文献类型：期刊文献

英文题名：Cation-Dependent Gold Recovery with a-Cyclodextrin Facilitated by Second-Sphere Coordination

作者：Liu, Zhichang[1];Samanta, Avik[1];Lei, Juying[2];Sun, Junling[1];Wang, Yuping[1];Stoddart, J. Fraser[1]

机构：[1]Northwestern Univ, Dept Chem, 2145 Sheridan Rd, Evanston, IL 60208 USA;[2]East China Univ Sci & Technol, Sch Resources & Environm Engn, 130 Meilong Rd, Shanghai 200237, Peoples R China

年份：2016

卷号：138

期号：36

起止页码：11643

外文期刊名：JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000383410700037)】；

基金：We thank Dr Roger Pettman for his useful suggestions and helpful discussions. We thank Drs. Charlotte L. Stern and Amy A. Sarjeant for carrying out the single-crystal XRD analyses. This work made use of the EPIC facility of the NUANCE Center at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); and the State of Illinois, through the IIN.

语种：英文

摘要：Herein, we report an alkali metal cation-dependent approach to gold recovery, facilitated by second-sphere coordination with eco-friendly alpha-cyclodextrin (alpha-CD). Upon mixing eight salts composed of Na+, K+, Rb+, or Cs+ cations and [AuX4](-) (X = Cl/Br) anions with alpha-, beta-, or gamma-CD in water, co-precipitates form selectively from the three (out of 24) aqueous solutions containing alpha-CD with KAuBr4, RbAuBr4, and CsAuBr4, from which the combination of alpha-CD and KAuBr4 affords the highest yield. Single-crystal X-ray analyses reveal that in 20 of the 24 adducts CD and [AuX4](-) anions form 2:1 sandwich-type second-sphere adducts driven partially by [C-H center dot center dot center dot X-Au] interactions between [AuX4](-) anions and the primary faces of two neighboring CDs. In the adduct formed between alpha-CD and KAuBr4, a [K(OH2)(6)](+) cation is encapsulated inside the cavity between the secondary faces of two alpha-CDs, leading to highly efficient precipitation owing to the formation of a cation/anion alternating ion wire residing inside a continuous alpha-CD nanotube. By contrast, in the other 19 adducts, the cations are coordinated by OH groups and glucopyranosyl ring O atoms in CDs. The strong coordination of Rb+ and Cs+ cations by these ligands, in conjunction with the stereoelectronically favorable binding of [AuBr4](-) anions with two alpha-CDs, facilitates the co-precipitation of the two adducts formed between alpha-CD with RbAuBr4 and CsAuBr4. In order to develop an efficient process for green gold recovery, the co-precipitation yield of alpha-CD and KAuBr4 has been optimized regarding both the temperature and the molar ratio of alpha-CD to KAuBr4.