Although many examples of mechanically flexible crystals are currently known, their utility in all-flexible devices is not yet adequately demonstrated, despite their immense potential for fabricating high performance flexible devices....
The dark-orange monomer
single crystals of 1,1′-dioxo-1H-2,2′-biindene-3,3′-diyldidodecanoate
(BIT-dodeca2) convert to a transparent single-crystalline
polymer (PBIT-dodeca2) material via a single-crystal-to-single-crystal
(SCSC) polymerization
reaction under sunlight, which then undergoes reverse thermal transformation
into BIT-dodeca2 single crystals, leading to reversible
photo-/thermochromism, coupled with mechanical actuation. We exploit
the properties of this unique material to demonstrate the formation
of monomer–polymer heterostructures in selected regions of
single crystals with micrometer-scale precision using a laser. This
is the first example of heterostructure patterning involving monomer–polymer
domains in single crystals. We reveal that the speed of photomechanical
bending induced by the polymerization reaction in this example is
comparable to those of the well-known diarylethene derivatives, in
which electrocyclic ring-closing–ring-opening reactions operate.
Furthermore, we characterize the distinct mechanical properties of
the monomer and polymer using a quantitative nanoindentation technique
as well as demonstrate photopatterning on a monomer-coated paper for
potential use in security devices. These crystals with several advantages,
such as photomechanical bending (weight lifting) even when the crystal
size is large, responsiveness to both UV and visible light, distinct
solubilities (the polymer is insoluble, whereas the monomer is soluble
in most organic solvents) and colors, provide unique opportunities
for their use at different length scales of the sample (μm to
mm) for various purposes.
One co-crystal and one salt of an antibacterial drug sulfathiazole with 4-aminobenzamide and 2,4dinitrobenzoic acid have been synthesized. These new forms are characterized by single crystal X-ray diffraction, infrared spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In solid state, sulfathiazole preferentially adopts the imidine tautomeric form.
The solids salinazide (Slz) and 3-chloro-2nitrobenzoic acid (CNB) are thermosalient (TS) in nature in their single component forms; upon cocrystallization with pentafluorobenzoic acid (PNB) and 4,4′-bipyridine (BPY), respectively, they produced a salt (Slz-PFB) and a cocrystal, CNB-BPY, which are also TS in nature. A detailed structural analysis of all the forms in question is carried out to verify if a solid that shows TS behavior in its single component form can be used as a TS template to generate new TS multicomponent solid forms. The study is significant as the multicomponent approach may allow the generation of a library of new TS forms, for instance, to alter the response time, temperature, etc. This may also allow imparting an additional functionality (e.g., mechanochromic luminescence, conductivity, chemical reactivity, etc.) to the new solids upon appropriate selection of coformer(s).
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