Bilayer Cylindrical Conduit Consisting of Electrospun Polycaprolactone Nanofibers and DSC Cross‐Linked Sodium Alginate Hydrogel to Bridge Peripheral Nerve Gaps

Herein, a bilayer cylindrical conduit (P‐CA) is presented consisting of electrospun polycaprolactone (PCL) nanofibers and sodium alginate hydrogel covalently cross‐linked with N,N′‐disuccinimidyl carbonate (DSC). The bilayer P‐CA conduit is developed by combining the electrospinning and outer–inner layer methods. Using DSC, as a covalent crosslinker, increases the degradation time of the sodium alginate hydrogel up to 2 months. The swelling ratio of the hydrogel is also 503% during the first 8 h. The DSC cross‐linked sodium alginate in the inner layer of the conduit promotes the adhesion and proliferation of nerve cells, while the electrospun PCL nanofibers in the outer layer provide maximum tensile strength of the conduit during surgery. P‐CA conduit promotes the migration of Schwann cells along the axon in a rat model based on functional and histological evidences. In conclusion, P‐CA conduit will be a promising construct for repairing sciatic nerves in a rat model.     

Applications of Tamm plasmon-liquid crystal devices

ABSTRACT

The Tamm-plasmon-polariton (TPP) occurs at the interface between a metallic film and the photonic-crystal (PC) substrate. Unlike conventional surface-plasmon-polariton (SPP), TPP can be directly excited by both the transverse electric (TE) and transverse magnetic (TM) electromagnetic waves without using additional coupling optics. The fact that the optical functionality of most plasmonics devices is determined after fabrication limits their applications. Tunable SPP devices by applying liquid crystals (LCs) have been widely demonstrated due to their large birefringence and easy controllability via external stimuli. However, actively tuning TPP is difficult because the localised electric field is between the metallic film and PC substrate, the change of refractive index above the metallic film has only small influences on TPP. This article is intended to briefly review recent progress towards using LCs for actively tuning TPP devices. Not only TPP devices can gain benefits from LCs, we will also discuss the applications of TPP for measuring the anisotropy of the alignment films of LC devices. The sensitivity of the proposed scheme will be discussed.     

O-Alkyldithiophosphate Nickel Complexes with dcpf Ligand as Efficient Electrocatalysts for Hydrogen Evolution

Six new O-alkyldithiophosphate nickel complexes with dcpf ligand, [(dcpf)Ni(S₂P{O}OR)] (dcpf = 1,1′-bis (dicyclohexylphosphino)ferrocene, R = CH₃ ( 1 ), CH₃CH₂ ( 2 ), Ph ( 3 ), 4-MeC₆H₄ ( 4 ), PhCH₂ ( 5 ) and PhCH₂CH₂ ( 6 )), have been synthesized by the treatment of dcpf with ((RO)₂PS₂)₂Ni in satisfactory yields. These complexes were characterized by elemental analysis, spectroscopy (FTIR, UV–vis, ¹H, ¹³C, and ³¹P NMR), thermogravimetric analysis and single crystal X-ray diffraction. The nickel atom in 1 , 2 ·CH₂Cl₂, 3 ·CH₂Cl₂, 4 ·2CH₂Cl₂·THF, and 2( 5 )·hexane adopts a slightly distorted square-planar coordination environment finished by two phosphorus atoms of dcpf ligand and two sulfur atoms of O-alkyldithiophosphate ligand. Furthermore, the electrochemical properties for complexes 1 – 6 were also investigated by cyclic voltammetry. With the addition of 120 mM trifluoroacetic acid (TFA), the turnover frequency (TOF) values for 1 – 6 are estimated to be 1243.83, 1046.54, 1331.71, 2545.29, 1899.03, and 1191.37 s⁻¹, with the overpotential (η) values of 0.62, 0.58, 0.71, 0.67, 0.60, and 0.56 V, respectively. The result of electrochemical studies indicates that all complexes can be used as efficient molecular eletrocatalysts for the reduction of protons to hydrogen in the presence of TFA in MeCN.     

Synthesis and characterization of dimeric μ-oxidovanadium complexes as the functional model of vanadium bromoperoxidase

Two vanadium (IV) complexes [V^IVO(Haeae-sal)(MeOH)]⁺ ( 1 ) and [V^IVO(Haeae-hyap)(MeOH)]⁺ ( 2 ) were prepared by reacting [VO(acac)₂] with ligands [H₂aeae-sal] ( I ) and [H₂aeae-hyap] ( II ) respectively. Condensation of 2-(2-aminoethylamino)ethanol with salicylaldehyde and 2-hydroxyacetophenone produces the ligands ( I ) and ( II ) respectively. Both vanadium complexes 1 and 2 are sensitive towards aerial oxygen in solution and rapidly convert into vanadium(V) dioxido species. Vanadium(V) dioxido species crystalizes as the dimeric form in the solid-state. Single-crystal XRD analysis suggests octahedral geometry around each vanadium center in the solid-state. To access the benefits of heterogeneous catalysis, vanadium(V) dioxido complexes were anchored into the polymeric chain of chloromethylated polystyrene. All the synthesized neat and supported vanadium complexes have been studied by a number of techniques to confirm their structural and functional properties. Bromoperoxidase activity of the synthesized vanadium(V) dioxido complexes 3 and 4 was examined by carrying out oxidative bromination of salicylaldehyde and oxidation of thioanisole. In the presence of hydrogen peroxide, 3 shows 94.4% conversion ( TOF value of 2.739 × 10² h⁻¹) and 4 exhibits 79.0% conversion (TOF value of 2.403 × 10² h⁻¹) for the oxidative bromination of salicylaldehyde where 5-bromosalicylaldehyde appears as the major product. Catalysts 3 and 4 also efficiently catalyze the oxidation of thioanisole in the presence of hydrogen peroxide where sulfoxide is observed as the major product. Covalent attachment of neat catalysts 3 and 4 into the polymer chain enhances substrate conversion (%) and their catalytic efficiency increases many folds, both in the oxidative bromination and oxidation of thioether. Polymer supported catalysts 5 displayed 98.8% conversion with a TOF value of 1.127 × 10⁴ h⁻¹ whereas catalyst 6 showed 95.7% conversion with a TOF value of 4.675 × 10³ h⁻¹ for the oxidative bromination of salicylaldehyde. These TOF values are the highest among the supported vanadium catalysts available in the literature for the oxidative bromination of salicylaldehyde.     

