Supramolecular Spectrometric Behavior Studies Based On P-Sulfonated Calix[n]Arenes

Supramolecular chemistry, as one of the current frontiers of many disciplines,was extensive and in-depth researched in molecular recognition, drug delivery, new materials, high-performance catalysts and other relevant fields. Calix[n]arenes, synthesized by the base-catalyzed condensation of formaldehyde and p-substituted phenols.due to its variable size of cavity, the conformation in varied forms, easy modification of functional groups, etc., It has become one of the most active areas of supramolecular chemistry which was affected the attention of many scientists.Calixarene was almost insoluble in water and solubility in common organic solvents is small too.When introducing some kinds of functional groups, Its solubility may have a improvement with a certain degree.The main elements of this study is based on calixarene modified on its upper edge by sulfonate structure which like a cone,called sulfonated calixarene.Sulfonated calixarene itself was non-fluorescent in aqueous, UV absorbance is very small too.This paper aims to explore the host-guest interactions between two kinds of molecules by using the ability of sulfonated calixarenes (n= 4,6,8) as a inclusion body molecules with the help of ultraviolet spectrophotometry spectrophotometric analysis, nuclear magnetic resonance spectroscopy and density functional theory calculation and other variety of characterization methods.This study emphasis on the stability of the inclusion complexes in different environments, the stoichiometric ratio between the host and the guest molecule inclusion model, the most reasonable assumption for main driving force of the inclusion interaction, In this paper, It is further broaden the scope of molecular recognition of water-soluble sulfonated calixarenes, lay the foundation for the detection and process of dye wastewater, provides the necessary theoretical support and experimental data for the development and design of new supramolecular drugs and new drug delivery system. The main contents of this paper are as follows:1.Describe the supramolecular chemistry, especially the structural characteristics and development of calixarenes and their derivatives briefly.Meanwhile,focus on the research status and important results of sulfonated calixarenes in molecular recognition, molecular catalysis, controlled release drug molecules, etc.2. In this chapter, The supramolecular interactions between a homologous series of p-sulfonated calix[n]arenes (SCnA, n= 4,6, 8) and chrome blue black R (EBBR) were studied by spectrofluorimetry and other various means.The inclusion of SCnA and EBBR was found to produce a 1:1 host-guest stable complex, the fluorescence intensity significantly decreased compared with EBBR blank solutions with same. Discussion from pH, ionic strength, temperature and other aspects of the factors affecting the inclusion process were also evaluated and the main driving force was verified by 1H NMR studies and density functional theory (DFT) calculation. By explaining the mechanism of interaction between subject and object, we establish the molecular model of host-guest inclusion.3.The cooperation between water-soluble sulfonated calixarenes and naftopidil was investigated by using fluorescence spectroscopy and UV spectrophotometry systematic. Fluorescence emission signal of naftopidil apparently quenching andthe 1:1 stoichiometric ratio of inclusion complex was also characterised. By calculating the values of △C, △H and AS under different temperature conditions,it is comfirmed that the enthalpy change is the thermodynamic driving force of the inclusion reactions.Different combination capabilities under different pH and the effect of ionic strength on inclusion complex were determined. In this paper, assumptions and arguments of the main driving force are put forward It is believed that hydrophobic effect and the size of the matching effect are the main driving force of the inclusion. By means of Gaussian density functional theory, it is demonstrated that in the structure of energy minimization, a part of naftopidil molecules enter into the hydrophobic cavity of sulfonated calixarene, and has been verified from the NMR spectra.4. With the help of fluorescence spectroscopy and NMR spectra, The selective recognition hydrochloric itopride by a homologous series of p-sulfonated calix[n]arenes (SC nA, n=4,6,8) as hosts were investigated. Under optimal conditions of pH, K value of the binding constant between itopride hydrochloride and sulfonated caiixarenes (n= 4,6,8) is calculated by the double reciprocal Benesi-Hildebrand curve, respectively. The obtained results were 1.00×104,1.18 × 105,1.96 × 105.Compared binding constant and fluorescence intensity in different temperatures, it is believed that inclusion complex in a certain temperature range is stabilized by temperature effects is minimal.Except that, common various ions and effects of ionic strength on the inclusion complex systems was also evaluated, the results show that the inclusion complex system were stable, minimal interference.By analyzing the the enormous differences of binding constant and offset of NMR spectra peaks, the most reasonable assumption to simulate different types of clathrate inclusion system were proposed.