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BACKGROUND: Renal cold ischemia-reperfusion injury (CIRI), a pathological process during kidney transplantation, may result in delayed graft function and negatively impact graft survival and function. There is a lack of an accurate and non-invasive tool for evaluating the degree of CIRI. Multi-parametric MRI has been widely used to detect and evaluate kidney injury. The machine learning algorithms introduced the opportunity to combine biomarkers from different MRI metrics into a single classifier. OBJECTIVE: To evaluate the performance of multi-parametric magnetic resonance imaging for grading renal injury in a rat model of renal cold ischemia-reperfusion injury using a machine learning approach. METHODS: Eighty male SD rats were selected to establish a renal cold ischemia -reperfusion model, and all performed multiparametric MRI scans (DWI, IVIM, DKI, BOLD, T1mapping and ASL), followed by pathological analysis. A total of 25 parameters of renal cortex and medulla were analyzed as features. The pathology scores were divided into 3 groups using K-means clustering method. Lasso regression was applied for the initial selecting of features. The optimal features and the best techniques for pathological grading were obtained. Multiple classifiers were used to construct models to evaluate the predictive value for pathology grading. RESULTS: All rats were categorized into mild, moderate, and severe injury group according the pathologic scores. The 8 features that correlated better with the pathologic classification were medullary and cortical Dp, cortical T2*, cortical Fp, medullary T2*, ∆T1, cortical RBF, medullary T1. The accuracy(0.83, 0.850, 0.81, respectively) and AUC (0.95, 0.93, 0.90, respectively) for pathologic classification of the logistic regression, SVM, and RF are significantly higher than other classifiers. For the logistic model and combining logistic, RF and SVM model of different techniques for pathology grading, the stable and perform are both well. Based on logistic regression, IVIM has the highest AUC (0.93) for pathological grading, followed by BOLD(0.90). CONCLUSION: The multi-parametric MRI-based machine learning model could be valuable for noninvasive assessment of the degree of renal injury.
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Modelos Animales de Enfermedad , Aprendizaje Automático , Ratas Sprague-Dawley , Daño por Reperfusión , Animales , Masculino , Daño por Reperfusión/diagnóstico por imagen , Daño por Reperfusión/patología , Ratas , Riñón/diagnóstico por imagen , Riñón/patología , Riñón/irrigación sanguínea , Imágenes de Resonancia Magnética Multiparamétrica/métodos , Imagen por Resonancia Magnética/métodosRESUMEN
Expanding the detection information of wearable smart devices in applications has practical implications for their use in daily life and healthcare. Damage and breakage caused by mechanical injuries and continuous use are unavoidable for polymer matrices so self-healing properties are expected to be conferred on flexible sensors to extend their life and durability. In addition, a good linearity of relative resistance change vs. strain (gauge factor, GF) facilitates the streamlined conversion of electrical signals to 3D information of human motion, whereas existing works on sensors neglect the quantitative analysis of signals. This letter reports a self-healable flexible electronic sensor based on hydrogen bonding and electrostatic interaction between maleic acid-grafted natural rubber (MNR), polyaniline (PANI), and phytic acid (PA). MNR is the flexible matrix and the template for aniline (ANI) polymerization, and PA acts as the dopant and crosslinking agent. The MNR-PANI-PA sensor shows easy self-healing at room temperature, enhanced mechanical behaviour (â¼2.5 MPa, 1000% strain), and excellent linearity (GF of 13.8 over 250% strain and GF of 32.0 over 250-100% strain). Due to the highly linear relationship between ΔR/R and bending angle, the electrical signals of human limb movement can output relevant information on bending angle and frequency. By constructing a sensing array, changes in the position and magnitude of applied pressure could also be detected in real-time. Based on these advantages, the MNR-PANI-PA composite sensor is expected to have potential applications in health monitoring, body motion detection, and electronic skins.
