Reactions in Elastomeric Nanoreactors Reveal the Role of Force on the Kinetics of the Huisgen Reaction on Surfaces

The force dependence of the copper-free Huisgen cycloaddition between an alkyne and a surface-bound azide was examined in elastomeric nanoreactors. These studies revealed that pressure and chain length are critical factors that determine the reaction rate. These experiments demonstrate the central role of pressure and surface structure on interfacial processes that are increasingly important in biology, materials science, and nanotechnology

Cooperatively Assembling Donor–Acceptor Superstructures Direct Energy Into an Emergent Charge Separated State

A novel supramolecular system composed of diketopyrrolopyrrole electron donors and perylene derived bisimide (PDI) electron acceptors forms superstructures that undergo fast photoinduced charge separation following assembly. This bioinspired route toward functional hierarchical structures, whereby assembly and electronic properties are closely coupled, could lead to new materials for artificial photosynthesis and organic electronics

Covalently Patterned Graphene Surfaces by a Force-Accelerated Diels–Alder Reaction

Cyclopentadienes (CPs) with Raman and electrochemically active tags were patterned covalently onto graphene surfaces using force-accelerated Diels–Alder (DA) reactions that were induced by an array of elastomeric tips mounted onto the piezoelectric actuators of an atomic force microscope. These force-accelerated cycloadditions are a feasible route to locally alter the chemical composition of graphene defects and edge sites under ambient atmosphere and temperature over large areas (∼1 cm²)

Superstructures of Diketopyrrolopyrrole Donors and Perylenediimide Acceptors Formed by Hydrogen-Bonding and π···π Stacking

Synthetic supramolecular systems can provide insight into how complex biological systems organize as well as produce self-organized systems with functionality comparable to their biological counterparts. Herein, we study the assembly into superstructures of a system composed of diketopyrrolopyrrole (DPP) donors with chiral and achiral side chains that can form triple hydrogen bonds with perylene diimide (PDI) acceptors into superstructures. The homoaggregation of the individual components as well as the heteroaggregate formation, as a result of π···π stacking and H-bonding, were studied by variable-temperature UV/vis and CD spectroscopies and electronic structure theory calculations. It was found that, upon cooling, the achiral PDIs bind to disordered DPP stacks, which drives the formation of chiral superstructures. A new thermodynamic model was developed for this unprecedented assembly that is able to isolate the thermodynamic binding parameters (Δ<i>H</i>°, Δ<i>S</i>°) for all the different noncovalent contacts that drive the assembly. This novel assembly as well as the quantitative model described in this work may help researchers develop complex self-assembled systems with emergent properties that arise as a direct result of their supramolecular structures

Extended Charge Carrier Lifetimes in Hierarchical Donor–Acceptor Supramolecular Polymer Films

We report that supramolecular polymer films composed of a 2:1 mixture of mono­diamidopyridine diketopyrrolopyrrole (DPP) electron donors and perylene bisdiimide (PDI) electron acceptors undergo photoinduced charge transfer in the solid state. Film formation is guided by complementary noncovalent interactions programmed into the molecular components, resulting in a film architecture comprised of polymer wires with order across the molecular-to-macroscopic continuum. Using ultrafast transient absorption spectroscopy, we show that recombination lifetimes increase 1000-fold compared to the same supramolecular polymers in solution. Supramolecular donor–acceptor polymer films, such as these, that are designed by considering structure and electron transfer dynamics synergistically could lead to breakthroughs in organic optoelectronics