Article
Chemistry, Multidisciplinary
Taisheng Wang, Haoxiang Wang, Lei Shen, Na Zhang
Summary: A force-induced strengthening was observed in a mechanochromic polymer based on a naphthalene-fused cyclobutane mechanophore (NCD). The strengthening was attributed to the mechanically induced retro-cycloaddition of NCD and subsequent crosslinking reactions between C=C bonds. This discovery suggests the potential application of NCD in smart materials fields.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Sunil K. Gupta, Shreya Banerjee, Erode N. Prabhakaran
Summary: This study discovers the presence of local van der Waals interactions at the cis amide bond in crystals of isobutyroyl-Pro-Val-OMe, and demonstrates that expanding this interaction volume leads to a corresponding sigmoidal increase in cis amide stabilization by up to -0.24 kcal mol(-1). These vdW interactions contribute 60% towards similar CH...pi interaction energies.
NEW JOURNAL OF CHEMISTRY
(2022)
Article
Chemistry, Applied
Ivan A. Yaremenko, Yulia Yu. Belyakova, Arina A. Demina, Peter S. Radulov, Igor V. Alabugin, Alexander O. Terent'ev
Summary: A selective reaction between bridged ozonides and Fe(II) salts has been found to proceed through O-O and C-C scissions and halogenation, leading to the formation of alpha-halogen substituted delta-ketoesters and delta-diketones in yields of 15-72%. This overall sequence demonstrates how a temporary peroxide functionality can be used to replace the acyl group within an acetoacetic ester unit with a halogen.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Organic
Du Chen, Liangxuan Xu, Bowen Ren, Zian Wang, Chao Liu
Summary: An effective method for synthesizing amides and esters at ambient temperature within 5 minutes has been developed, using a stable and easily accessible triflylpyridinium reagent. Remarkably, this method not only has a wide range of substrate compatibility, but also enables scalable synthesis of peptides and esters through continuous flow process. Moreover, it demonstrates excellent chirality retention during carboxylic acid activation.
Article
Chemistry, Multidisciplinary
Michael S. Crocker, Zihang Deng, Jeffrey N. Johnston
Summary: Amide synthesis is widely used in drug development and peptide synthesis, but waste elimination in this process has had limited success. Umpolung amide synthesis has been developed as a method for enantioselective synthesis, but it cannot forge N-aryl amides. This study presents a direct synthesis method for N-aryl amides using a simple Bronsted base as a promoter, using alpha-fluoronitroalkanes and N-aryl hydroxyl amines.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Robert J. Mayer, Harpreet Kaur, Sophia A. Rauscher, Joseph Moran
Summary: Metal ions can catalyze transamination under biologically relevant conditions, with Cu2+, Ni2+, Co2+, and V5+ identified as the most active. These ions primarily accelerate the reaction by stabilizing key imine intermediates or increasing the acidity of the bound imine. Direct metal ion-catalyzed amino group transfer is highly favored even in the absence of cofactors or protein catalysts under biologically compatible reaction conditions.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Polymer Science
Haley K. Beech, Shu Wang, Devosmita Sen, Dechen Rota, Tatiana B. Kouznetsova, Akash Arora, Michael Rubinstein, Stephen L. Craig, Bradley D. Olsen
Summary: The study explores reactivity-guided fracture in polymer networks with different compositions of strands. It is found that increasing the content of less reactive strands has a negligible impact on the fracture energy until a certain threshold, after which the fracture energy sharply increases. The study also reveals that the loss of percolated network structure is a necessary criterion for crack propagation in polymer networks.