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Compuestos de Anilina , Elastómeros , Movimiento , Dispositivos Electrónicos Vestibles , Humanos , Elastómeros/química , Movimiento/fisiología , Conductividad Eléctrica , Presión , Ácido Fítico/química , Goma/química , Maleatos/químicaRESUMEN
Purpose: Cold ischemia-reperfusion injury (CIRI) is one of the most serious complications following renal transplantation. The current study investigated the feasibility of Intravoxel Incoherent Motion (IVIM) imaging and blood oxygenation level-dependent (BOLD) in the evaluation of different degrees of renal cold ischemia-reperfusion injury in a rat model. Methods: Seventy five rats were randomly divided into three groups (N = 25 for each group): T0: sham-operated group, T2/T4: CIRI groups with different cold ischemia hours (2, 4 h, respectively). The rat model of CIRI group was established by left kidney cold ischemia with right nephrectomy. All the rats received a baseline MRI before the surgery. Five rats in each group were randomly selected to undergo an MRI examination at 1 h, day 1, day 2 and day 5 after CIRI. The IVIM and BOLD parameters were studied in the renal cortex (CO), the outer stripe of the outer medulla (OSOM), and the inner stripe of the outer medulla (ISOM) followed by histological analysis to examine Paller scores, peritubular capillary (PTC) density, apoptosis rate and biochemical indicators to obtain the contents of serum creatinine (Scr), blood urea nitrogen (BUN), superoxide dismutase (SOD) and malondialdehyde (MDA). Results: The D, D*, PF and T2* values in the CIRI groups were lower than those in the sham-operated group at all timepoints (all p < 0.05). The prolonged cold ischemia times resulted in gradually lower D, D*, PF and T2* values (all p < 0.05). The D and T2* values of cortex and OSOM in Group T0 and T2 returned to the baseline level (all p > 0.05) except Group T4. The D* and PF values of cortex, OSOM and ISOM in Group T2 and T4 still remained below the normal levels (all p < 0.05) except Group T0. D, D*, PF and T2* values were strongly correlated with histopathological (Paller scores, PTC density and apoptosis rate) and the biochemistry indicators (SOD and MDA) (|r|>0.6, p < 0.001). D*, PF and T2* values were moderately to poorly correlated with some biochemistry indicators (Scr and BUN) (|r|<0.5, p < 0.05). Conclusion: IVIM and BOLD can serve as noninvasive radiologic markers for monitoring different degrees of renal impairment and recovery after renal CIRI.
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Availability of light and CO2, substrates of microalgae photosynthesis, is frequently far from optimal. Microalgae activate photoprotection under strong light, to prevent oxidative damage, and the CO2 Concentrating Mechanism (CCM) under low CO2, to raise intracellular CO2 levels. The two processes are interconnected; yet, the underlying transcriptional regulators remain largely unknown. Employing a large transcriptomic data compendium of Chlamydomonas reinhardtii's responses to different light and carbon supply, we reconstruct a consensus genome-scale gene regulatory network from complementary inference approaches and use it to elucidate transcriptional regulators of photoprotection. We show that the CCM regulator LCR1 also controls photoprotection, and that QER7, a Squamosa Binding Protein, suppresses photoprotection- and CCM-gene expression under the control of the blue light photoreceptor Phototropin. By demonstrating the existence of regulatory hubs that channel light- and CO2-mediated signals into a common response, our study provides an accessible resource to dissect gene expression regulation in this microalga.
