Materials
with zero linear compressibility (ZLC) can counterintuitively
keep its crystal size along a specific direction under hydrostatic
high pressure, which makes ZLC materials novel promising functional
materials for compression resistance. Herein, for the first time,
we propose a modular “dumbbell”-like model for ZLC material
design, which is confirmed by three representative materials MCN2 (M = Ca, Fe or Li2) consisting of different structural
units. Density functional theory (DFT) calculations reveals that the
ZLC effect occurs along the alternatively stacking direction of the
negatively compressed NM pyramid and the positively compressed N–C–N
pillar. Our finding indicates that a “dumbbell”-like
structure endows materials ZLC property; meanwhile, the ZLC can be
furtherly tuned in value by submodule substituting. Moreover, “dumbbell”
ZLC candidates can be easily discovered, because of the high symmetry
and simplicity of the model. The findings provide new insights into
the mechanism of ZLC phenomenon and is inspirational for seeking and
designing new ZLC materials.
Selenanthrene with a folded geometry was used as a model to study the purely organic room-temperature phosphorescence (RTP) behavior under high pressure, and an unprecedented phenomenon of pressure-induced RTP enhancement was deeply studied.
Organic solid-state luminescent materials exhibit numerous exciting photoelectric properties that are central to emergent organic light-emitting diodes, smart sensors, and data encryption. However, the luminescence of pure organic rotor-free materials has been afflicted with strong intermolecular π−π stacking interactions. Herein, an unprecedented pressureinduced emission enhancement (PIEE) is realized in a system of rigid planar pure polycyclic aromatics, i.e., truxene crystals. The emission intensity is enhanced 7-fold below 3.0 GPa with a photoluminescence quantum yield increased to 10.17% compared with the initial value of 1.78%, and the emission colors change from green (520 nm) to red (640 nm) within 11.8 GPa. Spectral characterizations and first-principles calculations reveal that the PIEE and piezochromism can mainly be attributed to the restricted intermolecular vibration and the decreased energy gap. Our findings enrich the PIEE mechanism and provide a new guideline for designing pressureresponsive luminescent materials in advancing their photoelectric applications.
We herein report an ew coordination network that deforms in as mooth and reversible manner under either thermal or pressure stimulation. Concomitantly,t he organic fluorophores coordinatively bound to the channel in aface-toface arrangement respond to this structural deformation by finely adapting their conformation and arrangement. As ar esult, the material exhibits ar emarkable dual-stimuliresponsive luminescence shift across almost the entire visible region:T he emission color of the crystal gradually changes from cyan to green upon heating and then to red upon pressure compression. Furthermore,each stage exhibits alinear dependence of both the emission maximum and intensity on the stimulus and is fully reversible. Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.1002/anie.201900190. Angewandte Chemie Communications Angewandte Chemie Communications 5615
The
development of supramolecular coordination complexes (SCCs)
with a bright aggregate state or mechanical-stimuli-responsive luminescence
is very significant and challenging. Herein, we report the synthesis
of three different supramolecular platinum(II) metallacycles via coordination-driven
self-assembly of a diplatinum(II) acceptor and organic donors with
a triphenylamine, carbazole, or tetraphenylethylene moiety. The triphenylamine-modified
SCC exhibits aggregation-induced emission enhancement (AIEE) but no
mechanofluorochromism. The carbazole and tetraphenylethylene-based
SCCs exhibit changes in aggregate fluorescence and also exhibit reversible
mechanofluorochromism. This work not only reports three rare metallacycles
with AIEE, aggregate fluorescence change, or mechanofluorochromic
nature but also explores their potential applications in cell imaging
and solid-state lighting.
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