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Constructing organic materials with rigid‐planar molecules provides a unique platform for obtaining efficient photoluminescence (PL) by suppressing vibrational relaxation and extending the π‐conjugation. However, the presence of H‐aggregates/excimers resulting from interactions between π electrons and lone pairs during crystalization leads to aggregation‐caused quenching. Here, an alternative pressure‐treatment approach is presented for regulating molecular assembly to brighten rigid‐planar phthalic anhydride (PA) crystals with initial non‐emission. The pressure‐treated PA crystals exhibit significant blue‐light emission under ambient conditions, accompanied by a PL quantum yield of up to 15.7% and Commission International de I'Eclairage color coordinates of (0.20, 0.19). Detailed experiments and calculations reveal that pressure‐treated hydrogen bonds promote the planar rotation among PA molecules, which facilitates intermolecular π‐conjugation. This extended π‐conjugation alters the exciton relaxation channel, thereby triggering blue‐light emission based on charge transfer (CT) states. Remarkably, the obtained PA crystals also exhibit linear piezochromism (4.56 nm GPa−1) as a result of the structural sensitivity of the CT process. This work demonstrates the feasibility of regulating molecular assembly to achieve solid‐state emission in rigid‐planar molecules with initial non‐emission and opens up a new platform toward stimuli‐responsive crystalline materials. [ABSTRACT FROM AUTHOR]

There exist some perovskites materials with no photoluminescence (PL), which will greatly limit the practical applications in photodetection, display and lighting. Here, we achieve an exotic pressure-induced emission (PIE) at a mild pressure of 0.8 GPa from initially non-emissive 2D all-inorganic perovskite Cs3Sb2Br9 quantum dots, when the sample was subjected to external pressure. With the increase of pressure, the PL intensity gradually increases and the emission color transforms from red to green. Combined with subsequent experiments and computations, thus PIE behavior and piezochromism result from the SbBr6 octahedral distortion, accompanied by a structural phase transition from trigonal to monoclinic under pressure. Our work provides a robust strategy to boost the emission efficiency and to construct multi-functional PIE materials with piezochromism in environmentally friendly perovskites, thus facilitating the diverse applications in futural practices.

Piezochromic materials refer to a class of matters that alter their photoluminescence (PL) colors in response to the external stimuli, which exhibit promising smart applications in anti‐counterfeiting, optoelectronic memory and pressure‐sensing. However, so far, most reported piezochromic materials have been confined to organic materials or hybrid materials containing organic moieties with limited piezochromic range of less than 100 nm in visible region. Here, we achieved an intriguing piezochromism in all‐inorganic zero‐dimensional (0D) Cs3Cu2Cl5 nanocrystals (NCs) with a considerable piezochromic range of 232 nm because of their unique inorganic rigid structure. The PL energy shifted from the lowest‐energy red fluorescence (1.85 eV) to the highest‐energy blue fluorescence (2.83 eV), covering almost the entire visible wavelength range. Pressure‐modulated self‐trapped exciton emission between different energy levels of self‐trapped states within Cs3Cu2Cl5 NCs was the main reason for this piezochromism property. Note that the quenched emission, which is over five times more intense than that in the initial state, is retained under ambient conditions upon decompression. This work provides a promising pressure indicating material, particularly used in pressure stability monitoring for equipment working at extreme environments. [ABSTRACT FROM AUTHOR]

There exist some perovskites materials with no photoluminescence (PL), which will greatly limit the practical applications in photodetection, display and lighting. Here, we achieve an exotic pressure-induced emission (PIE) at a mild pressure of 0.8 GPa from initially non-emissive 2D all-inorganic perovskite Cs3Sb2Br9 quantum dots, when the sample was subjected to external pressure. With the increase of pressure, the PL intensity gradually increases and the emission color transforms from red to green. Combined with subsequent experiments and computations, thus PIE behavior and piezochromism result from the SbBr6 octahedral distortion, accompanied by a structural phase transition from trigonal to monoclinic under pressure. Our work provides a robust strategy to boost the emission efficiency and to construct multi-functional PIE materials with piezochromism in environmentally friendly perovskites, thus facilitating the diverse applications in futural practices. [ABSTRACT FROM AUTHOR]

Organic piezochromic materials that manifest pressure‐stimuli‐responses are important in various fields such as data storage and anticounterfeiting. The manipulation of piezofluorochromic behaviors for these materials is promising but remains a great challenge. Herein, a non‐luminous components regulated strategy is developed and organic molecular cages (OMCs), a burgeoning class of crystalline organic materials with structural dynamics, are first explored for the design of piezofluorochromic materials with tunable luminescence. A series of OMCs based on aggregation‐induced emission (AIE) chromophores, termed Cage 1–3, are synthesized and their piezofluorochromic behaviors are investigated by diamond anvil cell technique. Due to the sufficient voids between its flexible chromophores offered by the OMC structure, Cage 1 exhibits thermofluorochromic and piezofluorochromic properties. Moreover, the piezofluorochromic performance of this OMC could be further promoted by replacing its non‐luminous components with improved flexibilities, and a remarkable luminescence peak shift by 150 nm together with a response sensitivity of 13.8 nm GPa−1 was achieved upon hydrostatic compression. The cage structure plays a vital role in facilitating efficient and reversible piezofluorochromic behaviors. This study has shed light on the rational design and exploitation of OMCs as an exceptional platform to accomplish customizable piezofluorochromic behaviors and enlarge their potential applications in pressure‐based luminescence. [ABSTRACT FROM AUTHOR]

Lanthanide Single‐Molecule Magnets are fascinating objects that break magnetic performance records with observable magnetic bistability at the boiling temperature of liquid nitrogen, paving the way for potential applications in high‐density data storage. The switching of lanthanide SMM has been successfully achieved using several external stimuli such as redox reaction, pH titration, light irradiation or solvation/desolvation thanks to the high sensitivity of the magnetic anisotropy to any structural change in the lanthanide surrounding. Nevertheless, the use of applied high pressure as an external stimulus is largely underused, especially considering that it can be combined with high pressure X‐ray diffraction to establish a complementary structure‐property relationship. This Concept article summarizes the few relevant examples of investigations of lanthanide SMMs under applied high pressure, provides conclusions on the effect of such stimulus on molecular structures and magnetic anisotropy, and finally draws perspective on the future development of magnetic measurements under applied pressure. [ABSTRACT FROM AUTHOR]

By using complementary experimental methods including in situ high-pressure single-crystal X-ray diffraction and UV–Vis spectroscopy, the intricate connection between solvatochromism and solvatomorphism has been elucidated in a recent publication [Sobczak & Katrusiak (2024). IUCrJ, 11, 528–537]. The connection was demonstrated for an important pigment – Reichardt's dye – with potential applications in nonlinear optoelectronics and molecular pressure sensor development.

