Dual Cooperatively Grown J‐aggregates with Different Nucleus Size

Abstract

A molecule featuring two distinct cooperatively grown J-aggregates is investigated. Interestingly, when cooling a hot monomer solution, the thermodynamically less stable J 1 is exclusively formed even at a particularly slowed temperature dropping rate, which transforms to the more stable J 2 at room temperature with very slow kinetics. This observation is ascribed to the differed nucleus sizes of J 1 and J 2 . During the cooling process, smaller J 1 nuclei are formed first at a higher temperature, favored by the entropy effect. At intermediate temperatures, the elongation of J 1 outcompetes the nucleation of J 2 . Then, below the elongation temperature of J 2 , the formation of this thermodynamically stable aggregate is hindered kinetically, due to the depletion of monomer by the slow dissociation of J 1 . Additional evidence proving the larger nucleus size of J 2 is also identified with the varied-temperature spectral analyses and mathematic simulations.