Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and CoS Nanocrystals

The ability to selectively form one crystal structure among several options in a polymorphic system is an important goal in solid-state synthesis. Nanocrystal cation exchange, which proceeds rapidly under mild conditions, can retain key structural features and yield otherwise inaccessible phases, but the extent to which crystal structure can be retained and therefore selectively targeted during such reactions has been limited. Here, we show that nanocrystals of digenite Cu_2−xS transform to zincblende MnS and CoS upon cation exchange. Zincblende MnS and CoS, which are metastable in bulk, retain both the tetrahedral cation coordination and cubic close packed anion sublattice of digenite Cu_2−xS. Comparison with wurtzite MnS and CoS, which have been accessed previously through analogous cation exchange of roxbyite Cu_2−xS, demonstrates the selective formation of the related zincblende vs. wurtzite polymorphs by cation exchange of structurally distinct templates.     

Greener Dye Synthesis: Continuous,Solvent-Free Synthesis of Commodity Perylene Diimides by Twin-Screw Extrusion

A continuous, scalable, and solvent-free method for the synthesis of various naphthalic imides and perylene diimides (PDIs) using twin-screw extrusion (TSE) is reported. Using TSE, naphthalic imides were obtained quantitatively without the need for excess amine reactant or product purification. With good functional-group tolerance, alkyl and benzyl amine derived PDIs (incl. commercial dyes) were obtained in 50–99 % yield. Use of K₂CO₃, enabled synthesis of more difficult aniline-derived PDIs. Furthermore, an automated continuous TSE process for Pigments Black 31 and 32 is demonstrated, with a throughput rate of about 1500 g day⁻¹, corresponding to a space time yield of about 30×10³ kg m⁻³ day⁻¹, which is 1–2 orders of magnitude greater than for solvent-based batch methods. These methods provide substantial waste reductions and improved efficiency compared to conventional solvent-based methods.     

Polymerization of 1‐Phosphaisoprene: Synthesis and Characterization of a Chemically Functional Phosphorus Version of Natural Rubber

Macromolecules derived from 1,3‐dienes, such as polyisoprene (or natural rubber), are of considerable importance in polymer science. Given the parallels between P=C and C=C bonds, the prospect of polymerizing P‐containing 1,3‐dienes, such as 1‐phosphaisoprene, is intriguing due to the unique chemical functionality imparted by the heavier element combined with their structural relationship to natural rubber. Herein, we report the synthesis, characterization and coordination chemistry of the first polymers derived from Mes*P=CR−CH=CH₂ (Mes*=2,4,6‐t‐Bu₃C₆H₂; R=H, Me). In the case of 1‐phosphaisoprene (R=Me), the monomer is isolable and its anionic polymerization affords a polymer that retains P=C bonds in its microstructure. The chemical functionality of these novel materials is demonstrated by forming the macromolecular gold(I) complex where the P=C bond is retained for further chemical elaboration.     

High Uptake and Fast Transportation of LiPF6 in a Porous Aromatic Framework for Solid-State Li-Ion Batteries

Solid-state Li-ion batteries (SSLIBs) have recently attracted substantial attention from scientists for the advantages of better safety performance. However, there are still several key challenges in SSLIBs that need to be addressed, such as low energy density, poor thermal stability or cycle stability, and large interface resistance. This contribution introduces a novel SSLIB with a porous aromatic framework (PAF-1) accommodating LiPF₆ that was used as the solid-state electrolyte (SSE) replacing the liquid electrolyte and diaphragm of traditional Li-ion batteries. The charge, discharge capacity, rate performance and cycle stability of the SSLIB were remarkably enhanced.