Correction: A combined crystallography and DFT study on ring-shaped cucurbit[n]urils: structures, surface character, and host-guest recognition.

[This corrects the article DOI: 10.1039/D2RA00797E.].

Correction: A theoretical study on the on-off phosphorescence of novel Pt(ii)/Pt(iv)-bisphenylpyridinylmethane complexes.

[This corrects the article DOI: 10.1039/D2RA03060H.].

Study of the electronic effect and quantitative spectra predictions of o-methoxyaniline-terminated monoazonaphthols: a combined experimental and DFT study.

A combined experimental and density functional theory (DFT) study on the UV-Vis spectra of o-methoxyaniline-terminated mono azo dyes was conducted. By applying time-dependent-DFT calculations, details of excitation processes were determined and visualization by hole-electron analysis was undertaken. Fragment-divided analysis revealed the contributions of different parts of the structures for the UV-Vis spectra, that richer/poorer electron density on aromatic rings lead to greater/less maximum absorption wavelengths (λmax) and larger/smaller half peak width (W1/2). Combining theoretical prediction with experimental verification, we answered the question of how the electronegativities of substituents affected the electron densities and how it affected the spectra. In addition, a linear model connecting the λmax and W1/2 to the chemical shifts obtained by NMR spectroscopy was constructed, which laid the foundation for construction of a spectral library.

A theoretical study on the on-off phosphorescence of novel Pt(ii)/Pt(iv)-bisphenylpyridinylmethane complexes.

An in-depth theoretical study on the Pt(ii)/Pt(iv)-bisphenylpyridinylmethane complexes was carried out, which focused on the geometric/electronic structures, excitation procedures, on-off phosphorescence mechanisms, and structure-optical performance relationships. The key roles of the linkages (LK) connected in the middle of phenylpyridines were carefully investigated using multiple wavefunction analysis methods, such as non-covalent interaction (NCI) visualizations and natural bond orbital (NBO) studies. The phosphorescence-off phenomenon was considered by hole-electron analysis and visualizations, spin-orbit coupling (SOC) studies, and NBO analysis. Through these investigations, the relationship of the substituents in LK and the optical performances were revealed, as well as the fundamental principles of the phosphorescence-quenching mechanism in Pt(iv) complexes, which pave the way for further performance/structural renovation works. In addition, an intuitive visualization method was developed using a heatmap to quantitatively express the SOC matrix elementary (SOCME), which is helpful for big data simplification for phosphorescence analysis.

A combined crystallography and DFT study on ring-shaped Cucurbit[n]urils: structures, surface character, and host-guest recognition.

A combined crystallography and DFT study of cucurbit[n]urils (n = 5-8, 10) was carried out, and PBE0 was certified to be the most rational density functional method for optimization task. Steric hindrance and electronic effect of the hindered lone pair electrons in cucurbit[n]urils were qualitatively measured by bond order analysis, lone pair electron (LP) visualization and electrostatic potential (ESP) study. Together with energy decomposition analysis of some selected host-guest systems, we quantitatively verified the effect of size/cavity and noncovalent interaction in host-guest recognition. This solid study revealed that lone pairs electrons affect not only on host-guest identification mode but also on geometry stability, which pave the avenue for further sophisticated applications.

Chemodivergent Couplings of N-Arylureas and Methyleneoxetanones via Rh(III)-Catalyzed and Solvent-Controlled C-H Activation.

The efficient couplings of diverse N-arylureas and methyleneoxetanones have been realized via Rh(III)-catalyzed and solvent-controlled chemoselective C-H functionalization, which involved the tunable ß-H elimination and ß-O elimination processes, thereby giving divergent access to quinolin-2(1 H)-ones and ortho-allylated N-arylureas with broad substrate compatibility and good functional group tolerance. the divergent synthetic utilities of the transformations have also been exemplified by subsequently tandem C-H allylation, unsymmetrical C-H functionalization, alternative reaction mode, as well as removal of the carbamoyl group.

Synthesis and Photodynamic Activity of Peri-xanthenoxanthene Derivatives.

Photodynamic therapy (PDT) is a modern cancer therapy. But it is still difficult to obtain ideal photosensitizers. We synthesized six new peri-xanthenoxanthene derivatives rapidly and efficiently using solid-phase carbon-bath microwave irradiation technology, and investigated their in vitro photodynamic antitumor activity with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Our results showed that all compounds exhibited extremely low dark cytotoxicity and good phototoxicity against four human cancer cell lines. In particular, compound 3c showed the best in vitro PDT activity against Hela cells and Bel-7402 cells with IC50 values of 91 and 74 nmol/L, respectively. Its value of 1-octanol/water partition coefficient (log Kow) was 0.5309, suggesting that it is a promising photosensitizer for PDT due to its low dark cytotoxicity, high phototoxicity, and potential water solubility.

