Frank-Kasper phases in charge transfer complexes enable tunable photoelectronic properties.

Understanding how particles pack in space and the mechanisms underlying symmetry selection across soft matter is challenging. The Frank-Kasper (F-K) phase of complex spherical packing is amongst the most fascinating phases; however, it has not been observed in discotic liquid crystals until now. Herein, we report the first observation of F-K phases of charge transfer complexes (CTCs) obtained from triphenylene derivatives as donors and 2,4,7-trinitro-9-fluorenone as the acceptor. The CTCs were characterized using experimental and theoretical calculations, indicating that the F-K A15 cubic lattice possesses a unit cell containing 8 sphere-like supramolecules, each of which was self-assembled from 3 CTC complexes. The lattice constant was only 3.2 nm, which is by far the smallest for the A15 phase. Interestingly, the supramolecular assembly can be regarded as the molecular column splitting into isolated spherical fragments, impeding charge transfer and turning it into one insulator. This provides a simple and effective method for preparing asymmetric complex compounds for the design of unconventional self-assembled nanostructures.

Adsorption of triblock copolymers confined between two plates: An analytical approach.

We present an approximate analytical approach to the adsorption problem of ABA triblock copolymers confined between two parallel plates in a θ solvent and give the expression of the propagator q(x, t) as a piece-wise function by solving the modified diffusion equation. In this way, the role of separation between the two plates, adsorption energy and block lengths on segment concentration profile, chain conformations, and interaction potential is then investigated, which agrees well with the numerical results. It is demonstrated that there are parallels between lengthening adsorbing A blocks and increasing surface affinity: strong adsorption and long adsorbing blocks favor the formation of loops and bridges, whereas more tails and free chains exist in the case of weak adsorption and short A blocks at large separations. For moderate and strong adsorptions, the bridging fraction begins to plummet at a separation larger than the end-to-end distance of non-adsorbing B block RB and becomes negligible at above 2RB owing to the entropy effect. The depth of the potential well in the interaction potential profile depends on the adsorption energy and A block length, while the location of the potential minimum corresponds to the onset of the sharp decrease in bridges.