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Neutral and Anionic Guests and Their Effect on the Formation of Pseudorotaxanes by Using a Flexible Tetracationic Imidazolium Macrocycle
Author(s) -
Gong HanYuan,
Rambo Brett M.,
Lynch Vincent M.,
Keller Karin M.,
Sessler Jonathan L.
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201200304
Subject(s) - chemistry , salt (chemistry) , cationic polymerization , naphthalene , biphenyl , sulfonate , supramolecular chemistry , ion , molecular recognition , stereochemistry , molecule , crystallography , crystal structure , polymer chemistry , organic chemistry , sodium
Abstract The ability to control and direct molecular assembly has important implications in the design of environmentally responsive materials. Reported here is the use of competitive neutral‐ and anionic‐guest recognition to control the formation, disruption, replacement‐based construction and higher‐order assembly properties of pseudorotaxane structures involving a large, cationic tetraimidazolium receptor. In particular, we showed that the chloride anion (as the tetrabutylammonium (TBA + ) salt) serves to replace directly the 2,6‐naphthalene dicarboxylate dianion from the preformed complex, involving this dianion. In contrast, the addition of the nitrate anion (as the TBA + salt) serves to effect displacement of a pre‐bound 2,6‐naphthalene dicarboxylate dianion in a stepwise manner allowing for stabilization of a so‐called “outside”‐binding mode under appropriate conditions. We have also found that by using biphenyl‐3,4,3′,4′‐tetraamine as the guest, a 1D‐donor–acceptor–donor coordination polymer can be stabilized, whereas the addition of 6‐amino‐naphthalene‐2‐sulfonate anion to the pre‐formed complex between the tetraimidazolium receptor and the 2,6‐naphthalene dicarboxylate dianion produces a new pseudorotaxane complex. This guest‐based competition and subsequent molecular translocation is supported by solution‐state NMR spectroscopic studies as well as solid‐state single‐crystal X‐ray structural analyses. The results described herein provide initial evidence that guest competition can be used to control molecular “switching” and substrate binding within an appropriately designed anion receptor.