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As an important component of highly heterogeneous exosomes, exosomal microRNAs (miRNAs) have great potential as noninvasive biomarkers for cancer diagnosis. Therefore, a sensitive and simple sensor is the key for its clinical application. Herein, we designed an exponential amplification reaction (EXPAR) to induce the reactivation of the CRISPR-associated protein 9/small guide RNA (Cas9/sgRNA) complex, thus achieving sensitive and visual exosomal miRNAs-21 (miR-21) fluorescence sensing. In this design, we inactivated the sgRNA by hybridizing sgRNA and blocker DNA. Then, we used a trigger DNA to hybridize with miR-21 and produced a lot of activated DNA by EXPAR. Those activated DNA further hybridized with blocker DNA and released the free sgRNA to form the activated Cas9/sgRNA complex. Based on the quick cleavage of activated Cas9/sgRNA complex, the reporter DNA labeled by SYBR Green I was released from the surface of the magnetic nanoparticles (MNPs) into the supernatant, and thus was used to sensitively quantify the miRNAs concentration with a limit of detection of 3 × 103particles/mL. In addition, this fluorescence sensor has also been successfully employed to distinguish healthy people and cancer patients by naked-eye observation of the fluorescence, thus demonstrating its great potential for accurate and point-of-care cancer diagnosis.

Developing novel porous adsorbents for efficient wastewater treatment is significant to the environment protection. Herein, three porous polycalix[n]arenes (n= 4, 6, and 8) which had varying cavity sizes of the macrocycle (Azo-CX4P, Azo-CX6P, and Azo-CX8P) were prepared under mild conditions and tested for their potential application in water purification. Azo-CX8P with a larger cavity size of the macrocycle outperformed Azo-CX4P and Azo-CX6P in screening studies involving a range of organic micropollutants. It was proved that Azo-CX8P was especially efficient in the removal of cationic dyes because of its high negative surface charge. In terms of the adsorption of Rhodamine B with Azo-CX8P, the pseudo-second-order rate constant reaches 5.025 g·mg–1·min–1with the maximum adsorption capacity being 1345 mg·g–1. These values are significantly higher compared with those recorded for most adsorbents. In addition, the easily prepared Azo-CX8P can be reused at least six times without a loss of the adsorption efficiency, demonstrating its potential use in water purification.

This paper mainly studies the benefits of integrated energy services under the modes of independent investment and operation, independent investment and entrusted operation, cooperative investment and operation, and cooperative investment and entrusted operation. It also constructs a corresponding model for benefit evaluation and analysis by means of the subject feature method. This paper selects the integrated energy system of an industrial park in Southwest China as the research object. By analysing the operation modes of three different participating entities, this paper analyses their benefits by combining the cost-benefit model, and concludes that the State Grid Corporation has the greatest benefit under the independent investment and operation mode. The research results of this paper have certain practical guiding significance for the operation mode and benefit maximisation of integrated energy services.

In the context of energy shortage, the concepts of energy revolution and supply-side reform and development require the energy sector, to further promote the energy revolution, strive to promote the transformation of energy production and development, optimise the energy supply structure, improve energy efficiency, build a clean, low-carbon, safe and efficient modern energy system, and maintain national energy security. The current research on the pricing mechanism and estimation model of integrated energy services is not thorough enough. In this paper, we introduce a consistent pricing strategy and analyse the optimal decision and profit situation of manufacturers and retailers within the framework of this pricing strategy. It is found that the differentiated pricing strategy outperforms the unified pricing strategy in most cases for manufacturers and the entire supply chain. When consumers have moderate preferences for the online channel, a manufacturer's choice of a uniform pricing strategy can make it more affordable for manufacturers and suppliers, with less lost profit for the entire chain. In addition, when manufacturers have low pricing power (p< 55), they are more inclined to go for a consistent pricing strategy.

Previous research had validated the machinability of the new machining method of electrical discharge assisted milling (EDAM). However, the EDAM tool has shortcomings, such as its inability to compensate for the electrodes and small discharge area, which restricted further popularization and applications of the method. So, this research introduced a high frequency EDAM (HF-EDAM), based on a novel tool with flexible electrodes. Notably, the material removal mechanism of HF-EDAM under different machining parameters was deeply explored in this study. In particular, the discharge signal, electrode and workpiece surface topographies, cutting force, tool wear, and machined-surface integrity of HF-EDAM were analyzed to find the machining mechanism of HF-EDAM under different machining parameters. At the same time, a two-dimensional cutting force model of HF-EDAM was also established, and a series of experiments showed that the model had good prediction accuracy for cutting forces. Furthermore, the experiments also showed that the HF-EDAM greatly reduced the cutting force and tool wear, and improved the machined-surface integrity as compared to those under CM, respectively. In essence, the excellent machinability of HF-EDAM was verified by experiments and modeling. Hence, HF-EDAM is an effective method for high-quality and efficient machining of titanium alloys, which are difficult to machine.