Inkless and erasable printing (IEP) based on chromic materials holds great promise to alleviate environmental and sustainable problems. Metal–organic polymers (MOPs) are bright platforms for constructing IEP materials. However, it is still challenging to design target MOPs with excellent specific functions rationally due to the intricate component‐structure‐property relationships. Herein, an effective strategy was proposed for the rational design IEP‐MOP materials. The stimuli‐responsive viologen moiety was introduced into the construction of MOPs to give it potential chromic behaviors and two different coordination models (i. e. bilateral coordination model, M1; unilateral coordinated model, M2) based on the same viologen ligand were designed. Aided by theoretical calculations, model M1 was recommended secondarily as a more suitable system for IEP materials. Along this line, two representative viologen‐ZnII MOPs 1 and 2 with models M1 and M2 were synthesized successfully. Experiments exhibit that 1 does have quicker stimuli response, stronger color contrast and longer radical lifetime compared to 2. Significantly, the obtained 1‐IEP media brightly inherits the excellent chromic characteristics of 1 and the flexibility of the paper at the same time, which achieves most daily printing requirements, as well as enough resolution and durability to be used in identification by smart device. [ABSTRACT FROM AUTHOR]

A library of β-enamino diketones was prepared via base-mediated, three-component reaction of 4-hydroxycoumarins with various aromatic/aliphatic amines and β-nitrostyrenes under microwave irradiation conditions to investigate their photochemical properties. Among the prepared compounds, a thiophene derived β-enamino diketone was found to be light-sensitive and to exhibit unique photochromic behavior, that is, positive photochromism in solution and negative photochromism in crystalline phase. In addition, this prepared photochromic compound was further covalently linked to a structure-related, piezochromic β-enamino diketone moiety to explore its potential multi-stimuli responsive properties.

Manipulating the radical concentration to modulate the properties in solid multifunctional materials is an attractive topic in various frontier fields. Viologens have the unique redox capability to generate radical states through reversible electron transfer (ET) under external stimuli. Herein, taking the viologens as the model, two kinds of crystalline compounds with different molecule‐conjugated systems were designed and synthesized. By subjecting the specific model viologens to pressure, the cross‐conjugated 2‐X all exhibit much higher radical concentrations, along with more sensitive piezochromic behaviors, compared to the linear‐conjugated 1‐X. Unexpectedly, we find that the electrical resistance (R) of 1‐NO3 decreased by three orders of magnitude with the increasing pressure, while that in high‐radical‐concentration 2‐NO3 remained almost unchanged. To date, such unusual invariant conductivity has not been documented in molecular‐based materials under high pressure, breaking the conventional wisdom that the generations of radicals are beneficial to improve conductivity. We highlight that adjusting the molecular conjugation modes can be used as an effective way to regulate the radical concentrations and thus modulate properties rationally. [ABSTRACT FROM AUTHOR]

Piezochromic materials, which exhibit a fluorescence response with large emission spectral shifts and high sensitivity, may be useful in important applications, but there have been few reports of such organic luminophores. Herein, we report a new high‐sensitivity piezochromic material based on the incorporation of an o‐carborane unit, which exhibits aggregation‐induced emission properties. In a high‐pressure experiment, compared to carborane‐free MTY, which exhibits an emission spectral shift of 75 nm and a sensitivity of 19.1 nm ⋅ GPa−1, the o‐carborane dyad MTCb shows a larger emission wavelength difference of 131 nm and a higher sensitivity of 32.8 nm ⋅ GPa−1, demonstrating a performance that ranks among the best of organic piezochromic materials reported thus far. MTCb molecules adopt a J‐aggregated pattern and have relatively loose molecular packing in the crystalline state. Interestingly, nonconjugated spherical carborane can disrupt the π‐π interactions between adjacent molecules during compression, which results in excellent piezochromic performance. [ABSTRACT FROM AUTHOR]

[Display omitted] We have witnessed a wide range of theoretical as well as experimental investigations to envisage external stimuli induced changes in electronic, optical and magnetic properties in the metal organic complexes, while hybrid perovskites have recently joined this exciting league of explorations. The flexible organic linkers in such complexes are ideal for triggering not only spin transitions but also a plethora of various different responses under the influence of various external stimuli like pressure, temperature and light. A diverse range of applications particularly in the field of optoelectronics, spintronics and energy scavenging have been manifested. The hysteresis associated with the light induced transitions and spin-crossover governed by pressure and temperature, are promising phenomena for the design principles behind memory devices and optical switches. The pressure induced optical properties tuning or piezochromism has also emerged as one of the prominent areas in the field of hybrid perovskite materials family. It is thus imperative to have a clear understanding of how the tuning in electronic, optical and magnetic properties occur under various stimuli, and selectivity of the stimulus could be influential behind the maximum efficiency in the field of energy and optoelectronic research, and in what future directions this field could be driven from the perspective of futuristic material properties. This review though primarily focuses on the theoretical aspects of understanding the different mechanisms of the phenomena, does provide a unique overview of the experimental literature too, accompanied by the theoretical understanding such that relevant device applications can be considered through a future roadmap of tuning paradigm of external stimuli. It also provides an insight as to how energy and memory storage may be combined by using the principles of spin transition in metal organic complexes. [ABSTRACT FROM AUTHOR]

Halide perovskite materials stand out in the field of photoelectricity because of their excellent luminescence and variable discoloration luminescence properties, which is mainly due to their diverse phase transition phenomenon of halide perovskites and their derivatives materials. This work focused on the introduction of various phase-transition chromotropic properties of halide perovskite materials, including photochromism, piezochromism and thermochromic properties. The intrinsic phase-transition mechanism of the chromotropic properties induced by various external factors is mainly analyzed. Finally, the future research and application prospects of the chromotropic properties of halide perovskite materials are discussed. [ABSTRACT FROM AUTHOR]

