Molecular-Simulation-Inspired Synthesis of [6]-Prismane via Photoisomerisation of Octafluoro[2.2]paracyclophane.

Prismanes have been attracting interest for nearly 50 years because of their geometric symmetry, highly strained structures, and unique applications due to their high carbon densities and bulky structures. Although [3]-, [4]-, and [5]-prismanes have been synthesised, [6]-prismanes and their derivatives remain elusive. Herein, fluorine chemistry, molecular mechanics, molecular orbital package, and density functional theory calculations were used to design and implement the photoisomerisation of octafluoro[2.2]paracyclophane (selected based on the good overlap of its lowest unoccupied molecular orbitals and short distance between the benzene rings) into octafluoro-[6]-prismane. Specifically, a dilute solution of the above precursor in CH3CN/H2O/dimethyl sulfoxide (DMSO) (2:1:8, v/v/v) solution was irradiated with ultraviolet light, with the formation of the desired product confirmed through the use of nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. The product was thermally stable in solution but not under work-up conditions, which complicated the further analysis and single-crystal preparation. The key criteria for successful photoisomerisation were the presence of fluorine substituents in the cyclophane structure and DMSO in the solvent system. A more stable derivative design requires the isolation of prismane products. The proposed fluorination-based synthetic strategy is applicable to developing novel high-strain molecules/materials with three-dimensional skeletons.

Synthesis and Properties of Fluorocarbon-Hydrocarbon Hybrid Block Copolymers with Perfluorosulfonimide Acid.

Novel fluorocarbon-hydrocarbon hybrid block copolymer electrolytes were synthesized. The block copolymer electrolytes consist of poly(perfluoropropyl sulfonimide) (PC3SI) as a perfluorinated hydrophilic segment and poly(ether ether sulfone) as a hydrocarbon hydrophobic segment. The sulfonimide group of poly(perfluoropropyl sulfonimide) has superacidity, very low equivalent weight (EW = 293 g/equiv), and a proton conductivity of 1.2 × 10-2 S/cm under dry conditions and 25 °C, although soluble in water. The proton conductivity of the block copolymer was 1.7 × 10-3 S/cm at 20% relative humidity and 25 °C, which is three times as high as that of Nafion 112.

The origins of binding specificity of a lanthanide ion binding peptide.

Lanthanide ions (Ln3+) show similar physicochemical properties in aqueous solutions, wherein they exist as + 3 cations and exhibit ionic radii differences of less than 0.26 Å. A flexible linear peptide lanthanide binding tag (LBT), which recognizes a series of 15 Ln3+, shows an interesting characteristic in binding specificity, i.e., binding affinity biphasically changes with an increase in the atomic number, and shows a greater than 60-fold affinity difference between the highest and lowest values. Herein, by combining experimental and computational investigations, we gain deep insight into the reaction mechanism underlying the specificity of LBT3, an LBT mutant, toward Ln3+. Our results clearly show that LBT3-Ln3+ binding can be divided into three, and the large affinity difference is based on the ability of Ln3+ in a complex to be directly coordinated with a water molecule. When the LBT3 recognizes a Ln3+ with a larger ionic radius (La3+ to Sm3+), a water molecule can interact with Ln3+ directly. This extra water molecule infiltrates the complex and induces dissociation of the Asn5 sidechain (one of the coordinates) from Ln3+, resulting in a destabilizing complex and low affinity. Conversely, with recognition of smaller Ln3+ (Sm3+ to Yb3+), the LBT3 completely surrounds the ions and constructs a stable high affinity complex. Moreover, when the LBT3 recognizes the smallest Ln3+, namely Lu3+, although it completely surrounds Lu3+, an entropically unfavorable phenomenon specifically occurs, resulting in lower affinity than that of Yb3+. Our findings will be useful for the design of molecules that enable the distinction of sub-angstrom size differences.

Direct Recovery of the Rare Earth Elements Using a Silk Displaying a Metal-Recognizing Peptide.

Rare earth elements (RE) are indispensable metallic resources in the production of advanced materials; hence, a cost- and energy-effective recovery process is required to meet the rapidly increasing RE demand. Here, we propose an artificial RE recovery approach that uses a functional silk displaying a RE-recognizing peptide. Using the piggyBac system, we constructed a transgenic silkworm in which one or two copies of the gene coding for the RE-recognizing peptide (Lamp1) was fused with that of the fibroin L (FibL) protein. The purified FibL-Lamp1 fusion protein from the transgenic silkworm was able to recognize dysprosium (Dy3+), a RE, under physiological conditions. This method can also be used with silk from which sericin has been removed. Furthermore, the Dy-recovery ability of this silk was significantly improved by crushing the silk. Our simple approach is expected to facilitate the direct recovery of RE from an actual mixed solution of metal ions, such as seawater and industrial wastewater, under mild conditions without additional energy input.

Reduction of the Cytotoxicity of Copper (II) Oxide Nanoparticles by Coating with a Surface-Binding Peptide.

Copper (II) oxide nanoparticles (CuO-NPs) have been studied as potential antimicrobial agents, similar to silver or platinum nanoparticles. However, the use of excess NPs is limited by their safety and toxicity in beneficial microflora and human cells. In this study, we evaluated the cytotoxicity of CuO-NPs by coating with a novel cyclic peptide, CuO binding peptide 1 (CuBP1), cyclic-SCATPFSPQVCS, which binds to the surface of CuO-NPs. CuBP1 was identified using biopanning of a T7 phage display system and was found to promote the aggregation of CuO-NPs under mild conditions. The treated CuO-NPs with CuBP1 caused the reduction of the cytotoxicity against Escherichia coli, Lactobacillus helveticus, and five other microorganisms, including bacteria and eukaryotes. Similar effects were also demonstrated against human embryonic kidney (HEK293) cells in vitro. Our findings suggested that the CuO-NPs coated with a surface-binding peptide may have applications as a safe antimicrobial agent without excessive cytotoxic activity against beneficial microflora and human cells. Moreover, a similar tendency may be achieved with other metal particles, such as silver or platinum NPs, by using optimal metal binding peptides.