The design and synthesis of efficient and highly selective UO22+nanotraps still pose difficulties in the field of radionuclide removal. Herein, a stable polyimide covalent organic framework (PI-COF-6) was rationally synthesized for targeted uranium adsorption through the irreversible imidization reaction between nitrogen-rich monomer 5,5′,5″-(1,3,5-triazine-2,4,6-triyl)tris(pyridin-2-amine) (TTPA) and pyromellitic dianhydride (PMDA). The PI-COF-6 showed satisfactory uranium adsorption performance with high capacity (424.5 mg g–1), fast kinetics (98.0% removal rate in 50 min), ultrahigh selectivity among multiple metal ions, excellent stability, and outstanding recyclability. XPS characterization and DFT calculations identified that the uranium adsorption of PI-COF-6 mainly relied on the N–N–O nanotraps which were rationally constructed by pyridine nitrogen in TTPA coupling with the tertiary amine nitrogen and carbonyl oxygen in the imide ring. Moreover, the results of high-resolution U 4f XPS spectroscopy revealed that part of U(VI) was reduced into U(IV). Hence, according to the design of rational nanotraps for targeted radioactive nuclides, highly effective adsorbents for practical application (rare earth mining waste remediation) were successfully achieved.

Extracting uranium from seawater offers opportunities for sustainable nuclear fuel supply, but the task is quite challenging due to the low uranium concentration (∼3 ppb) in seawater. Here, based on the Knoevenagel condensation reaction of aldehyde and acetonitrile groups, a novel stable sp2carbon-linked three-dimensional covalent organic framework (3D COF), TFPM-PDAN-AO was prepared as a porous platform for uranium extraction from seawater. The TFPM-PDAN-AO designed with regular 3D pore channel of 7.12 Å provides a specific channel for uranyl diffusion, which exhibits high selectivity and fast kinetics for uranium adsorption. Meanwhile, the superior stability and optoelectronic properties enable it an excellent porous platform for uranium electroextraction. By applying alternating voltages between −5 and 0 V, uranyl ions can rapidly migrate and enrich into the porous structure of TFPM-PDAN-AO, then inducing the electrodeposition of uranium compounds to form the charge neutral species (Na2O(UO3H2O)x) with an unprecedentedly high adsorption capacity of 4,685 mg g−1. This work not only expands the application prospects of functionalized 3D COFs, but also provides a technical support for the electrodeposition adsorption of uranium from seawater.

Copper-beryllium (UNS C17200) has been shown to be a copper alloy with combined properties of flexibility, wear resistance, and high strength. In this research, a new machining method called high-frequency electrical discharge-assisted milling (HF-EDAM) based on copper-beryllium bundle electrodes was developed for Inconel 718. In particular, the machining results of HF-EDAM under different machining parameters were studied. Notably, the HF-EDAM experiments showed that the copper-beryllium bundle electrodes could not only soften the surface of the workpiece during EDM but also effectively clean the debris generated during the milling process of HF-EDAM. At the same time, due to the flexibility of the copper-beryllium bundle electrode, the surface to be machined could be matched in real-time with the electrode, thereby effectively improving the discharge efficiency. Additionally, compared with conventional milling (CM), HF-EDAM greatly reduced the cutting force, and the machined surface quality after HF-EDAM also effectively improved. Subsequently, the excellent machinability achievable with HF-EDAM based on copper-beryllium bundle electrodes was verified by a combination of experiments and theory in this research, demonstrating HF-EDAM as an effective method for high-quality and efficient machining of Inconel 718.

Robust and antibacterial dental resins are essential for repairing the shape and function of the teeth. However, an ingenious way to achieve a synergistic enhancement of these two properties is still lacking. In this work, guided by molecular dynamics (MD) calculations, a boron nitride nanosheet (BNN)/titanium dioxide (TiO2) nanocomposite system was synthesized and used to modify the dental flow resin to enhance its mechanical and antimicrobial properties. The mechanical and antimicrobial enhancement mechanisms were further explored. The modified resin demonstrated outstanding performance improvement with 88.23%, 58.47%, 82.01%, and 55.06% improvement in compressive strength (CS), microhardness (MH), flexural strength (FS), and elastic modulus (EM), respectively. Moreover, the modified resin could effectively inhibit the growth of Streptococcus mutans(S. mutans) regardless of aging in water and the inhibition rates were more than 90%. In conclusion, the modified resin is expected to be an ideal restorative material for clinical applications.

