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Organophotoredox catalytic four-component radical-polar crossover cascade reactions for the stereoselective synthesis of β-amido sulfones with high atom-, step-, and redox economy and excellent diastereoselectivity.

A green and practical divergent Ritter-type amination via a photoredox catalytic four-component radical-polar crossover process was developed. This versatile protocol presents a modular and powerful strategy to access functionalized β-sulfonyl imides and imines under mild conditions from readily available and stable substrates with high atom-, step- and redox economy. We manipulated carboxylic acids and benzotriazoles to precisely attack the nitrilium ion instead of the carbocation, thus preventing many complicated side reactions of the photocatalytic reactions. Furthermore, the synthetic utility of this divergent Ritter reaction is further demonstrated by the late-stage modification of pharmaceutical and natural product derivatives.

An iterative convergence control method (ICCM) based on the support vector regression (SVR) is proposed to realize the position–posture control of the planar four-link underactuated manipulator with a passive second link. Firstly, the particle swarm optimization (PSO) algorithm is used to obtain the target angles of all links according to the position–posture control objective. Then, two prediction models for the coupling relationship between the first link and the passive link, and the third link and the passive link are established based on the SVR, whose optimal parameters are selected by the chaos particle swarm optimization (CPSO) algorithm. By repeatedly controlling the first link or the third link to rotate an angle which is calculated by the trained SVR model, the passive link gradually converges to its target angle after several iterations. Next, the active links are controlled to rotate to their target angles with low speeds, and the passive link does not rotate due to friction. Finally, the experimental results verify the effectiveness and feasibility of the proposed method.

Dry eye syndrome (DES) is a common disease with various clinical manifestations. DES had a significant association with diabetes. Blink reflex (BR) is also known as trigeminal nerve facial reflex. The stimulation of corneal nerves is one of the origins of BR stimulation. The parasympathetic fibers sent out through the facial nerve are the outlet of tear reflexes. BR can be used to assess the function of the corneal nerve closed-loop; however, whether the BR changes in these patients is unclear.To understand the morphology and function of the corneal nerve in patients with dry eyes having diabetes or not.This study enrolled 131 patients who visited the inpatient and outpatient services of ophthalmology and endocrinology departments between January 2019 to August 2020 with subjective symptoms of dry eyes and non-dry eye reasons, as well as volunteers such as colleagues. The patients were divided into four groups: DEwDM, with dry eyes having type 2 diabetes mellitus (T2DM); DMnDE, with T2DM not having dry eyes; DEnDM, with dry eyes not having diabetes; and nDMnDE, with neither dry eyes nor diabetes. The tear film break-up time, Schirmer I test,The DEwDM, DMnDE, DEnDM, and nDMnDE groups included 56, 22, 33, and 20 patients, respectively. Sex and age were not statistically different among the four groups. The nerve fiber length (NFL) of patients in the DEwDM, DEnDM, and DMnDE groups reduced (The corneal nerve morphology changed in patients with dry eyes or diabetes, or with both, while the function of corneal nerve closed-loop reduced only in those with dry eyes and diabetes.

Three red iridium(iii) complexes with dithiocarbamate ligands were rapidly synthesized at room temperature with good yields, and their OLEDs exhibit an EQEmax of 30.54% with mild efficiency roll-off., Three red cyclometalated iridium(iii) complexes (4tfmpq)2Ir(dipdtc), (4tfmpq)2Ir(dpdtc) and (4tfmpq)2Ir(Czdtc) (4tfmpq = 4-(4-(trifluoromethyl)phenyl)quinazoline, dipdtc = N,N-diisopropyl dithiocarbamate, dpdtc = N,N-diphenyl dithiocarbamate, and Czdtc = N-carbazolyl dithiocarbamate) containing the unique four-membered Ir–S–C–S backbone ring were synthesized in five minutes at room temperature with good yields, and the Gibbs free energy calculation results indicate that all reactions are exothermic and thermodynamically favorable processes. The emission colors (λpeak = 641–611 nm), photoluminescence quantum efficiencies (ΦP = 58.3–93.0%) and bipolar properties can be effectively regulated by introducing different electron-donating substituents into the dithiocarbamate ancillary ligands. Employing these emitters, organic light emitting diodes (OLEDs) with double emissive layers exhibit excellent performances with a maximum brightness over 60 000 cd m–2, a maximum current efficiency of 40.68 cd A–1, a maximum external quantum efficiency (EQEmax) of 30.54%, and an EQE of 26.79% at the practical luminance of 1000 cd m–2. These results demonstrate that Ir(iii) complexes with sulfur-containing ligands can be rapidly synthesized at room temperature, which is key to the production of metal luminescent materials for large-scale application in highly efficient OLEDs.

