In Situ Probe Supramolecular Self-Assembly Dynamics and Chirality Transfer Mechanism at Air-Water Interface

The study of supramolecular self-assembly dynamics and the chirality transfer mechanism is of importance to the rational design of potentially functional chiral supramolecular materials and an understanding of the origin of homochirality in biological systems. Herein, we study the supramolecular assemblies constructed by the tetrakis(4-sulfonatophenyl) porphyrin (TPPS) molecules' adsorption on the enantiomer chiral amphiphilic molecules (l-/d-G12) using sum-frequency generation (SFG) and second harmonic generation (SHG) spectra. We first establish a dynamic model that involved adsorption and assembly and obtained the dynamic parameters by fitting this model. We then propose the chiral transfer mechanism from the chiral center of the l-/d-G12 molecule to the whole supramolecular assembly. Finally, we put forward an explanation that the sulfonic acid group and the phenyl group on the TPPS molecule show homochirality, but the porphyrin ring forms J-aggregation and shows mirror-symmetric structural chirality in the l-/d-G12 and TPPS self-assembly at these processes.