1498-89-1Relevant academic research and scientific papers
Investigating the Photochemistry of Spiropyran Metal Complexes with Online LED-NMR
Feuerstein, Thomas J.,Müller, Rouven,Barner-Kowollik, Christopher,Roesky, Peter W.
, p. 15479 - 15486 (2019)
As one of the best studied photoswitches, spiropyrans (SPs) have attracted significant interest in the scientific community. Among the many stimuli to alter the isomerization into the merocyanine (MC) isomer, such as temperature, pH, solvent polarity, redox potential, or mechanical force, the ability of the MC form to act as a ligand site for metal complexation has recently raised new attention. We herein synthesize hitherto undescribed coordination compounds of 8-methoxy-1′,3′,3′-trimethyl-6-nitrospiro-[chromene-2,2′-indoline] with s-block ([Ca(MC)4](ClO4)2), d-block ([Zn(MC)2(MeCN)2](ClO4)2, [Ni(MC)2(MeCN)2](ClO4)2), as well as f-block ([La(NO3)3(MC)2]) metals. All complexes are structurally described by X-ray crystallography and systematically investigated in solution via Job's method of continuous variations (Job plots), as well as online NMR spectroscopic kinetic experiments with in situ irradiation of the analyte solution inside the NMR spectrometer (LED-NMR). We can unambiguously identify the photoresponsive nature of the complexes in solution, which is a crucial step toward the application of these promising molecules in material science.
Photoprocesses in spiropyran-derived merocyanines: Singlet versus triplet pathway
Goerner, Helmut,Atabekyan, Levon S.,Chibisov, Alexander K.
, p. 59 - 64 (1996)
The properties of two indoline spirobenzopyrans, one (1) containing a 6-nitro and an 8-methoxy group in the benzopyran portion and the other no nitro group (2), were studied by nanosecond laser photolysis in solution at room temperature. A transient, which is ascribed to a cis photoisomer, was observed on excitation of either the spiropyran or the trans isomer of compound 1 (λexc = 353 and 530 nm, respectively). The activation parameters for thermal cis → trans isomerization were measured, and the ground state properties of the spiropyran - trans-merocyanine couple are described. The quantum yields of the spiropyran → merocyanine photocoloration and trans → cis photoisomerization were obtained in solvents of different polarity. A short-lived transient (≤ 10 μs) of compound 1 is identified as a triplet state of the trans isomer. The effects of excitation wavelength on the photophysical and photochemical properties of both compounds are discussed and a new mechanism is suggested.
Kinetic Analysis of Photochromic Systems under Continuous Irradiation. Application to Spiropyrans
Pimienta, V.,Lavabre, D.,Levy, G.,Samat, A.,Guglielmetti, R.,Micheau, J. C.
, p. 4485 - 4490 (1996)
The kinetics of spiropyran photochromic systems in solution in a stirred batch reactor continuously irradiated with monochromatic light was studied by UV/visible spectrophotometry.The plots of absorbance vs time were analyzed, and the desired parameters (quantum yields, UV/visible spectrum of the unstable photomerocyanine, ...) were extracted from an iterative computation which fitted the calculated curves to the experimental ones on the basis of a representative model of the reaction mechanism.The method was applied to spiro whose corresponding photomerocyanine has a lifetime of 100 s in toluene; the two quantum yields of the direct process of photocoloration and the reverse reaction of photobleaching could be determined along with the spectrum of the corresponding photomerocyanine.To demonstrate the general nature of the photokinetic method, it was applied to the reaction of spiro, where the main photochromic process is accompanied by a photodegradation.Despite this interfering phenomenon, the photokinetic method could be used to extract the parameters of the main photochromic process.It also showed that the photodegradation products catalyzed the termal back-isomerization.The order of magnitude of the rate constant of this catalytic process and the quantum yields of photodegradation were estimated.
Spectral Study of the Effect of Water on the Complex Formation of Photochromic Spiropyrans with Metal Ions in Acetonitrile
Barachevsky, V.А.,Gorelik, А.М.,Valova, Т.М.,Venidiktova, О. V.
, p. 1519 - 1525 (2021/09/11)
Abstract: A comparative spectral study of the complex formation of molecules of nitro-substituted indoline spiropyrans with metal ions in acetonitrile and water–acetonitrile solutions, and also in acid-containing acetonitrile, was carried out. It was shown that metal complexes are not formed in the presence of water, due to protonation of photochromic spiropyran molecules. Spectral and photochromic properties of the protonated complexes obtained in the presence of water differ from those of protonated complexes arising upon interaction with an acid. A photochromic method for detecting metal ions in aqueous solutions was proposed.
Decoloration rates of a photomerocyanine dye as a visual probe into hydrogen bonding interactions
Ciampi, Simone,Eggers, Paul K.,Haworth, Naomi L.,Darwish, Nadim,Wagner, Pawel,Coote, Michelle L.,Wallace, Gordon G.,Raston, Colin L.
supporting information, p. 4815 - 4818 (2015/03/18)
We have developed a visual marker for the investigation of hydrogen bonding (HB) effects. The decoloration rate of a photochromic dye that incorporates a latent intra-molecular HB feature can be linked to the HB character of the media. Kinetic and thermodynamic parameters of this simple decoloration approach for HB sensing are investigated both experimentally and by high level theoretical studies. This principle has been applied for the detection of changes in the HB character of stationary and fluidic systems. A major finding is the observation of a shear-related perturbation of the balance between intra- and inter-molecular HB within a dynamic thin film.