CoIII(salen)-X (X = Cl-, OAc-, and OTs-) mediated hydration of propylene oxide (PO) to propylene glycol has been investigated in detail using density functional theory (DFT) calculations. Two kinds of reaction mechanisms, the concerted and stepwise pathways, were scrutinized. For the eight concerted routes, the cooperative bimetallic route in which the middle carbon atom is attacked by the nucleophilic oxygen atom (route VI-m) was calculated to be the most favorable, and among the three catalysts examined H2O-CoIII-OTs was found to be the most active, due to the strong hydrogen bonding between the nucleophilic H2O and the ring oxygen atom in the epoxides as well as the extra π-π stacking interaction. For the stepwise mechanism which consists of the formation of H2O-CoIII-OH, the ring-opening of PO and propylene glycol formation, our studies reveal that different H2O-CoIII-Xs behave kinetically very similarly in the course of propylene glycol formation, but show a notable difference in the rate of H2O-CoIII-OH formation with Cl-OAc-OTs-. The rate ordering with which we rationalize the experimental phenomena well is disclosed to be consistent with the nucleophilicity of the counterions by molecular electrostatic potential, condensed Fukui function and condensed local softness. We show that the nucleophilicity of the counterion determines the favorable mechanism that PO hydration follows.

We studied the ring opening of propylene oxide (PO) by salen-M coordinated OH- group [M = Al(Ⅲ), Sc(Ⅲ), Cr(Ⅲ), Mn(Ⅲ), Fe(Ⅲ), Co(Ⅱ), Co(Ⅲ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Ru(Ⅲ) and Rh(Ⅲ)]. The results show that the ring opening energy barriers for M(II) complexes are much lower than those with M(III) complexes in the gas phase, and the barriers correlate linearly with the negative charges on the OH- group, the Fukui function condensed on the OH- group. The nucleophilicity ordering in gas phase can be rationalized by the ratio of formal positive charges/radius of M cations. Solvent effect greatly increases the barriers of M(II) complexes, but slightly changes the results of M(III) ones, making the barriers similar. Analysis indicates that the reaction heats are linearly proportional to the reverse reaction barriers. The relationships established here can be used to estimate the ring opening barriers and to screen epoxide ring opening catalysts.

This paper presents a control strategy for a planar three-link underactuated manipulator(UM) with a passive first link based on a wavelet neural network (WNN) model. Firstly, by using the particle swarm optimization (PSO) algorithm, the target angles of all links are calculated according to the established kinematic model and the given target position. Then, a WNN model is trained to describe the coupling relationship between the passive link and the second link. The difference between the current angle and the target angle of the passive link is converged to zero by repeatedly controlling the second link to rotate an angle which is calculated by the trained WNN model. Next, the active links are controlled to rotate to their target angles with low speeds. Finally, the effectiveness of the proposed control strategy is verified through experimental results.

A series of bifunctional metal-salen complexes bearing ionic liquid substituents were investigated as catalysts for the synthesis of cyclic carbonates from carbon dioxide (CO2) and epoxides using density functional theory (DFT) and energy span model. Detailed studies reveal that the three-step mechanism involving the ring-opening of propylene oxide (PO), CO2 insertion, and ring-closure to the cyclic carbonate is kinetically more favorable than the two-step mechanism. The effect of ionic liquids, epoxide substituents and metal center of the metal-salen complexes were explored. Amino functionalized ionic liquids substituents tethered to the salen ligand of the metal-salen complexes performed well. Epoxide substituents affect the cycloaddition mainly through the electronic effect and the substituent that lowers the negative charges of the ring carbon atom to be attacked favors the cycloaddition. When the salen ligand is fixed, the catalytic activity metal-salen complexes can be measured by the interaction between the oxygen atom (O) of epoxides and the central metal (M) and there is a linear relationship between the energy span and the M-O bond length, which can be used as a descriptor to screen CO2 conversion catalysts.

Tetrasulfonated aluminum phthalocyanine (AlS4Pc), a strongly red-emitting compound, shows high detection sensitivity, little effect of photobleaching, and photochemical stability, making it an excellent red-fluorescent probe. We have observed that in acid media, a low concentration of poly-L-lysine (PLL) has a strong fluorescence-quenching effect on AlS4Pc, forming the ion-pair complex as AlS4Pc-PLL with almost no fluorescence. However, in the presence of Bi3+, the fluorescence of AlS4Pc-PLL dramatically recovers and the emission is visual because of the remarkable recovery. Screening experiments with other metal ions reveal that only Bi3+ can restore the fluorescence of the AlS4Pc-PLL complex. The presence of other metal ions does not result in the recovery of fluorescence, indicating the high specificity of the response to Bi3+ of AlS4Pc-PLL. This is the key finding of the present study. It was also observed that the response to Bi3+ of AlS4Pc-PLL exhibits a linear relationship over a large concentration range (three orders of magnitude). Based on these findings, we have established a new quantitative analysis method for Bi3+ with high specificity and high sensitivity, using the ion-pair AlS4Pc-PLL complex as a red-fluorescent probe, and we discuss the reaction mechanism. The detection limit of this method is 0.0021 mg L−1. The linear relationship applies to the range of 0.007–34.9 mg L−1 with a correlation coefficient of 0.9993. The method established addresses the complex operation and time-consuming problems in traditional methods and is thus suitable for real applications. Satisfactory results have been obtained when the method was applied to the measurement of real samples. This study further expands the scope of new applications of phthalocyanine-based red-fluorescent probes in analytical sciences.