Molecular crystals of dicoronylene (C 48 H 20), a member of very large polycyclic aromatic hydrocarbons (PAHs), exhibits strong red fluorescence under ambient conditions. This strong fluorescence induced by visible light excitation obscures entire Raman spectrum of dicoronylene. We employed in-situ high-pressure photoluminescence spectroscopy to observe a reversible piezochromic effect, in which the fluorescence exhibits a drastic red-shift with a rapid quenching of intensity. Above 4 GPa, under red-shifted and reduced fluorescence, hidden Raman modes are observed with 532 nm green laser up to 20 GPa. In this work, we show that the application of pressure can finely tune the fluorescence of dicoronylene, allowing the observation of the Raman spectrum with an appropriate laser wavelength and we discovered that dicoronylene has high chemical stability among PAH molecules with multiple aromatic rings. [Display omitted] • Systematically investigated structure-property relation of C 48 H 20 at high pressure. • Piezochromic luminescence behaviour of C 48 H 20 from visible to near-IR range. • Piezochromic behaviour reveals the Raman modes of C 48 H 20 at high-pressure. • High-pressure IR and XRD revealed C 48 H 20 high stability and reversibility. [ABSTRACT FROM AUTHOR]

Viologen derived from 4,4'‐bipyridine has attracted much attention because of its color changing properties with electron transfer, unique redox stability and structural diversity. These characteristics have led to its successful use in various applications, in particular in color‐changing materials. In the past few years, researchers have been working on the syntheses of viologen‐based color‐changing functional materials, and such materials have been widely used in many fields. In photochromic materials, it is used as anti‐counterfeiting material; in thermochromic, it is used as memory storage material, and in electrochromic, it is used as a battery material. This Review discusses the progress of viologen in organic and inorganic discoloration materials in recent years. The syntheses of viologen and its derivatives are summarized, and its application in the field of discoloration materials is introduced. [ABSTRACT FROM AUTHOR]

• The BBOT crystal exhibits exceptional plastic twisting properties. • Under high pressure, the fluorescence wavelength of the BBOT crystal shifts from 448 nm to 592 nm, resulting in a total shift of 144 nm, showcasing its remarkable piezochromic properties. • As pressure increases, the intermolecular interactions within the crystal strengthen, leading to significant changes in absorption, fluorescence, and fluorescence lifetime. We report a blue-emitting plastic crystal based on a benzoxazole derivative, 2,5-bis(5-(tert‑butyl)benzo[d]oxazol-2-yl)thiophene (abbreviated as BBOT). The crystal exhibits significant plastic deformation under mechanical force while maintaining its intact morphology during twisting. However, upon mechanical grinding, the crystal transforms from a crystalline to an amorphous state, causing a slight blue shift in fluorescence (5 nm). In contrast, the fluorescence emission peak shifts significantly from 448 nm to 592 nm under hydrostatic high pressure, with a large red shift of 144 nm, demonstrating excellent high-pressure-induced fluorescence color-change performance. High-pressure absorption spectroscopy, fluorescence lifetime testing, and analysis of single-crystal data reveal that this fluorescence shift is due to enhanced intermolecular interactions under pressure. BBOT crystals have potential applications in flexible pressure sensing and offer new insights into the design of novel flexible piezochromic materials. [ABSTRACT FROM AUTHOR]

Fluorescence materials have attracted great attention in the last decades because of their modulable fluorescence properties and broad applications. Molecular packing is one of the most important factors that determines organic molecular piezochromic fluorescence behavior. Herein, we systematically investigated the fluorescence, vibrational, and structural properties of chrysene up to 20 GPa by using multiple experimental techniques and ab -initio calculations. We find the obvious color-changing with increasing pressure. Meanwhile, the phase transition at a pressure of about 6.6 GPa has been identified from both the frequency shifts and the changes in intensity of the Raman modes. However, the structure of chrysene at ambient pressure remains stable to at least P∼20.2 GPa from both experimental and theoretical x-ray diffraction results. Further structural analysis indicates that the angle between two molecular planes decreases with pressure, resulting in the packing alteration. The combined results from the experiments and computations demonstrated that the observed phase transition at 6.6 GPa is probably a result of the change of molecular packing. Furthermore, the intermolecular interactions have changed correspondingly due to the change of the molecular packing, which results in the color-changing of chrysene under pressure. These results provide further evidence that the intermolecular interactions play the important role in tuning the photo-physical properties, and this work will contribute to understanding the relationship between molecular packing and piezochromism in fluorescence materials. • The crystal optical color of chrysene undergoes obvious color-changing with increasing pressure. • The mode of molecular packing of chrysene has changed under pressure. • Piezochromic luminescence behavior of chrysene is result from the changes of intermolecular interactions. [ABSTRACT FROM AUTHOR]

Driven by the rapidly increasing demand for intelligent materials, the sensitivity of organic materials to pressure has been intensively investigated in recent years. Many examples describe material responses to both mechanical grinding and hydrostatic pressure, but only few materials have been identified with clear colour difference as well as strong penetrability, especially under high pressure, limiting development of pressure sensors. In this work, an asymmetric luminophore, MTBA was developed by end‐capping a (Z)‐3‐(benzo[c][1,2,5]‐thiadiazol‐4‐yl)‐2‐phenylacrylonitrile (TPAN) core with propeller‐like triphenylamine (TPA) and rigid 12b‐methyl‐5,12b‐dihydroindeno[1,2,3‐kl]acridine (MeIAc) units, revealing aggregation‐induced emission (AIE) behaviour. In high‐pressure and grinding experiments, MTBA exhibits a dramatically large colour difference of up to 164 nm and 112 nm in deep‐red and near‐infrared regions, respectively, for piezochromic performance that is among the best reports for pure organic materials. The experimental and theoretical analyses indicated that the excellent piezochromic performance of MTBA is due to its highly twisty and rigid conformation, which weakens intermolecular π‐π interaction and obstructs emission quenching during compression. [ABSTRACT FROM AUTHOR]

Overcrowded ethylenes composed of 10‐methyleneanthrone and two bulky aromatic rings contain a twisted carbon–carbon double (C=C) bond as well as a folded anthrone unit. As such, they are unique frustrated aromatic enes (FAEs). Various colored crystals of these FAEs, obtained in different solvents, correspond to multiple metastable conformations of the FAEs with various twist and fold angles of the C=C bond, as well as various dihedral angles of attached aryl units with respect to the C=C bond. The relationships between color and these parameters associated with conformational features around the C=C bond were elucidated in experimental and computational studies. Owing to the fact that they are separated by small energy barriers, the variously colored conformations in the FAE crystal change in response to various external stimuli, such as mechanical grinding, hydrostatic pressure and thermal heating. [ABSTRACT FROM AUTHOR]

By using complementary experimental methods including in situ high-pressure single-crystal X-ray diffraction and UV-Vis spectroscopy, the intricate connection between solvatochromism and solvatomorphism has been elucidated in a recent publication [Sobczak & Katrusiak (2024). IUCrJ, 11, 528-537]. The connection was demonstrated for an important pigment - Reichardt's dye - with potential applications in nonlinear optoelectronics and molecular pressure sensor development., (open access.)

