Effect Of Molecular Structure Research Articles

The effect of the molecular structure of naphthalene-based mesophase pitch on the properties of carbon fibers derived from it

AbstractMesophase pitch-based carbon fibers (MPCFs) have a high modulus of elasticity, low electrical resistivity and high thermal conductivity, so can be used in many fields. Carbon fibers were prepared from two naphthalene-based mesophase pitches, one synthesized by a HF/BF3 catalytic one-step method (AR-MP) and the other by an AlCl3 catalytic two-step method (N-MP). The mesophase pitches, spun pitch fibers, pre-oxidized fibers, carbonized fibers and graphitized fibers produced from them were characterized by TG-MS, FT-IR, 13C-NMR, MALDI-TOF-MS, XRD, SEM and elemental analysis. The molecular structures and properties of mesophase pitches were compared, and the effects of molecular structures on the structures and properties of the carbon fibers produced from them were measured. In comparison to N-MP, AR-MP has a rod-like semi-rigid molecular configuration containing more naphthenic structures and methyl side chains. The pre-oxidized fibers derived from AR-MP have a better carbon layer orientation, so that their graphitized fibers have a higher thermal conductivity of 716 W/(m·K). N-MP has a higher aromaticity with a disc-like rigid molecular configuration, so that the graphitized fibers prepared from it have a higher tensile strength of 3.47 GPa due to fewer defects being formed during preparation. The molecular structures of AR-MP and N-MP have an obvious influence on the structures and properties of their graphitized fibers.

Comparison of physicochemical characteristics, antioxidant and immunomodulatory activities of polysaccharides from wine grapes

In this study, an efficient ultrasonic-assisted extraction method was used for the extraction and optimization of four wine grape polysaccharides. A three-level, three-factor Box Behnken Design combined with the response surface approach was used to optimize the extraction conditions. Their physicochemical properties, molecular structure, antioxidant activity, immunomodulatory activity and hepatoprotective effects were examined and compared. These findings suggest that the four wine grape polysaccharides share similar basic structural features and monosaccharide composition. Furthermore, four wine grape polysaccharides exhibited antioxidant and immunomodulatory activities in a concentration-dependent manner. Moldova (MD) polysaccharide displayed better antioxidant activity and immunomodulatory ability. Furthermore, MD polysaccharide has a significant therapeutic effect on CCl4-induced rat liver injury by improving the antioxidant defense system and inhibiting oxidative stress, indicating that MD has a hepatoprotective effect. Taken together, the MD wine grape polysaccharide may have potential applications in prevention of liver disease in the functional food and pharmaceutical industries.

Effects of Molecular Structure of Cross-Linked Solid Polymer Electrolytes on Ionic Conduction Behavior

To improve the safety and energy density of Li batteries, all-solid-state batteries (ASSBs) are desired. Solid polymer electrolytes (SPEs) are expected to be promising candidates, owing to features such as their high flexibility and formability. To achieve high-performance ASSBs, we investigated molecular structure design by fabricating two types of SPEs. First, chemically cross-linked polyethylene oxide/polypropylene oxide (P(EO/PO))-based SPEs were formed with low-molecular-weight PEO as side chains. Second, physically cross-linked SPEs were fabricated with short PEO chains (G2) as soft-units and norbornene (NB) as hard-units with intramolecular phase separation. Evaluation of the physicochemical and electrochemical properties of these SPEs was carried out, and the degree of dissociation of the Li salt was investigated by Raman spectroscopy. The phenomenon of decoupling between the segmental motion of the SPEs and ionic conduction was confirmed by Vogel-Fulcher-Tamman equation analysis. P(NB/G2)-based SPEs also exhibited high thermal stability, which originated from the NB unit, according to TG-DTA and DSC measurements. Furthermore, ionic conductivity increased monotonically with the Li salt concentration, in contrast to conventional PEO-based SPEs. Physically cross-linked SPEs achieved the decoupling of ionic conduction from their segmental motion owing to their differences between the ionic and structural components of the SPEs.