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Chlamydomonas reinhardtii , Chlamydomonas , Chlamydomonas reinhardtii/metabolismo , Dióxido de Carbono/metabolismo , Fotosíntesis/genética , Regulación de la Expresión Génica , Chlamydomonas/metabolismo , Carbono/metabolismoRESUMEN
Photosynthetic algae have evolved mechanisms to cope with suboptimal light and CO2 conditions. When light energy exceeds CO2 fixation capacity, Chlamydomonas reinhardtii activates photoprotection, mediated by LHCSR1/3 and PSBS, and the CO2 Concentrating Mechanism (CCM). How light and CO2 signals converge to regulate these processes remains unclear. Here, we show that excess light activates photoprotection- and CCM-related genes by altering intracellular CO2 concentrations and that depletion of CO2 drives these responses, even in total darkness. High CO2 levels, derived from respiration or impaired photosynthetic fixation, repress LHCSR3/CCM genes while stabilizing the LHCSR1 protein. Finally, we show that the CCM regulator CIA5 also regulates photoprotection, controlling LHCSR3 and PSBS transcript accumulation while inhibiting LHCSR1 protein accumulation. This work has allowed us to dissect the effect of CO2 and light on CCM and photoprotection, demonstrating that light often indirectly affects these processes by impacting intracellular CO2 levels.
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Dióxido de Carbono , Chlamydomonas reinhardtii , Dióxido de Carbono/metabolismo , Complejo de Proteína del Fotosistema II/metabolismo , Fotosíntesis/genética , Proteínas/metabolismo , Chlamydomonas reinhardtii/metabolismoRESUMEN
In nature, photosynthetic organisms are exposed to different light spectra and intensities depending on the time of day and atmospheric and environmental conditions. When photosynthetic cells absorb excess light, they induce nonphotochemical quenching to avoid photodamage and trigger expression of "photoprotective" genes. In this work, we used the green alga Chlamydomonas reinhardtii to assess the impact of light intensity, light quality, photosynthetic electron transport, and carbon dioxide on induction of the photoprotective genes (LHCSR1, LHCSR3, and PSBS) during dark-to-light transitions. Induction (mRNA accumulation) occurred at very low light intensity and was independently modulated by blue and ultraviolet B radiation through specific photoreceptors; only LHCSR3 was strongly controlled by carbon dioxide levels through a putative enhancer function of CIA5, a transcription factor that controls genes of the carbon concentrating mechanism. We propose a model that integrates inputs of independent signaling pathways and how they may help the cells anticipate diel conditions and survive in a dynamic light environment.
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Multiple theoretical investigations on three new series of donor-bridge-acceptor substituted compounds are employed to aid in the design of NLO-phores with high first-hyperpolarizability ß. The effect of varying the acceptor (rhodanine, thiohydantoin and thiobarbituric acid derivative-based) and bridge parts of these D-π-A systems was analyzed in terms of geometric and optoelectronic parameters such as bond length alternation, ground state dipole moments, HOMO and LUMO energies, UV-vis absorption spectra, transition dipole moments, and electronic absorption energies. Various functionals with the AUG-cc-pVDZ basis set including B3LYP, PBE38, and ωB97XD, and the Hartree-Fock method were employed to calculate ß values, and the solvent effect was also considered by employing the SMD model. The variation of first-hyperpolarizabilities has been explained satisfactorily in terms of the PBE38/AUG-cc-pVDZ level calculated spectroscopic properties in the light of the sum-over-states method and the two-level model. The comprehensive study indicates that the most worthwhile targets for development as NLO-phores are compounds that include a longer π-bridge.
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Microalgae are potential candidate for biofuel production as alternative one for fossil fuels. CO2 in flue gas is available carbon source to support microalgae growth. In this study, the effects of different concentrations of the simulated flue gas onto algal growth and photosynthetic activity were evaluated for both Chlorella sp. AE10 and Chlorella sp. Cv. The growth profiles were correlated by a simple kinetic model. It was indicated that the simulated flue gas led to low pH and the photosynthetic activity was partially destroyed. Chlorella sp. Cv can tolerate full simulated flue gas, 10% CO2 + 200 ppm NOx + 100 ppm SOx . The pH in medium maintained at 6 and the photosynthetic activity was more than 0.6 at the first 6 days. If the concentration of NOx was more 100 ppm and that of SOx was more than 50 ppm, the pH was declined to 4 at day 2 or 3 for Chlorella sp. AE10. At the same time, the related photosynthetic activities of Chlorella sp. AE10 were less than 0.4, which was not suitable for algal growth. It was shown that Chlorella sp. Cv could be used for CO2 fixation from the simulated flue gas.