A major barrier for organizations to act sustainably is the lack of awareness of activities that can improve their sustainability performance while creating business value. To address this, we developed the Green CompassTMmethodology and tool, which helps manufacturers develop improvement plans based on their sustainability maturity level while considering cost and value creation. Manufacturers first assess their environmental sustainability performance across their operations, supply network, and product life cycles at the strategic, tactical, and operational levels. Based on the manufacturers’ costs and value creation goals, the tool helps them prioritize issues relevant to their businesses and guides them in charting their improvement plans. Experts from 13 organizations have reviewed the Green CompassTMmethodology, and 23 organizations, including 14 manufacturers, have used the tool. This paper describes the Green CompassTMmethodology, the findings from an application example, and the analysis of data collected from the manufacturers. We found that most manufacturers actively manage the energy, water, and material impacts from their operations but not their carbon emissions, supply network, and product life cycle impacts. Green CompassTMhas broadened the manufacturers’ understanding of environmental sustainability and developed their in-house capabilities to improve sustainability.

Background and Objective: Taohong Siwu Decoction (TSD) is a classic traditional Chinese medicine (TCM) compound with pharmacological effects such as vasodilation and hypolipidemia. Paeoniflorin (PF) is one of the active ingredients of TSD. The aim of this study was to evaluate the pharmacokinetics of PF in herbal extracts and their purified forms in rats. Method: A sensitive and rapid high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS-MS) method for the determination of PF in rat plasma was developed. Rats were divided into three groups, and given PF solution, water extract of white peony root (WPR), or TSD by gavage. At different predetermined timepoints after gavage, blood was collected from the orbital vein. The pharmacokinetic parameters of PF in the plasma of rats in the three groups was determined. Results: The pharmacokinetic studies showed that the time to reach maximum concentration (Tmax) of PF in the purified forms group was relatively high, while the half-lives (T½) of PF in the TSD and WPR groups were longer. Among the three groups, PF in the purified forms group had the maximum area under the concentration–time curve (AUC0-t= 732.997 µg/L·h) and the largest maximum concentration (Cmax= 313.460 µg/L), which showed a significant difference compared with the TSD group (P&lt; 0.05). Compared with the purified group, the clearance (CLz/F = 86.004 L/h/kg) and the apparent volume of distribution (Vz/F = 254.787 L/kg) of PF in the TSD group increased significantly (P&lt; 0.05). Conclusions: A highly specific, sensitive, and rapid HPLC–MS-MS method was developed and applied for the determination of PF in rat plasma. It was found that TSD and WPR can prolong the action time of paeoniflorin in the body.

The effect of the crystal orientations and precipitates on the corrosion behavior of Al-Cu-Li single crystals was studied by scanning electron microscopy, transmission electron microscopy, optical microscopy, immersion testing in exfoliation corrosion solution, and electrochemical testing. The results show that the corrosion rates of different orientations of the aged Al-Cu-Li alloy increase in the order of (001) < (101) < (111), which are different from those of the as-quenched alloy in the increasing order of (111) < (001) < (101). The precipitation of the T1phase deteriorated the corrosion resistance of the Al-Cu-Li alloy, and the degree of deterioration differed in different crystal plane orientations. The severe localized corrosion of the aged alloy propagates along the crystallography and extends along the {111}Alplane in the form of corrosion bands.

Two new alkaloids (1and 2), named 1,7-dimethoxy-2′-prenyl-1′,9-dihydropyrrolo-carbazole (1) and 1,7-dimethoxy-4′,5′-dimethylcyclopenta-carbazole-1′,3′-dione (2), along with thirteen known alkaloids (3–15) were isolated by means of silica gel, sephadex LH-20, and semi-preparative HPLC from the CHCl3extraction of Corydalis decumbensfor the first time. Their structures were determined by NMR, MS, IR, UV, and related references. Compounds (1–15) were evaluated for their antidepressant activities by measuring inhibition of monoamine neurotransmitter reuptake in vitro. Among them, compounds 1, 2, 4, and 6showed certain antidepressant activities.