A simple functionalized silica microsphere for fast PETN vapor detection based on fluorescence color changes via a catalyzed oxidation process.

In this work, we report a new fluorescent material for pentaerythritol tetranitrate (PETN) vapor detection. A series of fluorene substituted vinyl-SiO microspheres with different ratios has been designed and easily synthesized. Sensing films on quartz plates were obtained by a solid phase transfer method. With a specific diameter of SiO and a specific density of surrounding fluorene, the microspheres performed a rapid fluorescence color change via oxidation with highly selective PETN catalysis. The emission peak at 355 nm was rapidly quenched while an enhancement at 525 nm appeared under exposure to PETN saturated vapor. Herein, we present this fluorescent silica nanoparticle as an excellent sensing material towards vapor phase PETN, making contributions to many fields such as public security and military use.

Bran-New Four-Molecule and Five-Molecule Cascade Reactions for One-Pot Synthesis of Pyrano[3,2-c]chromen-5-ones and Spiro[benzo[b][1,4]diazepine-2,2'-pyrano[3,2-c]chromen]-5'-ones under Catalyst- and Solvent-Free Conditions.

Herein, two versatile bran-new methods have been developed for building three new kinds of complicated-framework compounds including 2,4,4-trimethyl-2-(phenylamino)-3,4-dihydro-2H,5H-pyrano[3,2-c]chromen-5-ones, 4,4,4',4'-tetramethyl-1,3,3',4,4',5-hexahydro-5'H-spiro-[benzo[b][1,4]diazepine-2,2'-pyrano[3,2-c]-chromen]-5'-ones, and 2,2,4',4'-tetramethyl-2,3,3',4'-tetrahydro-5H,5'H-spiro[benzo[b][1,4]-oxazepine-4,2'-pyrano[3,2-c]chromen]-5'-ones in a one-pot manner via four-molecule and five-molecule cascade reactions of commercially available 4-hydroxychromen-2-one, substituted anilines, and acetone. In consideration of these impressive features including no need of additional catalysts and solvents, moderate to good yields, excellent site-selectivity, and broad substrate/functional group tolerance, we believe that the two present protocols should have the potential for broad synthetic utility.

Analysis of volatile components in Dalbergia cochinchinensis Pierre by a comprehensive two-dimensional gas chromatography with mass spectrometry method using a solid-state modulator.

Volatile components in Dalbergia cochinchinensis Pierre were analysed using a comprehensive two-dimensional gas chromatography with mass spectrometry method featuring a new solid-state modulator. Compared to one-dimensional gas chromatography, the number of detected peaks were significantly increased. A total of 45 major compounds were identified in this study and the forward and reverse match factors of these compounds were both above 800. The results showed that the volatile components in Dalbergia cochinchinensis Pierre were primarily aldehyde and ketone compounds such as benzaldehyde, cinnamaldehyde, 4-chromanone, 1-(2-hydroxyphenyl)ethanone and acetophenone. In addition, a semi-quantitative analysis was conducted to determine the contents of the detected compounds based on peak area percentage. Moreover, the repeatability of the comprehensive two-dimensional gas chromatography-mass spectrometry analysis in this study was quite satisfactory with relative standard deviations less than 12.7% for intraday and 17.3% for interday measurements.

Preclinical Study of Novel Curcumin Analogue SSC-5 Using Orthotopic Tumor Xenograft Model for Esophageal Squamous Cell Carcinoma.

PURPOSE: Tumor xenograft model is an indispensable animal cancer model. In esophageal squamous cell carcinoma (ESCC) research, orthotopic tumor xenograft model establishes tumor xenograft in the animal esophagus, which allows the study of tumorigenesis in its native microenvironment. MATERIALS AND METHODS: In this study,we described two simple and reproducible methods to develop tumor xenograft at the cervical or the abdominal esophagus in nude mice by direct injection of ESCC cells in the esophageal wall. RESULTS: In comparing these two methods, the cervical one presented with more clinically relevant features, i.e., esophageal stricture, body weight loss and poor survival. In addition, the derived tumor xenografts accompanied a rapid growth rate and a high tendency to invade into the surrounding structures. This model was subsequently used to study the anti-tumor effect of curcumin, which is known for its potential therapeutic effects in various diseases including cancers, and its analogue SSC-5. SSC-5 was selected among the eight newly synthesized curcumin analogues based on its superior anti-tumor effect demonstrated in an MTT cell proliferation assay and its effects on apoptosis induction and cell cycle arrest in cultured ESCC cells. Treatment of orthotopic tumor-bearing mice with SSC-5 resulted in an inhibition in tumor growth and invasion. CONCLUSION: Taken together, we have established a clinically relevant orthotopic tumor xenograft model that can serve as a preclinical tool for screening new anti-tumor compounds, e.g., SSC-5, in ESCC.

