120 K. The observed dynamics can be accounted for by the presence of a conical intersection between the D1 and D0 states. For the cations with a small nitrogen substituent, this conical intersection could be accessed through a twist of one amino group, as already suggested for Wurster’s Blue. However, this coordinate cannot be invoked for the cation with bulky nitrogen subtituents, and more probably, pyramidalization of the nitrogen center and/or deformation of the phenyl ring play an important role. Consequently, the excited-state dynamics of these structurally very similar Wurster’s salts involves different decay mechanisms. ID - 1303 ER -