Water-and-mud inrush disasters have become a major challenge in underground engineering for the construction of tunnels in sandstone and slate interbedded Presinian strata. Disaster prediction and prevention rely in part on realistic modeling and observation of the disaster process, as well as the identification and examination of the underlying mechanisms. Based on the geological conditions and the historical records of the Xinping Tunnel on the China—Laos Railway, an engineering geological model of the water-and-mud inrush was established. A physical model test that accurately reproduced water-and-mud inrush during tunnel excavation in sandstone and slate interbedded strata was also carried out. Then, testing was conducted that examined the stress and strain, seepage pressure, and high-leakage flow of the surrounding rock. The results indicated that the water-and-mud inrush proceeded through three stages: seepage stage, high-leakage flow stage, and attenuation stage. In essence, the disaster was a catastrophic process, during which the water-resistant stratum was reduced to a critical safety thickness, a water-inrush channel formed, and the water-resistant stratum gradually failed under the influence of excavation unloading and in situ stress—seepage coupling. Parameters such as the stress and strain, seepage pressure, and flow of the surrounding rock had evident stage-related features during water-and-mud inrush, and their variation indicated the formation, development, and evolution of the disaster. As the tunnel face advanced, the trend of the stress—strain curve of the surrounding rock shifted from sluggish to rapid in its speed of increase. The characteristics of strain energy density revealed the erosion and weakening effect of groundwater on the surrounding rock. The seepage pressure and the thickness of the water-resistant stratum had a positive linear relationship, and the flow and thickness a negative linear relationship. There was a pivotal point at which the seepage pressure changed from high to low and the flow shifted from low to high. The thickness of the water-resistant stratum corresponding to the pivotal point was deemed the critical safety thickness.

Kelp (Laminaria japonica) is rich in resources and a variety of active substances. However, its fishy flavor, which is hard to remove, poses challenges to consumer preferences. This study investigated the removal of fishy odor from Saccharomyces cerevisiaeSK1.008 fermented kelp and kelp treated with fermentation combined natural antioxidant soaking through gas chromatography-mass spectrometry (GC-MS), odor activity values (OAVs) and gas chromatography-ion mobility spectrometry (GC-IMS). A total of 79 and 72 substances were identified in kelp using GC-MS and GC-IMS analysis, respectively. There were 16 volatile compounds (VOCs) with OAV>1 which were identified as key contributors to fishy odor, including (E,Z)-2,6-nonadienal, 1-octen-3-one, (E,E)-2,4-octadienal, (E,E)-2,4-decadienal and (E)-2-nonenal et al. The GC-MS analysis revealed that the removal efficiency of unsaturated aldehydes and ketones was 73.3% in kelp treated by fermentation combined soaking. The hierarchical cluster analysis and principal component analysis (PCA) constructed by GC-IMS revealed that the blank kelp, fermented kelp and kelp treated with fermentation combined soaking can be distinguished by volatile compounds. This study provides a reference for establishing a long-term effective deodorization method.

The WE43 magnesium alloy was prepared by squeeze casting, and the influence of squeeze casting parameters on mechanical properties and corrosion resistance was studied and compared with gravity casting. The gravity cast WE43 alloy shows uneven grain size distribution, and some grains even greater than 90 µm. While, the grain size of the squeeze cast WE43 alloy is mainly distributed in 20–50 µm. The Mg12Nd2Y phase morphology changes from large lamellar to strips after squeeze casting, whereas Mg24Y5phase exhibits no obvious change. The yield strength, tensile strength, and elongation of the gravity cast WE43 alloy are 127 MPa, 157 MPa, and 6%, respectively, and 145 MPa, 193 MPa, and 9.1% for squeeze cast alloy. For the squeeze cast WE43 alloy, the average corrosion rate is 0.6056 mm·year−1according to immersion test results, and according to electrochemical measurements, the corrosion current density is 78.13 µA·cm−2, which is better than that of the gravity cast WE43 alloy. Compared with gravity casting, the grains and second phase of the WE43 alloy by squeeze casting are refined, and the mechanical properties and corrosion resistance are improved. This may expand the applications of the WE43 alloy.

