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.