Controlled self-assembly has attracted extensive interest in biological and nanotechnological applications. Enzymatic or biocatalytic triggered self-assembly is widely used for the diagnostic and prognostic marker in different pathologies because of their nanostructures and biological effects. However, it remains a great challenge to control the self-assembly of peptides in living cells with a high degree of spatial and temporal precision. Here we demonstrate a light-triggered platform that enables spatiotemporal control of self-assembly from nanoparticles into nanofibers in living cells through subtle molecular conformational changes and internal H-bonding interactions. The platform contained 3-methylene-2-(quinolin-8-yl) isoindolin-1-one, which acts as the light-controlled unit to disrupt the hydrophilic/lipophilic balance through the change of molecular conformation, and a peptide that can be a faster recombinant to assemble via H-bonding interactions. The process has good biocompatibility because it does not involve waste generation or oxygen consumption; moreover, the assembly rate constant was fast and up to 0.17 min-1. It is applied to the regulation of molecular assembly in living cells. As such, our findings demonstrate that light-triggered controllable assembly can be applied for initiative regulating cellular behaviors in living systems.

Light-Triggered Self-Assembly of Peptide Nanoparticles into Nanofibers in Living Cells through Molecular Conformation Changes and H-Bond Interactions.

Molecular crystals with the ability to transform light energy into macroscopic mechanical motions are a promising class of materials with potential applications in actuating and photonic devices. In regard to such materials, coordination polymers that exhibit dynamic photomechanical motion, associated with a phase transition, are unknown. Herein, we report an intriguing photoactive, one-dimensional ZnII coordination polymer, 1, derived from 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene and 3,5-difluorobenzoate. Single crystals of 1 under UV light irradiation exhibit rapid shrinking and bending, violent bursting-jumping, splitting, and cracking behavior. Single-crystal X-ray diffraction analysis and 1H NMR spectroscopy reveal an unusual photoinduced phase transition involving a single-crystal-to-single-crystal [2+2] cycloaddition reaction that results in photomechanical responses. Interestingly, crystals of 1, which are triclinic with space group , are transformed into a higher symmetry, monoclinic cell with space group C2/c. This process represents a rare example of symmetry enhancement upon photoirradiation. The photomechanical activity is likely due to the sudden release of stress associated with strained molecular geometries and significant solid-state molecular movement arising from cleavage and formation of chemical bonds. A composite membrane fabricated from 1 and polyvinyl alcohol (PVA) also displays interesting photomechanical behavior under UV light illumination, indicating the material's potential as a photoactuator. 

Phase Transition‐Promoted Rapid Photomechanical Motions of Single Crystals of a Triene Coordination Polymer

Molecular crystals with the ability to transform light energy into macroscopic mechanical motions are a promising class of materials with potential applications in actuating and photonic devices. In regard to such materials, coordination polymers that exhibit dynamic photomechanical motion, associated with a phase transition, are unknown. Herein, we report an intriguing photoactive, one-dimensional Zn(II) coordination polymer, 1, derived from 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene and 3,5-difluorobenzoate. Single crystals of 1 under UV light irradiation exhibit rapid shrinking and bending, violent bursting-jumping, splitting and cracking behavior. Single-crystal X-ray diffraction analysis and 1H NMR spectroscopy reveal an unusual photoinduced phase transition involving a single-crystal-to-single-crystal [2 + 2] cycloaddition reaction resulting in photomechanical responses. Interestingly, crystals of 1, which are triclinic with space group P 1, are transformed into a higher symmetry, monoclinic cell with space group C2/c. This process represents a rare example of symmetry enhancement upon photoirradiation. The photomechanical activity is likely due to the sudden release of stress associated with strained molecular geometries and significant solid-state molecular movement arising from cleavage and formation of chemical bonds. A composite membrane fabricated from 1 and polyvinyl alcohol (PVA) also displays interesting photomechanical behavior under UV light illumination, indicating the material's potential as a photoactuator.

Phase Transition-Promoted Rapid Photomechanical Motions of Single Crystals of a Triene Coordination Polymer.

Mechano-/seeding-triggered crystal-to-crystal phase transition in luminescent switching cocrystals

Single-crystal to single-crystal (SCSC) transformation by phototrigger is presently attracting immense research interest in many fields such as sensors, actuators, artificial muscles, soft robotics, and energy harvesting. However, the only success of rare examples has been achieved by SCSC transformation so far, involving a change in molecular composition based on photocyclization reactions. Here, we show photoinduced SCSC transformation of 3-methylene-2-(quinolin-8-yl) isoindolin-1-one (MQIO) derivatives from monoclinic to triclinic phase via conformational change, just as “small input and big output”. UV light induces a molecular conformation change of MQIO-H with rotation (11.3°) of the carbon–nitrogen single bond. The conformational changes of MQIO-H lead to the slides of molecular packing in crystals, finally resulting in the SCSC transformation from the monoclinic to the triclinic phase. In addition, the SCSC transformation was accompanied by turn-on fluorescence and shape changes of single crystal. The shape changes of single crystals can be clearly observed by UV light triggering under an optical microscope. This work provides a strategy to achieve SCSC transformation via photoinduction. 

Photoinduced Single-Crystal to Single-Crystal Transformation via Conformational Change with Turn-On Fluorescence

acceptor-donor co-doping method is used here to introduce the acceptor-donor defect complexes, which acted as the electric dipole enhancing polarization with the electric Oxide dielectrics, such as HfO 2 , Al 2 O 3 , etc, are widely used to improve the performance of 2D semiconductors in electronic devices. However, future low-power electronic devices need a higher dielectric constant ( κ ) to reduce the leakage current, and these super-high- κ materials are challenging to pro-duce on wafer-scale. Here, the preparation of wafer-scale (Ga, Cu) co-doping ZnO films is reported with super-high dielectric constant ( κ > 50) and good homogeneity by a pulsed laser deposition method. By regulating the (Ga, Cu) co-doping concentration, the dielectric constants can range from 9 to 207. In addition, the performance of SnS 2 field-effect transistor reveals that the high- κ Al 2 O 3 /GCZO gate dielectric stack is suitable for 2D electronic devices. This GCZO dielectric films not only show higher κ than other conventional dielectrics in terms of compatibility to CMOS processes, but also keep their comparative advantages in the fabrication of high-performance electronic devices over conventional dielectrics.

Jing-Kun Yu

Papers

Photoinduced Single-Crystal to Single-Crystal Transformation via Conformational Change with Turn-On Fluorescence

Wafer‐Scale PLD‐Grown High‐κ GCZO Dielectrics for 2D Electronics (Adv. Electron. Mater. 12/2022)