Quartz Crystal Microbalance monitoring the real-time binding of lectin with carbohydrate with high and low molecular mass

A Quartz Crystal Microbalance (QCM) was used to monitor the mass changes on a quartz crystal surface containing immobilized lectins that interacted with carbohydrates. The strategy for lectin immobilization was developed on the basis of a multilayer system composed of Au–cystamine–glutaraldehyde–lectin. Each step of the immobilization procedure was confirmed by FTIR analysis. The system was used to study the interactions of Concanavalin A (ConA) with maltose and Jacalin with Fetuin. The real-time binding of different concentrations of carbohydrate to the immobilized lectin was monitored by means of QCM measurements and the data obtained allowed for the construction of Langmuir isotherm curves. The association constants determined for the specific interactions analyzed here were (6.4 ± 0.2) × 10⁴ M^− 1 for Jacalin–Fetuin and (4.5 ± 0.1) × 10² M^− 1 for ConA–maltose. These results indicate that the QCM constitutes a suitable method for the analysis of lectin–carbohydrate interactions, even when assaying low molecular mass ligands such as disaccharides.     

Synthesis of Boltorn 1,2,3‐triazole dendrimers by click chemistry

Second‐, third‐, and fourth‐generation hyperbranched aliphatic polyols namely Boltorn® H20, Boltorn H30, and Boltorn H40 were endcapped with azido and activated acetylenic groups in good to excellent yields (75–95%) following an acid catalyzed procedure. The resultant terminally functionalized dendritic azido and acetylenic groups undergo 1,3‐dipolar cycloaddition using methyl (or ethyl) propiolate and benzyl azide, respectively, under catalytic or noncatalytic conditions below 40 °C to yield 1,2,3‐triazole dendrimeric polymers in 82–95% yield, under extremely mild conditions that could be applied for compounds sensitive to acid, base, or heat. The dendritic azido and activated acetylenic derivatives may act as novel scaffolds to tune the mechanical properties of different polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3748–3756, 2009     

Summary of ISO/TC 201 standard: ISO 11775:2015 – Surface chemical analysis – Scanning probe microscopy – Determination of cantilever normal spring constants

This International Standard describes five methods for the determination of normal spring constants for atomic force microscope cantilevers to an accuracy of 5 to 10%. Each method is in one of the three categories of dimensional, static experimental and dynamic experimental methods. The method chosen depends on the purpose, convenience and instrumentation available to the analyst. For accuracies better than 5 to 10%, more sophisticated methods, not described in the standard, are required. Copyright © 2016 Crown copyright. Surface and Interface Analysis © 2016 John Wiley & Sons, Ltd.     

Inter- or intramolecular electron transfer between triruthenium clusters: we’ll cross that bridge when we come to it

The purpose of this review is to examine the fundamental differences between intermolecular self-exchange vs. intramolecular ET in mixed-valence complexes based on similar triruthenium structural units. The role of orbital overlap between ancillary ligands of the electron donor and acceptor are considered in self-exchange reactions which are found to be strongly adiabatic and again in bridged mixed-valence systems. The method of infrared (IR) reflectance spectroelectrochemistry for the determination of extremely fast (10¹¹–10¹³ s^?1) ET rate constants is reviewed as a tool to provide quantitative information about the time scales of localization and delocalization. The role of internal vibrations of the bridging ligand in strongly delocalized mixed-valence ions is investigated by resonance Raman and IR spectroscopies. The role of solvent dipolar relaxation times in determining the rates of ultrafast intramolecular ET reactions is reviewed in the context of inorganic mixed-valence chemistry. Finally, the concept of Robin–Day Class II/III “borderline” complexes is considered, and a concise definition of the localized to delocalized transition is provided in terms of the relative contributions of external solvent and internal complex ion vibrational modes to ET.