External Mechanical Stimulation Research Articles

Mechanochromism of π-conjugated borate derivatives and the effect of intermolecular non-covalent forces on molecular packing and mechanochromic property

We prepared three π-conjugated pinacol borate derivatives anthryl dioxaborolane (ANB), pyrenyl dioxaborolane (PYB) and perylenyl dioxaborolane (PEB) based on anthracene, pyrene and perylene moieties, and studied their optical properties in solid and solution. Interestingly, the three molecules were structurally similar, yet exhibited different optical properties and mechanochromic behavior. Crystal structure studies showed that the mechanical fluorescent response of ANB, PYB and PEB were closely related to the molecular packing modes. Although there were multiple π-π and σ-π interactions in all three molecules, the conjugation degree of ANB was relatively low, resulting in a weak π-π interaction. Therefore, the effective partial parallel packing between adjacent ANB could not form in the initial state, and external mechanical stimulation could not induce the change of optical properties. In PYB and PEB molecules with a high conjugation degree, the π-π interaction was stronger. A partial parallel packing state was formed between the molecules under the synergistic action of π-π and σ-π interaction. Under external disturbance, the relative slippage between molecules was easy to occur. Thus, the characteristic static excimer fluorescence was displayed due to the enhancement of parallel packing. Since the intermolecular interactions of PYB and PEB were a kind of weak non-covalent forces, the packing state changed by external force could return to the initial state at room temperature, showing reversible mechanochromic characteristic. This kind of room temperature reversible force sensitive material constructed by weak non-covalent interactions was expected to be applied and popularized in the fields of encrypted communication and anti-counterfeiting display.

Mechanochromism of π-conjugated borate derivatives and the effect of intermolecular non-covalent forces on molecular packing and mechanochromic property

We prepared three π-conjugated pinacol borate derivatives anthryl dioxaborolane (ANB), pyrenyl dioxaborolane (PYB) and perylenyl dioxaborolane (PEB) based on anthracene, pyrene and perylene moieties, and studied their optical properties in solid and solution. Interestingly, the three molecules were structurally similar, yet exhibited different optical properties and mechanochromic behavior. Crystal structure studies showed that the mechanical fluorescent response of ANB, PYB and PEB were closely related to the molecular packing modes. Although there were multiple π-π and σ-π interactions in all three molecules, the conjugation degree of ANB was relatively low, resulting in a weak π-π interaction. Therefore, the effective partial parallel packing between adjacent ANB could not form in the initial state, and external mechanical stimulation could not induce the change of optical properties. In PYB and PEB molecules with a high conjugation degree, the π-π interaction was stronger. A partial parallel packing state was formed between the molecules under the synergistic action of π-π and σ-π interaction. Under external disturbance, the relative slippage between molecules was easy to occur. Thus, the characteristic static excimer fluorescence was displayed due to the enhancement of parallel packing. Since the intermolecular interactions of PYB and PEB were a kind of weak non-covalent forces, the packing state changed by external force could return to the initial state at room temperature, showing reversible mechanochromic characteristic. This kind of room temperature reversible force sensitive material constructed by weak non-covalent interactions was expected to be applied and popularized in the fields of encrypted communication and anti-counterfeiting display.

Designing tunable emissions and mechanoluminescence in piezoelectric luminescent ions doped oxysulfide compounds by cations substitution for optical sensing

Piezoelectric mechanoluminescent materials capable of directly converting external mechanical stimulation into light are decisive for the development of optoelectronic sensing devices. However, emission spectral modulation is highly demanded for mechanoluminescent materials, which is important for applications. Here, we have doped luminescent ions into the piezoelectric semiconductor oxysulfide compounds (Sr,Ba)ZnOS using the salt-fusion method to form multi-mode emission materials. The prepared luminescent compounds can simultaneously generate photoluminescence and mechanoluminescence for temperature and stress sensing. The tunable photoluminescence can be obtained for multi-color emissions by controlling concentrations of luminescent ions Mn2+ and Er3+. Subsequently, the materials are combined with polydimethylsiloxane matrix to prepare smart mechanoluminescence films for optical sensing. The mechanoluminescence and tunable emissions from prepared film make this luminescent materials promising in the fields of dynamic imaging of force and anti-counterfeiting.