Photoreversible Zn2+ ion transportation across an interface using ion-chelating substituted photochromic 3,3′-indolospirobenzopyrans: Steric and electronic controlling effects
Roxburgh, Craig J.,Sammes, Peter G.,Abdullah, Ayse
experimental part, p. 4951 - 4960 (2009/04/13)
The photoreversible transportation of Zn2+ ions across an interface using photochromic substituted-spirobenzopyrans has been demonstrated. The inclusion of strategically placed sterically influencing 3′-methyl-3b and 3-spirocyclohexyl-3c groupings is investigated and compared to the unsubstituted analogue 3a. Significant control over the spiropyran ringopening? closing reaction, and hence Zn2+ ion transportation has been realised. Additionally, the spiropyran ring-opening? closing reactions of two skeletally identical spirobenzo pyrans 4 and 5, but possessing "electronically-modifying" 5-trifluoromethyl-substitutents have been studied by 1H NMR spectroscopy: this has enabled us to realise the additional biasing, on the ring-opening?closing process, excerpted on these systems through both selectively placed, inductively controlling functional-group substitution and/or, simultaneously, sterically influencing group substitution. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Photochromism of nitrospiropyrans: Effects of structure, solvent and temperature
Goerner
, p. 416 - 423 (2007/10/03)
The thermal and photochemical ring opening and ring closure of the spiropyran/merocyanine couple of three nitro-substituted spiropyrans (6-NO2: 6, 7 and 8-NO2: 8) were studied and the results were compared with those of other 6-NO2 spirobenzopyranindolines (BIPS) (1-5). The photocolouration, which occurs in the triplet manifold throughout, and the photochemical conversion and thermal relaxation of the two observable photomerocyanines into the closed spiropyran (Sp) form (decolouration) were quantified as a function of solvent polarity and temperature. The relaxation time (τt-Sp) at 25°C ranges from 2 s for 5 in methylcyclohexane to 104 s for 7 in ethanol. This large variation in τt-Sp is due to changes in both the activation energy (Ea = 75-105 kJ mol-1, increasing with polarity) and the pre-exponential factor (A = 1012-1015 s-1). The quantum yield of colouration with 308 nm pulses is substantial in solvents of low polarity (φcol = 0.3-0.8) and decreases (c→t = 30-40 kJ mol-1. The effects of substituents and medium properties are described and the mechanism of photochromism is discussed.
Thermo- and Photochromic Dyes: Spiro(indolinebenzopyrans) 2. - Detailed Assignment of the 1H NMR Spectra and Structural Aspects of the Closed Form of 1,3,3-Trimethylspiro(indoline-2,2'-benzopyrans)
Keum, Sam-Rok,Lee, Ki-Bong,Kazmaier, Peter M.,Manderville, Richard A.,Buncel, Erwin
, p. 1128 - 1131 (2007/10/02)
The proton NMR assignments for a series of 12 thermo- and photochromic 1,3,3-trimethylspiro(indoline-2,2'-benzopyrans) dyes is reported.All of the protons in the dye molecule were assigned through a combination of homonuclear decoupling experiments and correlation spectroscopy.The relative stereochemistry of the indolino gem-dimethyl groups was assigned so that, for the S-epimer, the pro-R methyl was found to resonate at 1.24 ppm while the pro-S methyl appeared at 1.37 ppm for compound 1. KEY WORDS: Thermo- and photochromic dyes, Spiro(indoline-2,2'-benzopyrans), 1H NMR assignments
Thermo- and photochromic dyes: indolino-benzospiropyrans. Part 1. UV-VIS spectroscopic studies of 1,3,3-spiro(2H-1-benzopyran-2,2'-indolines) and the open-chain merocyanine forms; solvatochromism and medium effects on spiro ring formation
Keum, Sam-Rok,Hur, Mun-Suk,Kazmaier, Peter M.,Buncel, Erwin
, p. 1940 - 1947 (2007/10/02)
A kinetic and ultraviolet-visible study of a series of thermo- and photochromic dyes is reported.Ultraviolet irradiation of the indolino-benzospiropyran derivatives 1'-4' leads to their transformation to the open-chain, colored merocyanine forms, which undergo thermal ring closure into the colorless spiro forms.The rate of this ring closure has been determined in different solvents.Plots of log (rate) vs. the solvent parameter ET are linear but are dependent on the nature of the substituent in the phenyl moiety, which yields information on the electronic characterof the ground state (IIa IIb) and the transition state.The ring-closure process is characterized by a zwitterionic type transition state, TS3.The merocyanine dyes exhibit a significant solvatochromic effect, which unexpectedly shows sensitivity to substituents on the phenyl group.This observation finds explanation through semiempirical molecular orbital (MOPAC) calculations.The MOPAC calculations also predict that the most stable configurational isomer of the merocyanines is the CTTC form. Key words: indolino-benzospiropyran-merocyanine interconversion, photochromic-solvatochromic dyes.
