Solid-phase synthesis of photochromic spiropyrans

[reaction: see text] A convenient solid-phase synthesis of spiropyrans is described. A succinate linker was employed, which allows base-catalyzed cleavage of the desired photochromophore derivatized with a succinimide. Excellent yields and purities were obtained for the compounds that comprise a library of 23 spiropyrans. Opening of the succinimide ring in spiropyran could be realized under mild conditions.     

Investigation of complexation of functionalized 1,3-benzoxazinone spiropyrans with metal ions

For the first time, complexation between the metal ions and the molecules of photochromic benzooxazine spiropyrans was found and studied. The observed spectral-kinetic changes are explained by the complex formation between molecules of the merocyanine type, resulted from the dissociation of -C-O- bonds, and by electrostatic interaction between complex components depending on the compound structure and the metal ion nature.     

Effect of complexation on spectral and kinetic properties of crown-substituted photochromic spironaphthoxazines

The insertion of benzo-15-crown-5 or benzo-18-crown-6 as a substituent at the 9'-position of a spironaphthoxazine molecule increases the lifetime of the open form of spironaphthoxazine by a factor ofca. 2. The complex formation between the crown groups and Mg²⁺ or Ba²⁺ ions changes the lifetime slightly. The addition of benzo-18-crown-6 at the 5'-position leads to an increase in the lifetime of the open form by an order of magnitude and the appearance of absorption with a maximum at 16420 cm^–1 under dark conditions, which testifies to the stabilization of the open form. The addition of Ba²⁺ ions to this compound results in a further increase in the lifetime byca. 35% due to complex formation. The luminescence of the benzo-15-crown-5-substituted compound is probably caused by both the complexation with Mg²⁺ and the photochemical reaction induced by photoactive light and is accompanied by the irreversible loss of photochromism.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2220–2224, September. 1996.     

Interaction studies between photochromic spiropyrans and transition metal cations: the curious case of copper

A series of four spiropyrans bearing different substituents on the indolic nitrogen were synthesized and their capability of binding mono and bivalent transition metal cations in solution was assessed via UV-visible absorption spectroscopy. All the compounds responded selectively to the presence of Cu(ii) ions producing intense absorption bands in the visible region of their spectra. Bidimensional (1)H-NMR and MALDI-TOF MS spectroscopies revealed the formation of SP dimers mediated by Cu(ii). This is the first example of cross-coupling mediated by copper(ii) in mild conditions causing the symmetric dimerization of spiropyran dyes.     

Synthesis and spectral kinetic study of photoinduced processes of photochromic nitro-substituted indoline and benzothienopyrroline spiropyrans in solutions

Nitro-substituted benzothienopyrroline spiropyrans containing substituents in the ben-zothienopyrroline moiety were synthesized. The comparative spectral kinetic study of the pho-tochromic transformations of these compounds and their indoline analogs in solvents of various polarity was carried out. On the basis of the results obtained and literature data, the photoin-duced aggregation of molecules of the merocyanine form in weakly polar solvents was suggested.     

Thermodynamic studies on complexation of pervanadyl ion with aminopolycarboxylates

The solution equilibria of the vanadium(V) complexes formed by N-methyliminodiacetic acid (MIDA), nitrilotriacetic acid (NTA) and ethylenediamine-N,N′-diacetic acid (EDDA) were investigated spectrophotometrically. In acidic media all three complexes have the same formula as VO₂Y, where Y represents aminopolycarboxylate anion. In alkaline media these complexes dissociate yielding HVO_4²⁻ and Y. The formation constants of 1:1 complexes (log K_VO2Y: 10·16 ± 0·12 for MIDA; 13·8 ± 0·4 for NTA; 14·5 ± 0·3 for EDDA at 25°C and I = 1·0 M) point to a cis configuration of the two oxygen atoms in the VO₂ unit. The protonation constants of aminopolycarboxylates were also determined potentiometrically.     

