Studies on the effect of solvents on self-assembled monolayers formed from organophosphonic acids on indium tin oxide

The preparation of self-assembled monolayers (SAMs) of organophosphonic acids on indium tin oxide (ITO) surfaces from different solvents (triethylamine, ethyl ether, tetrahydofuran (THF), pyridine, acetone, methanol, acetonitrile, dimethyl sulfoxide (DMSO), or water) has been performed with some significant differences observed. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and contact angle measurement demonstrated that the quality of SAMs depends critically on the choice of solvents. Higher density, more stable monolayers were formed from solvents with low dielectric constants and weak interactions with the ITO. It was concluded low dielectric solvents that were inert to the ITO gave monolayers that were more stable with a higher density of surface bound molecules because higher dielectric constant solvents and solvents that coordinate with the surface disrupted SAM formation.     

Polymer control of ligand display on gold nanoparticles for multimodal switchable cell targeting

The function of cell-specific ligands on gold nanoparticles can be selectively gated by the action of co-grafted thermosensitive polymers. Below the LCST the responsive chain-extended polymers prevent cell-surface receptors from accessing the affinity ligands while above the LCST, the polymers collapse exposing the ligands and allowing binding to receptors, which in turn promotes cell internalisation.     

Self‐Assembled Gels for Biomedical Applications

Natural and synthetic gel‐like materials have featured heavily in the development of biomaterials for wound healing and other tissue‐engineering purposes. More recently, molecular gels have been designed and tailored for the same purpose. When mixed with, or conjugated to therapeutic drugs or bioactive molecules, these materials hold great promise for treating/curing life‐threatening and degenerative diseases, such as cancer, osteoarthritis, and neural injuries. This focus review explores the latest advances in this field and concentrates on self‐assembled gels formed under aqueous conditions (i.e., self‐assembled hydrogels), and critically compares their performance within different biomedical applications, including three‐dimensional cell‐culture studies, drug delivery, and tissue engineering. Although stability and toxicity issues still need to be addressed in more detail, it is clear from the work reviewed here that self‐assembled gels have a bright future as novel biomaterials.     

Determining association constants from titration experiments in supramolecular chemistry

The most common approach for quantifying interactions in supramolecular chemistry is a titration of the guest to solution of the host, noting the changes in some physical property through NMR, UV-Vis, fluorescence or other techniques. Despite the apparent simplicity of this approach, there are several issues that need to be carefully addressed to ensure that the final results are reliable. This includes the use of non-linear rather than linear regression methods, careful choice of stoichiometric binding model, the choice of method (e.g., NMR vs. UV-Vis) and concentration of host, the application of advanced data analysis methods such as global analysis and finally the estimation of uncertainties and confidence intervals for the results obtained. This tutorial review will give a systematic overview of all these issues-highlighting some of the key messages herein with simulated data analysis examples.     

Macrocyclic Bis(phenanthroline‐pyrrole): A Convenient One‐Pot Synthesis,Structure(s), Spectroscopic,and Redox Properties,and the Binding of Amine Guests,Protons, and Lanthanide Ions

This paper reports a convenient, one‐pot, easily scalable and readily modifiable synthesis of a novel large‐ring bis(1,10‐phenanthrolinyl‐2,5‐pyrrole) macrocycle, H₂L_MC and describes its spectroscopic and electrochemical properties, protonation, cooperative amine binding, electrocatalysis of the oxidation of primary amines, photosensitization of the decomposition of dichloromethane, and the first lanthanide complexes of the hexaaza‐dianion L_MC ^2? including the novel dimer, [(NO₃)( L_MC )Eu(μ‐OH)Eu( L_MC )(H₂O)₂]?2py.     

Chiral molecular tapes from novel tetra(thiafulvalene-crown-ether)-substituted phthalocyanine building blocks

A tetra(thiafulvalene-crown-ether) phthalocyanine self-assembles into helical tapes nanometers wide and micrometers long. Formation of these scrolled molecular architectures is a first for phthalocyanine fibres and shows potential as a novel conducting material.     

A reconsideration of Legendre-Jacobi symbols

The classical definition of the Jacobi symbol (a:b) was badly conceived for negative values of b. Alternative useful definitions of (a:?1) are proposed here. This is an elaboration of a point in the article “Spinor genera of binary quadratic forms” in this issue.