Supramolecular Assemblies between a New Series of Gemini-Type Amphiphiles and TPPS at the Air/Water Interface:  Aggregation, Chirality, and Spacer Effect

Abstract

Supramolecular assemblies between a series of novel gemini amphiphiles (BisImC17Cn) and TPPS (tetrakis(4-sulfonatophenyl)porphine) at the air/water interface were investigated. It was found that the gemini amphiphiles could form stable complex monolayers at the air/water interface with TPPS through electrostatic interaction and π−π stacking. There is an inflection point in each of the surface pressure−area isotherms of the complex monolayers. At a certain pH value of the subphase, TPPS could complex with the gemini amphiphiles as a J-aggregate. AFM measurements revealed that nanofibers were formed in the transferred films onto solid substrates by a horizontal lifting method. Interestingly, all the complex films containing the J-aggregate of TPPS showed CD signals in the J-band although both of the amphiphiles and TPPS were achiral. Helical stacking of the TPPS underneath the gemini monolayers was suggested to be responsible for the supramolecular chirality of the multilayer films. The spacers in the gemini amphiphiles have great influence on the chirality of the system. For the film transferred at a surface pressure below the inflection point, the CD signals showed splitting only when the spacer length is larger than four methylene units. The films transferred at the surface pressure above the inflection points showed splitting CD signals of the Soret band of J-aggregates, which could be ascribed to the interaction between the J-aggregates. Moreover, for the film transferred above the inflection points, the CD intensity of the films decreased when the spacer length of the gemini amphiphile increased. It is further observed that many properties such as the width and thickness of the formed nanofibers showed a turning point at a spacer length of six methylene units. A mechanism including the convex of the spacers when they were larger than six methylenes was proposed.

Supramolecular chirality of the hydrogen-bonded complex Langmuir–Blodgett film of achiral barbituric acid and melamine

“…We suggested that the supramolecular chirality of BA-M film resulted from symmetry breaking on the air-water interface, whose direction was random [8]. These phenomena are essentially the same as we previously observed in the LB film [15][16][17][18][19][20].…”

“…This case is very important because it may relate to the origin of the chirality and even the origin of life. Recently, our group has focused on the supramolecular chirality of the interfacial organized molecular films from achiral amphiphiles and obtained some interesting results [15][16][17][18][19][20]. We have found that some organized molecular films of achiral compounds could show chirality if the molecules were rationally designed and assembled through noncovalent interactions, which involved J-aggregation, electrostatic interaction, coordination, and hydrogen bonding.…”

Induced Circular Dichroism of Anionic Porphyrin TPPS Aggregates in DNA Solutions

“…It can form stable J-aggregate or H-aggregate, which depends on the pH value and ionic strength in the system. TPPS aggregates can be easily induced to show chirality by many cationic chiral and achiral templates, such as L-(or D-) Trp film, 24 gemini-Type Amphiphiles, 25 polylutamic acid 26 and polylysine, 27 chitosan, 28 etc. Usually, these templates are just cationic, which can be directly interacted with the anionic TPPS.…”

Hexagonal Nanoarchitecture of Composite Monolayer of Magnetite Nanoparticles and Geminus Surfactant 1,3‐Propylenebis(dodecyldimethylammonium) Dibromide

“…1,[14][15][16][17] Itwas proved that the chemical structure of the geminus surfactants influenced strongly their properties at the air-liquid interface. for instance, Liu et al 18 designed a series of achiral geminus surfactant and found the supramolecular chirality of the TPPS-geminus amphiphiles systems at the air-water interface. In a simplest model, the shape of an individual solid domain was de termined to a large extent by the interplay of the molecular long-range dipolar electrostatic forces and the line tension.…”