NMR kinetic analysis of photochromic quinolone photoproducts

The whole photochromic reaction, photocolouration, thermal bleaching and photodegradation, of a quinolone derivative has been kinetically monitored by product-by-product NMR spectroscopy. The mechanism of reactions has been established from quantitative kinetic data analysis.     

Synthesis, photochromic properties, and light-controlled metal complexation of a naphthopyran derivative

A light-controlled reversible binding switch based on photochromic 3H-naphtho[2,1-b]pyran is under development for studying cellular oscillatory calcium signals. The binding affinities of the closed and open forms of substituted naphthopyran 1 for Ca(2+), Mg(2+), and Sr(2+) in buffer were determined. The photochemically ring-opened form of the receptor exhibited increased affinity compared to the thermally stable closed form of the receptor. The binding affinity difference for Ca(2+) was approximately 77-fold at pH 7.6.     

Synthesis and metal ion complexation studies of proton-ionizable calix

A series of novel N-chromogenic calix[4]arene azacrown ethers were synthesized as selective extractants of potassium ion. 1,3-Alternate calix[4]arene azacrown ethers were prepared by reacting 25,27-dipropyloxy-26,28-bis(5-chloro-3-oxapentyloxy) calix[4]arenes with p-toluenesulfonamide in the presence of potassium carbonate. The coupling reaction of calix[4]arene azacrown ether with 2-hydroxy-5-nitrobenzyl bromide in the presence of triethylamine in THF gave the chromogenic calix[4]arene azacrown ether in moderate yield. These compounds show high potassium selectivity over other metal ions as shown by two-phase extraction, bulk liquid membrane, and 1H NMR studies on a ligand-metal complex. It is assumed that the OH of the chromogenic group attached on nitrogen can assist the complexation by encapsulation of the metal.     

Synthesis and photochromic properties of spiropyrans containing a fused benzopyranone fragment

New spiro compounds of the indole, phthalazine, isobenzofuran, and benzopyran series, containing a fused benzopyranone fragment in the chromene moiety, were synthesized. Indole derivatives were found to exhibit photochromic properties under stationary conditions at 293 K. The thermal stability of merocyanine isomers sharply decreases upon introduction of electron-withdrawing nitro group into the indole fragment and fusion of a benzene ring to the chromene fragment.     

Structures of spiropyrans exhibiting photochromic properties in the solid state

Russian Chemical Bulletin - Solid-state photochromic indoline spiropyrans bearing a formyl group at the 6′ and 8′ positions of the 2H-chromene moiety of the molecules were...     

Synthesis and studies of new photochromic spiropyrans containing a formylcoumarin fragment

A computer search for new photoactive compounds among indoline spiropyrans of coumarin series was carried out using DFT B3LYP/6-31G(d,p) method. Based on the data obtained, the spiropyrans containing a formylcoumarin fragment annulated to the 2H-pyran ring and possessing photochromic properties were synthesized. The structure and photochromism of these compounds were studied by ¹H NMR, IR, and UV/Vis spectroscopy. The introduction of a formyl group into the coumarin moiety of spiropyrans led to a bathochromic shift of the long wavelength absorption maxima of merocyanine isomers, as well as to a considerable increase in their lifetime.     

Synthesis and characterisation of polymerisable photochromic spiropyrans: towards photomechanical biomaterials

A methodology for the synthesis of novel polymerisable spiropyrans with photomechanical properties suitable for subsequent copolymerisation with either vinyl or acrylate-based biomaterials is described. UV-vis spectroscopic characterisation of photoisomerism shows that photochromic behaviour with respect to related non-polymerisable compounds is retained and is solvent dependent. In acetone, conventional spiropyran-merocyanine photochromism is observed for nitro-spiropyran derivatives, whereas in dichloromethane both nitro-spiropyrans and spiropyrans isomerise to merocyanines which rapidly form H-aggregates. The monomers were designed such that an alkyl spacer of variable length, both electronically and sterically, separates the polymerisable moiety from the photochromic core and allows steric aspects of the resulting photomechanical behaviour to be explored.     

