Interfacial aggregation behavior of glutamide-azobenzene Langmuir-Blodgett films with dyes and its SERS, photoelectric conversion and chiral properties

Abstract

Artificial supramolecular materials have found extensive applications in many fields such as biology, chirality, and information science. The Langmuir-Blodgett (LB) film technology, as an effective means of molecular assembly, offers broad prospects for the preparation of functional materials with specific properties. This study focuses on a chiral and amphiphilic molecule - the glutamine-azobenzene molecule (GAZS) composite Langmuir-Blodgett film. Through the LB technique, GAZS molecules were successfully compounded with MB, ST, and RhB subphases to form multi-layer films. The interfacial aggregation behavior of this film was thoroughly explored, and its morphological characteristics and spectral properties were analyzed. The results show that the LB films which are prepared exhibit the same J-aggregation state. The surface-enhanced Raman scattering (SERS) experiment shows that the composite LB films which are prepared have outstanding Raman enhancement performance, with an enhancement factor (EF) of 2.46 × 10⁵. Additionally, the Raman intensity has a relative standard deviation of 12.30 %, which implies that the composite films possess excellent reproducibility and uniformity. Thus, they are suitable for the detection of trace molecules. The circular dichroism spectroscopy proves that the LB films formed after the combination of GAZS molecules and dye subphases exhibit obvious chiral signals, providing some insights into the performance research and application expansion of chiral photo-supramolecular material composite LB films. Through the photoelectric conversion test of transferring multi-layer films onto indium tin oxide (ITO), it is found that the self-assembled LB films exhibit outstanding photoelectrochemical characteristics. The GAZS molecules show a more powerful photoelectric conversion effect. under the RhB subphase, providing a reference for the further exploration of the applications of GAZS molecule composite LB films in optoelectronic devices.