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Poly(acrylamidoxime) adsorbents are often invoked in discussions of mining uranium from seawater. While the amidoxime-uranyl chelation mode has been established, a number of essential binding constants remain unclear. This is largely due to the wide range of conflicting pK(a) values that have been reported for the amidoxime functional group. To resolve this existing controversy we investigated the pK(a) values of the amidoxime functional group using a combination of experimental and computational methods. Experimentally, we used spectroscopic titrations to measure the pK(a) values of representative amidoximes, acetamidoxime, and benzamidoxime. Computationally, we report on the performance of several protocols for predicting the pK(a) values of aqueous oxoacids. Calculations carried out at the MP2 or M06-2X levels of theory combined with solvent effects calculated using the SMD model provide the best overall performance, with a root-mean-square deviation of 0.46 pK(a) units and 0.45 pK(a) units, respectively. Finally, we employ our two best methods to predict the pK(a) values of promising, uncharacterized amidoxime ligands, which provides a convenient means for screening suitable amidoxime monomers for future generations of poly(acrylamidoxime) adsorbents.

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4,7, was investigated in 50 % CH 3 OH/H 2 O (v/v) as a fluorescent sensor for heavy metal ions, and as the Cd II complex as a sensor for anions. The Pb II complex showed a unique strong emission at 447 nm, possibly a charge-transfer band involving the 6p←6s 2 transition of Pb II and the benzyl fluorophore. Zn II uniquely produced a significant emission at 353 nm, suggested to be due to an aggregation induced (AIE) mechanism, possibly involving exciplex formation. The free DB-cyclen ligand produces a fluorescence band at 354 nm above pH ca. 9, accompanied by the slow formation of an aggregate in suspension as indicated by the presence of light scattering peaks in the absorbance spectra, an AIE effect, due to formation of an [a] Materials: The ligand DB-cyclen (1,7-Dibenzyl-1,4,7,10-tetraazacyclododecane) was obtained from Alfa Aesar in 99.8 % purity (lot Eur.

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