Harmonic resonance and entrainment of propagating chemical waves by external mechanical stimulation in BZ self-oscillating hydrogels

Smart polymer materials that are nonliving yet exhibit complex "life-like" or biomimetic behaviors have been the focus of intensive research over the past decades, in the quest to broaden our understanding of how living systems function under nonequilibrium conditions. Identification of how chemical and mechanical coupling can generate resonance and entrainment with other cells or external environment is an important research question. We prepared Belousov-Zhabotinsky (BZ) self-oscillating hydrogels which convert chemical energy to mechanical oscillation. By cyclically applying external mechanical stimulation to the BZ hydrogels, we found that when the oscillation of a gel sample entered into harmonic resonance with the applied oscillation during stimulation, the system kept a "memory" of the resonant oscillation period and maintained it post stimulation, demonstrating an entrainment effect. More surprisingly, by systematically varying the cycle length of the external stimulation, we revealed the discrete nature of the stimulation-induced resonance and entrainment behaviors in chemical oscillations of BZ hydrogels, i.e., the hydrogels slow down their oscillation periods to the harmonics of the cycle length of the external mechanical stimulation. Our theoretical model calculations suggest the important roles of the delayed mechanical response caused by reactant diffusion and solvent migration in affecting the chemomechanical coupling in active hydrogels and consequently synchronizing their chemical oscillations with external mechanical oscillations.

Regulation of mechanical force on cardiomyocytes beating

The mechanical behavior of cardiomyocytes plays an essential role in the maintenance of life and health. It is traditionally believed that both electrical and chemical signals modulate the cardiomyocytes behaviors. Recent discoveries have elucidated that the physical cues of microenvironment can regulate cell activities such as proliferation, spreading, migration, and differentiation. However, researches concerning the regulation of cardiomyocytes beating through mechanical force remains sparse. Here, we prepared different polyacrylamide gels coating with different cell adhesion ligand proteins to simulate the physical microenvironment of cardiomyocyte. Then the mechanical loading forces were loaded by employing a tungsten probe to stretch elastic hydrogels which can emulate the mechanical oscillations induced by the beating of adjacent cardiomyocytes. We investigated the responsive behavior of cardiomyocytes to external mechanical oscillations within various physical microenvironments. Firstly， we loaded 1 Hz mechanical oscillation on the matrix (E=11 kPa) with different kinds and concentrations of ligands (0, 5, 20, 100 μg/ml) to stimulate cardiomyocytes and observed it's mechanical response behavior. Our findings indicate that all kinds of ligands including Laminin, Fibronectin and Collagen I , can mediate the cardiomyocytes response to extrinsic mechanical oscillatory stimuli, which might be due to distinct mechanisms of mechanical force coupling (Fig.1b). This suggests that mechanical force signals can regulate the beating of cardiomyocytes through matrix-ligand-cell signaling pathway, thereby inducing intercellular coupled oscillations for rhythmic control of cardiomyocytes. Cardiomyoctes cultured on 20μg/ml Laminin show the highest and most stable response fraction. We hypothesized that there exist dual force transduction pathways for Laminin binding to integrin and dystrophin glycoprotein complex (DGC) (Fig.1a). We further analyzed the cardiomyocytes behaviors under mechanical oscillation with different substrate stiffness (E=1.8, 11, 27 kPa) and concentrations of Laminin (0, 5, 20, 100 μg/ml). We found that cardiomyoctes cultured on 1.8 kPa coated with 20 μg/ml Laminin show the highest response fraction (Fig.1c). Our results demonstrate that the stiffness of substrate, the type and density of cell adhesion ligands, as well as the strength and rhythm of the mechanical signals can synergetic influence the cardiomyocytes responses to external mechanical stimulations, which provides the foundation for understanding the diseases such as cardiac arrhythmias and heart failure following myocardial infarction.

Electroluminescence, Mechanoluminescence, and Triboelectric from Superior Multimode Systems Based on Flexible Hydrogels for Human Motion Sensing

AbstractFlexible sensors have attracted extensive research interest due to their great application potential in biodetection, flexible display, and wearable devices. However, they still have a lot of room for improvement in terms of luminous color, flexibility, and self‐powered systems. A wearable, antifreeze, and discoloration sensing system based on electroluminescence, mechanoluminescence, and tribo‐power generation is developed in this paper. Triboelectric nanogenerator systems can harvest biomechanical energy from hand clapping and knee/elbow bending to generate real‐time electrical signals. The use of dielectric materials reduces the initial voltage and frequency of light‐emitting devices, enabling them to be driven by Triboelectric nanogenerators. At the same time, the device can produce red, blue, white, and other multicolor light. In addition, the system can produce an optical signal output due to external mechanical stimulation. As a result, the sensor system is simple to manufacture and unique to operate, proving its potential applications in areas such as cold‐resistant displays, wearable optoelectronics, soft robotics, and electronic skin.