2D hybrid organic–inorganic perovskites (HOIPs) are highly responsive to external stimuli and therefore have application potential as sensing materials. Though their optical properties upon singular thermal or pressure stimulation have been recently investigated, their dual‐stimuli‐responsive behaviors have not yet been explored. Here, the dual‐stimuli‐responsive luminescence of a pair of new enantiomeric 2D Dion–Jacobson HOIPs, R+[(4‐aminophenyl)ethylamine]PbI4 and S‐[(4‐aminophenyl)ethylamine]PbI4, is reported. The photoluminescence results show that their 485 nm emissions can be red‐shifted by ≈6 nm upon heating, and further increased to 529 nm under pressure. Such dual‐stimuli‐responsive emissions expand their Commission Internationale de L'Eclairage coordinates successively from (0.140, 0.272) to (0.283, 0.473). Detailed structural analysis and first principles calculations reveal that the temperature‐ and pressure‐responsive behaviors arise from the predominant electron–phonon interactions over thermal expansion effect and pressure‐induced in‐plane PbI bond contraction, respectively. The findings open up a new pathway to successively tune the optical emission of 2D HOIPs via a dual‐stimuli‐responsive approach. [ABSTRACT FROM AUTHOR]

Transition‐metal containing halides with Ruddlesden‐Popper (RP) perovskite structures have received extensive attention owing to their emerging and anisotropic photoelectric functionalities. Among them, A2CuX4 (A=alkali metal or organic cations, X=Cl, Br, I) series are particular, because of the Jahn‐Teller distortion of Cu2+ sensitive to external stimuli such as temperature and pressure. In this article, we report the structure evolution and physical property responses of RP perovskites Rb2CuCl4‐xBrx (x=1, 2) to external pressure. Dramatic structural phase transitions from orthorhombic to monoclinic occur around 3.0 GPa in both materials regardless of their distinct compositions. Structure analyses reveal the suppression and final vanishing of the Jahn‐Teller distortion of Cu2+ cations under compression and crossing the phase transition, respectively. Rb2CuCl4‐xBrx perovskites exhibit abrupt bandgap narrowing (from reddish‐brown to black) along with the structural phase transition, and an overall bandgap narrowing of 75% up to ∼27 GPa but still keeping semiconductive. During the compression processes, the resistances of Rb2CuCl4‐xBrx have been greatly reduced by 5‐orders of magnitude. Moreover, all of the pressure‐induced phenomena in Rb2CuCl4‐xBrx perovskites are reversible upon decompression and no obvious difference is observed for the pressure responses between [CuCl4Br2] and [CuCl4(Cl,Br)2] coordination environments. The impact of pressure on the structural and physical properties in two‐dimensional Rb2CuCl4‐xBrx provides in‐depth understanding on the structure design of functional halide perovskites at ambient conditions. [ABSTRACT FROM AUTHOR]

Transition‐metal containing halides with Ruddlesden‐Popper (RP) perovskite structures have received extensive attention owing to their emerging and anisotropic photoelectric functionalities. Among them, A2CuX4 (A=alkali metal or organic cations, X=Cl, Br, I) series are particular, because of the Jahn‐Teller distortion of Cu2+ sensitive to external stimuli such as temperature and pressure. In this article, we report the structure evolution and physical property responses of RP perovskites Rb2CuCl4‐xBrx (x=1, 2) to external pressure. Dramatic structural phase transitions from orthorhombic to monoclinic occur around 3.0 GPa in both materials regardless of their distinct compositions. Structure analyses reveal the suppression and final vanishing of the Jahn‐Teller distortion of Cu2+ cations under compression and crossing the phase transition, respectively. Rb2CuCl4‐xBrx perovskites exhibit abrupt bandgap narrowing (from reddish‐brown to black) along with the structural phase transition, and an overall bandgap narrowing of 75% up to ∼27 GPa but still keeping semiconductive. During the compression processes, the resistances of Rb2CuCl4‐xBrx have been greatly reduced by 5‐orders of magnitude. Moreover, all of the pressure‐induced phenomena in Rb2CuCl4‐xBrx perovskites are reversible upon decompression and no obvious difference is observed for the pressure responses between [CuCl4Br2] and [CuCl4(Cl,Br)2] coordination environments. The impact of pressure on the structural and physical properties in two‐dimensional Rb2CuCl4‐xBrx provides in‐depth understanding on the structure design of functional halide perovskites at ambient conditions. [ABSTRACT FROM AUTHOR]

The review is devoted to mechanically sensitive indoline spiropyrans and their structural features. Recent advances in the study of their isomerization processes are considered, special attention is paid to the effect of pressure on the behavior of spiropyrans in the composition of various photochromic materials and dyes, as well as in the process of the formation of J-aggregates in Langmuir–Blodgett films. [ABSTRACT FROM AUTHOR]

Near‐infrared piezochromic materials (PCMs), which show a fluorescence response with a clear color difference and strong penetrability, have important potential applications, but few such organic luminophores have been reported. High‐brightness donor (D)–acceptor (A) luminophores present great potential for preparing near‐IR PCMs with clear color differences. However, the intermolecular π–π interactions are sharply enhanced at high pressures, which is not beneficial for the improvement of the piezochromic properties. Herein, two crystalline polymorphs (TPEB‐α and TPEB‐γ) of a D–π–A‐type dye is presented, which emits deep‐red fluorescence with a high emission efficiency (53.2% and 28.1%, respectively). In crystalline state, dispersed dimers are observed and arranged in a herringbone pattern. Interestingly, each dimer is surrounded by four pairs of twisted tetraphenyl ethylene units, which could disrupt the π–π interactions between adjacent dimers during compression. As a result, this luminophor with dispersed dimeric stacking demonstrates the deep‐red to near‐infrared piezochromic behavior with a remarkable redshift (212 nm) and high sensitivity (19.8 nm GPa−1). [ABSTRACT FROM AUTHOR]

