Design and Synthesis of Open-Chain Hosts Having a Partial Structure of p-tert-Butylthiacalixarene

Naoya Morohashi, Kazuki Nanbu, Hayato Sonehara, Jun Ogihara, Takanori Shimazaki, Tetsutaro Hattori

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The development of separation materials for hard-to-separate molecular mixtures is highly desired from environmental and economic perspectives. Although the crystal of p-tert-butylthiacalix[4]arene exhibits high guest selectivity in inclusion from a mixture of molecules with similar sizes and shapes, it cannot include molecules larger than its calix cavity. To extend its guest inclusivity, we designed and synthesized an open-chain host, [3,3′-thiobis(5-tert-butyl-2-hydroxybenzene)-1,1′-diyl]diacetic acid (4). The competitive inclusion among toluidine isomers using compound 4 gave inclusion crystals containing the p-isomer in 1:1 (host/guest) ratio, with lesser amounts of other isomers and/or solvent molecules. The isomer selectivity varied between 66% and 97% depending on the solvent employed. X-ray analysis of inclusion crystals 4·p-toluidine·MeCN and 4·p-toluidine·(o-toluidine)0.5 revealed that compound 4 includes p-toluidine by forming macrocyclic 2:2 inclusion complex(es) and that its higher-order structure has vacant spaces, in which molecules other than p-toluidine are included. Compound 4 was then transformed into monopropyl ester 5 to fill the vacant spaces with propyl moieties. Compound 5 included p-toluidine with high selectivity (∼96%) without the coinclusion of other molecules, regardless of the solvent employed.

Original languageEnglish
Pages (from-to)2235-2243
Number of pages9
JournalJournal of Organic Chemistry
Volume83
Issue number4
DOIs
Publication statusPublished - 2018 Feb 16

ASJC Scopus subject areas

  • Organic Chemistry

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