Phase Behavior and Structure of Supramolecules Formed by Poly(4-vinylpyridine) and Fanlike Benzoic Acid Derivative with Long Hydrophobic Tails

We investigated the self-assembly behaviors of supramolecules formed by poly­(4-vinylpyridine) (P4VP) and a fanlike small molecule, 3,4,5-tris­(hexadecyloxy)­benzoic acid (THBA), via hydrogen bonding interactions. Different from other commonly studied small molecules, THBA bears three particularly long hydrophobic tails and tends to form stable crystals by itself, which gives rise to unusual phase behaviors and structures. We used FTIR to investigate the degree of complexation and find that it is not monotonically increased to a plateau with increasing THBA but reaches a maximum and then decreased. This is attributed to the crystallization of excess THBA that induces a debonding of the originally associated THBA. The crystallization-induced dissociation and macrophase separation are further evidenced by DSC and X-ray scattering analyses. Below the order–disorder transition temperature, a coexistence of lamellae and hexagonally packed cylinders is found in melted P4VP­(THBA) supramolecules. After the associated THBA crystallizes, the complexes exclusively form hexagonally packed cylinders due to the bulky tails of THBA, in the absence of the lamellar structure generally seen in other polymer-based supramolecules

Tetranuclear Silver(I) Clusters Showing High Ionic Conductivity in a Bicontinuous Cubic Mesophase

The synthesis and characterization of tetranuclear silver triazole metallomesogens, [Ag₄(L⁴-C_<i>n</i>)₆]­[BF₄]₄ (L⁴-C_<i>n</i> = 4-alkyl-1,2,4-triazoles where C_<i>n</i> stands for C_<i>n</i>H_2<i>n</i>+1 with <i>n</i> = 12, 14, 16, and 18), are reported. Upon heating, a phase transition sequence of Cr → SmC → Cub → SmA → isotropic liquid is observed for all of these compounds. Depending on the alkyl chain length, two types of cubic phases are found in this series of compounds. Those with shorter alkyl chains (<i>n</i> = 12 and 14) exhibit a micellar cubic phase, whereas long alkyl chains (<i>n</i> =16 and 18) show a bicontinuous cubic phase. Superior ionic conductivity at the bicontinuous cubic mesophase for [Ag₄(L₄-C₁₆)₆]­[BF₄]₄ is observed because of the presence of a three-dimensional ion-transporting channel. Doping a small amount of AgBF₄ enhances the ionic conduction dramatically, presumably via promotion of the migration of Ag^I ions in the channels