Macrocyclic versus open-chain carbazole receptors for carboxylate binding.

The anion recognition properties of six synthetic acyclic and macrocyclic carbazole-based receptors have been studied by 1H-NMR as well as with COSMO-RS calculations towards acetate, benzoate, lactate, sorbate and formate. The receptors differed by the number and geometry of hydrogen-bond donor (HBD) sites, the nature and length of the linker(s) between the HBD sites and the cyclic or non-cyclic nature. The binding ability of the receptors is strongly influenced by the structure and steric variables of the receptors and anions. It was found that when urea was replaced with the flexible diglycolyl as the connecting linker between carbazole subunits, the carboxylate binding affinity of the receptor decreased significantly. The effects of the receptors' structure on anion binding have been investigated and several intriguing cases have been identified and analysed. The current findings shed light on carboxylate anion binding and contribute to the systematic synthesis of receptors with beneficial functional selectivity for carboxylate anions.

Acidity of the chlorinated phenols: DFT study and experiential affirmation.

A quantum mechanical density functional theory (DFT) was successfully developed for the estimation of pKa values of chlorinated phenols in aqueous solution with a precision of 0.9 pKa units. The MP2/6-311++G(d,p)//B3LYP/6-31+G(d) level of theory was used for the gas phase calculation. For computation in the solution phase and to calculate the energy difference of the acid-base, the polarized continuum model (PCM) at the HF/6-31G(d,p) level was used. The pKa value was computed for each involved species using pentachlorophenol (PCP) as a reference molecule. Natural bond orbital (NBO) analysis considering the natural resonance theory (NRT) was carried out on an optimized geometry of studied compounds to give information about the nature of bonds. Graphical abstract Chlorinated phenols.

Synthesis and Characterization of Biodegradable Semi-Interpenetrating Polymer Networks Based on Star-Shaped Copolymers of ɛ-Caprolactone and Lactide.

In this paper, the focus is on a new kind of biodegradable semi-interpenetrating polymer networks, which is derived from ɛ-caprolactone, lactide, 1,4-butane diisocyanate and ethylenediamine and also its potential has been investigated in soft tissue engineering applications. The polymers were characterized by nuclear magnetic resonance (NMR) spectrometry, Fourier transform infrared spectroscopy (FT-IR), differential thermal analysis (DTA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). These experiments show that the polymers with the right composition and the expected molecular weight were achieved. Also, the in-vitro degradation of polymer network was examined in phosphate buffer solutions (pH 7.4) at 37 °C. Moreover, cell viability and adhesion tests were carried out with fibroblast cells by the MTT assay, which confirmed biocompatibility. Polyurethane materials have superior mechanical properties, so these biodegradable and biocompatible films demonstrate potential for future application as cell scaffolds in soft tissue engineering applications.