After the introduction of amino-ethyl-amino group between donor and
acceptor, the styryl moiety of MTPABT-APyc, MTPADP-APyc and MTPABD-APyc
still showed good planarity, in MTPAQL-APyc and MTPAPA-APyc molecules,
due to the more complex structure of the heterocyclic moiety, the steric
hindrance is larger, and a small dihedral angle appears. It should be
noted that although the donor moiety was modified with a different
heterocycle, the bond length of the acceptor moiety was almost
unchanged, indicating that the insertion of the amino-ethyl-amino group
disrupted the interaction between the donor and the acceptor. This will
facilitate the construction of charge-separated dyes.