Unprecedented parallel packing of unsymmetrical bolaamphiphiles driven by π–π stacking of cinnamoyl groups

Abstract

The self-assembly and molecular packing mode of a novel, unsymmetrical bolaamphiphile, sodium 4-(6-hydroxyhexyloxy) cinnamate (SHHC) was studied. Tube-like structures were obtained in SHHC aqueous solution at pH 9.2. Upon UV irradiation, the SHHC molecules in the system were found to undergo four-center-type photocyclodimerization and photoisomerization. The combination of IR, XRD and Zeta potential results suggested the formation of a tail-to-tail type bilayer membrane structure: the SHHC molecules stretched upright with the cinnamate headgroups toward the outside in each layer, whereas the tail OH groups of two layers remained inside and formed interlayer hydrogen bonds. This parallel packing mode of SHHC molecules in the membrane was also confirmed by the pHinduced self-assembly transition. With increasing pH from 9.2 to 12.0, the low-curvatured tubes transformed into spherical vesicles, which was in line with the increased outer leaflet head group area as increasing pH. Our results demonstrated that upon careful molecular design, the orientation of unsymmetrical bolaamphiphiles can be controlled; p-p interactions between cinnamoyl groups were found to be strong enough to drive the formation of well-oriented molecular assemblies.

Properties of binary surfactant systems of nonionic surfactants C12E10, C12E23, and C12E42 with a cationic gemini surfactant in aqueous solutions

“…11. As for 14-4-14 or C 12 E n /14-4-14, the four periodic reflection peaks suggest the existence of well-defined lamellar structures [52,53]. According to the Bragg equation, the layer spacing is about 2.42 nm, which indicates that bilayer aggregates are formed, and further confirms that the large aggregates observed by CryoTEM and TEM are vesicles.…”

“…9 and 10, respectively. It has been established that self-assembled structures of amphiphiles can be well preserved in casting films [52]. In order to determine the structural features of the aggregates, the cast films of the surfactant solutions has been prepared and measured by XRD, and the patterns are shown in Fig.…”

Organogelation‐Controlled Topochemical [2+2] Cycloaddition and Morphological Changes: From Nanofiber to Peculiar Coaxial Hollow Toruloid‐Like Nanostructures

“…19 This indicated that 2‐NA formed a cyclobutane structure in the gel. Meanwhile, the appearance of a bending vibration of the saturated C‐H of the cyclobutane at $\tilde \nu $ =1441 cm −1 in the spectrum of the 2‐NA precipitate (Figure S5) verified the topochemical reaction 20. The FTIR bands thus provided two indications for the occurrence of the [2+2] cycloaddition reaction: loss of the trans ‐vinylene CC bond and the appearance of cyclobutane.…”

“…Meanwhile, the appearance of a bending vibration of the saturated C-H of the cyclobutane at ñ = 1441 cm À1 in the spectrum of the 2-NA precipitate ( Figure S5) verified the topochemical reaction. [20] The FTIR bands thus provided two indications for the oc- currence of the [2+2] cycloaddition reaction: loss of the trans-vinylene C=C bond and the appearance of cyclobutane. Unambiguous evidence for the existence of the dimer was further provided by the MALDI-TOF data ( Figure S6), which showed a peak at m/z = 1682.7 for the precipitate, exactly corresponding to the dimer of 2-NA.…”

Helical Nanostructures: Chirality Transfer and a Photodriven Transformation from Superhelix to Nanokebab

“…Moreover, a new absorption of the bending vibration of saturated C−H of the cyclobutane at 1342 cm −1 appears after photoirradiation, thus verifying the photodimerization in the gel. By using the CH 2 symmetrical stretching vibration band at 2850 cm −1 as a reference, we could estimate the degree of photodimerization as about 29 % upon analysis of the integral area of the C=C vibration band, which is slightly higher than that from the NMR spectra. It is reasonable that the higher temperature could possibly cause the transformation from dimer to monomer.…”