Charles J. Pedersen's legacy to chemistry.

The serendipitous discovery in 1961 of dibenzo-18-crown-6 by Charles J. Pedersen marked the beginning of research on cyclic polyether macrocyclic compounds. These compounds have a remarkably selective affinity for certain metal ions and provide a framework for studying molecular recognition processes.

Challenges to achievement of metal sustainability in our high-tech society.

Achievement of sustainability in metal life cycles from mining of virgin ore to consumer and industrial devices to end-of-life products requires greatly increased recycling rates and improved processing of metals using conventional and green chemistry technologies. Electronic and other high-tech products containing precious, toxic, and specialty metals usually have short lifetimes and low recycling rates. Products containing these metals generally are incinerated, discarded as waste in landfills, or dismantled in informal recycling using crude and environmentally irresponsible procedures.

Charles J. Pedersen: innovator in macrocyclic chemistry and co-recipient of the 1987 Nobel Prize in chemistry.

Charles J. Pedersen began life in Korea where his father was employed as an engineer at a gold mine in a remote region of that country. He received his primary and secondary school education in Japan and university training in the United States.

Efficient immobilization of a cadmium chemosensor in a thin film: generation of a cadmium sensor prototype.

[reaction: see text] The development of an ion-selective chemosensor for Cd(2+) allows generation of a "real-time" sensor. Immobilization of the chemosensor on quartz was achieved in a simple monolayer and in a thin film using a polymer intermediary. As intended, the thin film contains much more chemosensor than the monolayer and provides measurable responses to aqueous Cd(2+) concentrations below 1 microM.

Syntheses and Metal Ion Complexation of Novel 8-Hydroxyquinoline-Containing Diaza-18-Crown-6 Ligands and Analogues.

Ten new 8-hydroxyquinoline-containing diaza-18-crown-6 ligands and analogues were synthesized via a one-pot or stepwise Mannich reaction, reductive amination, or by reacting diaza-18-crown-6 with 5,7-dichloro-2-iodomethyl-8-quinolinol in the presence of N,N-diisopropylethylamine. The Mannich reaction of N,N'-bis(methoxymethyl)diaza-18-crown-6 with 4-chloro-2-(1H-pyrazol-3-yl)phenol gave the NCH(2)N-linked bis(3-(5-chloro-2-hydroxy)pyrazol-1-ylmethyl)-substituted diazacrown ether (14) in a 98% yield. The reaction of bis(N,N'-methoxymethyldiaza)-18-crown-6 with 2.

New Tetraazacrown Ethers Containing Two Pyridine, Quinoline, 8-Hydroxyquinoline, or 8-Aminoquinoline Sidearms.

A series of macrocyclic tetraazacrown ethers containing two pyridine, quinoline, 8-hydroxyquinoline, or 8-aminoquinoline sidearms has been prepared. Crab-like cyclization of bis(alpha-chloroacetamide)s and diamines followed by reduction of the cyclic diamides was used to synthesize the selected crown ethers containing two unsubstituted macroring nitrogen atoms. The preparation of the macrocycles with sidearms was accomplished by reductive amination of the proper aldehydes with the crown ethers using sodium triacetoxyborohydride (NaBH(OAc)(3)) as the reducing agent.

Synthesis and Properties of 5-Chloro-8-hydroxyquinoline-Substituted Azacrown Ethers: A New Family of Highly Metal Ion-Selective Lariat Ethers.

New 5-chloro-8-hydroxyquinoline (CHQ)-substituted aza-18-crown-6 (4), diaza-18-crown-6 (1), diaza-21-crown-7 (2), and diaza-24-crown-8 (3) ligands, where CHQ was attached through the 7-position, and aza-18-crown-6 (11) and diaza-18-crown-6 (10) macrocycles, where CHQ was attached through the 2-position, were prepared. Thermodynamic quantities for complexation of these CHQ-substituted macrocycles with alkali, alkaline earth, and transition metal ions were determined in absolute methanol at 25.0 degrees C by calorimetric titration.

Chiral Pyridine-Based Macrobicyclic Clefts: Synthesis and Enantiomeric Recognition of Ammonium Salts.

An achiral (3) and two chiral pyridine-based macrobicyclic clefts (4 and 5) have been prepared by treating 2,6-bis[[2',6'-bis(bromomethyl)-4'-methylphenoxy]methyl]pyridine (2) with the appropriate achiral and chiral glycols. Starting 2 was prepared by first treating 2,6-bis(hydroxymethyl)-4-methylphenol with 2,6-[(tosyloxy)methyl]pyridine followed by phosphorus tribromide. Achiral macrobicyclic cleft 3 formed a complex at 25 degrees C in 50% CH(3)OH/50% CHCl(3) (v/v) with a primary ammonium salt (log K = 3.

Mannich Reaction as a Key Strategy for the Synthesis of Benzoazacrown Ethers and Benzocryptands.

A convenient method for the synthesis of mono- and polycyclic azacrown macrocycles containing aromatic fragments using the Mannich condensation of phenols and secondary diamines has been studied. This new approach allowed the synthesis of bisphenols connected by oligoazaoxaalkane units in good yields without the need to protect the phenolic OH groups. These bisphenols (13-16) were alkylated with ditosylates of polyethylene glycols to give benzoazacrown ethers 25-30.