18457-95-9Relevant articles and documents
Direct photoreduction and ketone-sensitized reduction of nitrospirobenzopyranindolines by aliphatic amines
Goerner, Helmut
, p. 8208 - 8215 (2011)
The photoreduction of 6-nitrospiro[2H-1-benzopyran-2,2′-indoline] (N1) and two derivatives (N2 and N3) by diethylamine or triethylamine (TEA) in solution was studied by pulsed and steady-state photolysis. The quantum yield of coloration of the ring-closed
Reversible photo-switching interaction between spiropyrans and polymer pyridine residues in a solid polymer membrane
Suzuki, Takayuki,Oda, Norihisa,Tanaka, Toshiyuki,Shinozaki, Hiraku
, p. 1803 - 1807 (2006)
A solid membrane of poly(2-ethylhexyl methacrylate-co-vinylpyridine) containing photochromic 6′-nitrospiropyran was prepared. In the rubbery copolymer membrane (Tg = -9 °C), the merocyanine (MC) form of the spiropyran isomerized into the spiro (SP) form by thermal decay after irradiation with UV light. The resulting decay showed two types of first-order kinetics, fast and slow. The activation energy for slow decay in the copolymer membrane was about 4 kcal mol-1 higher than that of fast decay. Furthermore, the standard enthalpy (ΔH°) of reversible isomerization (SP MC) without photolysis in the copolymer membrane was negative, in contrast to positive ΔH° values obtained for a homopolymer membrane of poly(2-ethylhexyl methacrylate) and for a liquid pyridine solution of spiropyrans. It was deduced that some of MC molecules in the copolymer membrane were thermodynamically stabilized. Additionally, the stabilized MC form in the copolymer membrane emitted intense green fluorescence (λem = 570 nm), while the simple MC form in the homopolymer or pyridine solution showed weak red emission (λem = 620-630 nm). The green fluorescence of the copolymer membrane was photo-reversible. These results suggest the existence of a photo-switchable interaction between spiropyrans and polymer pyridine residues in the solid copolymer membrane. The Royal Society of Chemistry 2006.
Study on the Chemical Reaction of Spiropyran in Medium- and High-Density Fluids
Kimura, Y.,Takebayashi, Y.,Hirota, N.
, p. 11009 - 11013 (1996)
We have studied the thermal conversion of 1,3',3'-trimethyl-6-nitrospiro (6-nitro-BIPS) in trifluoromethane (CHF3) and nitrous oxide (N2O) from near-critical to liquid-like density regions.The rate constant decreases with in
Photocyclization of diarylethenes: The effect of imidazole on the oxidative photodegradation process
Zakharov,Lvov,Rostovtseva,Metelitsa,Chernyshev,Krayushkin,Yadykov,Shirinian
, p. 1101 - 1109 (2019/05/24)
We have studied the photoreaction of 1,2-diarylethenes under aerobic conditions in the presence of various amines to prevent side processes promoted by singlet oxygen. It has been found that the most amines quite effectively deactivate processes associated with singlet oxygen, but primary and secondary amines unlike tertiary ones, react with substrates resulting in various side products. Among the studied amines, the most effective additive for preventing side processes, including those associated with singlet oxygen is imidazole, which is practically not consumed in photoreaction. It was shown that imidazole can also prevents the photodegradation of organic photochromes in solutions. The results obtained can be used in various branches of science, technology and medicine to improve the photostability of photosensitive organics (dyes).
Nanosecond laser flash photolysis of a 6-nitroindolinospiropyran in solution and in nanocrystalline suspension under single excitation conditions
Breslin, Vanessa M.,Barbour, Nicole A.,Dang, Duy-Khoi,Lopez, Steven A.,Garcia-Garibay, Miguel A.
, p. 741 - 749 (2018/06/21)
Nanosecond transient absorption spectroscopy was used to study the photochemical ring-opening reaction for a 6-nitroindolinospiropyran (SP1) in solution and in nanocrystalline (NC) suspension at 298 K. We measured the kinetics in argon purged and air saturated acetonitrile and found that the presence of oxygen affected two out of the three components of the kinetic decay at 440 nm. These are assigned to the triplet excited states of the Z- and E-merocyanines (3Z-MC? and 3E-MC?). In contrast, a long-lived growth component at 550 nm and the decay of a band centered at 590 nm showed no dependence on oxygen and are assigned, respectively, to the ground state Z- and E-merocyanines (Z-MC0 and E-MC0). Laser flash photolysis studies performed in NC suspensions initially showed a very broad, featureless absorption spectrum that decayed uniformly for ca. 70 ns before revealing a more defined spectrum that persisted for greater than 4 ms and is consistent with a mixture of the more stable Z- and E-MC0 structures. We performed quantum mechanical calculations on the interconversion of E- and Z-MCs on the S0 and S1 potential energy surfaces. The computed UV-vis spectra for a scan along the Z → E interconversion reaction coordinate show substantial absorptivity from 300-600 nm, which suggests that the broad, featureless transient absorption spectrum results from the contribution of the transition structure and other high-energy species during the Z to E isomerization.
Switchable polarity solvent (SPS) systems: Probing solvatoswitching with a spiropyran (SP)-merocyanine (MC) photoswitch
Boyd, Alaina R.,Jessop, Philip G.,Dust, Julian M.,Buncel, Erwin
, p. 6047 - 6055 (2015/02/20)
The switchable polarity solvent (SPS) of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and an alcohol (e.g. 1-propanol) reversibly switches to a higher polarity ionic liquid, [DBUH+][RCO3-], when treated with CO2. A long-lived species with unique properties was detected in an investigation into the use of SPS to control the lifetime of the merocyanine (MC) form in a spiropyran (SP)-MC molecular photoswitch. Irradiation of SP in 1-propanol (PrOH) in the presence of DBU generates a new species (λmax = 420 nm). This species converts to MC upon bubbling with CO2, which produces [DBUH+][PrOCOO-]. It is proposed that a mixture of 1,2 and 1,4 alkoxide addition products form as a result of nucleophilic attack on the conjugated diene system of MC, where alkoxide formation arises from equilibration of highly basic DBU and the alcohol. These adducts revert to MC upon application of CO2 or addition of acid. Determination of the overall equilibrium constant for alkoxide adduct formation involving DBU was afforded through Benesi-Hildebrand analysis. The Royal Society of Chemistry.
