Shapeshifting Nucleophile Singly Hydrated Hydroperoxide Anion Leads to the Occurrence of the Thermodynamically Unfavored SN2 Product.

Single water molecules alone may introduce unusual features into the kinetics and dynamics of chemical reactions. The singly hydrated hydroperoxide anion, HOO-(H2O), was found to be a shapeshifting nucleophile, which can be transformed to HO- solvated by hydrogen peroxide HO-(HOOH). Herein, we performed direct dynamics simulations of its reaction with methyl iodide to investigate the effect of individual water molecules. In addition to the normal SN2 product CH3OOH, the thermodynamically unfavored proton transfer-induced HO--SN2 path (produces CH3OH) was also observed, contributing ∼4%. The simulated branching ratio of the HO--SN2 path exceeded the statistical estimation (0.6%) based on the free energy barrier difference. The occurrence of the HO--SN2 path was attributed to the shallow entrance channel well before a submerged saddle point, thus providing a region for extensive proton exchange and ultimately leading to the formation of CH3OH. In comparison, changing the leaving group from Cl to I increased the overall reaction rate as well as the proportion of the HO--SN2 path because the CH3I system has a smaller internal barrier. This work elucidates the importance of the dynamic effect introduced by a single solvent molecule to alter the product channel and kinetics of typical ion-molecule SN2 reactions.

Shapeshifting Nucleophiles HO-(NH3)n React with Methyl Chloride.

The microsolvated anions HO-(NH3)n were found to induce new nucleophile NH2-(H2O)(NH3)n-1 via intramolecular proton transfer. Hence, the ion-molecule nucleophilic substitution (SN2) reaction between CH3Cl and these shapeshifting nucleophiles lead to both the HO- path and NH2- path, meaning that the respective attacking nucleophile is HO- or NH2-. The CCSD(T) level of calculation was performed to characterize the potential energy surfaces. Calculations indicate that the HO- species are lower in energy than the NH2- species, and the SN2 reaction barriers are lower for the HO- path than the NH2--path. Incremental solvation increases the barrier for both paths. Comparison between HO-(NH3)n and HOO-(NH3)n confirmed the existence of an α-effect under microsolvated conditions. Comparison between HO-(NH3)n and HO-(H2O)n indicated that the more polarized H2O stabilizes the nucleophiles more than NH3, and thus, the hydrated systems have higher SN2 reaction barriers. The aforementioned barrier changes can be explained by the differential stabilization of the nucleophile and HOMO levels upon solvation, thus affecting the HOMO-LUMO interaction between the nucleophile and substrate. For the same kind of nucleophilic attacking atom, O or N, the reaction barrier has a good linear correlation with the HOMO level of the nucleophiles. Hence, the HOMO level or the binding energy of microsolvated nucleophiles is a good indicator to evaluate the order of barrier heights. This work expands our understanding of the microsolvation effect on prototype SN2 reactions beyond the water solvent.

Drug Exposure and Risk of Microscopic Colitis: A Systematic Review and Meta-Analysis.

BACKGROUND AND OBJECTIVES: Microscopic colitis (MC) is a chronic inflammatory bowel disease characterized by watery diarrhoea and a normal radiological and endoscopic appearance. Concern regarding a potential association between drug exposure and MC has recently emerged. We sought to systematically review and summarize the evidence for the potential association. METHODS: A systematic review and meta-analysis were performed to evaluate the incidence of MC associated with exposure to drug. The PubMed and Embase databases were searched to identify potential studies for inclusion. RESULTS: Twelve case-control studies were included in the meta-analysis. The results showed exposure to NSAID (OR, 1.64; 95% CI: 1.14-2.37; p < 0.001), PPI (OR, 2.36; 95% CI: 1.59-3.52; p < 0.001), SSRI (OR, 2.16; 95% CI: 1.5-3.13; p < 0.001), or aspirin (OR, 2.84; 95% CI: 1.4-5.76; p < 0.001) was related to the incidence of MC; however, such relationships in PPI and SSRI may be modulated by the selection of controls. Furthermore, we did not found a positive association with other drug exposure and MC. CONCLUSION: This meta-analysis indicated that NSAID, PPI, SSRI, or aspirin consumption may increase the risk for MC. Further studies exploring drug-induced microscopic colitis should include control groups with diarrhoea and not only healthy controls.

Triaxial precise magnetic field compensation of a zero-field optically pumped magnetometer based on a single-beam configuration.