Study on the design, synthesis and structure-activity relationships of new thiosemicarbazone compounds as tyrosinase inhibitors.

52 Structure-based thiosemicarbazone compounds bearing various substituted-lipophilic part, including substituted-benzaldehyde, substituted-phenylalkan-1-one and their biphenyl-type thiosemicarbazone analogs, were designed, synthesized and evaluated as new tyrosinase inhibitors. The results demonstrated that 22 compounds have potent inhibitory activities against tyrosinase with the IC50 value of lower than 1.0 µM. On the basis of the obtained experimental data, the structure-activity relationships (SARs) were rationally derived. Besides, the inhibition mechanism and the inhibitory kinetics of selected compounds 3d and 6e were investigated, revealing that such type of compounds were belonged to the reversible and competitive tyrosinase inhibitors. To verify the safety of these developed thiosemicarbazone compounds, four randomly selected compounds 3d, 4e, 6a and 9a were also tested in 293T cell line for the evaluation of the cytotoxicity. Interestingly, all these compounds almost did not perform any toxicity to 293T cells even at a high concentration of 1000 µmol/L. Taken together, these results suggested that such compounds could serve as the highly efficient and more safe candidates for the treatment of tyrosinase-related disorders.

Exploration of metal-organic framework MOF-177 coated fibers for headspace solid-phase microextraction of polychlorinated biphenyls and polycyclic aromatic hydrocarbons.

Metal-organic frameworks (MOFs) have received much attention in analytical science for their large langmuir surface and high thermostability. Herein MOF-177-coated solid-phase micro-extraction (SPME) fibers were fabricated on etched stainless steel by an adhensive method, and applied to the enrichment of polychlorinated biphenyls (PCB01, PCB05, PCB29, PCB47, PCB98, PCB154, PCB171, PCB201) and polycyclic aromatic hydrocarbons (ANY, ANA, FLU, PHE, ANT, FLT, PYR) from environmental water samples. Several parameters affecting the extraction efficiency were optimized prior to the gas chromatography-mass spectrometry analysis, including extraction temperature and time, desorption time, stirring rate and salt addition. The results indicated that the coated fiber gave low detection limits (0.69-4.42 ng L(-1)) and good repeatability with the RSD ranging from 1.47% to 8.67% for PCBs and PAHs. The recoveries were between 81.8% and 113% with the spiked level of 10 ng L(-1) for the real water samples. Besides, the MOF-177 coated fiber was stable enough over 100 extraction cycles and the RSD for fiber-to- fiber reproducibility was less than 9.82% during the experiment.

[Study on Glycosides Constituents from Guangdong Liangcha Granules(II)].

OBJECTIVE: To study the glycosides from Guangdong Liangcha Granules. METHODS: The chemical constituents were isolated by various chromatographic techniques and the structures of chemical constituents were identified by spectroscopic analysis and literature. RESULTS: Six compounds were isolated and identified as ilexoside B (1), asprellanosides B (2), asprellanoside A (3), 4', 5 ,7 -tri- hydroxyflavone-6-O-ß3-D-glucopyranosyl ester(4), isoviolanthin (5),3-O-methy-lellagic acid 4'-O-rhamnopyranoside (6). CONCLUSION: Compounds 1 - 5 are firstly obtained from Guangdong Liangcha Granules.

Rh(III)-catalyzed and alcohol-involved carbenoid C-H insertion into N-phenoxyacetamides using α-diazomalonates.

Here we report a new and mild Rh(III)-catalyzed and alcohol-involved carbenoid C-H insertion into N-phenoxyacetamides using α-diazomalonates. This reaction provided a straightforward way for installing both an α-quaternary carbon center and a free-OH moiety into the phenyl ring, thus giving access to useful 2-(2-hydroxyphenyl)-2-alkoxymalonates with good substrate/functional group tolerance.