The aim is to establish a model of nonalcoholic fatty liver disease (NAFLD) caused by feeding with high-fat, high-fructose, and high-cholesterol diet (HFFCD) in golden hamsters, and to investigate the characteristics of the NAFLD model and metabolite changes of liver tissue. Golden hamsters were fed HFFCD or control diets for six weeks. Body weight, abdominal fat index, and liver index was assessed, serum parameters, hepatic histology, and liver metabolites were examined. The results showed that body weight, abdominal fat, and liver index of hamsters were significantly increased in the model group, the level of serum total cholesterol (TC), triglyceride (TG), and low density lipoprotein-cholesterol (LDL-C) were significantly increased in model group as well, and high density lipoprotein-cholesterol (HDL-C) was significantly decreased. In addition, lipid deposition in liver tissue formed fat vacuoles of different sizes. Metabonomics analysis of the liver showed that the metabolic pathways of sphingolipid, glycerophospholipids, and arginine biosynthesis were disordered in the NAFLD model. The modeling method is simple, short time, and uniform. It can simulate the early fatty liver caused by common dietary factors, and provides an ideal model for the study of the initial pathogenesis and therapeutic drugs for NAFLD.

Accurate magnetic field measurement is the key to evaluating the second-order Zeeman effect. The conventional method is to deduce the magnetic field by determining the center frequency of the magnetic-field-sensitive Ramsey fringes. In this Letter, we present a more rigorous theory for this method and demonstrate that the current peak-searching method has a non-negligible sub-Hz or even larger deviation. We introduce an improved method that considers more parameters and a strict formula that can correct the deviation and suppress it to below 0.1 Hz. Corresponding experiments on the ^85Rb atomic fountain demonstrate that this improved method is expected to enhance the precision of magnetic field measurement and improve the atomic fountain clock.

ABSTRACTCisplatin (DDP) therapy is widely used for the treatment of non-small cell lung cancer (NSCLC), but the curative effect is limited by chemoresistance. This study was designed to explore circ_0020123 function in DDP resistance of NSCLCDDP. Expression detection for circ_0020123, microRNA-140-3p (miR-140-3p) and homeobox B5 (HOXB5) was performed by real-time polymerase chain reaction (qRT-PCR). Half inhibitory concentration (IC50) of DDP and cell proliferation was detected by Cell Counting Kit-8 (CCK-8) assay. Colony formation ability was assessed using colony formation assay. Cell migration and invasion were evaluated via transwell assay. Cell apoptosis was examined by flow cytometry. Protein analysis was conducted by Western blot. Dual-luciferase reporter assay was used to affirm target interaction. Circ_0020123 expression was upregulated in DDP-resistant NSCLC cells. DDP resistance was reduced by downregulation of circ_0020123 in NSCLC cells. Circ_0020123 was identified as a miR-140-3p sponge. The effect of si-circ_0020123 on DDP resistance was partly associated with miR-140-3p upregulation. HOXB5 was a downstream target for miR-140-3p. Overexpression of HOXB5 mitigated miR-140-3p-induced inhibition of DDP resistance in NSCLC cells. Circ_0020123 upregulated the level of HOXB5 partly via sponging miR-140-3p. Also, circ_0020123 promoted tumor growth in NSCLC/DDP xenografts by regulating miR-140-3p and HOXB5 levels at least in part. These results revealed that circ_0020123 promoted DDP resistance in NSCLC cells partly by targeting miR-140-3p/HOXB5 axis, indicating that circ_0020123 might be used as a molecular target in DDP treatment for NSCLC.

Coordination complexes with aggregation-induced-emission (AIE) behavior has drawn much attention because of their promising applications. Conventionally, the AIE-active metal–organic complexes are prepared from an AIE-active organic ligand, and the construction of such coordination complexes from aggregation-caused-quenching (ACQ) ligands is still challenging. Herein, we have synthesized two new cyclic trinuclear complexes (CTCs), namely, 1and 2, from copper(I) and silver(I) and a ACQ ligand [4-(3,5-dimethyl-1H-pyrazol-4-yl)benzaldehyde, HL]. (1) exhibited AIE behavior, and the emission intensity is enhanced ∼20 times when it aggregates, which can be attributed to its tight packing and multiple intermolecular hydrogen bonds that restrained the intramolecular rotation, as confirmed by single-crystal X-ray diffraction analysis. On the other hand, (2) displayed ACQ effects, and the emission intensity is decreased ∼5 times when it aggregates. This ACQ behavior of 2is related to its loose packing and free rotation of the ligand in crystals, resulting in nonradiative decay and fluorescence quenching. Interestingly, the CTCs 1and 2both exhibited a good affinity to gold(III) ions, allowing selective detection and sensing of gold ions. More importantly, the 2shows a good limit of detection (3.28 μmol/L) and an ultrafast responsive time (∼2 s). Our studies pave a new route to designing novel AIE-active coordination complexes and further exploring the functionality of CTCs.