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Dióxido de Carbono/metabolismo , Chlorella/crecimiento & desarrollo , Concentración de Iones de Hidrógeno , Cinética , Modelos Biológicos , Óxidos de Nitrógeno/metabolismo , FotosíntesisRESUMEN
Microalgae are feedstocks for multiple product development based on algal biorefinery concept. The effects of light quality (white, red and blue light emitting diodes) and macro-element starvations on Chlorella sp. AE10 were investigated under 20% CO2 and 850⯵molâ¯m-2â¯d-1. Nitrogen and phosphorus starvations had negative effects on its growth rate. The biomass productivities were decreased from day 1 and the highest one was 1.90â¯gâ¯L-1â¯d-1 under white light conditions. Phosphorus starvation promoted carbohydrate accumulation under three LED light sources conditions and the highest carbohydrate content was 75.9% using red light. Blue light increased lutein content to 9.58â¯mgâ¯g-1. The content of saturated fatty acids was significantly increased from 37.51% under blue light and full culture medium conditions to 77.44% under blue light and nitrogen starvation conditions. Chlorella sp. AE10 was a good candidate for carbohydrate and lutein productions.
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Carbohidratos/biosíntesis , Chlorella/metabolismo , Ácidos Grasos/biosíntesis , Luteína/biosíntesis , Biomasa , Chlorella/crecimiento & desarrollo , Ácidos Grasos/análisis , Luz , Nitrógeno/metabolismo , Fósforo/metabolismoRESUMEN
It is important to study the effect of Fe(III) on the positive electrolyte, in order to provide some practical guidance for the preparation and use of vanadium electrolyte. The effect of Fe(III) on the thermal stability and electrochemical behaviour of the positive electrolyte for the vanadium redox flow battery (VRFB) was investigated. When the Fe(III) concentration was above 0.0196 mol l-1, the thermal stability of V(V) electrolyte was impaired, the diffusion coefficient of V(IV) species decreased from (2.06-3.33) × 10-6 cm2 s-1 to (1.78-2.88) × 10-6 cm2 s-1, and the positive electrolyte exhibited a higher electrolyte resistance and a charge transfer resistance. Furthermore, Fe(III) could result in the side reaction and capacity fading, which would have a detrimental effect on battery application. With the increase of Fe(III), the collision probability of vanadium ions with Fe(III) and the competition with the redox reaction was aggravated, which would interfere with the electrode reaction, the diffusion of vanadium ions and the performance of VRFB. Therefore, this study provides some practical guidance that it is best to bring the impurity of Fe(III) below 0.0196 mol l-1 during the preparation and use of vanadium electrolyte.
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Carbon dioxide and other greenhouse gas emissions leads to global warming. Biological capture through microalgae is a potential approach for solving this environmental problem. It is still a technical challenge to enhance the tolerance of microalgae to flue gas if CO2 is fixed from flue gas directly. A new strain, Chlorella sp. Cv was obtained through adaptive evolution (46â¯cycles) against simulated flue gas (10% CO2, 200â¯ppm NOx and 100â¯ppm SOx). It was confirmed that Chlorella sp. Cv could tolerate simulated flue gas conditions and the maximum CO2 fixation rate was 1.2â¯gâ¯L-1â¯d-1. In a two-stage process, the biomass concentration was 2.7â¯gâ¯L-1 and the carbohydrate content was 68.4%. Comparative transcriptomic analysis was performed for Chlorella sp. Cv under simulated flue gas and control conditions (10% CO2). These responses against simulated flue gas uncovered the significant difference between the evolved strain and the original strain. The metabolic responses to flue gas were explored with focus on various specific genes. Upregulation of several genes related to photosynthesis, oxidative phosphorylation, CO2 fixation, sulfur metabolism and nitrogen metabolism was beneficial for the evolved strain to tolerate the simulated flue gas. The upregulation of genes related to extracellular sulfur transport and nitrate reductase was essential to utilize the sulfate and nitrate from dissolved SOx and NOx. The results in this study are helpful to establish a new process for CO2 capture directly from industrial flue gas.
