Odd–Even Effect in Charge Transfer Complexes through the Regulation of the Alkyl Chain

Charge transfer (CT) complexes formed by donor–acceptor
(D-A) pairs play a critical role in organic optoelectronic devices,
where the CT effect is highly correlated with molecular packing and
intermolecular interaction. There are still challenges in exploring
the mechanisms of charge transfer in the noncrystal state. Most studies
regulated intermolecular charge transfer by altering the π-conjugated
backbone and substituents, which would lead to some uncertainties
in the packing-property relationship. Herein, we utilized triazatruxene
(TAT) with different alkyls as donors and 1,3,5-benzenetricarbonitrile
(TCNPh) derivatives as acceptors. The systems of the CT complex were
constructed by simply grinding the donor–acceptor mixture to
study the role of molecular arrangement in charge transfer, in which
an obvious odd–even effect could be observed. Thus, our study
further enriched the odd–even effect of alkyl chain regulation,
allowing for a more profound understanding of the relationship among
aggregation structures, CT interactions, and optoelectronic characteristics
of the CT complex.