Rate control by restricting mobility of substrate in specific reaction field. Negative photochromism of water-soluble spiropyran in AOT reversed micelles

Abstract

The thermocoloration of a water-soluble spiropyran, T,3',3'-trimethylspiro[2Ff-l-benzopyran-2,2'-indoline]-6-sulfonic acid (1), which has been newly synthesized in this work, in the anionic AOT reversed micelles has been investigated in order to evaluate the effect of the reversed micelles in controlling the reaction rates or pathways by restricting the mobility of the substrates being situated in a specific reaction field. The probe 1 showed a negative photochromism in polar solvents such as water, MeOH, and EtOH as well as in the AOT reversed micelles. The thermocoloration rates of 1 were retarded by about 20 times in the 0.2 M AOT/O.6 M H20/hexane micelles compared with those in MeOH in which microscopic polarity was comparable to that in the interior core of the reversed micelles adopted. This was explicable in terms of the restriction in the internal rotation of the 2,3 bond of 1 during the thermocoloration accompanied by the cis-trans isomerization in a largely restricted field as provided by the reversed micelles. The extent of deceleration in the thermocoloration in the AOT reversed Hydroboration Kinetics. 4. Kinetics and Mechanism of the Reaction of 9-Borabicyclo[3.3.1]nonane with Representative Haloalkenes.

Water‐Soluble Spiropyrans with Inverse Photochromism and Their Photoresponsive Electrostatic Self‐Assembly

“…The ring-opening causesc hargeaseparation,whichi nduces al arge dipolem omenti nM C. At the same time, this process is accompanied by as ubstantial structural change, which is not only spatial but also electronic in nature. [51][52][53][54] In the latter case, the sulfonate group is almosta lwaysi ntroduced by alkylation of the indoline nitrogen via as ultone. Furthermore, this increases the basicity of the MC isomer in comparison to SP and makes it pronet op rotona-tion.…”

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

“…1). [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.…”

Photocontrollable Cation Extraction with Crowned Oligo(spirobenzopyran)s

“…[1][2][3][4] Spirobenzopyrans, typical photochromic compounds, isomerize from their electrically neutral spirobenzopyran forms to the corresponding zwitterionic merocyanine form, which has a maximum absorption wavelength around 550 nm, by UV-light irradiation, and vice versa by visible-light irradiation and/or heat. [5][6][7][8][9] Since spirobenzopyrans change not only their conformation but also their electrical properties by photoirradiation, the interaction between the photoionized molecule and a cation may be affected considerably.We had already synthesized spirobenzopyran derivatives bearing a crown ether moiety, which we call crowned spirobenzopyrans [crowned mono(spirobenzopyran)].We studied their metal-ion complexing abilities, photochromism, and applications to photocontrollable devices. [10][11][12][13][14][15] Crowned spirobenzopyrans form complexes with metal ions and simultaneously isomerize from their spirobenzopyran form to the corresponding merocyanine form under dark condition, due to the ionic interaction between the phenolate anion of the merocyanine form and a metal ion complexed by their crown ether moiety (Scheme 1).…”

“…[1][2][3][4] Spirobenzopyrans, typical photochromic compounds, isomerize from their electrically neutral spirobenzopyran forms to the corresponding zwitterionic merocyanine form, which has a maximum absorption wavelength around 550 nm, by UV-light irradiation, and vice versa by visible-light irradiation and/or heat. [5][6][7][8][9] Since spirobenzopyrans change not only their conformation but also their electrical properties by photoirradiation, the interaction between the photoionized molecule and a cation may be affected considerably.…”