Thermoelectric properties of self-assembled thiophene derivatives: effect of molecular structure on doping efficiency and Fermi level alignment

Organic materials have emerged as promising candidates for thermoelectric (TE) applications, offering distinct advantages over their inorganic counterparts. While polymers have received considerable attention in this context, small organic semiconductors have not been widely explored due to the challenge of obtaining high conducting films. Advancing this field necessitates the development of novel materials and a deeper understanding of their structure-dependent TE properties. The present study reports how slight modifications to the molecular structure affect the TE characteristics of two thiophene-based small molecules (OT1 and OT2), which differ only in their end substitution with varying acceptor strengths. This difference led to distinct morphologies when self-assembled. OT2 doped with FeCl3 displayed high electrical conductivity and power factor (52.0 μW/mK2), while OT1 exhibited significantly lower conductivity and power factor (1.6 μW/mK2) under identical conditions. The weaker acceptor strength of the end group in OT2 resulted in higher doping efficiency. Improved charge carrier transport in OT2 was due to a low-lying highest occupied molecular orbital (HOMO) energy level and enhanced density of states around the HOMO after doping. Maintaining its self-assembly after doping was also crucial for better electrical properties. These findings emphasize the importance of molecular engineering in developing high-performance TE materials.

The effect of molecular weight and chemical structure of cross-linkers on the properties of redox-responsive hyaluronic acid hydrogels

In this work, we investigated the effect of the size and the chemical structure of crosslinkers on the properties of hyaluronic acid-based hydrogels prepared via an inverse electron demand Diels-Alder reaction. Hydrogels having loose and dense networks were designed by cross-linkers with and without polyethylene glycol (PEG) spacers of different molecular weights (1000 and 4000 g/mol). The study showed that the properties of hydrogels such as swelling ratios (20–55 times), morphology, stability, mechanical strength (storage modulus in the range 175–858 Pa), and drug loading efficiency (87 % ~ 90 %) were greatly influenced by the addition of PEG and changing its molecular weight in the cross-linker. Particularly, the presence of PEG chains in redox- responsive crosslinkers increased the doxorubicin release (85 %, after 168 h) and the degradation rate (96 %, after 10 d) of hydrogels in the simulated reducing medium (10 mM DTT). The in vitro cytotoxicity experiments conducted for HEK-293 cells revealed that the formulated hydrogels were biocompatible, which could be a promising candidate for drug delivery applications.

Tunable Aggregation-induced Emission and Emission Colors of Imidazolium and Pyridinium Based Hydrazones.

Aggregation-induced emission (AIE) materials have drawn great attention for their wide applications as optical materials. The applications of AIE materials, however, are restricted by the complicated syntheses, hydrophobic properties and short emission wavelengths. Herein, an imidazolium based hydrazone (E)-1-(4-methoxyphenyl)-2-((1-methyl-1H-imidazol-2-yl)methylene)hydrazine hydrochloride (1) and a pyridinium based hydrazone (E)-1-(4-methoxyphenyl)-2-(pyridin-4-ylmethylene)hydrazine hydrochloride (2) have been synthesized. Notably, 1 and 2 in crystals show distinct green and near-infrared (NIR) fluorescence, with emission peaks at 530 and 688nm, and Stokes shifts of 176 and 308nm, respectively. After grinding the crystals to powder, the absolute fluorescence quantum yield (ΦF) of 1 is increased from 4.2% to 10.6%, and the ΦF of 2 is increased from 0.2% to 0.7%. X-ray crystallography studies together with theoretical calculations indicate that the enhanced emission of 1 arises from hydrogen bonding induced rigid network, and the fluorescence in the NIR region and large Stokes shift of 2 are attributed to its twisted molecular structure and strong push-pull effect.

Gelation of cereal β-glucan after partial dissolution at physiological temperature: Effect of molecular structure

Cereal β-glucan is noted for its health benefits which are directly linked to its rheological properties. In this work, the gelation potential of cereal β-glucans with varying fine structure was evaluated after dissolution at physiological temperature. β-Glucans from 12 oat and 12 barley samples were extracted and screened for the relative abundance of trisaccharide to tetrasaccharide units (DP3:DP4 ratio), and four samples, representing the DP3:DP4 extremes from both, were selected for further tests. The β-glucans were dissolved at 37 °C at 1% (w/w) concentration, and the rheological properties were investigated after 2 h or 24 h storage. Lower DP3:DP4 ratios were seen in oat (1.8–1.9) than barley (2.4–2.8) β-glucans, and the results pointed to low variation among the studied Finnish cultivars. Dynamic oscillatory measurements indicated the formation of a gel-like structure in the oat β-glucans during the 24 h storage, while the barley β-glucans behaved as entangled polymer solutions, with little to no structure development. The results support the hypothesis that, following dissolution at 37 °C, a low DP3:DP4 ratio facilitates the gelation of β-glucan as it allows for sufficient opening of the structure while leaving undissolved regions that can act as nucleation sites for junction zone formation.

