16650-14-9Relevant articles and documents
Observation of photochromic γ-cyclodextrin host-guest inclusion complexes
Iyengar, Suman,Biewer, Michael C.
, p. 1398 - 1399 (2002)
Substituted photochromic spiropyrans were included in γ-CD inclusion complexes and the photochromic behavior was monitored optically.
Covalent modification of 2′-deoxyuridine with two different molecular switches
Barrois, Sebastian,Beyer, Christoph,Wagenknecht, Hans-Achim
, p. 711 - 716 (2012)
Two different molecular switches, a spiropyran and a diarylethene, were attached synthetically to the 5-position of 2-de-oxyuridine. The diarylethene-modified nucleoside can be incorporated synthetically into DNA while preserving its characteristic photochromism. Georg Thieme Verlag Stuttgart · New York.
Direct Access by Mechanochemistry or Sonochemistry to Protonated Merocyanines: Components of a Four-State Molecular Switch
Cola?o, Melwin,Carletta, Andrea,Van Gysel, Mégane,Robeyns, Koen,Tumanov, Nikolay,Wouters, Johan
, p. 520 - 526 (2018/08/06)
Direct access to the protonated merocyanine forms of two substituted spiropyrans by mechanosynthesis or sonochemistry was explored. The compounds were formed by the condensation reaction of the methyleneindolium iodide salt with salicylaldehyde derivatives. X-ray crystallography, 1H NMR spectroscopy, ab initio geometry optimization, and absorption spectroscopy were combined to provide a better understanding of the four-state molecular switch system in which the newly synthesized protonated merocyanines were found to play a central role. The results of this study suggest that the stability of the protonated merocyanines requires acidic conditions, as treatment with base led to the corresponding unprotonated merocyanines, which in turn spontaneously converted into photochromic closed spiropyrans.
Self-Assembled Pd(II) Barrels as Containers for Transient Merocyanine Form and Reverse Thermochromism of Spiropyran
Howlader, Prodip,Mondal, Bijnaneswar,Purba, Prioti Choudhury,Zangrando, Ennio,Mukherjee, Partha Sarathi
supporting information, p. 7952 - 7960 (2018/06/18)
Self-assembly of a cis-blocked Pd(II) 90° ditopic acceptor [cis-(tmeda)Pd(NO3)2] (M) with a tetradentate donor L1 [benzene-1,4-di(4-terpyridine)] in 2:1 molar ratio yielded two isometric molecular barrels MB1 and MB3 in DMSO [tmeda = N,N,N′N′-tetramethylethane-1,2-diamine]. Exclusive formation of the symmetrical tetrafacial barrel (MB1) was achieved when the self-assembly was performed in aqueous medium. The presence of a large confined cavity makes MB1 a potential molecular container. Spiropyran (SP) compounds exist in stable closed spiro form in visible light and convert to transient open merocyanine (MC) form upon irradiation with UV-light or upon strong heating. The transient MC form readily converts to the stable closed SP form in visible light. MB1 has been employed as a safe container to store the planar and unstable merocyanine isomers (MC1/2) of different spiropyran molecules (SP1/2) [SP1/2 = 6-bromo-spiropyran and 6-nitrospiropyran] for several days. The transient MC forms (MC1 and MC2) were found to be stable inside the molecular container MB1 under visible light and even in the presence of different stimuli such as heat and UV light for a long time. Such stabilization of MC forms inside the confined cavity of MB1 is noteworthy. This phenomenon was generalized by utilizing a carbazole-based molecular barrel (MB2) as a host, which also showed a similar stabilization of transient MC form in visible light at room temperature. Moreover, reverse thermochromism was observed as a result of heating of the MC1 ? MB2 complex, which de-encapsulates the guest in the form of SP1 to give a colorless solution. Moreover, both the host molecules (MB1, MB2) were capable of stabilizing transient MC2 even in the solid state. Such stabilization of transient MC forms in the solid state and transformation of SP forms to MC forms in the solid state in the presence of molecular barrel are remarkable, and these properties have been employed in developing a magic ink.
Greener route for the synthesis of photo- and thermochromic spiropyrans using a highly efficient, reusable, and biocompatible choline hydroxide in an aqueous medium
Pargaonkar, Jyotsna G.,Patil, Sanjay K.,Vajekar, Shailesh N.
supporting information, p. 208 - 215 (2017/12/26)
Here, we report the synthesis of photo- and thermochromic spiropyrans promoted by a highly efficient, biocompatible, and reusable choline hydroxide (ChOH) in greener solvent water. This procedure provides several advantages such as simple workup, mild reaction conditions, short reaction time, and high yields of the products. Furthermore, the ChOH could be reused at least five times without significantly losing its catalytic activity. The structures of the synthesized spiropyran derivatives were confirmed by several characterization methods such as 1H NMR, 13C NMR, and mass spectra.