Two cruciform‐shaped piezochromic materials, PBM‐DPA and PBM‐BCbz, have been developed. PBM‐DPA exhibits a higher photoluminescence quantum yields (PLQY) and redder emission than PBM‐BCbz owing to the formation of a hybridized local and charge‐transfer (HLCT) excited state. Furthermore, high‐pressure measurements indicate that PBM‐DPA displays a higher sensitivity (9.4 nm/GPa) than PBM‐BCbz (6.4 nm/GPa) under the same pressure range. Information from the crystal structures suggests that this is because of the easier planarization of diphenylamine (DPA) in PBM‐DPA. In contrast, PBM‐BCbz possesses a twisty conformation, owing to the large dihedral between the central benzene ring and carbazole (Cbz), which hinders the coplanarization of the whole PBM‐BCbz molecule. This phenomenon reveals that molecular structure can efficiently influence piezochromic contrast and sensitivity. Both the planarization and the HLCT excited‐state characteristics make PBM‐DPA a high‐performance piezochromic material. This research will help to design high‐performance pressure‐response materials. [ABSTRACT FROM AUTHOR]

Flexible crystals with plasticity and elasticity that exhibit phosphorescent emission are quite rare yet highly significant for their potential applications. In our study, we present an example of such flexible (both elastic and plastic) organic crystals based on 1,2-bis(3-bromophenyl)-ethane-1,2-dione (BBPED), which demonstrates a lifetime of 0.504 ms (517 nm) and a quantum efficiency of 26.12 % at room temperature. These crystals exhibit reversible elastic properties in both their original and twisted states, and possess optical waveguide properties with minimal optical loss coefficients in the range of 0.26–0.48 dB/mm. In addition, the above crystals exhibit phosphorescence to phosphorescence blueshift under hydrostatic pressure, whereas mechanical grinding produces a phosphorescence to phosphorescence redshift phenomenon. Theoretical calculations indicate that the alterations in molecular conformation and intermolecular interactions both contribute to the piezochromic phenomenon. In conclusion, this work provides a new approach to the design of multifunctional phosphorescent molecular crystals with flexible characteristics. • Flexible crystals with plasticity and elasticity. • Crystals with 1D to 3 D phosphorescent waveguide properties. • Crystals with piezochromism properties. [ABSTRACT FROM AUTHOR]

• Obvious luminescent piezochromism (62 nm). • Efficient thermochromism (80 to 300 K). • Multi-stimuli-responsive luminescence combines into one material. Luminescent coordination polymers (CPs) with one-dimensional (1D) closely-packed structures usually display poor performances in stimuli-responsive luminescence due to the low porosity and high rigidity. Here, we reported a multi-stimuli-responsive 1D luminescent [Cu 2 I 2 ]-cluster-based CP (CuIP-OPY) with piezochromic, thermochromic and oxygen sensing properties. Attributing to the flexibility of the OPY ligand, which twists under external forces and heating, respectively, CuIP-OPY shows obvious piezochromic and thermochromic luminescence. Moreover, although its porosity is only 1.1%, oxygen can still quench its luminescence intensity by 57.53%. To further confirm the related mechanism, we also synthesized a [Cu 2 Cl 2 ]-cluster-based CP with similar structure, namely CuClP-OPY, that displays higher rigidity, and compared the differences between these two CuXP-OPY (X = I, Cl) in the multi-stimuli-responsive behavior. [Display omitted] [ABSTRACT FROM AUTHOR]

The crystal structure of pyrene‐1‐carbaldehyde (PA), a model polyaromatic hydrocarbon, highly luminescent in the solid state and crystallizing in the triclinic system, has been re‐determined at several pressures ranging from atmospheric up to 3 GPa using a diamond anvil cell. A 'multi‐crystal' approach was used in crystal structure determination, significantly improving completeness of X‐ray diffraction data attainable for such a low‐symmetry system. The crystal structure consists of infinite π‐stacks of PA molecules with discernible dimers, which resemble aggregates formed by pyrene derivatives in solution as well as in the solid state. A series of measurements showed that the average inter‐planar distance between individual molecules within π‐stacks decreases with pressure in the investigated range. This results in piezochromic properties of PA: a significant sample color change as well as a red‐shift of fluorescence with pressure, as studied with UV–vis spectroscopy. Periodic DFT calculations allowed us to relate the variations in the crystal structure with pressure to the changes in the electronic structure of this material. [ABSTRACT FROM AUTHOR]

Abstract The iso -cis/trans-aminobenzopyranoxanthenes (iso -cis/trans-ABPXs), as one of popular leuco dyes, were investigated in solution or crystal phase. The introduction of benzo-pentacyclic-ester group in iso -cis/trans-ABPXs leads to remarkable multi-stimuli responsive behaviors, including protonation effect, photochromism and piezochromism with notable color changes. The iso -cis/trans-ABPXs show different in the responsive sensitivity and the iso -cis-ABPX is highly sensitive to environmental stimuli relative to the trans-form, which can be explained by their different C-H⋯O interaction and/or C-O bond length. Interestingly, as the ultraviolet light irradiation time increasing, the iso -cis/trans-ABPXs solution gradually becomes transparent and orange precipitates are achieved, which is identified as iso -ABPXs±. Multi-stimuli responsive behaviors on the iso -cis/trans-ABPXs provide a comprehensive insight into the chromogenic mechanisms of this type of materials, suggesting that they may be potential candidate materials for sensors and indicators. Graphical abstract Image 1 Highlights • The iso -cis/trans-ABPXs show remarkable color and spectral changes under different stimuli respectively. • The iso -cis -ABPXs is more sensitive to the stimuli due to the differences in structures. • The orange solid of iso -cis/trans-ABPXs± can be produced from iso -cis/trans-ABPXs solution under the UV light irradiation. [ABSTRACT FROM AUTHOR]

