Main-group-metal-mediated transformations of imines have earned a valued place in the synthetic chemist's toolbox. Their versatility allows the simple preparation of various nitrogen containing compounds. This review will outline the early discoveries including metallation, addition/cyclisation and metathesis pathways, followed by the modern-day use of imines in synthetic methodology. Recent advances in imine C-F activation protocols are discussed, alongside revisiting "classic" imine reactivity from a sustainable perspective. Developments in catalytic methods for hydroelementation of imines have been reviewed, highlighting the importance of s-block metals in the catalytic arena. Whilst stoichiometric transformations in alternative reaction media such as deep eutectic solvents or water have been summarised. The incorporation of imines into flow chemistry has received recent attention and is summarised within.
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http://dx.doi.org/10.1002/chem.202003108 | DOI Listing |
ACS Appl Bio Mater
January 2025
Advanced Magnetic Materials Research Center, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, North Kargar Street, Tehran 11155-4563, Iran.
Although 3D printing is becoming a dominant technique for scaffold preparation in bone tissue engineering (TE), developing hydrogel-based ink compositions with bioactive and self-healing properties remains a challenge. This research focuses on developing a bone scaffold based on a composite hydrogel, which maintains its self-healing properties after incorporating bioactive glass and is 3D-printable. The plain hydrogel ink was synthesized using natural polymers of 1 wt % N-carboxyethyl chitosan, 2 wt % hyaluronic acid aldehyde, 0.
View Article and Find Full Text PDFNat Chem
January 2025
Key Laboratory of Advanced Marine Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, China.
sp-carbon-linked covalent organic frameworks (spc-COFs) are crystalline porous polymers with repeat organic units linked by sp carbons, and have attracted increasing interest due to their robust skeleton and tunable semiconducting properties. Single-crystalline spc-COFs with well-defined structures can represent an ideal platform for investigating fundamental physics properties and device performance. However, the robust olefin bonds inhibit the reversible-reaction-based crystal self-correction, thus yielding polycrystalline or amorphous polymers.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City, 11884, Cairo, Egypt.
A Schiff base of Chitosan was prepared by condensing of the Chitosan (CS) with six aromatic aldehydes and confirmed by FT-IR, NMR, XRD, TGA, and DSC. XRD results showed the disappeared of peaks at 2θ = 10° for CS and appeared one peaks at around 2θ of 23° for Schiff bases, while TGA was demonstrated that the thermal stability of CS has improved after the modification with the corresponding aldehyde. Also, DSC shows endothermal peak of CS at 100 °C due to the loss of water and second thermal event related to the decomposition of amine units with an exothermic peak at 295 °C, while Schiff bases shows endothermal peak around 70-95 °C which is related to the loss of water for all samples and the second exothermic peak around 260-280 °C is related to the decomposition of the amine group in the polymer units.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
School of Chemistry and Pharmaceutical Science, Guangxi Normal University, Guilin 541004, China.
Imine-based covalent organic frameworks (COFs) have been widely applied in photocatalytic hydrogen peroxide (HO) production because of their highly crystalline properties and tunable chemical structures. However, the inherent polarization of C═N linkage brings a high energy barrier for π-electron delocalization, impeding the in-plane photoelectron transfer process, which leads to an inadequate efficiency of HO photosynthesis. In addition, the chemical stability of most imine-COFs remains insufficient due to the reversible nature of imine linkage.
View Article and Find Full Text PDFBiopolymers
January 2025
Bioactive Molecules Research Laboratory, Faculty of Sciences, Section II, Lebanese University, Lebanon.
Biomaterials with antimicrobial and muco-adhesive properties represent an efficient system for different applications. In this paper, a new biomaterial based on chitosan-camphor beads and their crosslinked form with glutaraldehyde was optimized. Low and high molecular weight chitosan were considered.
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