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Self‐Assembly of a Trilanthanide(III) Core Sandwiched between Two Thiacalix[4]arene Ligands
Author(s) -
Iki Nobuhiko,
Tanaka Teppei,
Hirooka Shoichi,
Shinoda Kozo
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201600762
Subject(s) - chemistry , core (optical fiber) , self assembly , calixarene , stereochemistry , combinatorial chemistry , nanotechnology , polymer chemistry , organic chemistry , molecule , materials science , composite material
Thiacalix[4]arene‐ p ‐tetrasulfonate (TCAS) incorporated a trilanthanide(III) core to form a 3:2 Ln 3 TCAS 2 complex in aqueous solution. The self‐assembly process was monitored at pH 9.5 and 7.4 by HPLC for all lanthanides except Pm III . Self‐assembly took place in three steps. First, TCAS and Ln III formed a 1:1 Ln 1 TCAS 1 complex. Second, two molecules of Ln 1 TCAS 1 condensed to form Ln 2 TCAS 2 . Finally, Ln 2 TCAS 2 reacted with additional Ln III to form Ln 3 TCAS 2 . This self‐assembly exhibited extremely slow kinetics and required 1–4 d to reach completion. Small amounts of minor species, including Ln 1 TCAS 1 , Ln 2 TCAS 2 , and Ln 4 TCAS 2 , were observed depending on the Ln III species and pH. The generation of these species is controlled by factors such as the stability of the Ln‐TCAS species, effect of coordinated water, and size of Ln III . XAFS spectra of aqueous Gd 3 TCAS 2 solutions established the solution structure of the tri‐Ln III cluster sandwiched by two TCAS ligands.