π-Complexes incorporating tetrakis(phenylethynyl)ethene

Tetrakis(phenylethynyl)ethene and the π-acceptors 2,4,7-trinitrofluoren-9-one and (2,4,7-trinitrofluoren-9-ylidene)malononitrile form highly ordered donor–acceptor π-complexes having 1:2 stoichiometry in the solid state. In solution, relatively weak 1:1 complexes are formed whose stabilities are related to the spatial disposition of the donor phenyl rings rather than the HOMO–LUMO interactions of the donor–acceptor pair. The orientation of the donor with respect to the acceptor in the solid state shows a good correlation with the atom-centred point charges on each component of the complex. However, there is a very poor correlation between the orbital coefficients of the donor HOMO and the acceptor LUMO suggesting that the solid state structure is dominated by electrostatic interactions.