Assessment of EtQxBox complexation in solution by steady-state and time-resolved fluorescence spectroscopy

Structural characterization of the supra-molecular complex between a tetra-quinoxaline-based cavitand and benzo-nitrile

The structural characterization is reported of the supra-molecular complex between the tetra-quinoxaline-based cavitand 2,8,14,20-tetra-hexyl-6,10:12,16:18,22:24,4-O,O'-tetra-kis-(quinoxaline-2,3-di-yl)calix[4]resorcinarene (QxCav) with benzo-nitrile. The complex, of general formula C84H80N8O8·2C7H5N, crystallizes in the space group P with two independent mol-ecules in the asymmetric unit, displaying very similar geometrical parameters. For each complex, one of the benzo-nitrile mol-ecules is engulfed inside the cavity, while the other is located among the alkyl legs at the lower rim. The host and the guests mainly inter-act through weak C-H⋯π, C-H⋯N and dispersion inter-actions. These inter-actions help to consolidate the formation of supra-molecular chains running along the crystallographic b-axis direction.

A summary of calixarene-based fluorescent sensors developed during the past five years

Calixarenes are "chalice like" phenol-based macrocycles that are one of the most fascinating studied scaffolds in supramolecular chemistry. Their preorganized nonpolar cavities and ion binding sites, and their well-defined conformations all lay important foundations for forming host-guest complexes. Conjugation of calixarene scaffolds with various fluorophores at either upper or lower rims has led to the development of smart fluorescent probes for inorganic molecules or ions, aliphatic or aromatic compounds, biomolecules, temperature and hypoxia, even multi-component traditional Chinese medicine (TCM). Moreover, significant advancements have been made for biological applications. This review critically summarizes the recent advances made in these areas.

Exploring the mode of binding between butylated hydroxyanisole with bovine serum albumin: Multispectroscopic and molecular docking study

Considering the harm of BHA on humans, thorough research of the effect of BHA on the structure of serum albumin is necessary. The binding mechanisms of BHA with bovine serum albumin (BSA) and the effects of other three food additives (butylated hydroxytoluene, benzoic acid and citric acid) on BHA-BSA system were researched by multispectroscopy and molecular docking. The fluorescence quenching experiment results showed that the fluorescence quenching mechanism of BSA by BHA was static quenching. The binding constant ((5.70 ± 0.38) × 103 M-1 at 298 K) and thermodynamic parameters (ΔH = 110.8 ± 2.91 kJ·mol-1 and ΔS = 443.3 ± 9.30 J·mol-1·K-1) indicated that BHA and BSA formed a relatively stable complex through hydrophobic interaction. Three-dimensional fluorescence spectra confirmed the conformation changes of BSA due to the binding of BHA. Site marker competitive experiments and molecular docking proved that BHA could bind BSA into site I in subdomain IIA. The results of molecular docking showed that BHA formed hydrophobic interactions with amino acid residues (Ala290, Leu237, Leu259, Ile263 and Ile289). The presence of other food additives weakened the binding of BHA to BSA.