Structural Engineering of Red Luminogens to Realize High Emission Efficiency through ACQ-to-AIE Transformation.

Deep red/near-infrared (NIR, >650 nm) emissive organic luminophores with aggregation-induced emission (AIE) behaviours have emerged as promising candidates for applications in optoelectronic devices and biological fields. However, the molecular design philosophy for AIE luminogens (AIEgens) with narrow band gaps are rarely explored. Herein, we rationally designed two red organic luminophores, FITPA and FIMPA, by considering the enlargement of transition dipole moment in the charge-transfer state and the transformation from aggregation-caused quenching (ACQ) to AIE. The transition dipole moments were effectively enhanced with a "V-shaped" molecular configuration. Meanwhile, the ACQ-to-AIE transformation from FITPA to FIMPA was induced by a methoxy-substitution strategy. The experimental and theoretical results demonstrated that the ACQ-to-AIE transformation originated from a crystallization-induced emission (CIE) effect because of additional weak interactions in the aggregate state introduced by methoxy groups. Owing to the enhanced transition dipole moment and AIE behaviour, FIMPA presented intense luminescence covering the red-to-NIR region, with a photoluminescence quantum yield (PLQY) of up to 38 % in solid state. The promising cell-imaging performance further verified the great potential of FIMPA in biological applications. These results provide a guideline for the development of red and NIR AIEgens through comprehensive consideration of both the effect of molecular structure and molecular interactions in aggregate states.

Photoinduced charge transfer in push-pull pyrazoline-based chromophores – Relationship between molecular structure and photophysical, photovoltaic properties

The manuscript describes the effect of molecular structure on the photophysical and photovoltaic properties of the pyrazoline-based donor-branched-π-system-acceptor compounds decorated with two end groups: phenyl or thiophene. Although the absorption to the first singlet excited state is strongly allowed, the emission quantum yield is low in all studied solvents. This behaviour was explained by the existence of two non-radiative deactivation channels: the back electron transfer process, especially operated in polar solvents, and internal conversion realized as the rotation of flexible rotors (cyano, keto phenyl or thiophene). The feasibility of the photoinduced electron transfer process was corroborated by electrochemical, spectroelectrochemical measurements as well as DFT calculations. DFT calculations also support the existence of multiple conformations in the ground state, which differ from one another in terms of charge distribution and the values of ground state dipole moment. Finally, the mechanism of the singlet excited state deactivation of the studied compounds was determined by ultrafast pump-probe measurements. Our studies revealed that charge/electron transfer process may undergo over carbonyl bridge, included in branched π-system. Moreover, the thiophene decorated pyrazoline is characterized by a better photovoltaic power conversion efficiency, while the phenyl-ended pyrazoline can be applied as a viscosity sensor.

Investigation into starch adsorption on hematite and quartz in flotation: Role of starch molecular structure

Various starches have been used as depressants in reverse flotation of iron ores. To date, the effect of molecular structures of starches on the depressing behavior is still not clear using simulation study. In this study, three starches with different ratios of amylose/amylopectin on the molecule (Normal Starch, Waxy Starch and Gelose 50) were used to study their depressing ability on the flotation of hematite and quartz. Microflotation, Zeta potential measurement, XPS analysis and AFM measurement were performed to investigate the interaction between the two minerals and the three starches. It was found that chemisorption occurred between hematite and the starches, while only hydrogen bonding was observed between quartz and the starches. In addition, it was obtained that the chemisorption strength between the starches and hematite under alkaline condition fell in the order: Waxy Starch > Normal Starch > Gelose 50, which was closely related to the ratios of amylose/amylopectin. The underlying mechanism for the different chemisorption strength was revealed via computational chemistry analysis. It is believed that the outcomes of this work could optimize the development of starch-based depressants in iron ore flotation.

