Electronic spectra and photochemistry of adsorbed organic molecules. VI. Binding effects of silica as a mechanistic probe in systems of photochemical interest

Weis, Lawrence D.; Evans, Ted R.; Leermakers, Peter A.

doi:10.1021/ja01024a030

Cited by 65 publications

(22 citation statements)

References 16 publications

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“…Spiropyrans and spirooxazines are the most investigated photochromic spiro compounds [ 3 , 4 ]. It is reported that spiropyrans and spirooxazines could also respond to other external stimuli such as thermal effects, pH, stress, and so on [ 5 , 6 ]. The structural transformation processes of spiropyrans and spirooxazines are shown in Scheme 1 [ 7 ].…”

Section: Introduction To Spiropyrans and Spirooxazinesmentioning

confidence: 99%

Advances in Spiropyrans/Spirooxazines and Applications Based on Fluorescence Resonance Energy Transfer (FRET) with Fluorescent Materials

2017

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Studies on the following were reviewed: (1) the structure of spiropyrans and spirooxazines (two kinds of spiro compounds) under external stimuli and (2) the construction and applications of composite systems based on fluorescence resonance energy transfer (FRET) with fluorescent materials. When treated with different stimuli (light, acids and bases, solvents, metal ions, temperature, redox potential, and so on), spiropyrans/spirooxazines undergo transformations between the ring-closed form (SP), the ring-opened merocyanine (MC) form, and the protonated ring-opened form (MCH). This is due to the breakage of the spiro C–O bond and the protonation of MC, along with a color change. Various novel, multifunctional materials based on photochromic spiropyrans and spirooxazines have been successfully developed because of the vastly differently physiochemical properties posssed by the SP, MC and MCH forms. Among the three different structural forms, the MC form has been studied most extensively. The MC form not only gives complexes with various inorganic particles, biological molecules, and organic chemicals but also acts as the energy acceptor (of energy from fluorescent molecules) during energy transfer processes that take place under proper conditions. Furthermore, spiropyran and spirooxazine compounds exhibit reversible physicochemical property changes under proper stimuli; this provides more advantages compared with other photochromic compounds. Additionally, the molecular structures of spiropyrans and spirooxazines can be easily modified and extended, so better compounds can be obtained to expand the scope of already known applications. Described in detail are: (1) the structural properties of spiropyrans and spirooxazines and related photochromic mechanisms; (2) composite systems based on spiropyrans and spirooxazines, and (3) fluorescent materials which have potential applications in sensing, probing, and a variety of optical elements.

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Section: Introduction To Spiropyrans and Spirooxazinesmentioning

confidence: 99%

Advances in Spiropyrans/Spirooxazines and Applications Based on Fluorescence Resonance Energy Transfer (FRET) with Fluorescent Materials

2017

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“…This system is a clear improvement with respect to other solid materials where reverse photochromism has been attempted, such as silica matrices. High polymerization degrees, or low hydrophobic/hydrophilic ratios,, are required in these materials to ensure reverse photochromism; however, this often leads to loss of the dye activity owing to degradation, excessive matrix rigidity, or too much MC stabilization ,. Although these drawbacks can be prevented by lowering the silica matrix polarity, they normally result in mixed reverse/direct photochromism.…”

Section: Methodsmentioning

confidence: 99%

Temperature‐Controlled Switchable Photochromism in Solid Materials

et al. 2016

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A novel strategy to achieve thermally switchable photochromism in solid materials is reported, which relies on the preparation of polymeric core–shell capsules containing solutions of photochromic dyes in acidic phase‐change materials. Upon changing the phase (solid or liquid) of the encapsulated medium, one of the two photochromic states of the system is selectively stabilized on demand, allowing for reversible interconversion between direct and reverse photochromism when thermally scanning through the melting temperature of the phase‐change material. This strategy, which does not require the addition of external agents or chemical modification of the dyes, proved to be general for different spiropyran photochromes and to be applicable to the fabrication of a variety of functional materials by simply embedding the capsules obtained into a solid matrix of choice.

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“…17 Weis et al reported that the polarity of silica gel is higher than that of methanol. 18 When 6 was irradiated in acetonitrile, ethanol or methanol, the Type II reaction products were also formed almost quantitatively as in benzene. The ratios of the Type II cyclization to elimination were nearly constant, although the ratio of the Type II cyclization to elimination in a polar solvent is slightly smaller than that in a non-polar solvent [( 9 / 9 ) MeOH /( 9 / 7 ) PhH ¼ 0.88], as known in the Type II reaction of phenyl ketones.…”

Section: Introductionmentioning

confidence: 97%

Type II photoreaction of benzoyl‐ and (benzoylmethyl)cyclohexanones: cyclohexanone ring inversion and other factors determining their photoreactivities

Hasegawa¹,

Yang²,

Kikuchi³

et al. 2005

J of Physical Organic Chem

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X-ray crystallographic structure analysis showed that a molecule of 2-benzoylcyclohexanone (2), which undergoes an efficient Type II reaction in solution but not in the crystalline state, is in a keto and chair form with an equatorial benzoyl group. Irradiation of 3-benzoylcyclohexanone (3) gives 7-phenylhepten-4,7-dione (4, 61%) and a mixture of cyclization products 5 (25%). High photoreactivity of 2 and 3 is caused by the efficient cyclohexanone ring inversion. Upon irradiation, 2-(benzoylmethyl)cyclohexanone (6) gives acetophenone (7), 2-cyclohexenone (8) and the cyclobutanol 9 in 59, 59 and 35% yield, respectively, and 1-phenyl-3-propylpentan-1,4-dione (10) gives 7 and the cyclobutanol 11 in 73 and 4% yield, respectively. The quantum yields for the disappearance of 6 and 10 are 0.68 and 0.67, respectively. Irradiation of 2-(benzoylmethyl)-2-ethoxycarbonylcyclohexanone (12) gives 7 and the cyclobutanol 13 in 46 and 51% yield, respectively. The quantum yield for the disappearance of 12 is 1.00, so that reverse hydrogen transfer is suppressed by intramolecular hydrogen bonding in the 1,4-biradical intermediate. When 6 is irradiated on a dry silica gel surface, the Type II reaction occurs to give 7, 8 and 9 in 38, 38 and 43% yield, respectively. The cyclization in the photoreaction of (benzoylmethyl)cyclohexane also increases from 68% in benzene to 81% on a dry silica gel surface. Restriction of conformational change in the 1,4-biradical is an important factor for the cyclization.

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Electronic spectra and photochemistry of adsorbed organic molecules. VI. Binding effects of silica as a mechanistic probe in systems of photochemical interest

Cited by 65 publications

References 16 publications

Advances in Spiropyrans/Spirooxazines and Applications Based on Fluorescence Resonance Energy Transfer (FRET) with Fluorescent Materials

Advances in Spiropyrans/Spirooxazines and Applications Based on Fluorescence Resonance Energy Transfer (FRET) with Fluorescent Materials

Temperature‐Controlled Switchable Photochromism in Solid Materials

Type II photoreaction of benzoyl‐ and (benzoylmethyl)cyclohexanones: cyclohexanone ring inversion and other factors determining their photoreactivities

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