Activation of a Copper Biscarbene Mechano-Catalyst Using Single-Molecule Force Spectroscopy Supported by Quantum Chemical Calculations.

Single-molecule force spectroscopy allows investigation of the effect of mechanical force on individual bonds. By determining the forces necessary to sufficiently activate bonds to trigger dissociation, it is possible to predict the behavior of mechanophores. The force necessary to activate a copper biscarbene mechano-catalyst intended for self-healing materials was measured.

Detection of stress in polymers: mechanochemical activation of CuAAC click reactions in poly(urethane) networks.

We report on copper(i)-bis(N-heterocyclic carbene)s (NHC) for quantitative stress-sensing, embedded within polyurethane networks, triggering a fluorogenic copper(i) azide alkyne cycloaddition (CuAAC) of 8-azido-2-naphtol and 3-hydroxy phenylacetylene. A completely transparent, force responsive poly(urethane) material is generated, allowing a quantification of the applied stress.

The CuAAC: Principles, Homogeneous and Heterogeneous Catalysts, and Novel Developments and Applications.

The copper-catalyzed azide/alkyne cycloaddition reaction (CuAAC) has emerged as the most useful "click" chemistry. Polymer science has profited enormously from CuAAC by its simplicity, ease, scope, applicability and efficiency. Basic principles of the CuAAC are reviewed with a focus on homogeneous and heterogeneous catalysts, ligands, anchimeric assistance, and basic chemical principles.

Mechanochemical Activation of Fluorogenic CuAAC "Click" Reactions for Stress-Sensing Applications.

Strategies for visualizing stress within polymeric materials are of growing interest during the past decade. In this paper, stress-sensing materials, triggered by a mechanoresponsive catalytic system based on latent copper(I)bis(N-heterocyclic carbene) mechanophores, are reported, which can be activated by compression force to trigger a fluorogenic copper(I)-catalyzed alkyne/azide "click" cycloaddition reaction, activating a fluorescent dye useful for stress-sensing applications in bulk polymeric materials. The focus is placed on the polymeric architecture, which is responsible for an efficient stress transmission, revealing the greatest activation for network-based mechanocatalysts, observing "click" conversions up to 44%, while chain-extended and linear mechanocatalysts activate either in a less efficient manner or are not completely latent in the initial state.