Strong π-stacking causes unusually large anisotropic thermal expansion and thermochromism

π-stacking in ground-state dimers/trimers/tetramers of N-butoxyphenyl(naphthalene)diimide (BNDI) exceeds 50 kcal ⋅ mol−1 in strength, drastically surpassing that for the *3[pyrene]2 excimer (∼30 kcal ⋅ mol−1; formal bond order = 1) and similar to other weak-to-moderate classical covalent bonds. Cooperative π-stacking in triclinic (BNDI-T) and monoclinic (BNDI-M) polymorphs effects unusually large linear thermal expansion coefficients (αa, αb, αc, β) of (452, −16.8, −154, 273) × 10−6 ⋅ K−1 and (70.1, −44.7, 163, 177) × 10−6 ⋅ K−1, respectively. BNDI-T exhibits highly reversible thermochromism over a 300-K range, manifest by color changes from orange (ambient temperature) toward red (cryogenic temperatures) or yellow (375 K), with repeated thermal cycling sustained for over at least 2 y.

Synthesis and Self-Assembly Properties of Bola-Amphiphilic Glycosylated Lipopeptide-Type Supramolecular Hydrogels Showing Colour Changes Along with Gel–Sol Transition

Supramolecular hydrogels formed by self-assembly of low-molecular-weight amphiphiles (hydrogelators) have attracted significant attention, as smart and soft materials. However, most of the observed stimuli-responsive behaviour of these supramolecular hydrogels are limited to gel–sol transitions. In this study, we present bola-amphiphilic glycosylated lipopeptide-type supramolecular hydrogelators that exhibit reversible thermochromism along with a gel–sol transition. The bola-amphiphiles have mono-, di-, tri- or tetra-phenylalanine (F) as a short peptide moiety. We investigate and discuss the effects of the number of F residues on the gelation ability and the morphology of the self-assembled nanostructures.

Single crystal of two-dimensional mixed-halide copper-based perovskites with reversible thermochromism

Facile synthesis of single crystal of two-dimensional mixed-halide copper-based perovskites with tunable band gaps and their capability of exfoliation and reversible thermochromism.

Molecular-Level Design of Excellent Reversible Thermochromism Polydiacetylene Materials with Simultaneously Coexisted Enhancement of Multiple Performances

Recently, colorimetrically reversible materials have been paid significant attention, not only to gain a better understanding of the fundamentals of their chromism, but also to create the ways of overcoming...

Structural diversification of bola-amphiphilic glycolipid-type supramolecular hydrogelators exhibiting colour changes along with the gel–sol transition

We diversified the structures of bola-amphiphilic glycolipid-type supramolecular hydrogelators that exhibit reversible thermochromism concurrently with a gel–sol transition.