Photoresponsive Liquid Membrane Transport of Alkali Metal Ions Using Crowned Spirobenzopyrans

Abstract

Several azacrown ether derivatives, which are monoaza-12-crown-4, -15-crown-5, and -18-crown-6 and diaza-12-crown-4 and -18-crown-6, bearing one or two spirobenzopyran(s), which we call crowned spirobenzopyran or crowned bis(spirobenzopyran), were synthesized and were used as carriers for liquid membrane transport of alkali metal ions. The passive alkali metal transports through liquid membranes containing crowned spirobenzopyrans were carried out under dark, and UV- and visible-light irradiation conditions. The metal ion transport was accelerated and retarded by UV- and visible-light irradiation, respectively. On the other hand, the photoresponse of the metal ion selectivity in membrane transport by crowned spirobenzopyrans was different, depending on the kind of crown ether units. Especially, diaza-12-crown-4-bis(spirobenzopyran) exhibited an excellently selective and effective transporting ability for Li(+). The uphill transports of Li(+) through a liquid membrane containing monoaza-12-crown-4-spirobenzopyran or diaza-12-crown-4-bis(spirobenzopyran) were realized under the conditions where the same aqueous solution was used as the source and receiving phases with UV and visible lights being irradiated onto the boundary phases between the source and membrane phases and between the receiving and membrane phases, respectively. The uphill transport of Li(+) from the source to receiving phases through a liquid membrane containing a crowned spirobenzopyran was also attained by the proton-concentration gradient between the source and receiving phases under dark conditions, and the transporting ability was remarkably increased by photoirradiation.

Analytical and Separation Chemistry by Taking Advantage of Organic Photochromism Combined with Macrocyclic Chemistry

“…39 In competitive alkali-metal ion transport systems using crowned spirobenzopyrans 1 -3 (R = C18H37), the liquid membranes containing crowned spirobenzopyrans bearing monoaza-12-crown-4 [1 (R = C18H37)], respectively. These metal-ion transport selectivities of the crowned spirobenzopyrans correspond to the metal-ion complexing selectivities of the crown ether moieties attached to the spirobenzopyran moiety.…”

“…The Li + transport behavior through a liquid membrane containing crowned spirobenzopyran 1 (R = C18H37) was examined under dark and photoirradiation conditions, using an aqueous solution containing several kinds of metal ions as the "source phase" and an aqueous solution without any metal ion as the "receiving phase". 39 The Li + transportability increased as follows: when visible light was irradiated to the interface between the source and membrane phases with the receiving phase being kept under dark conditions < when both the aqueous solutions were kept under dark conditions < when UV light was irradiated to the interface between the source and membrane phases with the receiving phase being kept under dark conditions < when UV and visible lights were irradiated to the both of the interfaces between the source and membrane phases and between the receiving and membrane phases, respectively.…”

Spiropyran-based optical approaches for mercury ion sensing: Improving sensitivity and selectivity via cooperative ligation interactions using cysteine

“…Using the unique properties of molecule binding and photochromism, spiropyrans have been employed not only in material chemistry for optical data store [19], but also in analytical chemistry as molecular sensors for metal ions (Scheme 1A) [20]. During the past decades, a number of diverse spiropyrans have been synthesized for optical sensing of heavy and transition metal ions [21][22][23][24], alkali metal [25,26] and alkaline-earth metal ions [27,28], and lanthanide ions [29,30].…”

“…Moreover, the relative strong chelating capability of N, O-atoms of the merocyanine with all heavy and transition metal ions makes it rather difficult to discriminate between chemically closely related cations [21]. In order for a spiropyran to selectively respond to a metal ion, more sophisticated systems, with multiple metal binding sites in the spiropyran-crown (or cryptand) ether conjugates have been developed [25][26][27][28]. However, the synthesis of such spiropyrans that comprise an appended crown accepts is a trivial task.…”

Molecular Design of Tetraazamacrocyclic Derivatives Bearing a Spirobenzopyran and Three Carboxymethyl Moieties and Their Metal-Ion Complexing Behavior

“…[1][2][3] Spirobenzopyran derivatives bearing a crown ether moiety, what we call crowned spirobenzopyrans, have some interesting characteristics, so they have been used as colorimetric reagents for metal ions in liquid-liquid extractions. 4,5 Crowned spirobenzopyrans can be isomerized from their spiropyran form to the corresponding merocyanine form by metal ion complexation even under dark conditions. [6][7][8][9][10][11][12] The metal-ion complexing ability of a crowned spirobenzopyran is drastically increased as compared to that of its parent crown ether moiety due to the interaction between the phenolate anion of the merocyanine moiety and a metal ion.…”