Electrochemiluminescence (ECL), as an advanced sensing process, can selectively control the generation of excited states by changing the potential. However, most of the existing ECL systems rely on poisonous coreactants to provide radicals for luminescence; although the ECL efficiency was improved, the athematic coreactants will cause unpredictable interference to the accurate analysis of trace targets. Herein, we realized the ECL of nonemitting molecules by performing intramolecular electron transfer in the olefin-linked covalent organic frameworks (COFs), with a high efficiency of 63.7%. Employing internal dissolved oxygen as the coreactant, it is well suitable for the analysis of various complex samples in the environment. Taking nuclear contamination analysis as the goal orientation, we further illustrated a design of a “turn-on” uranyl ion monitoring system integrating fast response, low detection limit, and high selectivity, showing that new ECL-COFs are promising to facilitate environment-related sensing analysis and structure-feature correlation mechanism exploration.

Flavonolignans, for example, silymarin and silybin, have interesting biological activities. For the first time, three new flavonolignans named oenanthenoid A-C (1–3) and nine known flavonolignan derivatives (4–12) were isolated from Oenanthe javanica. Comprehensive spectroscopic data analysis and references were used to identify all of the compounds. The anti inflammatory activities of these isolates (1–12) on RAW264.7 macrophage cells were investigated. Three new compounds (1–3) demonstrated anti inflammatory activity with IC50values ranging from 6.5 ± 0.6 to 14.7 ± 1.6 µM. Furthermore, two compounds (11and 12) demonstrated moderate anti inflammatory activity, with IC50values ranging from 24.1 ± 1.2 to 62.5 ± 1.9 µM.

To investigate the capability of π–π stacking motifs to enable spin–spin coupling, we designed and synthesized three pairs of regio-isomers featuring two radical moieties joined by a [2.2]paracyclophane (CP) unit. By fusing indeno units to CP, two partially stacked fluorene radicals are covalently linked, exhibiting evident antiferromagnetic (AFM) coupling regardless of the orientation of two spins. Remarkably, while possessing high diradical indices of 0.8 and 0.9, the two molecules demonstrate good air stability by virtue of their singlet ground state. Single crystals help unravel the structural basis of their AFM coupling behaviors. When two radical centers are arranged at the pseudometa-positions around CP, the face-to-face stacked phenylene rings intrinsically confer orbital interactions that promote AFM coupling. On the other hand, if two radicals are directed in the pseudopara-orientation, significant orbital overlapping is observed between the radical centers (i.e., C9 of fluorene) and the aromatic carbons laid on the side, rendering AFM coupling between the two spins. In contrast, when two fluorene radicals are tethered to CP via C9 through a single C–C bond, ferromagnetic (FM) coupling is manifested by both diradical isomers featuring pseudometa- and pseudopara-connectivity. With minimal spin distributed on CP and thus limited contribution from π–π stacking, their spin–spin coupling properties are more similar to a pair of nitroxide diradical analogues, in which the two spins are dominantly coupled via through-space interactions. From these results, important conclusions are elucidated such as that although through-space interactions may confer FM coupling, with weakened strength shown by PAH radicals due to their lower polarity, face-to-face stacked π-frameworks tend to induce AFM coupling, because favorable orbital interactions are readily achieved by PAH systems hosting delocalized spins that are capable of adopting varied stacking motifs.

Polymorphism is known to show a significant effect on the crystal packing structures and physical properties of molecular complexes. On the basis of our previous works on the spin-crossover (SCO) complex [Fe(tpa)(NCS)2] (tpa = tris(2-pyridylmethyl)amine), we have prepared the analogous complex [Fe(tpa)(NCSe)2] using a NCSe–coligand and obtained a series of crystalline polymorphs, namely SeI–SeIV, respectively, by controlled synthetic processes. Single-crystal X-ray diffraction studies reveal that these polymorphs show different packing modes and different intermolecular interactions. Various SCO behaviors are thus observed. Moreover, an obvious coligand effect on SCO behaviors is found by a comparison of the present study and the reported complex [Fe(tpa)(NCS)2]. The NCSe–complexes show a critical shift of T1/2values to a higher temperature range and a more gradual transition process in comparison to those for the isostructural complexes using NCS–, indicating a stronger ligand-field strength and a weaker cooperativity for the NCSe–coligand.