Separating reagents based on macrocyclic and tripodal compounds with specific structural effects, secondary amido compounds with extremely weak affinity of δ⁺ nature, and adsorbents based on biomass wastes have been prepared in our group. Calixarene derivatives as macrocyclic host compounds exhibited specific extraction property for target metal ions, and adsorbents incorporating these calixarene derivatives also exhibited specific adsorption property by maintaining the property. Adsorbents based on biomass wastes with various functional groups for metal adsorption exhibited metal adsorption property. In this paper, based on the lead extraction property with acetic acid derivative of calix[4]arene and other target metal extraction property with other derivative of calixarene, the preparation and metal adsorption using four types of adsorbents incorporating the derivatives of calixarenes were reported. Gold adsorption and the following reduction using adsorbents based on biomass wastes, human hair and microalgae, were also reported.

Looking back on the 40 years of ion exchange research, the studies mainly focusing on the supramolecular analytical reagents developed at Sophia University were summarized. The selective transduction of molecular recognition events into physical or chemical signals is a key concept for the design of novel supramolecular sensors. By using various combinations of fluorescent probes and azoprobes possessing the binding sites of phenylboronic acids and dipycolyl amines with cyclodextrins (CDs), the unique recognition functions for metal ions, sugars, and phosphate derivatives were achieved by CD complexes, chemically modified CD complexes, and CD gel complexes based on their synergistic functions. To realize a novel supramolecular chirality, the twisted structure of two ditopic azoprobes inside the CD was successfully controlled by multi-point recognition of guest ions in water. The CD nanogels and dendrimer nanoparticles having phenylboronic acid binding sites were found to discriminate the bacteria spacies. These unique functions of supramolecular CD complexes and nanogel sensors are reviewed in relation to their supramolecular structures.

A novel core-shell ion-exchange resin (St-60) at a fixed core:shell monomer weight ratio of 40:60 and different degrees of cross-linking (10% and 40%) in the porous shell was prepared. The effect of cross-linking degree (10–55%) for these resins and St-60 (55%) in the porous shell on the separation of carbohydrates was examined under strong alkaline conditions. A mixture of inositol, glucose, fructose, and sucrose was separated using 0.10 or 0.15 mol/L NaOH eluent at flow rates of 0.3–0.7 mL/min. The retention times of glucose, fructose, and sucrose on St-60 (40% and 50% degrees of cross-linking) were shorter than those on the fully porous resin (55% degree of cross-linking). The retention times of these carbohydrates increased as the degree of cross-linking in the porous shell decreased. The theoretical plate number for glucose and sucrose also increased as the degree of cross-linking decreased.