Reversible Near-Infrared Light Directed Reflection in a Self-Organized Helical Superstructure Loaded with Upconversion Nanoparticles

Abstract

Adding external, dynamic control to self-organized superstructures with desired functionalities is an important leap necessary in leveraging the fascinating molecular systems for applications. Here, the new light-driven chiral molecular switch and upconversion nanoparticles, doped in a liquid crystal media, were able to self-organize into an optically tunable helical superstructure. The resulting nanoparticle impregnated helical superstructure was found to exhibit unprecedented reversible near-infrared (NIR) light-guided tunable behavior only by modulating the excitation power density of a continuous-wave NIR laser (980 nm). Upon irradiation by the NIR laser at the high power density, the reflection wavelength of the photonic superstructure red-shifted, whereas its reverse process occurred upon irradiation by the same laser but with the lower power density. Furthermore, reversible dynamic NIR-light-driven red, green, and blue reflections in a single thin film, achieved only by varying the power density of the NIR light, were for the first time demonstrated.

Hollow Structured Y2O3:Yb/Er–CuxS Nanospheres with Controllable Size for Simultaneous Chemo/Photothermal Therapy and Bioimaging

“…6−17 Thus, NIR irradiated UC emissions may have a wide application in the biological field. 18,19 Meanwhile, materials with hollow structures have attracted special attention due to their attractive typical features including large surface area, low density, tunable pore size, and high loading capacity based on the large cavity. 20−22 Compared with the solid materials, the large interior space and the hollow structure induced large surface area can store/adsorb more drug molecules, and the mesoporous shells can provide accessible channels for drug molecules diffusion and mass transfer.…”

Rare Earth Based Anisotropic Nanomaterials: Synthesis, Assembly, and Applications

“…5.23c) from Tm 3+ are observed to trigger the reversible process of the blueshifted absorption of liquid crystal (Fig. 5.23d) [141].…”

Stimuli‐Directed Dynamic Reconfiguration in Self‐Organized Helical Superstructures Enabled by Chemical Kinetics of Chiral Molecular Motors

“…Among numerous external stimuli, light is known to have superior advantages of remote, instant, and precise controllability in an uncontacted way. In this regard, many efforts have been devoted to advance photoresponsive molecular switches and motors in the realm of intelligent liquid‐crystalline materials 8, 9, 10, 11, 12, 13, 14. Light‐driven dynamic self‐organized helical superstructures, i.e., cholesteric liquid crystals (CLCs), could be obtained upon doping the chiral molecular motors into achiral LC hosts, where the orientation of helical axes is typically expressed as three configurations: (1) parallel to the substrate with a fingerprint texture (lying helixes) resulting from the periodical helical pitch ( p ) defined as the distance as the molecular rotation by 360° twist along the helical axis; (2) perpendicular to the substrate with a Grandjean texture (standing helixes) performing unique Bragg reflection of circularly polarized light at wavelength λ = np , where n is the average refractive index of LC; (3) spatial disorder alignment with a focal conic (FC) texture, which can strongly scatter incident light.…”