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Evolución Biológica , Dióxido de Carbono/fisiología , Chlorella/fisiología , Calentamiento Global , Adaptación Biológica , Microalgas/fisiologíaRESUMEN
The external molecular environment like the aggregation of molecules can significantly change the intrinsic third-order nonlinear optical (NLO) property of π-conjugated chromophores. A combined experimental and theoretical study was performed to understand the influence of the aggregation of cyanines on the third-order NLO property in spin-coated thin films. Our result indicates that the H and J type cyanine dimers prefer the polyene-like structures and the P type dimer displays a comparatively smaller bond length alternation (BLA). The polarizable continuum model (PCM)-tuned, range-separated (RSE) density functional approach was used to describe the screening effect of the cyanine aggregation. In the thin film, the P aggregate has very small positive isotropic averaged second hyperpolarizability γ, while the J aggregate has the largest positive γ due to the most polarized face-to-tail cyanine-cyanine interaction. Hence, the γ of the isolated cyanines (negative γ) may get cancelled against that of the cyanine aggregates (positive γ) in the thin film. The forward degenerate four-wave mixing technique also confirms a decrease in the magnitude of γ with an increase in the aggregation degree of cyanines. Since the large positive γ of the cyanine also implies strong two-photon absorption (TPA), the J aggregation of cyanines can be used as a potential fabrication method for applications involving TPA.
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A coarse-grained model-based molecular dynamics simulation was employed to investigate the mechanical properties of NR-graft-rigid-polymer/rigid-polymer systems (N30-g-(R3)6/R10). An external factor (the strain rate) as well as internal factors such as the nonbonding interaction strength, the proportion of rigid polymers, and architecture parameters (the length and number of graft chains in a molecule) were examined for their effect on the tensional behavior of N30-g-(R3)6/R10 systems. Simulation results show that a higher strain rate can promote the enhancement of mechanical performance, such as a higher modulus or yield stress. Moreover, the stress and modulus increase with an increase of the nonbonding interaction strength within rigid polymers or of the rigid polymer proportion in the systems. However, the increasing stress was found to reach a limit with a continuously increasing rigid polymer proportion. On increasing the number of graft chains in a molecule, the stress increases at small strains. However, at large strains, the evident increase in stress was found in systems in which a graft molecule has longer graft chains. In addition, our research shows that N30-g-(R3)6/R10 blends exhibit improved mechanical properties and better compatibilities relative to N30/R10, which is consistent with the experimental results. Lastly, comparisons with experimental observations were also made to ensure the rationality of the simulation results. Overall, bond stretching, bond orientation, and nonbonding interactions were found to be crucial in governing the mechanical properties of the N30-g-(R3)6/R10 systems. These findings may provide important information for further experimental and simulation studies of NR hybrid materials.
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Current antigen-encapsulated multifunctional nanovaccines for oncotherapy suffer from limited antigen loading efficiency, low yield, tedious manufacture, and systemic toxicity. Here, an antigen-directed strategy for the fabrication of multifunctional nanovaccine with ultrahigh antigen loading efficiency in a facile way for tumor photothermal-immunotherapy is shown. As a proof of concept, a model antigen ovalbumin (OVA) is used as a natural carrier to load a representative theranostic agent indocyanine green (ICG). Mixing OVA and ICG in aqueous solution gives the simplest multifunctional nanovaccine so far. The nanovaccine owns antigen loading efficiency of 80.8%, high yield of >90%, intense near-infrared absorption and fluorescence, excellent reproducibility, good aqueous solubility and stability, and favorable biocompatibility. These merits not only guarantee sensitive labeling/tracking and efficient stimulation of dendritic cells, but also reliable imaging-guided photothermal-immunotherapy of tumors and tumor prevention. The proposed strategy provides a facile and robust method for large-scale and reproducible fabrication of multifunctional nanovaccines with ultrahigh antigen loading efficiency for tumor therapy.
