Synthesis and structures of O-anthrylmethyl-substituted hexahomotrioxacalix[3]arenes

O-Alkylation of 7,15,23-tri-tert-butyl-25,26,27-trihydroxy-2,3,10,11,18,19-hexahomo-3,11,19-trioxacalix[3]arene (1H₃) with 9-chloromethylanthracene 5 was carried out under different reaction conditions. Variation of the number of anthrylmethyl group introduced at the phenolic rim of hexahomotrioxacalix[3]arene 1H₃ was achieved through selective O-alkylation using stoichiometric amounts of 9-chloromethylanthracene 5 in acetone to afford the mono-O-alkylated product 2H₂An, the di-O-alkylated product 3HAn₂ and the tri-O-alkylated product partial-cone-4An₃, respectively. Interestingly, by using an acetone/benzene (1:1 v/v) mixed solvent system, the cone-4An₃ was successfully synthesized. These results suggest that the solvent can also control the conformation of the O-alkylation products. The possible reaction routes of the cone-4An₃ and partial-cone-4An₃ are also discussed

A pyrene-functionalized triazole-linked hexahomotrioxacalix[3]arene as a fluorescent chemosensor for Zn²⁺ ions

A new pyrenyl appended hexahomotrioxacalix[3]arene L featuring 1,2,3-triazole linkers was synthesized as a fluorescent chemosensor for Zn²⁺ in mixed aqueous media. It exhibited high affinity toward Zn²⁺, and the monomer and excimer emission of the pyrene moieties could be adjusted. The binding stoichiometry of the L·Zn²⁺ complex was determined to be 1:1, and the association constant (Ka) was found to be 7.05 × 10⁴ M⁻¹. The binding behavior with Zn²⁺ has been confirmed by ¹H NMR spectroscopic analysis

Synthesis and evaluation of a novel fluorescent sensor based on hexahomotrioxacalix[3]arene for Zn²+ and Cd²+

A novel type of selective and sensitive fluorescent sensor having triazole rings as the binding sites on the lower rim of a hexahomotrioxacalix[3]arene scaffold in a cone conformation is reported. This sensor has desirable properties for practical applications, including selectivity for detecting Zn²⁺ and Cd²⁺ in the presence of excess competing metal ions at low ion concentration or as a fluorescence enhancement type chemosensor due to the cavity of calixarene changing from a ‘flattened-cone’ to a more-upright form and inhibition of PET. In contrast, the results suggested that receptor 1 is highly sensitive and selective for Cu²⁺ and Fe³⁺ as a fluorescence quenching type chemosensor due to the photoinduced electron transfer (PET) or heavy atom effect

2-(Hy­droxy­meth­yl)pyridin-3-ol

In the crystal structure of the title compound, C6H7NO2, the mol­ecules are are linked by inter­molecular O—H⋯N and O—H⋯O hydrogen bonds; π–π stacking is observed between parallel pyridine rings of adjacent mol­ecules [centroid-to-centroid distance = 3.7649 (12) Å]

Click-modified hexahomotrioxacalix[3]arenes as fluorometric and colorimetric dual-modal chemosensors for 2,4,6-trinitrophenol

A new type of chemosensor-based approach to the detection of 2,4,6-trinitrophenol (TNP) is described in this paper. Two hexahomotrioxacalix[3]arene-based chemosensors 1 and 2 were synthesized through click chemistry, which exhibited high binding affinity and selectivity toward TNP as evidenced by UV–vis and fluorescence spectroscopy studies. ¹H NMR titration analysis verified that CH⋯O hydrogen bonding is demonstrated as the mode of interaction, which possibly facilitates effective charge-transfer

A screened predictive model for esophageal squamous cell carcinoma based on salivary flora data