Rational design, synthesis and structure-activity relationships of 4-alkoxy- and 4-acyloxy-phenylethylenethiosemicarbazone analogues as novel tyrosinase inhibitors.

In continuing our program aimed to search for potent compounds as highly efficient tyrosinase inhibitors, here a series of novel 4-alkoxy- and 4-acyloxy-phenylethylenethiosemicarbazone analogues were designed, synthesized and their biological activities on mushroom tyrosinase were evaluated. Notably, most of compounds displayed remarkable tyrosinase inhibitory activities with IC50 value of lower than 1.0µM. Furthermore, the structure-activity relationships (SARs) were discussed and the inhibition mechanism and the inhibitory kinetics of selected compounds 7k and 8d were also investigated. Taken together, these results suggested that such compounds could serve as the promising candidates for the treatment of tyrosinase-related disorders and further development of such compounds might be of great interest.

Structure-based modification of 3-/4-aminoacetophenones giving a profound change of activity on tyrosinase: from potent activators to highly efficient inhibitors.

In this study, we developed 3-/4-aminoacetophenones and their structure-based 3-/4-aminophenylethylidenethiosemicarbazide derivatives, respectively, as novel tyrosinase activators and inhibitors. Notably, all the obtained thiosemicarbazones displayed more potent tyrosinase inhibitory activities than kojic acid. Especially, compound 7k was found to be the most active tyrosinase inhibitor with IC50 value of 0.291 µM. The structure-activity relationships (SARs) analysis showed that: (1) the amine group was absolutely necessarily for determining the tyrosinase activation activity; (2) the introduction of thiosemicarbazide group played a very vital role in transforming tyrosinase activators into tyrosinase inhibitors; (3) the phenylethylenethiosemicarbazide moiety was crucial for determining the tyrosinase inhibitory activity; (4) the type of acyl group had no obvious effect on the inhibitory activity; (5) the position of amide substituent on the phenyl ring influenced the tyrosinase inhibitory potency. Moreover, the inhibition mechanism and inhibition kinetics study revealed that compound 7k was reversible and non-competitive inhibitor, and compound 8h was reversible and competitive-uncompetitive mixed-II type inhibitor.

One-pot cascade synthesis of N-methoxyisoquinolinediones via Rh(III)-catalyzed carbenoid insertion C-H activation/cyclization.

Here a new, mild and versatile method for one-pot cascade synthesis of diverse N-methoxyisoquinolinediones via Rh(III)-catalyzed regioselective carbenoid insertion C-H activation/cyclization of N-methoxybenzamides with α-diazotized Meldrum's acid has been achieved. Extension of the developed Rh(III) catalysis for building new analogs of the marketed drug Edaravone has also been demonstrated.

Design, synthesis and biological evaluation of hydroxy- or methoxy-substituted 5-benzylidene(thio) barbiturates as novel tyrosinase inhibitors.

Here a new class of hydroxy- or methoxy-substituted 5-benzylidene(thio)barbiturates were designed, synthesized and their inhibitory effects on the diphenolase activity of mushroom tyrosinase were evaluated. The results showed that several compounds had more potent tyrosinase inhibitory activities than the widely used tyrosinase inhibitor kojic acid (IC50=18.25µM). In particular, 3',4'-dihydroxylated 1e was found to be the most potent inhibitor with IC50 value of 1.52µM. The inhibition mechanism analysis revealed that the potential compounds 1e and 2e exhibited such inhibitory effects on tyrosinase by acting as the irreversible inhibitors. Structure-activity relationships' (SARs) analysis also suggested that further development of such compounds might be of interest.

Synthesis and evaluation of some new aza-B-homocholestane derivatives as anticancer agents.

Using analogues of some marine steroidal oximes as precursors, a series of aza-B-homocholestane derivatives possessing different substituted groups at the 3-position of the steroidal nucleus were synthesized. Their biological activity against cancer cell proliferation was determined with multiple cancer cell lines. Aza-B-homocholestane derivatives possessing 3-hydroxyl, 3-hydroximino and 3-thiosemicarbazone groups displayed remarkable cytotoxicity to cancer cells via apoptosis inducing mechanism. Compounds 5, 10, 12, 15 and 18 exhibited better potency to inhibit cancer cell proliferation. In addition, compound 15 was further evaluated with three dimensional (3D) multicellular spheroids assay to determine its potency against spheroid growth. The structure-activity relationship (SAR) generated in the studies is valuable for the design of novel chemotherapeutic agents.