Design and synthesis of novel amphiphilic calixarenes, amphiphilic urea sulfonate salts and fluorescent anion receptors.

Antimicrobial resistance has become a growing threat over the last decade to the health and safety of the human populous, with the task of developing new antimicrobials having become the responsibility of academic researchers. Current antimicrobials are largely based on those that interact with specific proteins, but these are becoming increasingly less and less effective as microbials develop resistance to the antimicrobials currently in circulation. Work published by Hiscock et al. has developed a novel class of amphiphilic antimicrobials that target the phospholipid membrane rather than common protein targets. Building on the past work within the Hiscock group and extending this research is the basis for the work described herein. Amphiphilic antimicrobial calix[4]arene derived compounds have been synthesised and amphiphilic urea-sulfonate salts have been designed, the properties of which have been studied in the solid, liquid and gas states.The study of the urea-sulfonate salts in the solid state showed that the compound tends to form extended structures with several different binding modes. In the gas phase, low level complexes are visible which indicate the bonds formed between the structures are strong as they survive the experimental conditions. Studies in the solution state show that the compounds form larger structures in DMSO, whilst one compound formed larger structures in an H2O: EtOH 19:1 solution. The results obtained thus far prove the compounds to be amphiphilic, but do not indicate antimicrobial activity, so, further study is required.The detection of anions in the environment is an ever-growing concern in modern society as the world becomes more aware of the impact that anionic pollutants are having upon the Earth. Anionic receptors are molecules designed to detect, respond to, and recognise species carrying a negative charge. The application of anionic receptors to modern day science is varied and includes organocatalysts which may be catalysed through hydrogen bond formation, in the separation of anionic mixtures in industrial or radioactive waste as well as applications in biology, for the treatment of ion channel based diseases such as cystic fibrosis.1 Novel fluorescent anionic receptors have been designed and synthesised based on works published by Hiscock et al., with properties studied in the solid, liquid and gas state also.Studies in the solid state showed the formation of intramolecular bonds with two of the compounds synthesised, along with the formation of intermolecular bonds between one compound and water that is used to stabilise the extended crystal structure. In the gas phase, one compound showed the presence of low-level complexes. In the solution state all the receptors detected the presence of anions and showed selectivity to specific anions also, where the order of selectivity showed an inverse in the Hofmeister series.