Charge–transfer complexes of pyrimidine Schiff bases with aromatic nitro compounds

Charge–transfer (CT) complexes of pyrimidine Schiff bases, derived from condensation of 2-aminopyrimidine and substituted benzaldehydes, with some aromatic polynitro compounds were prepared and investigated using IR, UV, visible and 1H NMR spectroscopy. For all solid complexes, the main interaction between the donor and acceptor molecules takes place through the π–π* interaction. Strong and some weak acidic acceptors, in addition interact through proton transfer from the acceptor molecule to the basic centre of the electron donor. Also, an n–π* transition was detected in some complexes.

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► Aminopyrimidine Schiff bases CTC with nitrobenzene acceptors are isolated.
► The main interaction occurs through HOMO–LUMO electron transfer.
► Acidic acceptors may exhibit proton transfer besides.
► Depending on molecular orientation, n–π* may be observed.