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Vacunas contra el Cáncer/química , Antígenos , Humanos , Inmunoterapia , Verde de Indocianina , Neoplasias , Reproducibilidad de los Resultados , Nanomedicina TeranósticaRESUMEN
Enhancement of stress tolerance to high concentration of salt and CO2 is beneficial for CO2 capture by microalgae. Adaptive evolution was performed for improving the tolerance of a freshwater strain, Chlorella sp. AE10, to 30â¯g/L salt. A resulting strain denoted as Chlorella sp. S30 was obtained after 46 cycles (138â¯days). The stress tolerance mechanism was analyzed by comparative transcriptomic analysis. Although the evolved strain could tolerate 30â¯g/L salt, high salinity caused loss to photosynthesis, oxidative phosphorylation, fatty acid biosynthesis and tyrosine metabolism. The related genes of antioxidant enzymes, CO2 fixation, amino acid biosynthesis, central carbon metabolism and ABC transporter proteins were up-regulated. Besides the up-regulation of several genes in Calvin-Benson cycle, they were also identified in C4 photosynthetic pathway and crassulacean acid metabolism pathway. They were essential for the survival and CO2 fixation of Chlorella sp. S30 under 30â¯g/L salt and 10% CO2.
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Chlorella , Fotosíntesis , Cloruro de Sodio , Dióxido de Carbono , Agua Dulce , MicroalgasRESUMEN
Accumulated carbohydrate in microalgae is promising feedstock for bioethanol fermentation. Selection of suitable cultivation conditions in semi-continuous cultivation is critical to achieve a high carbohydrate productivity. In the current study, the effects of macro-nutrient (nitrogen, phosphorus, and sulfur) limitations and light intensity were evaluated for the carbohydrate accumulations of Chlorella sp. AE10 under 10% CO2 conditions. It was shown that nitrogen limitation and high light intensity were effective for improving carbohydrate productivity. The average carbohydrate and biomass productivity in semi-continuous cultivation with 1/4 N medium and 1000 µmol photons m-2 s-1 was 0.673 and 0.93 g L-1 day-1, respectively. Sulfur and phosphorus limitations could improve the carbohydrate content but they could not enhance the carbohydrate productivity. The cell cycle progression and chlorophyll a were investigated using flow cytometry (FCM). The results showed that macro-nutrient limitation and high light intensity indeed influenced cell cycle progression and led to the formation of polyploid cells along with the carbohydrate accumulation in a certain range. FCM was rapid and accurate method to investigate the operation conditions why 1/4 N, 2 days as a cycle, and high light intensity were optimal ones. In addition, the remaining high level of photosynthesis activity was also important for achieving a high carbohydrate productivity. Dynamic tracking of carbohydrate accumulation is helpful for establishment of a semi-continuous cultivation for enhancing carbohydrate productivity in microalgae.