Mechanical cycling-induced evolution of structure and local mechanical properties in a PdCuNiP bulk metallic glass

To improve the ductility of bulk metallic glasses (BMGs), external mechanical stimulations can be applied. Thereby, cyclically loading the samples at stress levels below the macroscopic elastic limit leads to permanent structural changes, which can alter the plasticity in bulk metallic glasses. Here, the effect of systematic variations of Pd43Cu27Ni10P20 BMG's structural state, achieved through cyclically loading the material to 70, 80, and 90% of the yield strength, on a range of mechanical properties like modulus, hardness, yield strength, strain rate sensitivity, activation volume, maximum shear stress and stiffness at different probing volume is studied. It is observed that samples rejuvenated from the non-cycled state to the 70% of yield stress state, relaxed when cycled up to 80% of yield stress, and finally rejuvenated again when cycled up to 90% of yield stress. This rejuvenation to relaxation transition might be due to the random atomic rearrangement during the cycling.

Evaluation of the Basic Designs of a Micro Device that Provides Vibrational Stimulation to Cells

It is known that the cells responds to external mechanical stimulations. Although the effectiveness of vibrational stimulation for the osteoanagenesis has been reported, the clarification of detailed mechanism for this phenomenon is insufficient. In this study, a micro device has been developed to evaluate the cell dynamics and responses to vibrations. The micro device has an array of moving micro stages which have transparent 5 µm thick thin film to enable them to observe the cell responses to vibrational stimulations by using an optical microscope. The moving micro stages are moved with a needle actuated by piezo actuator. Microfabrication processes, such as conventional photolithography, lift-off, and sacrificial layer etching, were used to fabricate the micro device. We designed two types of concepts for supporting and vibrating moving micro stages. Prototypes were fabricated and evaluated under vibrational conditions. Proposed design with the moving micro stages vibrating perpendicular to the beams generated simple linear oscillation without rotation. It was verified that the fabricated micro stage could be vibrated at the acceleration amplitude of 0.1 and 0.2 G with frequency 15, 45, and 90 Hz.

Effects of substitution position with different charge characteristics groups on mechanofluorochromic behaviors of the pyridine-based difluoroboron compounds

Two donor-acceptor type pyridine-based difluoroboron compounds (3F-Py-TPA BF2 and TPA-Py-3F BF2) were designed and successfully synthesized, which including triphenylamine unit acted as the electron donor and difluoroboron moiety and 3,4,5-trifluorophenyl group served as the electron acceptors. Combined with the results of the photophysical properties, it was found that compound 3F-Py-TPA BF2 with 4-position of pyridine skeleton substituted by 3,4,5-trifluorophenyl unit and triphenylamine unit location at the end of the bridged phenyl displayed more excellent intramolecular charge transfer character and solvatochromic effect. Moreover, the solid emission spectrum of 3F-Py-TPA BF2 was red-shifted from 550 to 594 nm, that of TPA-Py-3F BF2 was red-shifted from 526 to 546 nm under external mechanical stimulation, which caused by phase transformation between the ordered crystalline and disordered amorphous states according to the powder X-ray diffraction measurements. Based on the results of theoretical calculations and X-ray single-crystal diffraction analysis, we speculated that TPA-Py-3F BF2 with 4-position of pyridine skeleton substituted by triphenylamine unit and 3,4,5-trifluorophenyl unit location at the end of the bridged phenyl had higher molecular polarity and too loose molecular packing mode, resulting in the mechanofluorochromic behavior was worser than that of 3F-Py-TPA BF2. This work presented a strategy for regulating mechanofluorochromic behaviors of the pyridine-based difluoroboron molecular materials.

Extracellular ATP-induced calcium oscillations regulating the differentiation of osteoblasts through aerobic oxidation metabolism pathways.

The increase of ATP concentration in the extracellular space represents one of the effective signals that stimulate the physiological activities of cells when the bone is exposed to external mechanical stimulation such as stretching and shear stress force throughout life. However, the effects of ATP on osteoblast differentiation and related mechanisms are not well understood. In this study, the roles of extracellular ATP on osteoblast differentiation, intracellular calcium ([Ca2+]i) levels, metabolomics, and the expression of proteins related to energy metabolism were investigated. Our results showed that 100μM extracellular ATP initiated intracellular calcium ([Ca2+]i) oscillations via the calcium-sensing receptor (P2R) and promoted the differentiation of MC3T3-E1 cells. Metabolomics analysis showed that the differentiation of MC3T3-E1 cells depended on aerobic oxidation, but little glycolysis. Moreover, the differentiation of MC3T3-E1 cells and aerobic oxidation were suppressed with the inhibition of AMP-activated protein kinase (AMPK). These results indicate that calcium oscillations triggered by extracellular ATP can activate aerobic oxidation through AMPK-related signaling pathways and thus promote osteoblast differentiation.

