Photochromic transformations of amphiphilic spiropyran in acetonitrile solutions and at the air/water interface (original) (raw)
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Protection of Metals and Physical Chemistry of Surfaces, 2019
The work presents the results of a study of the negative photochromism and luminescent properties of 1',3'-dihydro-3',3'-dimethyl-6-nitro-1'-octadecyl-[1-benzopyran-2,2'-indole]-8-methyl pyridinium chloride (SP2) in solutions, Langmuir monolayers, and cast films. It has been demonstrated that the introduction of the pyridine substituent into the chromene part of the amphiphilic spiropyran leads to stabilization of the open form of the compound under dark conditions, both in the dissolved and in the ordered planar state. The kinetic characteristics of photoreactions occurring in organic solvents upon irradiation by visible light and during relaxation in darkness are determined. Negative solvatochromism of SP2, which consists in the hypsochromic shift of the maximum absorption of the merocyanine form of the compound upon increase of the solvent polarity, is revealed. The luminescent properties of solutions of negative spiropyran and its cast films are investigated. For the first time, SP2 monolayers are formed at the air/water interface and their properties are studied. It is established that SP2 retains its photochromic properties upon transition from solutions to a two-dimensional condensed state. The results obtained open up broad prospects for the development of switchable optoelectronic and information systems based on negative spiropyrans.
Controls of photochromic reactions in spiropyran Langmuir-Blodgett films
Thin Solid Films, 1988
The possibility of controlling photochromic reactions has been investigated in Langmuir-Blodgett (LB) films. The formation of J aggregates of a spiropyran (SP1822) with two long chains has been found previously. We have studied another possibility using LB films of l'-octadecyl-3',3'-dimethyl-6-nitro-8-methoxyspiro[2H-l-benzopyran-2,2'-indoline] (SP1801). SP1801 at the air-water interface gave a monolayer which showed the photomerocyanine form. The LB film of the compound returned to the spiropyran form in the dark. The LB film of the hetero structure with SP1801 and stearic acid, however, turned to J aggregates from the photomerocyanine form spontaneously in the dark. The absorption of the J aggregates was a sharp and intense band, and the half-decay period in the dark was 104 times longer than that of conventional spiropyrans. SP1801, in addition to SP1822, is suggested as a candidate for a multifrequency optical memory system with several J-aggregated photochromic compounds having different sharp absorption bands.
Dynamics of a photochromic spiropyran under aqueous conditions
EPJ Web of Conferences, 2013
The dynamics of a water soluble spiropyran is investigated by means of femtosecond transient absorption spectroscopy in the visible and infrared spectral range revealing an ultrafast reversible switching behavior under aqueous conditions with a high fatigue resistance.
The photochromism of spiropyrans bound on side-chains of soluble polymers
European Polymer Journal, 1981
The effect was investigated of the distance of the photochromic ce ltre of 5'-aminomethyll',3',3'-trimethyl-6-nitrospiro[2H-l-benzopyran-2,2'-indoline] from the methyl methacrylate chain on the kinetics of the discolouration process. The centre was bound through an amide bond on side-chains consisting of various numbers of methylene groups of ~-amino acids. The thermal discolouration of acetone solutions followed first-order kinetics. Elongation of the side-chain on which the spiropyran unit was bound caused an increase in the thermal discolouration rate. In nonpolar solutions, an effect of polar centres of the polymer chain was superimposed on the dependence.
Photochromic Behavior of Spiropyran in Polyurethane Thin Films
The International Conference on Chemical and Environmental Engineering
The aim of this work is to characterize the photochromic properties of a commercial grade of polyurethane (PU) that contains small quantities of spiropyran (SP) [1-hexyle-3,3-dimethyl-6'-nitrospiro (indoline-2',2'-benzopyran)]. PU photochromic films were illuminated with ultraviolet irradiation (365 nm) at room temperature and the absorbance spectra are recorded after scanning from 400 to 800 nm (visible zone). The effects of film thickness, irradiation time, and SP concentration on the polymer photochromic response have been studied. Furthermore, the photochromic behavior of polymer films under stretching and the kinetics of thermal decoloration of these films will be discussed.
Quantitative study of the photostability of spiropyrans
Journal of Photochemistry and Photobiology A: Chemistry, 1989
The method of determination of the quantum yields of the irreversible photodegradation of photochromic spiropyran solutions is discussed. The proposed method is based on the simultaneous determination of the concentration of the spirocyclic form using pulsed photolysis (by formation of photoinduced form B) and absorption spectra of the products. Photodegradation occurs during the action of a continuous source of monochromatic light. Quantum yields of photodegradation cpc for 63 spiropyrans from five different classes (differing in heterocyclic moiety) are determined. For all the compounds studied the cpc value is affected by the structure of the benzochromene moiety in the molecule (with the exception of the dithiolane series). It is considered that the photodegradation of spiropyran is caused by the interactions between the solvent and the isomer of the coloured 3X form of spiropyran.