Visible-Light-Switchable Tellurium-Based Chalcogen Bonding: Photocontrolled Anion Binding and Anion Abstraction Catalysis.

Exploring new noncovalent bonding motifs with reversibly tunable binding affinity is of fundamental importance in manipulating the properties and functions of supramolecular self-assembly systems and materials. Herein, for the first time, we demonstrate a unique visible-light-switchable telluro-triazole/triazolium-based chalcogen bonding (ChB) system in which the Te moieties are connected by azobenzene cores. The binding strengths between these azo-derived ChB receptors and the halide anions (Cl- , Br- ) could be reversibly regulated upon irradiation by visible light of different wavelengths. The cis-bidentate ChB receptors exhibit enhanced halide anion binding ability compared to the trans-monodentate receptors. In particular, the telluro-triazolium-based ChB receptor can achieve both high and significantly photoswitchable binding affinities for halide anions, which enable it to serve as an efficient photocontrolled organocatalyst for ChB-assisted halide abstraction in a Friedel-Crafts alkylation benchmark reaction.

Evaluation of the reliability of the upper lip bite test and the modified mallampati test in predicting difficult intubation under direct laryngoscopy in apparently normal patients: a prospective observational clinical study.

BACKGROUND AND AIMS: Difficult endotracheal intubation is one of the most challenging operations in anesthesia. How to better predict difficult airway and make corresponding preparations to reduce the occurrence of accidents is a difficult task faced by anesthesiologists every day. This study decide to evaluate the value of the Upper Lip Bite Test (ULBT) and the Modified Mallampati Test (MMT) in predicting difficult intubation under direct laryngoscopy and find out the most intuitive and simple method to predict difficult intubation under direct laryngoscopy in apparently normal patients. PATIENTS AND METHODS: This descriptive-analytical study was performed on 450 patients for elective surgery under general anesthesia requiring endotracheal intubation. The ULBT and MMT grading were evaluated preoperatively and Cormack and Lehane's (CL) classification was recorded on the day of surgery during intubation under direct laryngoscopy. The accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio (LR), Youden index and area under ROC curve of ULBT and MMT respectively and in combination were calculated and compared. And the consistency between the total scores of ULBT and MMT combined in different ways and CL grading was counted. RESULTS: Of the 450 patients, 69 (15.3%) were classified as difficult cases of direct laryngoscopy. The accuracy, sensitivity, specificity, PPV and NPV of ULBT were 81.33, 11.59, 93.96, 25.81, 85.44%; and those the corresponding values for MMT were 66.22, 62.32, 69.29, 26.88 and 91.03%. A combination of ULBT and MMT did not improve the sensitivity in the sample tested. The combined total scores of ULBT and MMT in both ways were less consistent with CL grading in predicting difficult intubation under direct laryngoscopy. CONCLUSION: Based on findings of current study, we conclude that ULBT and MMT for difficult intubation have only poor to moderate discriminative power when used alone. The combination of the two tests in fractional form is also not a good predictor of difficult intubation under direct laryngoscopy. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2100052987, Registered 07 November 2021, http://www.chictr.org.cn.

A Visible-Light-Induced Dynamic Mechanical Bond as a Linkage for Dynamic Materials.

Exploring dynamic bonds and their applications in fabricating dynamic materials has received great attention. A photoinduced [2]rotaxane-based dynamic mechanical bond (DMB) features visible-light-triggered dynamic bonding behavior that is essentially distinguished from conventional dynamic chemical bonds. In this DMB, a photoisomerizable ortho-fluoroazobenzene unit is introduced as a steric-controllable stopper, the visible-light-induced dynamic wagging movement of which enables the photoregulated threading of the macrocycle. This allows reversible in situ de-/reforming of the mechanical bond without involving dynamic chemical linkage. The DMB-cross-linked polymeric gel shows interesting photoinduced degradation behavior upon visible light irradiation. Benefiting from the distinctive dual dynamic nature of reversible bonding behavior and mechanical interlocked structure, this DMB is expected to serve as a new type of dynamic bond that can be applied in designing dynamic soft materials.

