title: Synthesis and photochromism of spirobenzopyrans and spirobenzothiapyran derivatives bearing monoazathiacrown ethers and noncyclic analogues in the presence of metal ions.
abstract: Spirobenzopyrans bearing monoazathiacrown ethers and noncyclic analogues were synthesized, and their ion-responsive photochromism depending on the dual metal ion interaction with the crown ether and the phenolate anion moieties was examined using alkali and alkaline-earth metal ions, Ag(+), Tl(+), Pb(2+), Hg(2+), and Zn(2+). The prepared spirobenzopyrans showed a selective binding ability to Mg(2+) and Ag(+) with negative and positive photochromism, respectively. Among the metal ions, only Ag(+) facilitated photoisomerization to the corresponding merocyanine form. Depending on the ring size of the monoazathiacrown ether moieties, soft metal ions such as Hg(2+) and Ag(+) showed significant shifts in the UV-vis absorption spectra, while hard metal ions such as Mg(2+), Zn(2+), and Pb(2+) did not afford any meaningful shift. This result reflects that the monoazathiacrown ether and phenolate anion moieties prefer soft and hard metal ions, respectively. Therefore, the Mg(2+) and Ag(+) selectivities are mainly derived from the phenolate anion and monoazathiacrown ether moieties, respectively. On the other hand, a spirobenzothiapyran bearing 3,9-dithia-6-monoazaundecane showed a remarkable selectivity to Ag(+).
authors.affiliation: Special Division for Human Life Technology, National Institute of Advanced Industrial Science and Technology, 1-8-31, Midorigaoka, Ikeda, Osaka 563-8577, Japan.
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Tanaka
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Ikeda
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xu
authors.forename: Hisanori
authors.initials: H
authors.lastname: Ando
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Shibutani
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Setsuko
authors.initials: S
authors.lastname: Yajima
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kimura