Triaxial magnetic field compensation is crucial for a zero-field optically pumped magnetometer (OPM) in pursuit of a zero-field environment. In this work, we demonstrate a triaxial magnetic field compensation method for zero-field OPM based on single-beam configuration. It consists of two procedures: (1) pre-compensation to preliminarily cancel out ambient residual magnetic field by low-frequency magnetic field modulation; and (2) precise compensation to further compensate the residual magnetic field by high-frequency magnetic field modulation. This scheme enables rapid and precise compensation of a large-scale magnetic field and supports real null-point acquisition of the triaxial residual magnetic fields with simple processes. The experimental results show that the compensation resolution on the sensitive axis is better than 1 pT and significantly less than the fluctuation of experimental environments. Our work targets on the quick generation of a zero-field environment for high precision OPM, which is especially advantageous for emerging applications including magnetocardiography (MCG) and magnetoencephalography (MEG).

Three-axis closed-loop optically pumped magnetometer operated in the SERF regime.

We propose a three-axis closed-loop optically pumped magnetometer with high sensitivity. The closed-loop magnetometer has a three-axis sensitivity of approximately 30 fT/Hz1/2 using two orthogonal laser beams for pumping and probing the alkali metal atoms. In the closed-loop mode, the dynamic range is improved from ±5 nT to ±150 nT. The bandwidth is increased from about 100 Hz to over 2 kHz with 10 kHz modulation fields in x- and y-axes and another 6 kHz modulation field along the z-axis. Compared with single-axis or dual-axis magnetometers, the proposed magnetometer not only provides the direction and magnitude of the magnetic field but also has high robustness in a challenging environment. The magnetometer has applications in biomagnetic measurements, magnetic resonance imaging, and fundamental physics.

Investigating the competing E2 and SN2 mechanisms for the microsolvated HO-(H2O)n=0-4 + CH3CH2X (X = Cl, Br, I) reactions.

We characterized the anti-E2, syn-E2, inv-SN2, and ret-SN2 reaction channels for the reaction of microsolvated HO-(H2O)n anions with CH3CH2X (X = Cl, Br, I), using the CCSD(T)/PP/t//MP2/ECP/d level method, to understand how a solvent influences the competing E2 and SN2 reactions. The calculated sequence of barrier for the four channels is ret-SN2 > syn-E2 > anti-E2 > inv-SN2. The barrier heights increase with incremental hydration as the system transfers from the gas phase to microsolvation, and to bulk solvation (using the PCM implicit solvent model). As the degree of hydration n increases, good correlations have been found between barrier heights and several thermodynamic, geometric and charge parameters, including the reaction enthalpy, proton/ethyl-cation affinity of the hydrated nucleophile, geometric looseness (%L‡) and asymmetry (%AS‡) and charge asymmetry (Δq(X-O)) of the transition structures. Under a molecular orbital scheme, the HOMOs of nucleophiles are stabilized by stepwise hydration, explaining the rise in the barriers. Considering the effect of the leaving group, the barrier heights exhibit linear correlation with the halogen electronegativity and H-acidity of substrate CH3CH2X. In terms of E2/SN2 competition, the barrier difference, , first increases then decreases as the number of explicit water molecules increases, under both microsolvation and bulk solvation conditions, but the inv-SN2 pathway is always favored over the anti-E2 pathway. Energy decomposition analysis attributes the increase of barrier difference to the greater geometric distortion in the anti-E2 transition structure.

Self-assembly preparation of Zn2+ -immobilized silica hybrid monolith and application in solid-phase micro-extraction of ß-agonists.

Exploiting adsorbents with highly efficient extraction performance is of great promise for extracting small organic molecules from biological samples. In this work, a novel Zn2+ -immobilized chitosan@silica hybrid monolith was prepared through a simple self-assembly Zn2+ -immobilization process. Exploited as an adsorbent in solid-phase micro-extraction for extracting trace ß-agonists, the monolith exhibited high extraction efficiencies for salbutamol, clenbuterol, and ractopamine with the enrichment factors approaching 120, 85, and 52, respectively. These could be attributed to the effective interaction between Zn2+ ions and the target molecule via coordination or other intermolecular interactions. Under optimized extraction operations, a sensitive determination was successfully developed coupling with high-performance liquid chromatography-ultraviolet detection. The linear range was 0.17-58.8, 0.12-68.5, and 0.18-65.5 ng/ml for salbutamol, clenbuterol, and ractopamine. The limits of detection of the ß-agonists were from 0.04 to 0.07 ng/ml, and the limits of quantification were from 0.12 to 0.18 ng/ml. The recoveries of spiking in mutton samples were observed in the range of 85.9%-95.7%, with relative standard deviations <8.0% (n = 3). Application tests demonstrated this newly developed determination was practical, accurate, and convenient for detecting trace content ß-agonists in meat.