A Deep Cavitand Templates Lactam Formation in Water.

Cyclization reactions are common processes in organic chemistry and show familiar patterns of reaction rates vs ring size. While the details vary with the nature of bond being made and the number of unsaturated atoms, small rings typically form quickly despite angle strain, medium size rings form very slowly due to internal strains, and large rings form slowly (when they form at all) because fewer and less probable conformations bring the ends of the substrate together. High dilution is commonly used to slow the competing bi- and higher molecular processes. Here we apply cavitands to the formation of medium size lactams from ω-amino acids in aqueous (D2O) solution. The cavitands bind the amino acids in folded conformations that favor cyclization by bringing the ends closer together. Yields of a 12-membered lactam are improved 4.1-fold and 13-membered lactam 2.8-fold by the cavitand template. The results open possibilities for moving organic reactions into water even when the processes involve dehydration.

Colorful surface architectures with three different types of dynamic covalent bonds: integration of anthocyanins, tritylium ions and flavins.

Although they combine the best of covalent and non-covalent bonds, dynamic covalent bonds are usually not used together. Building on pioneering examples for functional systems with two orthogonal dynamic covalent bonds, we herein elaborate on multicomponent surface architectures that operate with three different types of dynamic covalent bonds. Disulfide exchange under basic conditions is used to grow single π stacks directly on oxide surfaces, hydrazone exchange under acidic conditions to add a second string or stack, and boronic-ester exchange under neutral conditions to build the third one. In this study, we show that this synthetic approach to complex systems provides access to emergent properties, as exemplified with ordered stacks of anthocyanins, pyrocatchol violet and riboflavins. The integration of anthocyanins, the central component of the pigments of plant flowers, is interesting to protect the blue flavylium cation against deprotonation, deplanarization and degradation. The integration of pyrocatchol violet is of interest to stabilize the blue, disfavored tritylium cation. The red riboflavin stacks are attractive because they generate high photocurrent. These colorful examples hint at the potential of synthetic methods that use three different types of dynamic covalent bonds in concert to build complex systems with emergent properties.

Complex Functional Systems with Three Different Types of Dynamic Covalent Bonds.

Multicomponent surface architectures are introduced that operate with three different dynamic covalent bonds. Disulfide exchange under basic conditions accounts for the growth of π stacks on solid surfaces. Hydrazone exchange under acidic conditions is used to add a second coaxial string or stack, and boronic ester exchange under neutral conditions is used to co-align a third one. The newly introduced boronic ester exchange chemistry is compatible with stack and string exchange without interference from the orthogonal hydrazone and disulfide exchange. The functional relevance of surface architectures with three different dynamic covalent bonds is exemplified with the detection of polyphenol natural products, such as epigallocatechin gallate, in competition experiments with alizarin red. These results describe synthetic strategies to create functional systems of unprecedented sophistication with regard to dynamic covalent chemistry.

Alkyl groups fold to fit within a water-soluble cavitand.

We report here a widened, deep cavitand host that binds hydrophobic and amphiphilic guests in D2O. Small alkanes (C6 to C11) are bound in compressed conformations and tumble rapidly within the space. Longer n-alkanes (C13 to C14), n-alcohols, and α,ω-diols are taken up in folded conformations. The guests' termini are exposed to solvent while atoms near the alkane's center are buried and protected. The cavitand acts as a concave template that pushes terminal atoms of the guest closer together. The unexpected binding modes are interpreted in terms of the size and shape of the space accessible in the new cavitand.

Self-assembly of three-dimensional supramolecular polymers through cooperative tetrathiafulvalene radical cation dimerization.

