DFT Study on Methanofullerene Derivative [6,6]-Phenyl-C61 Butyric Acid Methyl Ester

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) with hybrid functional B3LYP were used to investigate several physical and chemical properties of [6,6]-phenyl-C₆₁ butyric acid methyl ester (PCBM), including the geometry, electron structure, charge population, bond properties, as well as IR, Raman and electronic absorption spectra. The analysis of the natural bond orbital (NBO) suggested that there were about 0.11 electrons transferred from moiety phenyl and butyric acid methyl ester group of PCBM to fullerene cage. The strongest IR and Raman peaks came from different modes with the frequencies of 1773 and 1492 cm⁻¹, respectively. The calculated isotropic polarizability, polarizability anisotropy invariant, and hyperpolarizability were 577.7, 96.9, and −22.8 a.u., respectively. Based on TDDFT, the electronic absorption spectra of PCBM were calculated and analyzed. The calculated absorption band near 349 nm agreed well with the experimental measurement.     

Weighted estimates for multilinear commutators of Marcinkiewicz integral

Let μ be the n-dimensional Marcinkiewicz integral and μb the multilinear commutator of μ. In this paper, the following weighted inequalities are proved for ω ∈ A∞ and 0 〈 p 〈 ∞,
｜｜μ（f）｜｜LP（ω）≤C｜Mf｜LP（ω） and ｜｜μb（f）｜｜LP（ω）≤C｜｜ML（log L）^1/r f｜｜LP（ω）.
The weighted weak L（log L）^1/r -type estimate is also established when p=1 and ω∈A1.     

Mutability-Landscape-Guided Engineering of l-Threonine Aldolase Revealing the Prelog Rule in Mediating Diastereoselectivity of C−C Bond Formation

l -threonine aldolase (LTA) catalyzes C−C bond synthesis with moderate diastereoselectivity. In this study, with LTA from Cellulosilyticum sp (CpLTA) as an object, a mutability landscape was first constructed by performing saturation mutagenesis at substrate access tunnel amino acids. The combinatorial active-site saturation test/iterative saturation mutation (CAST/ISM) strategy was then used to tune diastereoselectivity. As a result, the diastereoselectivity of mutant H305L/Y8H/V143R was improved from 37.2 %_syn to 99.4 %_syn. Furthermore, the diastereoselectivity of mutant H305Y/Y8I/W307E was inverted to 97.2 %_anti. Based on insight provided by molecular dynamics simulations and coevolution analysis, the Prelog rule was employed to illustrate the diastereoselectivity regulation mechanism of LTA, holding that the asymmetric formation of the C−C bond was caused by electrons attacking the carbonyl carbon atom of the substrate aldehyde from the re or si face. The study would be useful to expand LTA applications and guide engineering of other C−C bond-forming enzymes.     

Polyoxometalate-Cyclodextrin-Based Cluster-Organic Supramolecular Framework for Polysulfide Conversion and Guest–Host Recognition in Lithium-sulfur Batteries

Developing polyoxometalate-cyclodextrin cluster-organic supramolecular framework (POM-CD-COSF) still remains challenging due to an extremely difficult task in rationally interconnecting two dissimilar building blocks. Here we report an unprecedented POM-CD-COSF crystalline structure produced through the self-assembly process of a Krebs-type POM, [Zn₂(WO₂)₂(SbW₉O₃₃)₂]¹⁰⁻, and two β-CD units. The as-prepared POM-CD-COSF-based battery separator can be applied as a lightweight barrier (approximately 0.3 mg cm⁻²) to mitigate the polysulfide shuttle effect in lithium-sulfur batteries. The designed Li−S batteries equipped with the POM-CD-COSF modified separator exhibit remarkable electrochemical performance, attributed to fast Li⁺ diffusion through the supramolecular channel of β-CD, efficient polysulfide-capture ability by the dynamic host–guest interaction of β-CD, and improved sulfur redox kinetics by the bidirectional catalysis of POM cluster. This research provides a broad perspective for the development of multifunctional supramolecular POM frameworks and their applications in Li−S batteries.     

Upconversion Luminescence in Mononuclear Yb/Sm Co-crystal Assemblies at Room Temperature

Metal-based upconversion luminescence transforming high-energy photons into low-energy photons is an attractive anti-Stokes shift process for fundamental research and promising applications. In this work, we developed the upconversion luminescence in co-crystal assemblies consisting of discrete mononuclear Yb and Sm complexes. The characteristic visible emissions of Sm³⁺ were observed under the excitation of absorption band of Yb³⁺ at 980 nm. A series of co-crystal assemblies were investigated based on mononuclear Yb and Sm complexes, and the strongest luminescence was obtained when the molar concentration between Yb³⁺ and Sm³⁺ is equivalent. The crystal structure was fully characterized by the single crystal X-ray diffraction and upconverting energy transfer mechanisms were verified as cooperative sensitization upconversion and energy transfer upconversion. This is the first example of Sm³⁺-based upconverting luminescence in discrete lanthanide complexes which present as co-crystal assemblies at room temperature.     