Surface design of g-C3N4 quantum dot-decorated TiO2(001) to enhance the photodegradation of indoor formaldehyde by experimental and theoretical investigation.

Formaldehyde (CHOH), a common volatile organic compound, causes many adverse effects on human health. The highly exposed TiO2(001) facet possesses a high photodegradation efficiency of CHOH due to its excellent ability to trap photogenerated holes and high density of surface unsaturated Ti atoms (Ti5c) to bind CHOH. However, the rapid recombination of photoinduced electron-hole pairs of TiO2(001) limits the photodegradation efficiency. We adopted a strategy of decorating TiO2(001) with g-C3N4 quantum dots (QDs), exploiting the quantum effect of g-C3N4QDs and their combined staggered band structure. This decoration improves the photocatalytic activity of TiO2(001). Moreover, the chemical configuration of g-C3N4QDs/TiO2(001) and the combination mode between the g-C3N4QDs and TiO2(001) support were explored in detail using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. Following the physiochemical characteristic results, the transport mechanism of photoinduced carriers was further analyzed by ultraviolet photoelectron spectroscopy (UPS), electron paramagnetic resonance (EPR), and Heyd-Scuseria-Ernzerh (HSE) exchange-correlation functional calculations. Finally, the performance and reaction mechanism of the photodegradation of CHOH by TiO2(001) and g-C3N4QDs/TiO2(001) were thoroughly investigated. The results show that the g-C3N4QDs were composed of an N-defect tri-s-triazine supported by TiO2(001) via a strong C-O-Ti chemical bond, which accelerated the separation of photoinduced carriers through a Z-scheme route. The photodegradation and mineralization efficiencies of CHOH were significantly promoted by 30% and 60% for g-C3N4QDs/TiO2(001) compared with those of TiO2(001). The photodegradation mechanism proceeded as CHOH - dioxymethylene - formate - carbonate - CO2. This study provides a surface engineering means to design highly active modified TiO2 for CHOH photodegradation.

Regioisomer-Free Difluoro-Monochloro Terminal-based Hexa-Halogenated Acceptor with Optimized Crystal Packing for Efficient Binary Organic Solar Cells.

Herein, we synthesized new hetero-halogenated end groups with well-determined fluorinated and chlorinated substitutions (o-FCl-IC and FClF-IC), and synthesized regioisomer-free small molecular acceptors (SMAs) Y-Cl, Y-FCl, and Y-FClF with distinct hetero-halogenated terminals, respectively. The single-crystal structures and theoretical calculations indicate that Y-FClF exhibits more compact three-dimensional network packing and more significant π-π electronic coupling compared to Y-FCl. From Y-Cl to Y-FCl to Y-FClF, the neat films exhibit a narrower optical band gap and gradually enhanced electron mobility and crystallinity. The PM6 : Y-FClF blend film exhibits the strongest crystallinity with preferential face-on molecular packing, desirable fibrous morphology with suitable phase segregation, and the highest and balanced charge mobilities among three blend films. Overall, the PM6 : Y-FClF organic solar cells (OSCs) deliver a remarkable efficiency of 17.65 %, outperforming the PM6 : Y-FCl and PM6 : Y-Cl, which is the best PCE for reported hetero-halogens-based SMAs in binary OSCs. Our results demonstrate that difluoro-monochloro hetero-terminal is a superior regio-regular unit for enhancing the intermolecular crystal packing and photovoltaic performance of hetero-halogenated SMAs.

Reconstruction of the esophagus of patients with middle thoracic esophageal carcinoma using the remnant stomach following Billroth II gastrectomy.