Abstract Piezochromic luminescence behaviours of 9, 10-distyrylanthracene (DSA) derivatives with different substituents based on their single crystal structures were investigated under hydrostatic pressure via a diamond anvil cell (DAC), compared with the anisotropic force produced from grinding. Upon grinding, three single crystals show identifiable blue-shifts in fluorescent spectra because of the disturbance for ordered crystal structure to amorphous state, but nearly sightless color changes. The high-pressure fluorescent experiments applied by DAC reveal three DSA crystals all show large red-shifts. High pressure absorption spectra display that a new charge transfer state appears when -CH 3 or -2CN is introduced to DSA and all of them show obvious red-shifts. Once the pressure was relieved gradually to the ambient pressure, the fluorescence and absorption spectra both entirely recovered, indicating this geometric change is reversible in a certain pressure region, which is further confirmed by Raman spectra. The relationships between molecular structures and spectroscopic behaviours were further discussed by their single crystal data. This work provides deep insights into the relationship between molecular structure and photo-physical properties of practical mechanochromic luminescent materials, and is significant in the potential applications of pressure transducers. Graphical abstract Image 1 Highlights • Photo-physical behaviors of three DSA crystals with different substituents are disclosed. • DSA crystals exhibit different responses to anisotropic/isotropic pressures. • Self-recovery of DSA crystals during compression. • Remarkably large Red-shift of emission band under pressure is observed. • Introduction of -CH 3 and –CN to DSA cause a new CT state. [ABSTRACT FROM AUTHOR]

Abstract A naphthaldehyde based Schiff base, HMP has been synthesized by simple one-pot synthesis and characterized by IR, NMR and mass spectral techniques. HMP was non-emissive in acetonitrile, but its emission intensity was enhanced drastically (68 folds) upon addition of water, demonstrating typical aggregation induced emission (AIE) behaviour. Fluorescence quantum yield was increased drastically on aggregation from 0.3% (f w = 0%) to 8.1% (f w = 99%). Lifetime decay measurements were also performed in support of AIE property. Single crystal X-ray diffraction and DFT studies reveal that conformational transformation from benzenoid to quinonoid form induces restricted intramoleclar rotation (RIR) which contributes to AIE property. HMP was found to exhibit strong luminescence and piezochromism in solid state. Interestingly, dark yellow luminescence of crystalline HMP was changed to light green in response to grinding and a blue shift from 544 nm to 531 nm was observed. HMP exhibits good parent crystalline maintenance capability during grinding. Synthetic ease and reversible transformation of HMP are the key features to establish its application in pressjet printing and pressure sensing. Graphical abstract A Schiff base (E)-1-(3-(((2-hydroxynaphthalen-1-yl)methylene)amino) phenyl) displaying remarkable aggregation induced emission and unique piezochromism has been synthesized and characterized. Image 1 Highlights • A simple and cost effective Schiff base has been synthesized and characterized. • It offers a unique aggregation induced emission (AIE) and piezochromic behaviour. • UV−Vis, fluorescence spectroscopy and SEM-TEM is used to study the AIE property. • Piezochromic property is monitored by PXRD and solid state fluorescence. • It is utilised in stress detection and security technologies. [ABSTRACT FROM AUTHOR]

A library of β-enamino diketones was prepared via base-mediated, three-component reaction of 4-hydroxycoumarins with various aromatic/aliphatic amines and β-nitrostyrenes under microwave irradiation conditions to investigate their photochemical properties. Among the prepared compounds, a thiophene derived β-enamino diketone was found to be light-sensitive and to exhibit unique photochromic behavior, that is, positive photochromism in solution and negative photochromism in crystalline phase. In addition, this prepared photochromic compound was further covalently linked to a structure-related, piezochromic β-enamino diketone moiety to explore its potential multi-stimuli responsive properties., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Manjappa, Fan and Yang.)

Two 9,10‐distyrylanthracene‐based luminophores exhibiting aggregation‐induced emission and stimuli‐responsive properties were synthesized. Seven‐ or five‐color luminescence switching based on a single organic molecule was achieved for the first time. These phase transitions can be induced by physical stimuli such as grinding by mortar and pestle, heating, and exposure to the vapors of organic solvents. Moreover, a strategy for the design of new mechanoresponsive materials with π‐conjugated luminophores is proposed. Seven‐color luminophore: Piezochromism based on aggregation‐induced emission with distinct seven‐color luminescence switching built on a single organic molecule was achieved for the first time. The fluorescence switching process (see figure) can be smoothly triggered by disrupting the ordered molecular packing (mechanical grinding) and repacking (heating or solvent annealing). [ABSTRACT FROM AUTHOR]

Multi-stimuli responsive fluorescent (MSRF) materials can change their photophysical properties upon application of two or more external stimulus such as temperature, mechanical stress, and acid-base vapors. These smart materials have received great attention due to their evident advantages in sensors, probes, displays, data recording, and bioimaging. The synthesis and characterization of (E)-4-hydroxy-N′-(2-hydroxy-4-methoxybenzylidene) benzohydrazide ( 1 ) and their two new organoboron compounds are described [4-(10-methoxy-2-phenylbenzo[ h ] [1,3,5,6,2]dioxadiazaboronin-4-yl)phenol ( 2 ) and 4,4′-(2,2′-(1,4-phenylene)bis(10-methoxybenzo[ h ] [1,3,5,6,2]dioxadiazaboronine-4,2-diyl))diphenol ( 3 )]. The compounds were characterized by NMR ( 1 H, 13 C), UV/vis, fluorescence spectroscopy and high-resolution mass spectrometry (HRMS). The photophysical properties of organoboron were investigated; we found low fluorescence emission (Compound 2 Φ F : 0.89%, compound 3 Φ F : 0.93%) but in solid state showed interesting luminescent properties such as reversible thermochromism, piezochromism, vapochromism, and mechanochromism are reported. [ABSTRACT FROM AUTHOR]

Abstract: Three novel smart fluorescent on‐off materials based on hemicyanine, 3‐(2‐((1E,3E)‐4‐(3‐(4‐Fluorophenyl)‐1‐isopropyl‐1H‐indol‐2‐yl)buta‐1,3‐dien‐1‐yl)naphtho[1, 2‐d]thiazol‐1‐ium‐1‐yl)propane‐1‐sulfonate (NTPS‐FPI), (E)‐3‐(2‐(2‐(2‐hy‐droxynaphthalen‐1‐yl)vinyl)naphtho[1, 2‐d]thiazol‐1‐ium‐1‐yl)propane‐1‐sulfonate (NTPS‐HN) and (E)‐2‐(2‐(2‐hydroxynaphthalen‐1‐yl)vinyl)‐1,1,3‐trimethyl‐1H‐benz‐o[e]indol‐3‐ium iodide (BI‐HN), have been developed. They exhibit red or near‐infrared (NIR) emission and tunable on‐off solid‐state luminescent switch by multi‐stimuli, including physical or chemical mode. Single crystal, powder X‐ray diffraction, differential scanning calorimetry and scanning electron microscopy studies provide deep insight on polymorphism‐dependent piezochromism mechanism. Intriguingly, NTPS‐HN and BI‐HN show reversible solid‐state fluorescent on‐off characteristics by exposing in acid‐base vapor, which are ascribed to chemical deprotonation/protonation of terminal hydroxyl group. On the basis of multi‐stimuli response, the dual molecular level basic logic gates are established by using the appropriate external stimulus channel as the inputs and fluorescent colors as the readout data. [ABSTRACT FROM AUTHOR]

