Chemical binding

About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.

Nanomolar Binding of Peptides Containing Noncanonical Amino Acids by a Synthetic Receptor

Abstract: This paper describes the molecular recognition of phenylalanine derivatives and their peptides by the synthetic receptor cucurbit[7]uril (Q7). The 4-tert-butyl and 4-aminomethyl derivatives of phenylalanine (tBuPhe and AMPhe) were identified from a screen to have 20–30-fold higher affinity than phenylalanine for Q7. Placement of these residues at the N-terminus of model tripeptides (X-Gly-Gly), resulted in no change in affinity for tBuPhe-Gly-Gly, but a remarkable 500-fold increase in affinity for AMPhe-Gly-Gly, which bound to Q7 with an equilibrium dissociation constant (Kd) value of 0.95 nM in neutral phosphate buffer. Structure–activity studies revealed that three functional groups work in a positively cooperative manner to achieve this extraordinary stability (1) the N-terminal ammonium group, (2) the side chain ammonium group, and (3) the peptide backbone. Addition of the aminomethyl group to Phe substantially improved the selectivity for peptide versus amino acid and for an N-terminal vs nonterminal...

Layered LiTiO2 for the protection of Li2S cathodes against dissolution: mechanisms of the remarkable performance boost

Abstract: Lithium sulfide (Li2S) cathodes have been viewed as very promising candidates for next-generation lightweight Li and Li-ion batteries. Prior work on the deposition of carbon shells around Li2S particles showed reduced dissolution of polysulfides and improved cathode stability. However, due to the substantial volume changes during cycling and the low chemical binding energy between carbon and sulfides, defects almost inevitably forming in the carbon shell during battery operation commonly lead to premature cell failure. In this study, we show that conformal coatings of layered LiTiO2 may offer better protection against polysulfide dissolution and the shuttle effects. Density functional theory (DFT) calculations revealed that LiTiO2 exhibits a strong affinity for sulfur species (Li2Sx) and, most importantly, induces a rapid conversion of longer (highly soluble) polysulfides to short polysulfides, which exhibit minimum solubility in electrolytes. Quite remarkably, even the mere presence of the electronically conductive layered oxides (LiMO2, M = metal) such as LiTiO2 in the cathodes (e.g., as a component of the mix with Li2S) enhanced the cell rate and cycling stability dramatically. Advanced material characterization in combination with quantum chemistry calculations provided unique insights into the mechanisms of the incredible performance boost, such as interactions between Li2Sx and the LiTiO2 surface, leading to breakage of S–S bonds.

Spectroscopic Analysis of Metal Ion Binding in Spiropyran Containing Copolymer Thin Films

Abstract: In this article, we describe the synthesis and characterization of a series of spiropyran containing copolymers that were used as colorimetric sensors for a series of divalent metal ions. The composition of spiropyran contained in the polymer backbone was varied from 10−100 mol % to investigate the influence of free volume and sterics on the photochromic response. Fourier transform-infrared (FT-IR) spectroscopy was used to characterize the photoinduced conversion, as well as the merocyanine−metal ion (MC−M2+) interaction. FT-IR spectra were analyzed using chemometric methods to elucidate the chemical binding environment between MC and M2+ and to selectively identify different metal ions bound to MC. By means of UV−vis absorption spectroscopy, we also demonstrate that each metal ion gives rise to a unique colorimetric response that is dependent on the amount of spiropyran comonomer contained in the polymer backbone and that by increasing the concentration of chromophore in the copolymer, the selectivity be...