The self-assembly of a new type of three-dimensional (3D) supramolecular polymers from tetrahedral monomers in both organic and aqueous media is described. We have designed and synthesized two tetraphenylmethane derivatives T1 and T2, both of which bear four tetrathiafulvalene (TTF) units. When the TTF units were oxidized to the radical cation TTF(.+) , their pre-organized tetrahedral arrangement remarkably enhanced their intermolecular dimerization, leading to the formation of new 3D spherical supramolecular polymers. The structure of the supramolecular polymers has been inferred on the basis of UV/Vis absorption, electron paramagnetic resonance, cyclic voltammetry, and dynamic light scattering (DLS) analysis, as well as by comparing these properties with those of the self-assembled structures of mono-, di-, and tritopic control compounds. DLS experiments revealed that the spherical supramolecular polymers had hydrodynamic diameters of 68 nm for T1 (75 µM) in acetonitrile and 105 nm for T2 (75 µM) in water/acetonitrile (1:1). The 3D spherical structures of the supramolecular polymers formed in different solvents were also supported by SEM and AFM experiments.

Folded alkyl chains in water-soluble capsules and cavitands.

A deep cavitand with ionic "feet" dimerizes around hydrophobic compounds in D2O. Longer n-alkane guests, C14-C18, are encapsulated in contorted conformations and NMR is used to deduce their shapes. Competition experiments establish the driving forces involved and how they compensate for the steric clashes in the folded structures of the encapsulated alkanes. Bolaamphiphiles instead prefer to bind in the monomeric cavitand with conformations that bury the methylenes but expose the polar head groups to solvent.

Hydrogen-bonded capsules in water.

Hydrogen-bonded capsules constrain molecules into small spaces, where they exhibit behavior that is inaccessible in bulk solution. Water competes with the formation of hydrogen bonds, and other forces for assembly, such as metal/ligand interactions or hydrophobic effects, have been applied. Here we report the reversible assembly of a water-soluble cavitand to a robust capsule host in the presence of suitable hydrophobic guests. The complexes are characterized by conventional NMR methods. Selectivity for guest length and fluorescence quenching of a stilbene guest are used as evidence for hydrogen bonding in the capsule.

Toward a single-layer two-dimensional honeycomb supramolecular organic framework in water.

The self-assembly of well-defined 2D supramolecular polymers in solution has been a challenge in supramolecular chemistry. We have designed and synthesized a rigid stacking-forbidden 1,3,5-triphenylbenzene compound that bears three 4,4'-bipyridin-1-ium (BP) units on the peripheral benzene rings. Three hydrophilic bis(2-hydroxyethyl)carbamoyl groups are introduced to the central benzene ring to suppress 1D stacking of the triangular backbone and to ensure solubility in water. Mixing the triangular preorganized molecule with cucurbit[8]uril (CB[8]) in a 2:3 molar ratio in water leads to the formation of the first solution-phase single-layer 2D supramolecular organic framework, which is stabilized by the strong complexation of CB[8] with two BP units of adjacent molecules. The periodic honeycomb 2D framework has been characterized by various (1)H NMR spectroscopy, dynamic light scattering, X-ray diffraction and scattering, scanning probe and electron microscope techniques and by comparing with the self-assembled structures of the control systems.

Redox-responsive reverse vesicles self-assembled by pseudo[2]rotaxanes for tunable dye release.

Reverse vesicles exhibiting functions similar to those of normal vesicles have been constructed through the self-assembly of TTF/CBPQT(4+)-based pseudo[2]rotaxanes in a nonpolar solvent. The ends of the threads of the pseudo[2]rotaxanes are attached with a Fréchet-type G-3 dendron and a hydrogen-bonded arylamide foldamer. These vesicles exhibit a response to redox. By exploiting the dynamic feature-spontaneously slow disassociation of the pseudorotaxanes-the sustained release of dyes embedded in the reverse vesicles has been demonstrated, which can be further tuned by changing the solvent polarity.

Comparison of the Effectiveness of Various Drug Interventions to Prevent Etomidate-Induced Myoclonus: A Bayesian Network Meta-Analysis.