Tetrasubstituted trimethyl ammonium iodide aluminum phthalocyanine (TTMAAlPc), a positively charged phthalocyanine compound, is an emerging and potentially useful red-emitting fluorescence probe. The study showed that the fluorescence of TTMAAlPc could be quenched by RNA with high efficiency in weak alkaline media, and the degree of quenching has a linear relationship with RNA in a wide concentration range. The mechanism of quenching behavior of RNA on TTMAAlPc was discussed. It was attributed by the static interaction between RNA and TTMAAlPc, and the assembly of TTMAAlPc induced by RNA. Based on this new discovery, a novel method for quantitative determination of RNA at nanogram level has been established. The factors, including the pH of medium, buffer system, reaction time, reaction temperature, the usage of TTMAAlPc as well as the interferences, which affected the determination, were investigated and discussed. Under optimum conditions, the linear range of the calibration curve was 7.71-1 705.57 ng x mL(-1). The detection limit for RNA was 1.55 ng x mL(-1). This method has been applied to the analysis of practical samples with satisfied results. The constructed method is of high sensitivity and has a wide linear range, it also showed strong ability in the tolerance of foreign substances from anions, cations, surfactants and vitamins, all of which are common interferences encountered in the determination of RNA. Besides, it is the first report that the fluorescence quantum yield of TTMAAlPc has been measured at different pH by reference method in this work. The achieved data indicated that the fluorescence quantum yield of TTMAAlPc is larger than 20% and it keeps constant in a wide range of acidity, implying that TTMAAlPc is a high-quality red-emitting fluorescence probe, it has great potential for practical applications, thus is worthy of further study. This work expands the application of phthalocyanine compound in analytical sciences.

Correction for ‘Rapid room temperature synthesis of red iridium(iii) complexes containing a four-membered Ir–S–C–S chelating ring for highly efficient OLEDs with EQE over 30%’ by Guang-Zhao Lu et al., Chem. Sci., 2019, 10, 3535–3542.

Determination of chondroitin sulfate in the biomedical field has an important value. The conventional methods for the assay of chondroitin sulfate are still unsatisfactory in sensitivity, selectivity or simplicity. This work aimed at developing a novel method for sensitive and selective determination of chondroitin sulfate by fluorimetry. We found that some kinds of cationic surfactants have the ability to quench the fluorescence of tetrasulfonated aluminum phthalocyanine (AlS4Pc), a strongly fluorescent compound which emits at red region, with high efficiency. But, the fluorescence of the above-mentioned fluorescence quenching system recovered significantly when chondroitin sulfate (CS) exits. Tetradecyl dimethyl benzyl ammonium chloride(TDBAC) which was screened from all of the candidates of cationic surfactants was chosen as the quencher because it shows the most efficient quenching effect. It was found that the fluorescence of AlS4Pc was extremely quenched by TDBAC because of the formation of association complex between AlS4Pc and TDBAC. Fluorescence of the association complex recovered dramatically after the addition of chondroitin sulfate (CS) due to the ability of chondroitin sulfate to shift the association equilibrium of the association, leading to the release of AlS4Pc, thus resulting in an increase in the fluorescence of the reaction system. Based on this phenomenon, a novel method with simplicity, accuracy and sensitivity was developed for quantitative determination of CS. Factors including the reaction time, influencing factors and the effect of coexisting substances were investigated and discussed. Under optimum conditions the linear range of the calibration curve was 0.20~10.0 μg · mL(-1). The detection limit for CS was 0.070 μg · mL(-1). The method has been applied to the analysis of practical samples with satisfied results. This work expands the applications of AlS4Pc in biomedical area.

The conventional spectrophotometric method that is often applied to determine ribonuclease (RNase) has disadvantages that include cumbersome manipulation, time-consuming processing and a lack of linear range. We had found that a low concentration of RNA could induce cationic aluminum phthalocyanine (tetra(trimethylammonio)aluminum phthalocyanine (TTMAAlPc)), which emitted strong red fluorescence to aggregate in neutral media, resulting in an almost complete quenching of fluorescence from the cationic aluminum phthalocyanine. The RNA is degraded through hydrolysis by RNase, which destroys the induced aggregation of TTMAAlPc on RNA and releases free TTMAAlPc, leading to a significant fluorescence recovery of the reaction system. Based on this new finding, a method to detect RNase by enhanced fluorescence was established using the TTMAAlPc-RNA association complex as a new fluorogenic substrate of RNase. The optimal conditions were determined, and the interfering foreign substances were investigated. Under optimal conditions, the linear range was 0.05 - 50 μg/L, and the detection limit was 0.02 μg/L. This method was applied for the analysis of ribonuclease in urine specimens from normal adults, and the results were consistent with those determined by conventional spectrophotometric methods. The developed method is easy to operate and highly sensitive, and has a wide linear range, thus solving issues with conventional methods. This study applied, for the first time, cationic phthalocyanine as a fluorescent probe in the detection of nuclease, which provides new applications of phthalocyanine as a fluorescent probe emitting at the red wavelength region.