It seems impossible to reconstruct the esophagus of patients with middle thoracic esophageal carcinoma with a history of distal gastrectomy using the remnant stomach. Although surgeons have made multiple efforts to reconstruct the esophagus using the remnant stomach, it can only be successfully used in cases of lower thoracic esophageal cancer. Additionally, the surgery is more complex than traditional esophagogastrostomy due to challenges including mobilization of the remnant stomach with the spleen and transposition of the pancreatic tail into the left hemithorax. Our operation proved that the remnant stomach, which we named as the completely mobilized remnant stomach after dissection of the feeding vessels, remained viable. We successfully integrated the completely mobilized remnant stomach in the reconstruction of the lower thoracic esophageal tract and then integrated it in Ivor Lewis esophagogastrostomy. We describe this new alternative surgical technique for the treatment of middle thoracic esophageal carcinoma in patients with a history of distal gastrectomy in this study. Clinical data of 23 patients from 2008 to 2019 were retrospectively analyzed. All patients underwent the Ivor Lewis procedure. All remaining vessels of the remnant stomach were dissected at their origins, and Roux-en-Y reconstruction or Braun anastomosis was performed. After esophagectomy during right thoracotomy, anastomosis of the remnant stomach and esophagus was performed. Two-field lymph node dissections were performed. There was no case of necrosis of the remnant stomach or of perioperative death. Serious complications included anastomotic leak in three cases, afferent-efferent loop syndrome in one, and anastomotic stricture in two. Application of the completely mobilized remnant stomach in Ivor Lewis esophagogastrostomy is feasible, and the surgical procedure is similar to that of normal esophagogastrostomy.

Modified left subsuperior segmentectomy via 2-cm uniportal video-assisted thoracoscopic surgery.

Independent subsuperior segmentectomy (S*) via uniportal video-assisted thoracoscopic surgery (VATS) has rarely been reported. We describe our modified technique of performing simplified left subsuperior segmentectomy for a lung nodule, via 2-cm uniportal VATS. The uniportal approach was different from the traditional approach made by blunt separation into the thorax without electrocautery. Our modified technique minimizes damage to the intercostal nerves and muscles. We also simplified the subsuperior segmentectomy procedure according to the findings of three-dimensional (3D) computed tomography angiography and bronchography. Combining these two techniques achieves a new more minimally invasive method for subsuperior segmentectomy.

Modified 2-cm super single port vs. the traditional 3-cm single port for video-assisted thoracoscopic surgery lobectomy.

PURPOSES: We introduce a novel 2-cm single port designed to minimize intercostal muscle and nerve damage in video-assisted thoracoscopic surgery (VATS) lobectomy, and compared it with the 3-cm traditional single port. METHODS: We analyzed, retrospectively, the clinical data, safety, convenience, incision complications, and postoperative pain and numbness in 81 patients who underwent either modified (n = 42) or traditional (n = 39) single-port VATS lobectomy. RESULTS: The preoperative variables were comparable between both single-port VATS lobectomy groups after matching. There were no serious complications and there was no mortality in either group. There were no remarkable differences between the groups in intraoperative blood loss, chest tube duration, lymph node dissection, or postoperative complications. The modified single-port group had a longer operation time (p < 0.05), but the static and dynamic postoperative VAS scores and incisional numbness were better in the modified single-port group (p < 0.05). The modified single-port group also had an obvious advantage in incision seepage, healing, and appearance. CONCLUSIONS: Our 2-cm modified single port for lobectomy is safe and effective, and results in less postoperative pain and incisional numbness than the 3-cm traditional single port.

LDH, CRP and ALB predict nucleic acid turn negative within 14 days in symptomatic patients with COVID-19.

AIMS: To search for biochemical indicators that can identify symptomatic patients with COVID-19 whose nucleic acid could turn negative within 14 days, and assess the prognostic value of these biochemical indicators in patients with COVID-19. PATIENTS AND METHODS: We collected the clinical data of patients with COVID-19 admitted to our hospital, by using logistic regression analysis and AUC curves, explored the relationship between biochemical indicators and nucleic acid positive duration, the severity of COVID-19, and hospital stay respectively. RESULTS: A total of two hundred and thirty-three patients with COVID-19 were enrolled in the study. We found patients whose nucleic acid turned negative within 14 days had lower LDH, CRP and higher ALB (P < 0.05). ROC curve results indicated that lower LDH, TP, CRP and higher ALB predicted the nucleic acid of patients turned negative within 14 days with statistical significance(P < 0.05), AST, LDH, CRP and PCT predicted the severe COVID-19 with statistical significance, and CRP predicted hospital stay >31days with statistical significance (P < 0.05). After verification, the probability of nucleic acid turning negative within 14 days in patients with low LDH (<256 U/L), CRP (<44.5 mg/L) and high ALB (>35.8 g/L) was about 4 times higher than that in patients with high LDH, CRP and low ALB (P < 0.05). CONCLUSIONS: LDH, CRP and ALB are useful prognostic marker for predicting nucleic acid turn negative within 14 days in symptomatic patients with COVID-19.