Reversible multistimuli-response fluorescent switch based on tetraphenylethene-spiropyran molecules
Qi, Qingkai,Qian, Jingyu,Ma, Suqian,Xu, Bin,Zhang, Sean Xiao-An,Tian, Wenjing
, p. 1149 - 1155 (2015/03/05)
Two tetraphenylethene (TPE)-functionalized spiropyran (SP) molecules with very similar structure were designed and synthesized. The two molecules exhibit aggregation-induced emission (AIE) properties, as well as multistimuli-responsive color-changing prop
Photochromism of spirobenzopyranindolines and spironaphthopyranindolines
Chibisov,Goerner
, p. 424 - 431 (2007/10/03)
The photocolouration of five spiro[2H-1-benzopyran-2,2′-indoline] compounds (1-5) and two spironaphthopyranindolines (6, 7) to give the ring-opened merocyanine(s) and the subsequent thermal relaxation back to the closed form was studied. A trans-merocyanine but no cis-photoisomer were detected for 1-7 using λexc = 308 nm and a singlet pathway accounts for photocolouration. In contrast to nitrospiropyrans the yield of colouration of spiropyrans is essentially independent of solvent polarity. The relaxation times at 25°C range from 0.01 s for 6 in methylcyclohexane to 17 s for 5 in ethanol, which is due to differences in both activation energies (65-80 kJ mol-1) and the pre-exponential factor (1012-1014 s-1). The photomerocyanine yield is substantially increased upon naphthalene- or acetone-sensitized excitation, where otherwise the same spectral changes, relaxation time and activation parameters were found. Upon excitation of the trans-merocyanine (λexc = 530 nm), a cis-merocyanine with lifetime in the sub ms range could be detected at lower temperatures. Deactivation of the excited trans-merocyanine occurs mainly in the excited singlet state. For 4 and 5, due to an internal heavy-atom effect of bromine substituents, and for 1, a triplet state as a precursor of the cis- and trans-merocyanines could be observed. The effects of structure and medium properties on the photoprocesses are described and the mechanisms of photochromism and thermal decolouration are discussed.
Thermal racemization of substituted indolinobenzospiropyrans: Evidence of competing polar and nonpolar mechanisms
Swansburg, Susan,Buncel, Erwin,Lemieux, Robert P.
, p. 6594 - 6600 (2007/10/03)
A series of 6-substituted indolinobenzospiropyrans were resolved by chiral stationary phase HPLC and rate constants k(rac) for their thermal racemization were measured by circular dichroism spectropolarimetry at 60 °C in three different solvents: cyclohexane, 90:10 hexanes/2-propanol, and acetonitrile. Results show that the spiropyrans undergo thermal racemization most rapidly in acetonitrile, with k(rac) values ranging from 9.3 x 10 -5 to >5.0 x 10 -3 s -1, and least rapidly in cyclohexane, with k(rac) values ranging from 6.8 x 10 -6 to 4.6 x 10 -4 s -1. V-shaped plots of log k(rac) vs Hammett σ(p) constants in 90:10 hexanes/2-propanol and acetonitrile suggest that thermal racemization of the 6-substituted spiropyrans proceed via two competing mechanisms: a polar mechanism involving heterolytic C(sp3)-O bond cleavage with anchimeric assistance from the indoline nitrogen and a nonpolar electrocyclic ring opening mechanism with no anchimeric assistance from the indoline nitrogen. The outcome of this competition appears to be strongly influenced by solvent polarity: plots of log k(rac) vs σ(p) and σ- in cyclohexane show a near-linear correlation with negative slope, which is consistent with the nonpolar mechanism. However, an increase in solvent polarity results in a shift toward a linear correlation with positive slope, which is consistent with the polar mechanism.
Novel syntheses of spiropyran photochromatic compounds using ultrasound
Torres,Vazquez,Gonzalez
, p. 105 - 110 (2007/10/02)
Photochromatic derivatives 1,3,3-trimethylindoline-2-spiro-2'-benzopyran, were synthesized using ultrasound as energy source (55 watt), reaction times are between 10 to 20 min, obtaining higher or slightly lower yield than the conventional reported methods.
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