Tetraphenylethylene (TPE) and its derivatives are the most typical and most widely studied organic compounds showing aggregation-induced emission (AIE). Due to their propeller-like structures, V-like clefts exist between the aryl rings, which make them promising host compounds. However, such a possibility is seldom explored. Herein, it is reported that TPE derivatives bearing two or four pyridine rings at the para positions of the phenyl rings (TPE-Pys) can selectively include triangular (Δ-like) m-phthalic acid from a mixture of o-, m-, and p-phthalic acids due to their shape complementary to form host-guest co-crystals, which showed redder emission than the TPE-Pys themselves. The emission of co-crystals 1- 5 could be reversibly switched between yellow and red by alternating exposure to HCl and ammonia vapor. The host-guest co-crystals not only exhibited great potential for selectively recognizing and separating m-phthalic acid and as multicolor emission materials, but are also suitable for use as secret ink due to their reversible color change on varying the host-guest interactions. [ABSTRACT FROM AUTHOR]

Chromic behavior and electrical conductivity of poly(3-methylthiophene) nanoparticles - coated polyester fabric was investigated by chemical polymerization method. The electrochromic behavior of poly(3-methylthiophene) coated polyester fabrics were measured by digital voltmeter on the samples surface and the reflectance spectra were recorded. The effects of reaction time, temperature, and oxidant concentration on conductivity and other properties of the coated fabric were studied. Scanning electron microscopy confirmed that the surface of fabric has entirely been coated with poly(3-methylthiophene) particles at range of nanometer. Further characterizations were investigated using Fourier transform infrared spectroscopy to provide evidence of forming nanoparticles onto the fabric, UV-Vis absorption spectroscopy, electrical surface resistivity and pressure dependence visible reflectance spectrophotometer measurements. It can be found that the oxidant polymerization has been done physically without any structural changes. Results showed that the increasing of reaction time and temperature (less than 40°C) and oxidant to monomer molar ratio up to 3:1 led to a decrease in the electrical resistance of polymer-coated fabric. Also, the strength of samples was decreased during the polymerization (raw polyester fabric's strength, 23.36 kgf; coated polyester fabric's strength, 19.42 kgf). The blue shift in the reflectance spectra under high pressure represented the piezochromism in poly(3-methylthiophene) nanoparticlescoated polyester fabric.

A series of carbazole-based diphenyl maleimide dyes with different N-substituent were synthesized through an Ullmann reaction in high yields. The dyes exhibit an intense emission in the solid state for their twisted conformation fixed by weak intermolecular interactions, resulting in the hindrance of the internal rotations. Their solid-stated emission wavelength and intensity are sensitive to external stimuli (like heat, pressure and vapor), due to a crystal-to-crystal or crystal-to-amorphous phase transition. Based on the multi-stimuli-responsive fluorescence properties of the N -benzyl analogue, two kinds of applications were explored. One is rewritable data recording processes including solvent writing and vapor writing. The other is sensing for low hydrostatic pressure (0–25 MPa). Interestingly, nanoparticles of the dyes formed in aqueous solution could effectively detect explosive and pH changes. A 15 ppm concentration of picric acid quenched the fluorescence of the N -methyl analogue with the detectable limit calculated to be 0.13 ppm. The N -methyl analogue also showed a different emission color and intensity over the pH range 12–14, which originated from the hydrolysis of the dye molecules in the strongly basic solution. [ABSTRACT FROM AUTHOR]

Three D-π-A 1,4-dihydropyridine derivatives with aggregation-induced emission characteristics were synthesized. The molecules comprise of a 4-(dimethylamino)styryl group as the electron donor group and different end groups, dicyanomethylene, vinylcyanoacetate, and 2-methylene-1 H -indene-1,3(2 H )-dione, as the electron acceptor, respectively. These target compounds display different stimulus-responsive fluorescent properties in the solid state. The original samples with the dicyanomethylene and vinylcyanoacetate groups do not show fluorescence color changes in response to external force stimuli, whereas the compound containing the 2-methylene-1 H -indene-1,3(2 H )-dione unit exhibits reversible piezochromism and solvent-induced emission changes due to the transformation between the crystalline and amorphous states, which can be ascribed to their different molecular stacking mode in the solid state. Furthermore, these compounds show different acid/base-induced solid-state fluorescence switching properties due to the different sites of the protonation. Additionally, all of the derivatives can be fabricated into biocompatible fluorescent nanoparticles and used for MCF-7 cell imaging. [ABSTRACT FROM AUTHOR]

Two conjugated molecules based on triphenylamine and 1,3- indandione have been synthesized by employing Knoevenagel condensation. Both materials demonstrated aggregation-induced emission behavior, and solvato- and piezochromic properties. These red luminescence materials are able to respond to F- and I- sensitively. The emission wavelength changed by almost 100 nm in the presence of F- and I-, and could be observed by the naked eye under daylight and UV light. [ABSTRACT FROM AUTHOR]

We report the synthesis of trisalkoxy substituted 9, 10-bis styrylanthracene derivatives (C8-ant and C12-ant) by Heck coupling with very good yield and their photophysical properties. Both C8-ant and C12-ant exhibit aggregation induced emission (AIE), mechnoflurochromism and thermochromism. Trisubstituted 9, 10-distyrylanthracene molecules having all the luminescent properties in a single molecule are first of its kind. [ABSTRACT FROM AUTHOR]