Electrospun Piezoelectric Scaffold with External Mechanical Stimulation for Promoting Regeneration of Peripheral Nerve Injury.

Safe and efficient provision of electrical stimulation (ES) for nerve repair and regeneration is a problem that needs to be addressed. In this study, a silk fibroin/poly(vinylidene fluoride-co-hexafluoropropylene)/Ti3C2Tx (SF/PVDF-HFP/MXene) composite scaffold with piezoelectricity was developed by electrospinning technology. MXene was loaded to the scaffold to enhance the piezoelectric properties (Output voltage reaches up to 100 mV), mechanical properties, and antibacterial activity. Cell experiments demonstrated piezoelectric stimulation under external ultrasonication for promoting the growth and proliferation of Schwann cells (SCs) cultured on this electrospun scaffold. Further in vivo study with rat sciatic nerve injury model revealed that the SF/PVDF-HFP/MXene nerve conduit could induce the proliferation of SCs, enhance the elongation of axon, and promote axonal myelination. Under the piezoelectric effect of this nerve scaffold, the rats with regenerative nerve exhibited a favorable recovery effect of motor and sensory function, indicating a safe and feasible method of using this SF/PVDF-HFP/MXene piezoelectric scaffold for ES provision in vivo.

Numerical study of the mechanical behavior of the hip joint under therapeutic acoustic impact

Degenerative diseases are one of the main causes of disability in the middle-aged and older population. One of the most common diseases is osteoporosis and osteonecrosis of the femoral head. For the prevention and treatment of osteoporosis, osteopenia, and osteonecrosis, external mechanical stimulation based on ultrasound and shock wave exposure is used, based on local ultrasonic or shock wave exposure in the area of pathology. The effect of external mechanical action is based on mechanobiological principles, the essence of which is that a certain level of pressure (mechanical stress) and deformation leads to the growth and differentiation of various types of biological tissue. To obtain a therapeutic effect, it is necessary to correctly choose the parameters of exposure and the place of its application. Usually, these problems are solved empirically. In this work, the possibility of creating conditions for bone tissue regeneration under external acoustic impact on a healthy hip joint and a joint affected by osteonecrosis was studied numerically. The study was carried out using the method of mobile cellular automata. The results obtained showed the effectiveness of the use of medium- and high-intensity ultrasound exposure for the prevention of osteopenia and osteoporosis. When exposed to ultrasound on a joint with osteonecrosis of the head, the creation of conditions for osteogenesis and chondrogenesis in the affected area is observed only with high-intensity loading. Thus, the hypothesis that low-intensity ultrasound therapy is effective only in combination with other methods of treatment was con-firmed. It was found that shock-wave action of low intensity promotes the division of biological cells and their transfer, thereby creating conditions for the regeneration of bone tissues. This conclusion is consistent with the results of most experimental studies.

Remote shockwaves to externally activate piezoelectric PVDF-TrFE nanofibers for peripheral nerve system regeneration.

Electric stimulation (ES) has the potential to enhance cellular function in major cell types involved in peripheral nervous system (PNS) repair through augmenting regeneration of axons, extending dorsal root ganglion neurites, and mediating the plasticity of Schwann cells. Furthermore, ES has been shown to induce calcium dependent nerve growth factor release in Schwann cells. Together, these phenomena may be harnessed to promote nerve regeneration by enhancing survival and outgrowth of damaged nerves. Electrospun polyvinylidene flouride-triflouroethylene (PVDF-TrFE) nanofibers are biocompatible piezoelectric materials capable of producing electrical currents in response to mechanical deformations. Here we introduce PVDF-TrFE as a cell stimulation platform able to deliver controlled ES in response to external mechanical stimulation from shock waves. We first characterize current generated from shock waves stimulated PVDF-TrFE scaffolds with treatments at pressure and frequency values of 0.5 bar at 1 Hz, 1 bar at 1 Hz, and 3 bar at 2 Hz. PVDF-TrFE nanofibers were seeded with NIH-3T3 fibroblasts and RT4-D6P2T Schwann cells and subjected to 1000 counts of 0.5 bar 1 Hz every 24 hours. Results indicated significant cell proliferation for treatment groups on days 2 and 4 of culture compared to controls for both cell types. This platform can be further engineered to optimize ES on cells to elucidate mechanisms associated with generating a “pro-repair” phenotype in Schwann cells and the PNS.

