Phosphonous acid dichlorides and tricyclic phosphoranes from hexafluoro- and trifluoropentane-2,4-dione

1,1,1,5,5,5-Hexafluoro-2-hydroxy-2-pentene-4-one reacted diastereospecifically with phosphonous acid di-chlorides, RPCl₂ (R = Me, Et, iPr, tBu, Me₃SiCH₂, PhCH₂, Ph) to give in a concerted mechanism thermally stable tricyclic λ⁵σ⁵P phosphoranes containing two five- and one six-membered ring. In one case, hydrolysis gave 3,5-dihydroxy-2-oxo-1,2λ⁵σ⁴-oxaphosphalane, whereas methanol added to the double bond in the six-membered ring furnishing two isomeric phosphoranes. When 1,1,1-trifluro-2-hydroxy-2-pentene-4-one was reacted with RPCl₂ (R = Et, Me₃SiCH₂, PhCH₂, Ph), diastereomerically pure regioisomeric phosphoranes were obtained. The solid-state molecular structures of three λ⁵σ⁵P species exhibited two oxygen atoms in the axial position of a slightly distorted trigonal-bipyramidal geometry at phosphorus. Surprisingly, the two CF₃ groups bonded to an sp³-hybridized carbon were in a cisoid arrangement, having closest nonbonding F · · · F distances of 301.4 or 273.5 pm. These findings reflect the “through-space” F-F coupling constants of the tricyclic phosphoranes (J_FF = 4.0–7.0 Hz) in solution. The solid-state structure of the phospholane revealed the two hydroxy groups to be directed to one side of the five-membered ring. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:173–181, 1998     

Highly Efficient Production of Nanoporous Block Copolymers with Arbitrary Structural Characteristics for Advanced Membranes

The great significance of boosting the design of percolating nanopore structures in block copolymers (BCPs) for various cases has been widely demonstrated in the past several decades. However, it still remains challenging to prepare the desired porous structures in a rapid, facile, and universal manner. Here we have developed an unconventional and benchtop strategy to rapidly generate the nanoporous polystyrene-based BCPs with arbitrary structural characteristics regardless of the BCP bulk morphology. This universal pore-forming strategy enables the sustainable CO₂-based BCPs to form advanced membranes after 1 s soaking for efficiently rejecting 94.2 % brilliant blue R (826 g mol⁻¹). Meanwhile, the water permeance retains around 1020 L (m² h bar)⁻¹, which is 1–3 orders of magnitude higher than that of other membranes. This strategy may offer an excellent opportunity to introduce percolating pore structures in those newly developed BCPs with which the previously reported pore-forming methods may not deal.     

Use of a solid-state nanopore for profiling the transferrin receptor protein and distinguishing between transferrin receptor and its ligand protein

A nanopore device is capable of providing single-molecule level information of an analyte as they translocate through the sensing aperture—a nanometer-sized through-hole—under the influence of an applied electric field. In this study, a silicon nitride (Si_xN_y)-based nanopore was used to characterize the human serum transferrin receptor protein (TfR) under various applied voltages. The presence of dimeric forms of TfR was found to decrease exponentially as the applied electric field increased. Further analysis of monomeric TfR also revealed that its unfolding behaviors were positively dependent on the applied voltage. Furthermore, a comparison between the data of monomeric TfR and its ligand protein, human serum transferrin (hSTf), showed that these two protein populations, despite their nearly identical molecular weights, could be distinguished from each other by means of a solid-state nanopore (SSN). Lastly, the excluded volumes of TfR were experimentally determined at each voltage and were found to be within error of their theoretical values. The results herein demonstrate the successful application of an SSN for accurately classifying monomeric and dimeric molecules while the two populations coexist in a heterogeneous mixture.