Ultra-Small Air-Stable Triplet-Triplet Annihilation Upconversion Nanoparticles for Anti-Stokes Time-Resolved Imaging

Image contrast is often limited by background autofluorescence in steady-state bioimaging microscopy. Upconversion bioimaging can overcome this by shifting the emission lifetime and wavelength beyond the autofluorescence window. Here we demonstrate the first example of triplet-triplet annihilation upconversion (TTA-UC) based lifetime imaging microscopy. A new class of ultra-small nanoparticle (NP) probes based on TTA-UC chromophores encapsulated in an organic–inorganic host has been synthesised. The NPs exhibit bright UC emission (400–500 nm) in aerated aqueous media with a UC lifetime of ≈1 μs, excellent colloidal stability and little cytotoxicity. Proof-of-concept demonstration of TTA-UC lifetime imaging using these NPs shows that the long-lived anti-Stokes emission is easily discriminable from typical autofluorescence. Moreover, fluctuations in the UC lifetime can be used to map local oxygen diffusion across the subcellular structure. Our TTA-UC NPs are highly promising stains for lifetime imaging microscopy, affording excellent image contrast and potential for oxygen mapping that is ripe for further exploitation.     

Phosphorescent and Test Strips Detection Properties of ClO− Probes Based on Iridium(III) Complexes with Pivaloyl Unit as Recognition Site

Three green phosphorescent Iridium(III) complex-based probes with different ligands (Cl⁻ ( Ir-1 ), NCS⁻ ( Ir-2 ) and NCO⁻ ( Ir-3 )) had been developed to detect hypochlorite (ClO⁻) using pivaloyl group as recognition site. The introduction of strong field ligand NCS and NCO caused an increase of quantum yields and phosphorescent lifetime both in solid and solution states. All the three probes could selectively and rapidly detect ClO⁻ through the changes in UV-visible and phosphorescence spectra. Upon addition of ClO⁻ to the solution of probes, green phosphorescent color of probes displayed obvious quench. Meanwhile, using a portable UV lamp, test strips which were pre-immersed with the above-mentioned probes could achieve easy detection of ClO⁻. The sensing process was confirmed by NMR, IR and ESI-MS.     

Engineering Mechanical Strong Biomaterials Inspired by Structural Building Blocks in Nature

The intricate multiscale architectures in natural structural building blocks provide many sources of inspiration for the designs of artificial biomaterials. In nature, the assembly of highly ordered molecular crystals and amorphous aggregates often derives from inter- and intra-molecular interactions of biomacromolecules, e.g., proteinaceous materials. The structural biomaterials derived from the protein self-assembly behave with remarkable mechanical performance. However, there is still a grand challenge to mimic the mechanical properties of natural protein-based biomaterials in a rational design fashion to yield comparable man-made synthetic ensembles. In this review, a brief perspective on current challenges and advances in terms of bioinspired structural materials is presented. We outline a framework for mimicking protein self-assembly of natural building blocks across multiscale and highlight the critical role of synthetic biology and chemical modifications in material biosynthesis. Particularly, we focus on the design and promising applications of protein-based fibers, adhesives, dynamic hydrogels and engineered living materials, in which natural mechanical functions are effectively reproduced.     

Poly-Hydride [AuI7(PPh3)7H5](SbF6)2 cluster complex: Structure,Transformation, and Electrocatalytic CO2 Reduction Properties

Hydride Au^I bonds are labile due to the mismatch in electric potential of an oxidizing metal and reducing ligand, and therefore the structure and structure–activity relationships of nanoclusters that contain them are seldom studied. Herein, we report the synthesis and characterization of [Au₇(PPh₃)₇H₅](SbF₆)₂ (abbrev. Au₇H₅ ²⁺ ), an Au cluster complex containing five hydride ligands, which decomposed to give [Au₈(PPh₃)₇]²⁺ (abbrev. Au₈ ²⁺ ) upon exposure to light (300 to 450 nm). The valence state of Au^I and H⁻ was verified by density functional theory (DFT) calculations, NMR, UV/Vis and XPS. The two nanoclusters behaved differently in the electrocatalytic CO₂ reduction reaction (CO₂RR): Au₇H₅ ²⁺ exhibited 98.2 % selectivity for H₂, whereas Au₈ ²⁺ was selective for CO (73.5 %). Further DFT calculations showed that the H⁻ ligand inhibited the CO₂RR process compared with the electron-donor H.     

Strong Protein Adhesives through Lanthanide-enhanced Structure Folding and Stack Density

Generating strong adhesion by engineered proteins has the potential for high technical applications. Current studies of adhesive proteins are primarily limited to marine organisms, e.g., mussel adhesive proteins. Here, we present a modular engineering strategy to generate a type of exotic protein adhesives with super strong adhesion behaviors. In the protein complexes, the lanmodulin (LanM) underwent α-helical conformational transition induced by lanthanides, thereby enhancing the stacking density and molecular interactions of adhesive protein. The resulting adhesives exhibited outstanding lap-shear strength of ≈31.7 MPa, surpassing many supramolecular and polymer adhesives. The extreme temperature (−196 to 200 °C) resistance capacity and underwater adhesion performance can significantly broaden their practical application scenarios. Ex vivo and in vivo experiments further demonstrated the persistent adhesion performance for surgical sealing and healing applications.