Propeller-like Hydrogen-Bonded Banana−Melamine Complexes Inducing Helical Supramolecular Organizations

Abstract

The results of the study presented here show a new example of the use of liquid crystals and the interactions involved in the mesomorphic state to build up complex molecular organizations. We have pursued a design strategy in which hydrogen bonding allows the combination of the pi-stacking tendency of melamine and the lateral interaction capability of V-shaped molecules, which has been extensively demonstrated through nematic, smectic, or columnar mesophases. This combination addresses the formation of columnar arrangements with inherent helical organization. In this work, nonmesomorphic as well as mesomorphic V-shaped acids, with a structure similar to banana liquid crystals, have been complexed to a 2,4,6-triamino-1,3,5-triazine derivative in a proportion 3 to 1, respectively. Hydrogen-bonded supramolecules whose formation and stability in solution have been proven by infrared and NMR techniques have been thus obtained. DOSY experiments have allowed us to assess in solution the presence of the complexes and their tetrameric composition. All the complexes display mesogenic ability, and their mesomorphic organization has been studied by X-ray diffraction and CD spectroscopy. Results allow us to propose a helical columnar model for the mesophase originated from a propeller-like conformation of the supramolecular complexes.

Desymmetrization of 3,3′‐Bis(acylamino)‐2,2′‐bipyridine‐Based Discotics: The High Fidelity of Their Self‐Assembly Behavior in the Liquid‐Crystalline State and in Solution

“…[1] However, in Col r1 and Col r2 phases an unusual value of Z = 4 was calculated based on density considerations (Table 2). [43] When comparing the lattice parameters, b is similar for all phases for both discotic 1 and discotic 2, but a in Col r1 and Col r2 is nearly twice a in the Col r3 . It is assumed that at lower temperatures the symmetry decreases, and as a result two unit cells of Col r3 combined to give rise to the new unit cell of the Col r2 and Col r1 phases (Figure 4c).…”

Multiresponsive self-assembled liquid crystals with azobenzene groups

“…The CN group was sensitive to the change of the electric field, which was widely used in the commercial liquid-crystal materials [12]. Even though similar complexes have been reported by Sierra and co-workers for the light-driven supramolecular chirality [31,32], the multiresponsive properties in the liquid-crystalline phase were rarely discussed. As we expected both A and A 3 T show liquid-crystalline phases in a certain temperature range.…”

“…Introduction of photochromic and electric-responsive properties to liquid-crystalline composites will be useful for the development of liquid crystals (LCs) as advanced memory materials. Self-assembly materials containing azo linkages have attracted tremendous attention because of their light-induced photo-switchable and elastic properties [23][24][25][26][27][28][29][30][31][32]. However, in most cases, the liquid-crystalline phase of azobenzene compound transferred to the isotropic phase on irradiation because of the unstabilization of the liquid-crystalline phase by cis-azobenzene [11][12][13][14][15][16][17]26].…”

Spontaneous Assembly of Extremely Long, Horizontally‐Aligned, Conductive Gold Micro‐Wires in a Langmuir Monolayer Template

“…The synthesis of OM molecule was carried out according to published procedures. [ 31,32 ] Briefl y, a mixture of 2-chloro-4,6-diamino-1,3,5-triazine (19 mmol), octadecylamine (19 mmol) and anhydrous sodium hydrogencarbonate (19 mmol) in 1,4-dioxan (75 mL) was refl uxed under argon atmosphere for 6 hrs. The reaction mixture was then cooled and poured into water (100 mL).…”