Haoyun An

A novel two-step method to prepare new unsymmetrical cryptands

Abstract A novel two-step method to prepare unsymmetrical cryptands from available diethanolamine, oligoethylene glycol dichloride and other dihalides is reported. A new cryptand with two bridges each containing one methylene unit exhibited a sodium over potassium selectivity of more than 1,000.

The synthesis of new diaza-N-pivot lariat 15-crown-5 and 18-crown-6 macrocycles

Abstract Nine diaza-15-crown-5 and nine diaza-18-crown-6 macrocycles containing tertiary aminoalkyl and hydroxyalkyl side groups attached to one of the ring nitrogen atoms have been prepared in good yields. The ring closure step involved the reaction of a bis -secondary amine containing the tertiary aminoalkyl or hydroxyalkyl substituent with ethylene glycol bis -(2-iodoethyl)ether or diethylene glycol bis -(2-chloroethyl)ether plus sodium iodide. The starting tertiary aminoalkyl- or hydroxyalkyl-substituted bis -secondary aimine was prepared by reacting N-[2-(2-chloroethoxy)ethyl]acetamide or its benzamide analogue with a primary amine.

Studies on the synthesis and properties of open-chain and macrocyclic crown compounds

Eight new open-chain crown compounds (1–8) and two new macrocyclic crown ethers (9 and10) were synthesized from 1,5-bis(2-aminophenoxy)-3-oxapentane (15) and 1,8-bis(2-aminophenoxy)-3,6-dioxaoctane (16) which were prepared by the catalytic hydrogenation of the corresponding bis(2-nitrophenoxy) derivatives13 and14. The fluorescent property investigation of two open-chain crown ethers (7 and8) indicated that they exhibit complexing effects on Ag+ and Mn2+ cations and can be used as fluorescent reagents for the microanalysis of the metal cations. The pyrolysis kinetics measurement for compounds5 and6 in nitrogen and air was carried out, and their reaction orders and activation energy were obtained. They are one-step and two-step pyrolysis reactions in nitrogen and air, respectively.

The synthesis of bis(benzo-15-crown-5) derivatives and their use in potassium-PVC membrane electrodes

Five new bis(benzo-15-crown-5) derivatives with different connecting groups were synthesized. Potassium ion-selective PVC membrane electrodes based on these bis(crown ether)s were prepared and their selective properties were measured. The results showed that most of these electrodes are stable over a wide pH range and their selectivity coefficients were better than those of an electrode based on natural valinomycin.

Structure and Thermodynamic Aspects of Macrobicyclic Polyether—Metal Ion Interactions

The crystals structure of a K+-diptychand-I5CS-18C6 iodide complex has been determined from X-ray data. The complexed bicyclic molecule crystallizes in the triclinic space group PĪ with a = 9.99S(4) A, b = 10.097(4) A, c = 13.72S(6) A, α = 90.12(3)°, β = 93.62(4) °, γ = 97.S6(3)°. The structure was solved using heavy atom methods and refined to R = 0.032 for 3262 independent reflections. In the crystal structure, the K + lies between the two crown ether rings, and is coordinated by the nine donor atoms of the ligand molecule. The complexation properties of the ligand with K + and Na + were studied by titration calorimetry in 90% (v/v) MeOH/H20 solution. The studies indicate the formation of 1 : 1 ligand: metal ion complexes in both solid state and solution.