A metastable molecular array guided by the synergy of confinement and charge repulsion for piezochromic sensors

Piezochromic fluorescent materials have attracted the interest of the scientific community due to their obvious fluorescence emission or color change in response to external pressure or mechanical grinding stimulation.

Refinement of sensitive azides via in situ generated azole-based metal-organic frameworks towards stable energetic materials.

Energetic materials (EMs) have been widely employed in both military and civilian areas for nearly two centuries. The introduction of high-energy azide anions to assemble energetic metal-organic frameworks (EMOFs) is an efficient strategy to enhance energetic properties. However, azido-based EMOFs always suffer low stabilities to external mechanical stimulation. Herein, we employed an in situ hydrothermal reaction as a technique to refine azide anions with a neutral triazole-cyano-based ligand TrzAt (TrzAt = 2-(1H-1,2,4-triazol-1-yl)acetonitrile) to yield two tetrazole-based EMOFs, namely, [ZnBr(trmetz)]n1 and [Cd(trmetz)2]n2 (Htrmetz = 5-(1,2,4-triazol-1-ylmethyl)-1H-tetrazole). Compound 1 features a closely packed 2D layered network, while compound 2 exhibits a 3D architecture. With azide anions inlaid into a nitrogen-rich and chelating ligand in the EMOFs, compounds 1 and 2 present remarkable decomposition temperatures (Tdec ≥ 300 °C), low impact sensitivities (IS ≥ 32 J) and low friction sensitivities (FS ≥ 324 N). The calculated heat of detonation (ΔHdet) values of 1 and 2 are 3.496 and 4.112 kJ g-1, respectively. In particular, the ΔHdet value of 2 is higher than that of traditional secondary explosives such as 2,4,6-trinitrotoluene (TNT, ΔHdet = 3.720 kJ g-1). These results indicate that EMOFs 1 and 2 may serve as potential replacements for traditional secondary explosives. This work provides a simple and effective strategy to obtain two EMOFs with satisfactory energy densities and reliable stabilities through an in situ hydrothermal technique for desensitization of azide anions.

Multicolor Mechanochromic Epoxy Thermosets That Recognize the Intensity, Type, and Duration of Mechanical Stimulation.

Mechanochromic polymers that exhibit multiple color changes under external mechanical stimulation show great potential for sensor applications. Herein, an epoxy thermoset that can reveal the intensity, type, and duration of mechanical stimulation via a combination of disulfide (DS) and rhodamine (Rh) mechanochromophores is reported. A unique multicolor transition occurs upon ball mill or manual grinding because of the different activation energies of DS and Rh. The epoxy changes color depending on the ball mill grinding duration. Simultaneous activation occurs with a mechanochromic time lag between DS and Rh, and the collision energy strongly affects the relative intensity. A more dramatic multicolor response is observed using a mortar and pestle, as sequential activation occurs upon gentle and strong grinding. Various types of mechanical stimulation can cause different aggregates of the activated Rh moiety and vary the relative mechanosensitivities of Rh and DS, which lead to a different color response.

Facile construction of electrochemical and self-powered wearable pressure sensors based on metallic corrosion effects

Flexible mechanical sensors are essential components for smart wearables. Conventional resistive, capacitive, or transistor-based mechanical sensors consume energy continuously, while piezoelectric and triboelectric sensors respond selectively to dynamic or transient mechanical stimulations. Developing mechanical sensors that do not necessitate external power supply but are able to monitor static mechanical stimuli can compensate for the deficiencies of existing sensing devices. Here, we present the facile construction of a new paradigm of electrochemical mechanical sensors based on ubiquitous metallic corrosion effects. The intrinsic differences in corrosion activities of diverse metals (e.g., zinc, aluminum, copper, etc.) are utilized to create potential differences between two electrodes, followed by encoding external mechanical stimulations into the potential difference variations via carefully selected solid electrolytes. The developed electrochemical mechanical sensors exhibit comparable performance (e.g., sensitivity, recovery/response speed, reproducibility, etc.) with that of conventional sensors, but possess significantly superior simplicity, cost-efficiency, and desirable capability in resolving static or slowly-varying mechanical stimulations in a self-powered manner. As proof-of-concept demonstrations, machine learning enabled speech recognition with high accuracy of 99.07% and monitoring of diverse human physiological activities are successfully demonstrated. These proposed unique electrochemical mechanical sensors based on the ubiquitous metallic corrosion phenomena provide a simple but effective approach for the burgeoning human-machine interfacing requirements with great benefit to the resource efficiency and sustainability of our society.