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Biomasa , Metabolismo de los Hidratos de Carbono , Ciclo Celular , Chlorella/crecimiento & desarrollo , Clorofila/metabolismo , Citometría de Flujo/métodosRESUMEN
BACKGROUND: Microalgae are highly efficient cellular factories that capture CO2 and are also alternative feedstock for biofuel production. Carbohydrates, proteins, and lipids are major biochemical components in microalgae. Carbohydrates or starch in microalgae are possible substrates in yeast fermentation for biofuel production. The carbon partitioning in microalgae could be regulated through environmental stresses, such as high concentration of CO2, high light intensity, and nitrogen starvation conditions. It is essential to obtain carbohydrate-rich microalgae via an optimal bioprocess strategy. RESULTS: The carbohydrate accumulation in a CO2 tolerance strain, Chlorella sp. AE10, was investigated with a two-stage process. The CO2 concentration, light intensity, and initial nitrogen concentration were changed drastically in both stages. During the first stage, it was cultivated over 3 days under 1% CO2, a photon flux of 100 µmol m-2 s-1, and 1.5 g L-1 NaNO3. It was cultivated under 10% CO2, 1000 µmol m-2 s-1, and 0.375 g L-1 NaNO3 during the second stage. In addition, two operation modes were compared. At the beginning of the second stage of mode 2, cells were diluted to 0.1 g L-1 and there was no cell dilution in mode 1. The total carbohydrate productivity of mode 2 was increased about 42% compared with that of mode 1. The highest total carbohydrate content and the highest starch content of mode 2 were 77.6% (DW) and 60.3% (DW) at day 5, respectively. The starch productivity was 0.311 g L-1 day-1 and the total carbohydrate productivity was 0.421 g L-1 day-1 in 6 days. CONCLUSIONS: In this study, a novel two-stage process was proposed for improving carbohydrate and starch accumulation in Chlorella sp. AE10. Despite cell dilution at the beginning of the second stage, environmental stress conditions of high concentration of CO2, high light intensity, and limited nitrogen concentration at the second stage were critical for carbohydrate and starch accumulation. Although the cells were diluted, the growths were not inhibited and the carbohydrate productivity was improved. These results were helpful to establish an integrated approach from CO2 capture to biofuel production by microalgae.
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DFT method can severely overestimate the response properties for π-conjugation systems. The range-separated exchange and recently developed optimal IP-tuning process are evaluated on the prediction of static second hyperpolarizabilities of streptocyanines of increasing molecular length. The finite field results have shown that the exact exchange at midium and long distance can relieve only a part of the overshooting but still beyond satisfaction. The exact exchange at short distance has the oppsite effects showing the failure of converntional hGGA. The optimal tuned range-separated exchange functionals show little improvements performing worse than the default ones. Importantly, the electronic structure-property relationship, bond order alternation-γ, is not well established with DFT method. © 2017 Wiley Periodicals, Inc.
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One of the major challenges in anion recognition is to design hosts that can be used to distinguish between anions of different shapes. Urea-based molecules are widely used in anion recognition because the pair of -NH groups acts as an electron acceptor. Although these hosts can bind to both spherical anions (halides) and Y-shaped anions (oxoanions), experimental evidence to date does not provide a clear picture of what differences in the nature of the hydrogen bonding interactions could be used to distinguish between anions of different shapes. Here, we use several computational topology analyses to study the non-covalent interactions between Cr(CO)3-based organometallic urea-like hosts and halides and Y-shaped oxoanions. Our results suggest that the F(-) and AcO(-) anions are recognized experimentally due to a combination of strong interaction and large infrared (IR) shifts upon complexation, verifying the remarkable IR-reporting ability of the Cr(CO)3 moiety and its potential applications in anion recognition. The lone pairs of the oxygen atom in Y-shaped oxoanions directly interact with the -NH groups of the hosts, while all the shell electrons of the halides participate as a group in the interaction; however, the relative contributions of electrostatic and charge-transfer interactions are quite similar for the two types of anions. This insight into the nature of the anion-host interactions can be used to provide guidance for the design of hosts that differentiate between anions.
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Aniones/química , Cromo/química , Modelos Moleculares , Urea/química , Enlace de Hidrógeno , Conformación MolecularRESUMEN
A novel organometallic chromophore with potential infrared (IR) chemical sensing property, named as N'-(2-pyridinyl)-N-phenylurea tricarbonyl chromium, was synthesized and systematically characterized by nuclear magnetic resonance (NMR), mass spectra (MS) and elemental analysis. The recognition and IR sensing behavior toward fluoride and acetate anions was investigated in chloroform. The results of IR titration indicated that, when the concentration of the two anions was greater than 10(-5) mol.L-1, a good linear relationship between the stretching vibration of metal carbonyl of N'-(2-pyridinyl)-N-phenylurea tricarbonyl chromium and the concentration of the two anions was observed, which exhibits expected application in trace analysis of fluoride and acetate with detection error less than 5%.