Useful spectrokinetic methods for the investigation of photochromic and thermo-photochromic spiropyrans

This review reports on the main results of a set of kinetic elucidation methods developed by our team over the last few years. Formalisms, procedures and examples to solve all possible AB photochromic and thermophotochromic kinetics are presented. Also, discussions of the operating conditions, the continuous irradiation experiment, the spectrokinetic methods testing with numerical integration methods, and the identifiability/distinguishability problems, are included.     

Influence of the matrix on the complexation of metal ions by chelating ion exchangers

Summary Chelating ion exchangers show distribution coefficients that are considerably lower than those expected from complexation equilibria with the corresponding free ligands in solution. Furthermore, dependence of distribution coefficients on the concentration of exchanging ions in solution is observed. Both effects are due to the influence of the surrounding matrix on the anchor groups. The distribution coefficients of Fe³⁺, Ni²⁺, Cu²⁺, Pb²⁺ and UO ₂₊ ² on two cellulose exchangers carrying different anchor groups are investigated as function of the concentration in solution. In case of the anchor group of high flexibility a strong increase of the distribution coefficients with decreasing concentration in solution is measured. This is explained by the fact that the anchor groups located at the surface are less affected by interactions with the matrix, with the result of higher distribution coefficients. The explanation is in agreement with the sorption isotherm.

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Einfluß der Matrix auf die Komplexierung von Metallionen durch chelatbildende Ionenaustauscher

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Dedicated to Prof. Dr. G. Tölg on the occasion of this 60th birthday     

Photo-and thermochromic spiranes 31.* Structure and photochromic properties of functionalized benzoxazine spiropyrans

An X-ray diffraction study gave the structure of a 4-oxohydro-2H-1,3-benzoxazine spiropyran with molecular formula C₂₈H₂₅N₃O₇, in which the π-electron-withdrawing formyl group is replaced with a chelatophoric hydrazine fragment containing a methoxy group. The structural parameters of this spiropyran were determined and compared with the data for similar spiropyrans. The photochromic properties of this compound in acetonitrile were studied in the presence of zinc ions. Dedicated to Professor A. F. Prozharskii on the occasion of his 70th jubilee. * For Communication 30 see [1]. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1699–1706, November, 2008.     

Surface potential switching by metal ion complexation/decomplexation using bipyridinethiolate monolayers on gold

Surface potential switching on gold(111) surfaces is induced by complexation/decomplexation reactions of a bipyridine (BP) derivative and palladium(II) chloride, as observed by Kelvin probe force microscopy (KFM). On the basis of the theoretical predictions, a 4-(5-phenylethynyl-2,2'-bipyridine-5'-yl-ethynyl)benzenethiol (PhBP) derivative was synthesized and used as an active monolayer to catch transition metal ions. By using the microcontact printing (CP) technique, micron-size patterned PhBP monolayers, which act as effective hosts to coordinate palladium(II) chloride, were prepared on gold(111) surfaces. The KFM signal decreases by complexation of the Pd(II) chloride in PhBP monolayers and is recovered by removal of Pd ions using an ethylenediamine solution, as confirmed by X-ray photoelectron spectroscopy. This process is reversible, indicating that the surface potential switching is realized by complexation/decomplexation of Pd(II). A CP PhBP monolayer, when it detects the target palladium ion, shows sensitivity for the picomolar level detection judged from surface potential changes in KFM measurements. The dipole moment estimated by the surface potentials is much smaller than the calculated value, indicating that mechanisms for the reduction of the surface dipole moment exist in real monolayers prepared by the CP method.     

Synthesis,metal ion binding,and photochromic properties of benzo- and naphthopyrans annelated by crown ether moieties

Combining a photochromic chromene with a crown ether moiety results in systems in which photochromism and ionophoric properties could significantly influence each other. In this paper, we report the synthesis of several chromenes annelated by 15(18)-crown-5(6) ethers. The approach involves the building of the photochromic fragment upon the initial crown ether via phenols. The two main routes for chromene preparation are discussed. The complex formation of the synthesized photochromic crown-containing naphthopyran with magnesium(II) and barium(II) cations was studied. The kinetic behavior of the colored form of the compound is affected by complex formation.