Single crystal X-ray of 1-[(1,2,4-triazole-4-yl)imino]diacetyl monoxime (L) as a novel triazole and the characterization and biological studies of its chelates of Co2+, Pd2+, and Fe3+

A novel and efficient synthesis of 1-[(1,2,4-triazole-4-yl)imino]diacetyl monoxime ( L ) is described. The advantages of this method are that it is inexpensive, the starting reactants are readily available, and it has good yield and short reaction times. The hull of the product was suggested by elemental analyses, spectral and single crystal X-ray. Novel Co ²⁺ , Pd²⁺, and Fe ³⁺ chelates derived from L were characterized by Fourier transform infrared spectroscopy, suggesting that L acts as bidentate via the two azomethine groups. Tetrahedral geometry for Fe³⁺ and Co²⁺ and square-planar geometry around the Pd²⁺ chelate were suggested depending on the spectral and magnetic data. The results of density functional theory were applied to illustrate the geometry of L towards the metal ions. Coats–Redfern and Horowitz–Metzger methods were applied to investigate the kinetic and thermodynamic parameters of the chelates. Cyclic voltammetry was carried out to study the stability of the Co²⁺ and Fe³⁺ chelates. L and its complexes were tested against three types of cancer cells, antibacterial and antifungal.     

Reversible and Stepwise Single-Crystal-to-Single-Crystal Transformation of a Platinum(II) Complex with Vapochromic Luminescence

The vapochromic single-crystal-to-single-crystal (SCSC) transformation of a highly luminescent Pt^II complex bearing an N-heterocyclic carbene [Pt(CN)₂(tBu-impy)] (tBu-impyH⁺=1-tert-butyl-3-(2-pyridyl)-1H-imidazolium) is reported. The trihydrate form of the complex, which exhibits blue ³MMLCT emission owing to weak Pt⋅⋅⋅Pt interactions, changed its luminescence color from blue to yellowish-green upon the desorption of water molecules while keeping the high emission quantum yield of more than 0.45. Variable-temperature and continuous in-situ tracking of single-crystal X-ray diffraction measurements revealed that the SCSC transformation proceeds reversibly by the release and reabsorption of water molecules, thereby changing the stacked structure slightly. As a result, the dynamics of vapor-induced SCSC transformation were elucidated: that the anhydrous form returned to the original trihydrate form in a two-step process under a water vapor atmosphere. In addition, the Pt^II complex exhibited a similar SCSC response accompanied by a luminescence color change in the presence of methanol vapor, while being inactive toward ethanol vapor.     

A facile route to germanium(IV) binaphthoxide complexes: crystal structure of a chiral resolved germanium(IV) binaphthoxide

A method for the facile synthesis of chiral germanium(IV) binaphthoxide complexes from the corresponding binaphthols and an organogermanium trichloride has been developed, which allows these unusual types of compounds to be synthesized in high yields. The crystal structure of one such complex, (S)-[Ge{O2C20H10(SiMe3)2-3,3'}{Cl}{Ph}], has been determined.     

基于分子工程的方法设计首例具有Sr2Be2B2O7 (SBBO)结构的深紫外氟碳酸盐双折射晶体AMgLi2(CO3)2F (A=K,Rb)※

分子结构设计是开发新化合物和通过原子尺度操纵优化晶体结构的一种引人注目的策略. 在这个工作中, 利用分子工程的思想, 基于SBBO结构, 成功设计并合成两个新型氟碳酸盐KMgLi₂(CO₃)₂F和RbMgLi₂(CO₃)₂F. 在两个结构中, a-b平面是由CO₃和LiO₃F阴离子基团组成的无限[Li₃C₃O₆F₃]_∞层, 进一步相邻的层通过F原子连接形成一个独特的[Li₆C₆O₁₂F₃]_∞双层. 这种结构特征对改善晶体的层状生长习性和消除晶体的多晶性有很大的帮助. 光学测试表明, 该系列晶体具有大的双折射和短的紫外截止边, 是深紫外双折射晶体良好的候选材料.     

Comparative structural analysis of a histone-like protein from Spiroplasma melliferum in the crystalline state and in solution

A solution of a histone-like protein from Spiroplasma melliferum (HUSpm) was examined by small-angle X-ray scattering (SAXS). The experimental SAXS curve was compared with those calculated for the HUSpm structures from the PDB databank obtained by both X-ray diffraction analysis and nuclear magnetic resonance spectroscopy. The model of the HUSpm structure in solution, which best agrees with the experimental SAXS data, has a shorter distance between the centers of mass of the HUSpm monomers compared to the crystal structure, indicating that the HUSpm monomers can be located closer to each other in solution than in the crystalline state.