Background: Myoclonic movement is a very common but undesirable phenomenon during the induction of general anesthesia using etomidate. Such movement may cause unnecessary problems. Currently, there is an increasing number of drugs for preventing etomidate-induced myoclonus (EM). However, direct comparisons of various drugs are lacking, and this interferes with clinical decision-making. Our network meta-analysis (NMA) aimed to compare the efficacy of different drugs for the prevention of moderate-to-severe general myoclonus. Methods: Using several biomedical databases, randomized controlled trials (RCTs) published in English from inception to August 22, 2021 were searched. Among the various interventions, we selected nine types of intervention drugs (dexmedetomidine, etomidate, lidocaine, NMDA receptor antagonist, κ opioid receptor agonist, µ opioid receptor agonist, muscle relaxant, gabapentin, and midazolam) for comparison, according to the number of studies. Bayesian NMA was performed using STATA16 and R softwares. The relative risk of EM was assessed using risk ratios (RRs) and the corresponding 95% confidence intervals (CI). Results: A total of 31 RCTs (3209 patients) were included. NMA results showed that, compared with a placebo, etomidate (RR 4.0, 95%CI 2.1-7.8), κ opioid receptor agonist (RR 2.9, 95%CI 1.9-4.6), µ opioid receptor agonist (RR 3.1, 95%CI 2.3-4.3), NMDA receptor antagonist (RR 1.7, 95%CI 1.0-2.8), dexmedetomidine (RR 2.4, 95%CI 1.5-3.9), lidocaine (RR 2.1, 95%CI 1.2-3.9), and midazolam (RR 2.2, 95%CI 1.5-3.2) can significantly reduce the risk of EM. In contrast, the effects of muscle relaxants (RR 2.1, 95%CI 0.81-5.3) and gabapentin (RR 2.8, 95%CI 0.92-9.3) were inconclusive. Further subgroup analyses showed that preoperative low-dose etomidate, µ-opioid receptor agonist, and κ-opioid receptor agonist were significantly better than other interventions in the prevention of moderate to severe EM. Conclusion: Preoperative use of small doses of etomidate or opioids may be the most effective way to avoid EM, especially moderate and severe EM, which makes anesthesia induction safer, more stable, and aligns better with the requirements of comfortable medicine. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], [CRD4202127706].

Effect of Exercise Interventions on Health-Related Quality of Life in Patients with Fibromyalgia Syndrome: A Systematic Review and Network Meta-Analysis.

Objective: Several guidelines highlight the beneficial impact of exercise on the management of symptoms and health-related quality of life (HRQOL) in patients with fibromyalgia syndrome (FMS). However, few analyses have compared different types of exercise. We, therefore, intent to compare the effects of different exercise types on improving the overall HRQOL and typical symptoms in patients with FMS. Methods: Medline, Embase, the Cochrane Register of Clinical Trials, and NIH ClinicalTrials.gov were searched from inception to April 21, 2022. Randomized clinical trials (RCTs) were included to assess the impact of exercise intervention on health parameters in adult FMS patients. Data were extracted independently and a frequentist network meta-analyses (NMA) was performed to rank the effects of interventions according to P-scores. The NMA evidence certainty was assessed using the method recommended by Grading of Recommendations Assessment, Development, and Evaluation Working Group. Results: A total of 57 RCTs were identified, including 3319 participants, involving 9 interventions (7 types of exercise, 2 controls). Of all treatments compared with usual care in efficacy outcomes, Mind-body exercise was associated with the best HRQOL (SMD, -12.12; 95% CI, -15.79 to -8.45). On the other characteristic symptom dimensions, based on moderate quality evidence, sensorimotor training was associated with minimal pain scores compared with usual care (SMD, -1.81; 95% CI, -2.81 to -0.82), whole body vibration therapy was most promising for improving sleep quality (SMD, -6.95; 95% CI, -10.03 to -3.87), pool-based aerobic exercise was most likely to ease anxiety (SMD, -4.83; 95% CI, -7.47 to -2.19), and whole body vibration was most likely to improve depression (SMD, -10.44; 95% CI, -22.00 to 1.12). Conclusion: Mind-body exercise seems to be the most effective exercise to improve the overall HRQOL of patients with FMS. But at the same time, clinicians still need to develop individualized exercise plans for patients according to their symptoms and accessibility.

Foldamer-tuned switching kinetics and metastability of [2]rotaxanes.

Slip sliding away: foldamers can function as modular stoppers to regulate the slippage and de-slippage of pseudorotaxanes and the switching kinetics and metastability of bistable rotaxanes. By simply changing the solvent or the length of the hydrogen-bonded foldamer, the lifetime of the metastable co-conformation state can be increased dramatically, from several minutes to as long as several days.