Isolation, characterization, proteome, miRNAome, and the embryotrophic effects of chicken egg yolk nanovesicles (vitellovesicles)

Egg yolk constitutes about a third of the structure of the chicken egg however, the molecular structure and physiological effects of egg yolk-derived lipid membranous vesicles are not clearly understood. In this study, for the first record, the egg yolk nanovesicles (vitellovesicles, VVs) were isolated, characterized, and used as a supplement for porcine embryo culture. Yolks of ten freshly oviposited eggs were filtered and ultracentrifuged at 100,000 × g for 3 h to obtain a pellet. Cryogenic transmission electron microscopy and nanoparticle tracking analysis of the pellet revealed bilipid membranous vesicles. Protein contents of the pellet were analyzed using tandem mass spectrometry and the miRNA content was also profiled through BGISEQ-500 sequencer. VVs were supplemented with the in vitro culture medium of day-7 hatched parthenogenetic blastocysts. After 2 days of blastocyst culture, the embryonic cell count was increased in VVs supplemented embryos in comparison to the non-supplemented embryos. TUNEL assay showed that apoptotic cells were increased in control groups when compared with the VVs supplemented group. Reduced glutathione was increased by 2.5 folds in the VVs supplemented group while reactive oxygen species were increased by 5.3 folds in control groups. Quantitative PCR analysis showed that VVs significantly increased the expression of lipid metabolism-associated genes (monoglyceride lipase and lipase E), anti-apoptotic gene (BCL2), and superoxide dismutase, while significantly reducing apoptotic gene (BAX). Culturing embryos on Matrigel basement membrane matrix indicated that VVs significantly enhanced embryo attachment and embryonic stem cell outgrowths compared to the non-supplemented group. This considers the first report to characterize the molecular bioactive cargo contents of egg yolk nanovesicles to show their embryotrophic effect on mammalian embryos. This effect might be attributed to the protein and miRNA cargo contents of VVs. VVs can be used for the formulation of in vitro culture medium for mammalian embryos including humans.

Density, viscosity, and H2S solubility of N-butylmorpholine bromide iron-based ionic liquids

The density and viscosity of N-butylmorpholine bromide iron-based ionic liquids (rFeCl3/ [Nbmm]Br) with two iron-morpholine ratios (r = 0.8 and 1.0) mol·mol−1 were measured at 303.15–348.15 K and 101.3 kPa. Density and viscosity data were fitted by empirical correlations for temperature. The average relative errors were less than 0.02 % and 2 %, respectively. The density and viscosity decrease with increasing temperature. The density increases with the increase of r, while the viscosity shows the opposite trend. The gas-liquid equilibrium data of H2S in rFeCl3/[Nbmm]Br were measured by the isochoric pressure drop method at temperatures of 303.15–348.15 K, pressures of 0–200 kPa, and r of 0.8 and 1.0 mol·mol−1. The total solubility of H2S increases with decreasing temperature, increasing pressure, and decreasing r. The measured solubility data were fitted by the reaction equilibrium thermodynamic model. Chemical reaction equilibrium constant and the Henry's constant at different temperatures and different r were obtained. The average relative error of model fitting is less than 3 %. The results show that the chemical reaction equilibrium constant and the Henry’s constant both decrease with the increase of r, and decrease of temperature. Effect of molecular structure on reaction equilibrium constants was explained by quantum chemistry calculation. The absorption of H2S in rFeCl3/ [Nbmm]Br at low pressure is dominated by chemical absorption. With the increase of pressure, the proportion of physical absorption continues to increase, and gradually occupies the main part.

Static and in situ small-angle X-ray scattering analyses of the effect of molecular structure on the tensile properties of cross-linked curdlan hydrogels and stretched, dried gel-films

Random-coil and triple-helix curdlan hydrogels cross-linked with ethylene glycol diglycidyl ether were fabricated using curdlan alkaline solutions with different concentrations. Triple-helix hydrogels had higher tensile strengths than random-coil hydrogels. Small-angle-X-ray scattering analyses revealed that triple-helix hydrogels contained aggregates, which were likely bundles of triple helices. Moreover, in situ small-angle-X-ray scattering analyses indicated orientation of these triple-helix bundles during elongation. Cross-linked curdlan hydrogels were stretched up to 3 times and subsequently dried to prepare stretched, dried gel-films. Triple-helix dried gel-films exhibited a maximum strength of 200 MPa, which was markedly higher than that of random-coil dried gel-films. Triple-helix curdlan hydrogels and dried gel-films exhibited higher tensile strengths than their random-coil counterparts, suggesting that triple-helix bundles underwent crystallization and orientation.