Esophageal squamous cell carcinoma (ESCC) is a malignant tumor of the digestive system in the esophageal squamous epithelium. Many studies have linked esophageal cancer (EC) to the imbalance of oral microecology. In this work, different machine learning (ML) models including Random Forest (RF), Gaussian mixture model (GMM), K-nearest neighbor (KNN), logistic regression (LR), support vector machine (SVM) and extreme gradient boosting (XGBoost) based on Genetic Algorithm (GA) optimization was developed to predict the relationship between salivary flora and ESCC by combining the relative abundance data of Bacteroides, Firmicutes, Proteobacteria, Fusobacteria and Actinobacteria in the saliva of patients with ESCC and healthy control. The results showed that the XGBoost model without parameter optimization performed best on the entire dataset for ESCC diagnosis by cross-validation (Accuracy = 73.50%). Accuracy and the other evaluation indicators, including Precision, Recall, F1-score and the area under curve (AUC) of the receiver operating characteristic (ROC), revealed XGBoost optimized by the GA (GA-XGBoost) achieved the best outcome on the testing set (Accuracy = 89.88%, Precision = 89.43%, Recall = 90.75%, F1-score = 90.09%, AUC = 0.97). The predictive ability of GA-XGBoost was validated in phylum-level salivary microbiota data from ESCC patients and controls in an external cohort. The results obtained in this validation (Accuracy = 70.60%, Precision = 46.00%, Recall = 90.55%, F1-score = 61.01%) illustrate the reliability of the predictive performance of the model. The feature importance rankings obtained by XGBoost indicate that Bacteroides and Actinobacteria are the two most important factors in predicting ESCC. Based on these results, GA-XGBoost can predict and diagnose ESCC according to the relative abundance of salivary flora, providing an effective tool for the non-invasive prediction of esophageal malignancies

rac-Methyl 2-(2-formyl-4-nitro­phen­oxy)hexa­noate

In the racemic title compound, C14H17NO6, the plane of the ester group of the methyl hexa­noate side chain makes a dihedral angle of 80.0 (2)° with the benzene ring, while the nitro group is approximately coplanar with the benzene ring [dihedral angle = 10.3 (2)°]. In the crystal, mol­ecules form weak aromatic C—H⋯Onitro hydrogen-bonding inter­actions, giving inversion dimers [graph set R 2 2(8)]

A novel fluorescence “on–off–on” chemosensor for Hg²⁺ via a water-assistant blocking heavy atom effect

Upper rim pyrene-functionalized hexahomotrioxacalix[3]arene L was synthesized via Click chemistry, and its fluorescence behaviors toward several common metal cations were investigated. L exhibited a significant fluorescence quenching response to Hg²⁺ in CH₃CN solution, which was unaffected by the coexistence of other competitive metal cations. Thus, L can be utilized as a highly selective and sensitive fluorescent chemosensor for Hg²⁺ with a detection limit in the nM level. Interestingly, the quenched fluorescence emission can be successfully revived upon the addition of water. In this process, the heavy atom effect of Hg²⁺ can be blocked by further coordination of a water molecule and resulted in the revival of the fluorescence emission of L/Hg²⁺ complex. Particularly, other polar solvents such as CH₃OH and CH₃CH₂OH also have the ability to revive the fluorescence emission of the L/Hg²⁺ complex, but on a much smaller scale than observed for H₂O. The heavy atom effect and blocking thereof were demonstrated within the same system by the use of a C₃-symmetric homooxacalix[3]arene scaffold. The present studies provided further evidence for the blocking heavy atom effect

Preparation and properties of a washable flame-retardant coated fabric

In this study, a flame-retardant-coating (FRC) agent has been prepared using hydrophobic organic silicone-phosphorus-nitrogen flame retardant and acrylic emulsion. Polyester-cotton blend fabric (P/C) has been treated with FRC agent, and the finishing process, thermal decomposition, flame retardancy, washability, softness and other properties are studied. Results show that the treated fabrics are of good flame retardancy; LOI is up to 32%, thermal degradation rate reduces by 7.8 %/min and thermal damage reduces by 74%. Limiting oxygen index (LOI) is found to be 24.6% and 23.7% for 5 and 10 times washing. The fastness shows excellent washability