Novel spirobenzopyran derivatives carrying monoazacrown moieties at the 8-position undergo selective complexation of alkali metal ions and thereby isomerization to their corresponding merocyanine form in the dark; the isomerization is enhanced especially by Li+ that is likely to interact with the phenolate anion intramolecularly when bound to the crown rings.
Potential response and its photoresponse for plasticized-poly(vinyl chloride) membranes containing a lipophilic crowned spirobenzopyran were surveyed and compared with those for membrane systems of a spirobenzopyran deriative not carrying any crown ether moiety. On UV-light irradiation, an intriguing type of time-course change was found with the membrane potential for the crowned spirobenzopyran system in the presence of alkali metal ions, i.e., the potential first increases and then decreases. The photoresponse profile for the crowned spirobenzopyran system was affected considerably by the sort of metal ions and the pH conditions of aqueous phases. This phenomenon is explained by an ion-exchange mechanism specific to crowned spirobenzopyran, that is, fast proton exchange followed by slow metal-ion exhange of its merocyanine form. The system for the corresponding spirobenzopyran without crown ether moiety exhibited a steady potential photoresponse that depends on the pH conditions of aqueous phases.
A spirobenzothiapyran derivative bearing a monoaza-12-crown-4 moiety affords significant thermal stability enhancement in the UV light induced colored merocyanine form of its photochromic moiety by metal-ion complexation of its crown ether moiety, although the complexation hardly induces the isomerization without photoirradiation.
Cation Complexation, Photochromism, and Photoresponsive Ion-Conducting Behavior of Crowned Spirobenzopyran Vinyl Polymers
作者:Keiichi Kimura、Hidefumi Sakamoto、Ryoko M. Uda
DOI:10.1021/ma035644g
日期:2004.3.1
Vinyl polymers incorporating a crowned spirobenzopyran moiety at the side chain were synthesized, and their alkali metal-ion complexation, photochromism, and photoresponsive ion-conducting behaviors were studied in comparison with similar polymers incorporating crown ether and spirobenzopyran moieties independently. The metal-ion complexation by their crown ether moiety significantly affected the photochromism of their spirobenzopyran moiety. The crowned spirobenzopyran polymers are similar to their corresponding monomeric analogue in their metal-ion complexing property and photochromism, with some difference induced by polymer effect. Almost no significant aggregation of the photoinduced merocyanine moiety was found in the crowned spirobenzopyran polymer, unlike the polymers carrying spirobenzopyran and crown ether moiety independently. The crowned spirobenzopyran polymers were applied successfully as components of photoresponsive ion-conducting materials.