Photoswitchable guanidinium compounds for removal of oxyanions from liquid solutions

Inventors

Custelcean, Radu • Moyer, Bruce A. • Einkauf, Jeffrey

Assignees

UT Battelle LLC

Abstract

A compound having the following structure: wherein: R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 are independently selected from (i) hydrogen atom, (ii) hydrocarbon groups (R) containing 1-30 carbon atoms and optionally substituted with one or more fluorine atoms, (iii) —OR′ groups, (iv) —NR′2 groups, (v) —C(O)R′ groups, and (vi) halogen atoms, wherein R′ groups are independently selected from R groups and hydrogen atoms, and wherein the R group optionally includes a C(O), ether, or amino linkage; Xm− is an anionic species with a magnitude of charge m, where m is an integer of at least 1; and n is a number, provided that n×m=1. Also described herein are methods for removing one or more oxyanions from a liquid source by use of the above compound or mono-pyridyl derivative thereof.

Core Innovation

The disclosed invention relates to photoswitchable dipyridyl/monopyridyl iminoguanidinium oxyanion-precipitating compounds of Formula (1)/(1a)/(2) that complex and precipitate oxyanions from liquid sources. Binding occurs in an open E,E form in which the precipitating compound can complex an oxyanion in solution, and the compounds are characterized by substituent scope (R1–R10) and by the presence of an anionic species X^m− and integers n and m such that n×m=1.

Irradiation with electromagnetic radiation, including visible and/or UV wavelengths, converts the compounds from an open E,E form to a closed Z,Z form. In the closed Z,Z form, the compound cannot bind the oxyanion, which enables non-chemical anion release. The document further describes thermal reversion from the closed Z,Z form back toward the open E,E form and indicates that cycling can be performed without fatigue.

For sulfate as a representative oxyanion system, the document reports photoisomerization behavior and performance support, including quantitative switching of binding strength by more than five orders of magnitude. It also reports binding stoichiometries for sulfate adducts (1:1, 2:1, and 1:2) and includes crystal structures showing an E,E sulfate-bound form and a Z,Z nonbinding form. The disclosed scope covers related oxyanions and supports an oxyanion removal workflow that includes precipitation followed by regeneration of the precipitating compound using electromagnetic exposure.

Claims Coverage

The partial content identifies two independent claims: a structural compound claim and a method of removing an oxyanion from a liquid source. Across these independent claims, the main inventive features include a defined photoswitchable oxyanion-precipitating compound structure with a charge-matched exchangeable anionic species X^m− and a method that relies on precipitation of an oxyanion salt with an anionic species that is exchangeable with the oxyanion prior to contact with the liquid source.

The identified independent claim set anchors protection around a structurally defined oxyanion-precipitating compound and around an oxyanion-removal method that uses precipitation of an oxyanion salt via an exchangeable anionic species X^m−.

Stated Advantages

Documented Applications