A Synergistic Strategy of Manipulating the Number of Selenophene Units and Dissymmetric Central Core of Small Molecular Acceptors Enables Polymer Solar Cells with 17.5 % Efficiency.

A dissymmetric backbone and selenophene substitution on the central core was used for the synthesis of symmetric or dissymmetric A-DA'D-A type non-fullerene small molecular acceptors (NF-SMAs) with different numbers of selenophene. From S-YSS-Cl to A-WSSe-Cl and to S-WSeSe-Cl, a gradually red-shifted absorption and a gradually larger electron mobility and crystallinity in neat thin film was observed. A-WSSe-Cl and S-WSeSe-Cl exhibit stronger and tighter intermolecular π-π stacking interactions, extra S⋅⋅⋅N non-covalent intermolecular interactions from central benzothiadiazole, better ordered 3D interpenetrating charge-transfer networks in comparison with thiophene-based S-YSS-Cl. The dissymmetric A-WSSe-Cl-based device has a PCE of 17.51 %, which is the highest value for selenophene-based NF-SMAs in binary polymer solar cells. The combination of dissymmetric core and precise replacement of selenophene on the central core is effective to improve Jsc and FF without sacrificing Voc .

The role of neutrophil-lymphocyte ratio and lymphocyte-monocyte ratio in the prognosis of type 2 diabetics with COVID-19.

OBJECTIVES: To assess the prognostic value of neutrophil-lymphocyte ratio, lymphocyte-monocyte ratio and red cell distribution width in type 2 diabetics with COVID-19. METHODS: We collected the data of type 2 diabetics with COVID-19 treated in our hospital from January 28 to March 15, 2020 and performed a retrospective analysis. Using severity, duration of hospital stay, and the time required for nucleic acid results became negative as prognostic indicators, we explored the relationship between these inflammation-based markers and prognosis of type 2 diabetics with COVID-19. RESULTS: A total of 134 type 2 diabetics with COVID-19 were selected for this study. Correlation analysis showed that NLR, LMR and RDW were correlated with prognosis (P < 0.05). In multivariate regression analysis after controlling for the relevant confounding factors, COVID-19 diabetes patients with higher NLR had heavier severity, longer duration of hospital stay, more time required for nucleic acid results became negative, and heavier hospital expenses (P < 0.05). ROC curve result displayed that higher NLR predicted all prognostic indicators with statistical significance, and lower LMR predicted severe and extremely severe with statistical significance (P < 0.05). CONCLUSIONS: NLR is a more powerful and practical marker for predicting the prognosis of type 2 diabetic COVID-19 patients that is simple and fast.

Dual-Site Fluorescent Probe to Monitor Intracellular Nitroxyl and GSH-GSSG Oscillations.

Nitroxyl (HNO), the one-electron-reduction product of NO has recently been revealed to have potentially beneficial pharmacological properties in cardiovascular health as a result of interactions with specific thiols such as glutathione (GSH). To disentangle the complicated inter-relationship between HNO and GSH in the signal transduction and oxidative pathways, we designed and synthesized a dual-site fluorescent probe NCF to indicate cellular HNO and GSH-GSSG balance. The sensitive and selective detection of HNO was achieved by incorporating an organophosphine group to naphthaldehyde-TCF. Then the resulted fluorescent product is able to monitor the conversion of GSH and GSSG reversibly. Additionally, outstanding biocompatibility make it capable of monitoring intracellular HNO and consequently GSH-GSSG oscillationsin living cells. We anticipate that NCF will be a unique molecular tool to investigate the interplaying roles of HNO and GSH.

Theoretical investigation on the reaction mechanism and kinetics of a Criegee intermediate with ethylene and acetylene.

