|Title||Tunable columnar mesophases utilizing C2 symmetric aromatic donor-acceptor complexes.|
|Publication Type||Journal Article|
|Year of Publication||2006|
|Authors||Reczek, JJ, Villazor, KR, Lynch, V, Swager, TM, Iverson, BL|
|Journal||Journal of the American Chemical Society|
|Keywords||Biomimetic Materials, Biomimetic Materials: chemistry, Crystallization, Crystallography, Electrons, Imides, Imides: chemistry, Liquid Crystals, Liquid Crystals: chemistry, Molecular Conformation, Naphthalenes, Naphthalenes: chemistry, Phase Transition, Thermodynamics, X-Ray, X-Ray Diffraction|
Derivatives of relatively electron rich 1,5-dialkoxynaphthalene (Dan) donors and relatively electron deficient 1,4,5,8-naphthalenetetracarboxylic diimide (Ndi) acceptors have been exploited in the folding and self-assembly of a variety of complex molecular systems in solution. Here, we report the use of Dan and Ndi derivatives to direct assembly of extended columns with alternating face-centered stacked structure in the solid state. A variety of 1:1 Dan:Ndi mixtures produced mesophases that were found to be stable over temperature ranges extending up to 110 degrees C. Analysis of these mesophases indicates mixtures with soft/plastic crystal phases and a few mixtures with the thermodynamic properties of true liquid crystals, all composed of alternating donor-acceptor columns within. Importantly, a correspondence was found between the clearing and crystallization points of the mesophase mixtures and the melting/clearing points of the component Ndi and Dan units, respectively. This correspondence enables the predictable tuning of mesophase phase transition temperatures. The study of sterically hindered derivatives led to a set of mixtures in which a dramatic and sudden color change (deep red to yellow) was observed upon crystallization of the mesophase due to a phase separation of the component donor and acceptor units.