Revealing the Mechanism of Bilayer Heterogeneous Polyelectrolytes to Suppress the Self‐Discharge of Symmetric Supercapacitors

The electrochemical supercapacitors with high power density, long cycle life, and excellent safety represent one of the most promising energy storage devices for flexible and portable electronics, but their spontaneously rapid drop of open‐circuit voltage (self‐discharge) greatly limits their wide applications. Herein, a series of bilayer heterogeneous polyelectrolyts (BHPs) consisting of a polyanion complex and a polycation complex are designed, to regulate the self‐discharge performance of supercapacitors. The BHP‐based supercapacitors possess comparable energy storage properties with those of devices based on traditional homogeneous polymer electrolyte, but exhibit a unique and noteworthy suppressed effect on the self‐discharge performance of devices. The experimental results and theoretical simulation reveal that the zeta potential difference between the used polyanion/polycation complexes has effect on the self‐discharge rate of BHP‐based supercapacitor, and the electrostatic interaction between polyelectrolytes and the mobile counterions also greatly affects the self‐discharge performance of devices. Herein, the effect of molecular structures and their interaction of polyelectrolyte complexes in BHPs on the electrochemical performance of the resultant supercapacitors are systemmatically investigated, which provides a general strategy to design novel polymer electrolytes to build high‐performance flexible supercapacitors with long self‐discharge time.

Understanding SiOC atomic structures via synchrotron X-ray and reactive force field potential studies

Silicon oxycarbide (SiOC) is a unique system that can generate various compositions and microstructures via different polymeric precursors and pyrolysis conditions. However, understanding of the atomic structure evolution, such as cluster formation, phase evolution, and atomic coordination, is lacking. In this study, cluster evolution and atomic coordination for different SiOC ceramics pyrolyzed at 1200 °C and 1500 °C were investigated by high energy X-ray diffraction (HE-XRD) and radial distribution function (RDF) analysis. A new Reactive Force Field (ReaxFF) molecular dynamics modeling approach was developed to understand nanocluster separation and early-stage atomic radial coordination. For the first time, we demonstrate that orthorhombic SiO2 forms and converts to growth resistant amorphous SiO2. Cubic β-SiC also forms at lower temperatures than reported, along with a minor amount of hexagonal SiC that has never been reported. The RDF data support such phase evolution understanding. ReaxFF simulation provides direct data on atomic mixing, elemental separation, and effects of precursor molecular structures and compositions, especially in the early stage of the pyrolysis. The simulated RDF data complement the experimental data, revealing the significant presence of C–H bonds along with Si–O and C–C bonds.

Bioaccumulation of Per- and Polyfluoroalkyl Substances (PFAS) in Ferns: Effect of PFAS Molecular Structure and Plant Root Characteristics.

The present study assessed the bioaccumulation potential of per- and polyfluoroalkyl substances (PFAS) in ferns and linked root uptake behaviors to root characteristics and PFAS molecular structure. Tissue and subcellular-level behavioral differences between alternative and legacy PFAS were compared via an electron probe microanalyzer with energy dispersive spectroscopy (EPMA-EDS) and differential centrifugation. Our results show that ferns can accumulate PFAS from water, immobilize them in roots, and store them in harvestable tissue. The PFAS loading in roots was dominated by PFOS; however, a substantial amount of associated PFOS could be rinsed off by methanol. Correlation analyses indicated that root length, surface and project area, surface area per unit length of the root system, and molecular size and hydrophobicity of PFAS were the most significant factors affecting the magnitude of root uptake and upward translocation. EPMA-EDS images together with exposure experiments suggested that long-chain hydrophobic compounds tend to be adsorbed and retained on the root epidermis, while short-chain compounds are absorbed and quickly translocated upward. Our findings demonstrated the feasibility of using ferns in phytostabilization and phytoextraction initiatives of PFAS in the future.

Effects of molecular structure and functional groups on the performance of carbonyl organic compounds as cathodes for aluminum batteries

Organic electrode materials have received extensive and long-term research and attention due to their safety, environmental friendliness, and lower price, and have also been used in aluminum-ion batteries (AIBs). The performance of existing applications in AIBs using organics as cathode materials still lags behind inorganics, especially in terms of battery capacity and voltage. Carbonyl groups have great potential as active sites for redox reactions in AIBs. Here, six carbonyl organic compounds were used as cathode for AIBs to investigate their performance differences and the factors affecting the performance. Through a combination of experiments and theoretical calculations (DFT), BDTO was first identified as the best performing cathode material in six organics, leading the organic materials with a high specific capacity of 236.8 mAh g−1 and 500 stable cycles. Moreover, it is proved that the symmetry of ring structure and molecular structure has an important influence on the properties of organic cathodes. These research results provide a direct reference for the selection and design of rational organic as cathode materials, which is an important step on the road to develop high-performance aluminum-organic batteries as soon as possible.