Photo-Controlled Macroscopic Self-Assembly Based on Photo-Switchable Hetero-Complementary Quadruple Hydrogen Bonds.

A photo-switchable hetero-complementary quadruple H-bonding array, which consists of an azobenzene-derived ureidopyrimidinone (UPy) module (Azo-UPy) and a nonphotoactive diamidonaphthyridine (DAN) derivative (Napy-1), is constructed based on a reversible photo-locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo-switchable quadruple H-bonded dimerization between Azo-UPy and Napy-1 can be achieved with exhibiting 4.8×104 -fold differences in binding strength (ON/OFF ratios). Furthermore, smart polymeric gels with unique photo-controlled macroscopic self-assembly behavior can be fabricated by introducing such quadruple H-bonding array as photo-regulable noncovalent interfacial connections.

Vesicle self-assembly by tetrathiafulvalene derivatives in both polar and nonpolar solvents and pseudo-rotaxane mediated vesicle-to-microtube transformation.

This paper reports the self-assemblies of vesicles from two tetrathiafulvalene (TTF) derivatives (T1 and T2), that bear four or two amphiphilic side chains, in both polar and nonpolar solvents. The formation of vesicles is evidenced by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) experiments, while the microstructural aspects of the vesicles are investigated by UV-vis, (1)H NMR, and high resolution TEM, which support a monolayer model for the vesicles. It is revealed that the formation of vesicles is driven by the combination of multiple noncovalent interactions, including pi-pi stacking, hydrogen-bonding, van der Waals force, and S...S interactions. It is also found that, in the presence of electron-deficient cyclobis(paraquat-p-phenylene) tetracation cyclophane, vesicles of T2 can transform into microtubes as a result of the formation of the pseudo[2]rotaxane between the TTF unit of T2 and the cyclophane. This process can be reversed by introducing pristine TTF into the solution of microtubes, due to release of T2 from the pseudo[2]rotaxane through the formation of a more stable complex between pristine TTF and tetracation cyclophane.

Towards photoswitchable quadruple hydrogen bonds via a reversible "photolocking" strategy for photocontrolled self-assembly.

Developing new photoswitchable noncovalent interaction motifs with controllable bonding affinity is crucial for the construction of photoresponsive supramolecular systems and materials. Here we describe a unique "photolocking" strategy for realizing photoswitchable control of quadruple hydrogen-bonding interactions on the basis of modifying the ureidopyrimidinone (UPy) module with an ortho-ester substituted azobenzene unit as the "photo-lock". Upon light irradiation, the obtained Azo-UPy motif is capable of unlocking/locking the partial H-bonding sites of the UPy unit, leading to photoswitching between homo- and heteroquadruple hydrogen-bonded dimers, which has been further applied for the fabrication of novel tunable hydrogen bonded supramolecular systems. This "photolocking" strategy appears to be broadly applicable in the rational design and construction of other H-bonding motifs with sufficiently photoswitchable noncovalent interactions.

Tunable Water-Soluble Supramolecular Polymers by Visible-Light-Regulated Host-Guest Interactions.

The development of artificial self-assembling systems with dynamic photo-regulation features in aqueous solutions has drawn great attention owing to the potential applications in fabricating elaborate biological materials. Here we demonstrate the fabrication of water-soluble cucurbit[8]uril (CB[8])-mediated supramolecular polymers by connecting the fluorinated azobenzene (FAB) containing monomers through host-enhanced heteroternary π-π stacking interactions. Benefiting from the unique visible-light-induced E→Z photoisomerization of the FAB photochromophores, the encapsulation behaviors between the CB[8] macrocycle and the monomers could be regulated upon visible light irradiation, resulting in the depolymerization of such CB[8]-mediated supramolecular polymers.

Toward bidirectional photoswitchable colored photochromic molecules with visible light stability.

Photochromic [2]rotaxanes with bidirectional photoswitchability were fabricated, whose colored states exhibit remarkable visible-light and thermal stabilities as revealed by systematically spectroscopic investigations.