Tunable Mechanical Response from a Crystal Undergoing Topochemical Dimerization: Instant Explosion at a Faster Rate and Chemical Storage of a Harvestable Explosion at a Slower Rate

Abstract

Strain developed in crystals in response to stimuli causes mechanical response. Methods to tune such mechanical response is important for practical applications. Crystals of a monomer having azide and alkyne units pre-organized in a ready-to-react orientation, undergo thermal topochemical dimerization and show rate-dependent mechanical response. When the reaction rate is fast, the crystals explode violently. When the reaction rate is slow, the crystals absorb water from the surroundings contemporaneously with the reaction to form the dimer-hydrate in a single-crystal-to-single-crystal (SCSC) manner. Crystals of the dimer-hydrate upon dehydration also undergo explosion. Thus, at slow reaction rate, the strain gets stored in crystals by hydration and the explosion can be harvested, at will, by dehydration. Use of this rate-dependent explosion in the automatic activation of a remedial electrical circuit in case of a sudden rise in temperature has been demonstrated.

Single-crystal-to-single-crystal synthesis of a pseudostarch via topochemical azide–alkyne cycloaddition polymerization

“…Briefly, myo -inositol ( 3 ) was protected to yield the symmetric ditriflate 5 , which on selective sequential nucleophilysis with azide followed by DMSO resulted in azido- myo -inositol derivative 7 . 12 Propargylation of the remaining –OH group, followed by acidic hydrolysis yielded tetrol 1 as a white solid. We obtained the plate-like crystals (mp 317 °C) of tetrol 1 via slow evaporation of its saturated solution in acetonitrile.…”

The Current Understanding of how 2D Polymers Grow Photochemically

“…There are also some recent articles by the Sureshan group on the effects of strain in single crystals. [17] What needs to be mentioned in the current context though is how crystals globally manage strain that occurs locally. Any reaction event causes local strain by the sizable change of intermolecular bond lengths, and the associated strain field affects not yet reacted growth pairs, i. e. aligned anthracenes, in the direct vicinity.…”

“…In single crystals it is the well-known photochemically triggered [4 + 4]-cycloaddition within anthracene/anthracene-pairs. [17] While adsorbed monolayers are also irradiated, the interaction between the light and the metallic substrate can result in [4 + 4]-cycloaddition triggered by a hot electron (or hole) tunnelling mechanism, a kind of chemistry known from plasmon-induced chemical reaction (PICR). [18] Also these differences might have a bearing on the mechanistic aspects, which are at the very heart of the present publication.…”

Stimuli-responsive dynamic pseudorotaxane crystals

“…8) in the crystal state by the intramolecular reaction of azide and alkyne groups, which releases strain that provides mechanical output. 79 They observed instant explosion of the crystals upon fast heating. In contrast, a silent crystal-to-crystal pathway occurs during the absorption of water molecules at a slow rate.…”