Effects of molecular structure and existing forms on degradation of emerging contaminants by LaFeO3/NDA−99−oxygen vacancy−driven photo−Fenton system

The selective elimination of emerging contaminants (ECs) by means of advanced oxidation processes is gaining more and more interest. The LaFeO3/NDA−99−oxygen vacancy−driven photo−Fenton system was chosen as a typical advanced oxidation process to investigate the effect of the previously neglected ECs molecular structure and existing forms on the degradation efficiency. Tetracycline antibiotics (TCs), quinolone antibiotics (QNs) and sulfonamide antibiotics (SAs) were used as target contaminants. TCs were found to have removal efficiencies more than 85.00% (91.52%, 88.68%, 86.55%, and 85.83%). Three parameters ((energy gap (ΔE, 27.50%), energy of the highest occupied molecular orbital (EHOMO, 17.00%), vertical ionization potential (VIP, 17.00%)) obtained the highest contributions (61.50% in total) on the removal efficiency. The effect of the existing forms on the removal efficiency in different pH was also explored. ECs in neutral form are more easily degraded. DFT calculation may anticipate the degradation pathways of different−structured contaminants based on intermediate detection and analysis. With the new insights gained from this research, wastewater treatment will have a theoretical foundation for optimizing the degradation potential of contaminants with varying molecular structures and existing forms.

Designing a Length‐Modulated Azide Photocrosslinker to Improve the Stretchability of Semiconducting Polymers

AbstractTo impart high stretchability to semiconducting polymers, researchers have used a photocrosslinking approach based on the nitrene chemistry of an azide‐incorporated molecular additive. However, understanding of the molecular design of azide crosslinkers with respect to their effects on the electrical and mechanical properties of semiconducting polymer thin films is lacking. In this study, the effects of an azide photocrosslinker's molecular length and structure on the microstructural, electrical features, and stretchability of photocrosslinked conjugated polymer films is investigated. For a systematic comparison, a series of nitrene‐induced photocrosslinkers (n‐NIPSs) with different numbers of ethylene glycol repeating units (n = 1, 4, 8, 13) that bridge two tetrafluoro‐aryl azide end groups is synthesized. Two semicrystalline conjugated polymers and two nearly amorphous conjugated polymers are co‐processed with n‐NIPSs and crosslinked by brief exposure to UV light. It is found that, among the synthesized n‐NIPSs, the shortest one (1‐NIPS) is the most efficient in improving the stretchability of crosslinked indacenodithiophene‐benzothiadiazole films and that the improvement is achieved only with nearly amorphous polymers, not with semicrystalline conjugated polymers. On the basis of systematic studies, it is suggested that crosslinking density in amorphous regions is important in improving thin film stretchability.

Multiple Flexibilities Trigger Luminescent Piezochromism of Closely Packed Cu(I) Coordination Polymers

AbstractThe packing states of luminescent molecules can be affected by external stimuli, leading to changes in the emission energy. Compared with the traditional organics and metal−organic frameworks, closely packed coordination polymers (CPs) have more transition types and better stabilities, respectively. However, little attention is paid to the closely packed CPs in the field of piezochromism, and much less to the corresponding optical mechanism. For studying the effect of molecular structure and the energy transfer on piezochromism, ten [Cu2I2] cluster‐based CPs with bridging aromatic ligands and terminal triphenylphosphine ligands are constructed to explore the pressure‐dependent luminescence, especially the influences of bridging ligand length, supramolecular interactions, and halogen atoms on the wavelength shift for luminescent piezochromism. In these CPs, the conformational and structural flexibilities can be effectively increased by lengthening the bridging ligand and addition of pendent methyl groups in the phosphine ligands, respectively, resulting in more obvious piezochromism. In addition, the XLCT/MLCT ratios are efficiently modulated by adjusting the flexibility of halogen electron cloud, which further affects the piezochromic property. Upon the combined effect of multiple flexibilities, a closely packed CP with a large wavelength shift (77 nm) and reversible piezochromism is found.