The detailed reaction mechanism of the Criegee intermediate CH2OO with ethylene and acetylene has been investigated by using the HL//M06-2X/AUG-cc-pVTZ method. The 1,3-cycloaddition of CH2OO to the unsaturated bond of ethylene or acetylene forms a five-membered ring adduct. For the reaction of CH2OO with ethylene, the subsequent ring-opening, H-shift isomerization and decomposition result in the formation of ethenol + HCHO and acetaldehyde + HCHO, and for the reaction of CH2OO with acetylene, the adduct proceeds via ring-opening and H-shift isomerization forming malonaldehyde. The calculated overall rate constant increases in the temperature range of 200-500 K, and at 298 K, it is 3.91 × 10-15 cm3 molecule-1 s-1 for the CH2OO + C2H4 reaction and 1.27 × 10-16 cm3 molecule-1 s-1 for the CH2OO + C2H2 reaction. The product branching ratio of the CH2OO + C2H4 reaction is pressure dependent, and the adduct tends to decompose to ethenol + HCHO and acetaldehyde + HCHO at lower pressures and higher temperatures. For the CH2OO + C2H2 reaction, the adduct isomerizes completely to malonaldehyde in the temperature range of 200-500 K and the pressure range of 100-1000 Torr.

Self-Catalytic Reaction of SO3 and NH3 To Produce Sulfamic Acid and Its Implication to Atmospheric Particle Formation.

Sulfur trioxide (SO3) is one of the most active chemical species in the atmosphere, and its atmospheric fate has profound implications to air quality and human health. The dominant gas-phase loss pathway for SO3 is generally believed to be the reaction with water molecules, resulting in sulfuric acid. The latter is viewed as a critical component in the new particle formation (NPF). Herein, a new and competitive loss pathway for SO3 in the presence of abundant gas-phase ammonia (NH3) species is identified. Specifically, the reaction between SO3 and NH3, which produces sulfamic acid, can be self-catalyzed by the reactant (NH3). In dry and heavily polluted areas with relatively high concentrations of NH3, the effective rate constant for the bimolecular SO3-NH3 reaction can be sufficiently fast through this new loss pathway for SO3 to become competitive with the conventional loss pathway for SO3 with water. Furthermore, this study shows that the final product of the reaction, namely, sulfamic acid, can enhance the fastest possible rate of NPF from sulfuric acid and dimethylamine (DMA) by about a factor of 2. An alternative source of stabilizer for acid-base clustering in the atmosphere is suggested, and this new mechanism for NPF has potential to improve atmospheric modeling in highly polluted regions.

Magnetometry for precision measurement using frequency-modulation microwave combined efficient photon-collection technique on an ensemble of nitrogen-vacancy centers in diamond.

Sensitivity of magnetometers that use color centers is limited by poor photon-collection and detection efficiency. In this paper, we present the details of a newly developed all-optical collection combined frequency-modulated microwave method. The proposed method achieves a high sensitivity in static magnetic-field detection both theoretically and experimentally. First, we demonstrate that this collection technique enables both a fluorescence collection as high as 40% and an efficient pump absorption. Subsequently, we exploit the optically detected magnetic resonance (ODMR) signal and quantitative magnetic detection of an ensemble of nitrogen vacancy (NV) centers, by applying a frequency-modulated (FM) microwave method followed by a lock-in technique on the resonance frequency point. Based on the results obtained using all-optical collection combined FM microwaves, we verified that the sensitivity of the magnetometer can achieve approximately 14 nT/√Hz at 1 Hz, using a discrete Fourier transform detection method experimentally. This method provides a compact and portable precision-sensor platform for measuring magnetic fields, and is of interest for fundamental studies in spintronics.

Controlled Polymerization of Isoprene with Chromium-Based Metal-Organic Framework Catalysts: Switching from Cyclic to cis-1,4-Selectivity Depending on Activator.

Chromium-based metal-organic framework (MOF) Cr-MIL-100/101 activated by activator and aluminum trialkyl compound serve as unique, highly efficient heterogeneous single-site catalysts for the controlled polymerization of isoprene, which not only exhibit quasi-living nature in isoprene polymerization but also unprecedentedly switch from cyclic to cis-1,4-selectivity depending on the activator used to yield low molecular weight cyclic PIPs or extremely high molecular weight cis-1,4-PIPs. Such heterogeneous Cr-MOF catalysts can be recycled approximately five times. Based on nitrogen sorption isotherm tests and powder X-ray diffraction, a cationic mechanism is suggested, in which the polymerization takes place inside the open nanochannels of MOF catalysts and the space confinement effect of narrow open nanochannels originated from the coordination of PhNMe2 from activator [PhNHMe2 ][B(C6 F5 )4 ] with the multiple metal centers of MOF catalysts might give a rational explanation for such controlled adjustment on the PIP's structure and properties.