Guest Capture and Separation by Temperature Responsive Cyclophane-PNIPAM Conjugates

Conjugates of thermo-responsive poly(N-isopropylacrylamide) with cyclophane monomers and pentamers were synthesized. The conjugates exhibited lowest critical solution temperatures (LCSTs) and each aqueous solution of the conjugates became turbid above their LCSTs upon heating. The conjugates have enough water-solubility below their LCSTs and bound fluorescence guests. Heating of the conjugate-guest solutions followed by centrifugation gave insoluble materials (captured guests and the conjugates). The efficiency of guest-separation from bulk aqueous phase by the pentamers was much higher than those by the monomers. Conjugates of thermo-responsive poly(N-isopropylacrylamide) with cyclophane monomers and pentamers exhibited LCSTs. Each aqueous solution of the conjugates became turbid above their LCSTs upon heating. The conjugates have enough water-solubility below their LCSTs and bound fluorescence guests. Heating of the conjugate-guest solutions followed by centrifugation gave insoluble materials. The efficiency of guest-separation by the pentamers was much higher than the monomers.