This article describes several projects in our laboratory relating to stimuli-responsive conjugated materials using functional side chain moieties. Although side chain engineering has become increasingly important in controlling the packing of conjugated materials, these groups have typically been reserved for imparting solubility to otherwise insoluble materials. By incorporating solubilizing side chains through photocleavable nitrobenzyl linkers, new conjugated polymers behave as negative photoresists upon exposure to ultraviolet light with minimal photobleaching. Our approach enables photopatterning and solution-based fabrication of multilayer conjugated polymer films without the use of orthogonally soluble materials. Work to understand the electronic effects of the aromatic side chain substituents in these materials led to the subsequent discovery of aromatic interactions between side chains and main chains that control the conformations of solid-state phenylene-ethynylene oligomers, including highly twisted conjugated backbones. Such materials, when appropriately substituted, display reversible piezochromic and mechanofluorochromic behavior. [ABSTRACT FROM AUTHOR]

The elastic properties of a fully aromatic polyimide were measured for the first time by Brillouin scattering in a high-pressure diamond anvil cell. Its isothermal compressibility and pressure dependence of mechanical moduli (K s , E, and G) were studied and determined up to 6.4 GPa. Further, piezochromic behavior of the polyimide film was observed and studied in detail by spectroscopic analysis. Pressure-induced red shift of the absorption edge and a hysteretic phenomenon were found, due to an enhancement of the van der Waals interaction upon decreasing the interchain distances and partially collapsing the free volume under extreme pressure. A comprehensive study of elastic properties and piezochromism behavior of polyimide film under high pressure will provide useful information for developing pressure sensitive coatings, pressure sensors, pressure resistance parts and components. [ABSTRACT FROM AUTHOR]

The straightforward coordination of the Lewis acid B(C6F5)3 to classical, non-emitting aldehydes results in solid-state photoluminescence. Variation of the electronic properties of the carbonyl moieties lead to the modulation of the solid-state emission colors, covering the entire visible spectrum with quantum yields up to 0.64. Steady-state spectroscopy in combination with X-ray diffraction analysis and DFT calculations confirm that intermolecular interactions between the Lewis adducts are responsible for the observed luminescence. Alteration of the latter interactions induces, moreover, remarkable solid-state phenomena such as piezochromism. The versatility and simplicity of our approach facilitate the future development of solid-state emitting materials. [ABSTRACT FROM AUTHOR]

A simple grinding of the purple β-CoMoO 4 molybdate leads to the formation of the green polymorph α-CoMoO 4 (PDF file: 01–073-1331). The change of color under the effect of grinding or pressure in general is called the piezochromism phenomenon. The β-CoMoO 4 molybdate (PDF File: 00–021-0868) is a piezosensitive compound, sensitive to grinding. On the other hand, heating the green α-CoMoO 4 powder to 500°C at room pressure allows obtaining the purple β-CoMoO 4 variety; this is the thermochromism phenomenon. [Display omitted] • Sol–gel route was adopted for the synthesis of the CoMoO 4 molybdates. • TGA-DTA, XRD, Structural refinement, Raman spectroscopy, SEM and TEM analysis were used for characterization... • The average size of the particles of the β-CoMoO 4 powders obtained by sol–gel method was estimated of less than 60 nm. • The heat treatment of the green powder α-CoMoO 4 at 500 °C (ambient pressure) allows obtaining the purple variety β-CoMoO 4 (thermochromism phenomenon). • The analysis of the UV–Visible spectra allows us to affirm that the thermochromism phenomenon is due to the displacement of the O2–→Mo6+charge transfer band towards high energies. The molybdenum-based binary oxides CoMoO 4 have been synthesized using the sol–gel method. Thermal analysis (TGA-DTA), X-ray diffraction (XRD), and Rietveld refinement data were used to characterize the nanocrystalline powders that were produced. A simple grinding of the purple β-CoMoO 4 molybdate leads to the formation of the green polymorph α-CoMoO 4 (piezochromism phenomenon). Heating the green α-CoMoO 4 powder to 500 °C at room pressure allows obtaining the purple β-CoMoO 4 variety (thermochromism phenomenon). The T 1/2 transition temperature which corresponds to the transformation of half of the phase α into β is about 435.5 °C. According to the Rietveld refinement results, the refinement parameters showed that the observed and refined XRD patterns are in good agreement and the CoMoO 4 (α and β) monoclinic molybdate samples are totally pure. Scanning electron microscope (SEM) of β-CoMoO 4 powder obtained from cobalt nitrate (G 1 gel) showed a mixture of porous agglomerates with dispersed nanoparticles. Meanwhile, pre-sintering was observed in the powders obtained from cobalt chloride (G 2 gel). Transmission electron microscopy (TEM) analysis of β-CoMoO 4 molybdate indicated quasi-spherical particles with nanometric sizes ranging from 10 to 60 nm. The analysis of the UV–Visible spectra allows us to affirm that the thermochromism phenomenon is due to the displacement of the O2–→Mo6+charge transfer band towards high energies. [ABSTRACT FROM AUTHOR]

Two new AIE-active triphenylamine-based aza-N,O-chelated boron difluoride dyes (E)-3-(4-(diphenylamino)benzylidene)-2,2-difluoro-5-phenyl-2,3-dihydro-1,3,4,2-oxadiazaborol-3-ium-2-uide (TPA-H) and (E)-5-(4-chlorophenyl)-3-(4-(diphenylamino)benzylidene)-2,2-difluoro-2,3-dihydro-1,3,4,2-oxadiazaborol-3-ium-2-uide (TPA-Cl) were designed and synthesized. The reversible mechanochromism and piezochromism for TPA-H and TPA-Cl under mechanical stimulus and hydrostatic pressure were observed, while TPA-Cl with a chlorine atom gave a more sensitive and pronounced mechanochromic and piezochromic response under mechanical stimulus and hydrostatic pressure. Powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), the field emission scanning electron microscopy (FESEM), high-pressure PL and UV–vis absorption spectra analysis were applied to further investigated their different mechanochromism and piezochromism. Fine-tuning the molecular structures of triphenylamine-based aza-N,O-chelated boron difluoride dyes allowed convenient modulation of their optical properties and mechanoresponsive behaviors. • The reversible mechanochromism and piezochromism for TPA-H and TPA-Cl were observed. • TPA-Cl gave a more sensitive and pronounced mechanochromic and piezochromic response. • The two dyes can sense exact hydrostatic pressure higher than 11 GPa with good reversibility. • TPA-Cl with a chlorine atom showed a sensitivity of 12.20 nm GPa−1. [ABSTRACT FROM AUTHOR]