Pattern Formation in a Spatially Extended Model of Pacemaker Dynamics in Smooth Muscle Cells

Spatiotemporal patterns are common in biological systems. For electrically coupled cells, previous studies of pattern formation have mainly used applied current as the primary bifurcation parameter. The purpose of this paper is to show that applied current is not needed to generate spatiotemporal patterns for smooth muscle cells. The patterns can be generated solely by external mechanical stimulation (transmural pressure). To do this we study a reaction-diffusion system involving the Morris–Lecar equations and observe a wide range of spatiotemporal patterns for different values of the model parameters. Some aspects of these patterns are explained via a bifurcation analysis of the system without coupling — in particular Type I and Type II excitability both occur. We show the patterns are not due to a Turing instability and that the spatially extended model exhibits spatiotemporal chaos. We also use travelling wave coordinates to analyse travelling waves.

Mechanical activation drives tenogenic differentiation of human mesenchymal stem cells in aligned dense collagen hydrogels

Tendons are force transmitting mechanosensitive tissues predominantly comprised of highly aligned collagen type I fibres. In this study, the recently introduced gel aspiration-ejection method was used to rapidly fabricate aligned dense collagen (ADC) hydrogel scaffolds. ADCs provide a biomimetic environment compared to traditional collagen hydrogels that are mechanically unstable and comprised of randomly oriented fibrils. The ADC scaffolds were shown to be anisotropic with comparable stiffness to immature tendons. Furthermore, the application of static and cyclic uniaxial loading, short-term (48 h) and high-strain (20%), resulted in a 3-fold increase in both the ultimate tensile strength and modulus of ADCs. Similar mechanical activation of human mesenchymal stem cell (MSC) seeded ADCs in serum- and growth factor-free medium induced their tenogenic differentiation. Both static and cyclic loading profiles resulted in a greater than 12-fold increase in scleraxis gene expression and either suppressed or maintained osteogenic and chondrogenic expressions. Following the 48 h mechanoactivation period, the MSC-seeded scaffolds were matured by tethering in basal medium without further external mechanical stimulation for 19 days, altogether making up 21 days of culture. Extensive cell-induced matrix remodeling and deposition of collagen types I and III, tenascin-C and tenomodulin were observed, where initial cyclic loading induced significantly higher tenomodulin protein content. Moreover, the initial short-term mechanical stimulation elongated and polarized seeded MSCs, and overall cell alignment was significantly increased in those under static loading. These findings indicate the regenerative potential of the ADC scaffolds for short-term mechanoactivated tenogenic differentiation, which were achieved even in the absence of serum and growth factors that may potentially increase clinical translatability.

Design, synthesis, and mechanochromic luminescence of twisted donor–acceptor bisarylic methanone derivatives

Two bisarylic methanone derivatives, DBF-BZ-POZ and DBF-BZ-PTZ, which have phenoxazine or phenothiazine as electron donors and carbonyl group as electron acceptor are presented. Both molecules have highly distorted molecular conformation and exhibit obvious intramolecular charge transfer (ICT), effective solid-state emissions, and high-contrast mechanofluorochromic (MFC) properties. Both DBF-BZ-POZ and DBF-BZ-PTZ have good solid-state luminescence, efficiencies that reach 33.5% and 38.9%, respectively. The fluorescence colors of the as-prepared powders for both molecules are bright blue-green. The colors change to bright yellow with external mechanical stimulation and red shifts of 104 and 82 nm are observed in the photoluminescence (PL) spectra. Moreover, the MFC behavior of DBF-BZ-POZ and DBF-BZ-PTZ are reversible when their ground samples are subjected to fuming with the DCM vapor. Powder X-ray diffraction results indicate that the MFC phenomenon of DBF-BZ-POZ and DBF-BZ-PTZ may be attributed to crystalline-to-amorphous transitions in the material. The red shifts observed in the PL spectra after the material is ground are due to the smaller band gap induced by the planar intramolecular charge transfer (PICT) and the increased π-π interactions, the increase of exciton coupling, as well as the increased orbital overlap between neighboring molecules.