Null Excitonic Interaction in Greek Cross (+) Aggregate

The independent discovery of dye aggregate by Jelley and Scheibe marked the beginning of a spectacular development in the field of aggregate photophysics. Subsequent research warranted a model for defining the exciton interactions in aggregates, proposed by Kasha and Davydov independently, which was later modified by incorporating the short-range excitonic coupling. The first crystalline evidence for the chromophoric Greek cross (+) assembly exhibiting monomer-like optical properties was reported in 2018 (Figure 1).[1] The manifestation of selective hole transfer coupling in the edge-to-edge arranged Greek cross (+) perylenediimide dimer resulted in ultrafast dissociation of null exciton and evolution of the charge-separated state in a polar solvent, providing a way forward in the fundamental understanding of null aggregates.[2]

References:

[1]  E. Sebastian, A. M. Philip, A. Benny, M. Hariharan, Angew. Chem. Int. Ed., 2018, 57,15696
[2]  M. P. Lijina, A. Benny, R. Ramakrishnan, N. G. Nair, M. Hariharan, J. Am. Chem. Soc., 2020, 142, 17393