Article
Chemistry, Physical
Masaya Asakura, Masanari Okuno
Summary: This work demonstrates hyper-Raman spectroscopy of N-methylacetamide for the first time and provides fundamental knowledge of amide bands in HR spectra. The HR spectra of NMA show various amide bands with different intensity patterns and can be a powerful tool for studying the molecular structure and environment of biomolecules with peptide bonds.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Physical
Adam A. Kelemen, Andras Perczel, Daniel Horvath, Imre Jakli
Summary: The cis-trans isomerization of amide bonds plays a crucial role in the structural and functional changes of proteins. This study investigates the energetics of cis-trans isomerization in N-methylacetamide center dot 2H(2)O at different protonation states. The results reveal that the barriers for cis-trans interconversion at room temperature are too high, but a previously undescribed low energy transition state suggests a pathway for the proton transfer, enabling the trans -> cis transition to occur.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Organic
Eleonora Tosi, Jean-Marc Campagne, Renata Marcia de Figueiredo
Summary: A copper(II)/HOBt-catalyzed microwave-assisted synthesis method for dipeptides and general amides has been developed. Instead of traditional carboxylic acid activation, the method utilizes N-acyl imidazoles as activated amino partners, providing a nonconventional approach for the synthesis of dipeptides and amides through the less studied N-* C direction. The method has been successfully applied in the synthesis of various dipeptides and amides on a gram-scale, and the mild reaction conditions allow for coupling reactions with sensitive amino acids without racemization. Experimental observations have led to the proposal of a plausible reaction pathway for the couplings.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Physics, Applied
Zheng Yu, Nicholas E. Jackson
Summary: We propose a physics-based machine learning approach that detects and simulates bond breaking events in polymer networks with near quantum-chemical accuracy in atomistic simulations. By coarse-graining highly correlated neighboring bonds, the prediction accuracy is significantly improved. Compared to existing quantum mechanics/molecular mechanics methods, our approach is approximately two orders of magnitude more efficient and exhibits improved sensitivity towards rare bond breaking events at low strain. This bond breaking molecular dynamics scheme enables fast and accurate modeling of strain hardening and material failure in polymer networks and can accelerate the design of polymeric materials under extreme conditions.
APPLIED PHYSICS LETTERS
(2023)
Article
Polymer Science
Antoine Bardin, Pierre-Yves Le Gac, Pierre-Antoine Albouy, Herve Bindi, Bruno Fayolle
Summary: By tuning the hydrolysis duration of PEBA, specimens with different macromolecular structures were produced. The impact of phase interconnection changes on strain-induced crystallization (SIC) was studied for a given hard phase structure. The correlation between stress and crystallinity induced under strain was highlighted regardless of the number of chain scissions.
Article
Chemistry, Multidisciplinary
Zeynep Guven, Lars Denker, Daniela Wullschlager, Juan Pablo Martinez, Bartosz Trzaskowski, Rene Frank
Summary: This study presents an easy way to access alumaborane species with electron precise Al-B sigma-bond. The reductive rearrangement of certain compounds leads to the formation of alumaborane species with a covalent Al-B sigma-bond. The Al-B sigma-bond can perform reductive scission of multiple bonds, resulting in the incorporation of different bridging groups.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
Francisco de Azambuja, Alexandra Loosen, Dragan Conic, Maxime van den Besselaar, Jeremy N. Harvey, Tatjana N. Parac-Vogt
Summary: The study explores the catalytic activity of Zr-6-based metal-organic frameworks in peptide bond formation, showing good stability and recyclability in dipeptide cyclization reactions without the need for additional activators. The results indicate that the catalyst can be applied to substrates with bulky and Lewis basic groups, and the reaction is driven by a mechanism involving Lewis acid activation of carboxylate groups towards amine addition.
Article
Chemistry, Organic
Jason P. Hibbard, Jessalyn G. Yam, Eyad B. Alsalek, Ana Bahamonde
Summary: A mild sustainable protocol has been developed to couple primary alkyl chlorides and bromides with amides, allowing access to a remarkably orthogonal scope without the need for strongly basic conditions, high temperatures, or organometallic catalysts. K3PO4 is used to facilitate the formation of secondary and tertiary amides, with alkylated amide products obtained in good to excellent yields, showing no substantial limitations based on the steric and electronic properties of the coupling partners.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
