Photolysis of ((3-(Trimethylsilyl)propoxy)phenyl)phenyliodonium Salts in the Presence of 1-Naphthol and 1-Methoxynaphthalene

Gu, Haiyan; Zhang, Wenqin; Feng, Kesheng; Neckers, Douglas C.

doi:10.1021/jo000058w

Cited by 25 publications

(18 citation statements)

References 24 publications

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“…We have reported extensively on our studies in this area 2 ' 3,4 and other investigators have also been active in this field. 5,6,7,8 There are several mechanisms by which the photosensitization of onium salts take place, however, electron-transfer photosensitization appears to be the most efficient and generally applicable process. 9 A generalized mechanism for the electron-transfer photosensitization of diaryliodonium salts is shown in Scheme 1.…”

Section: Ptmentioning

confidence: 99%

Phenothiazine Photosensitizers for Onium Salt Photoinitiated Cationic Polymerization

Gomurashvili

Crivello

2003

ACS Symposium Series

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The syntheses of several different substituted phenothiazines are described and the ability of these compounds to photosensitize the photolysis of different onium salt cationic photoinitiators is described. These photosensitizers (PS) are generally operative in the mid-and long-range regions of the UV spectrum. The efficiencies of photosensitization of the cationic photopolymerizations of several typical epoxide and vinyl ether monomers by different substituted phenothiazine compounds were evaluated and compared. In addition, a phenothiazine-containing monomer and polymer were prepared and were shown to be effective photosensitizers.Currently, the most commonly used photoinitiators employed for photoinduced cationic polymerizations are diaryliodonium, I, and triarylsulfonium salts, Π, with the general structures shown below in which MtX n " represents a weakly nucleophilic counterion. Another promising class of photoinitiators is dialkylphenacylsulfonium salts, HI.

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Section: Ptmentioning

confidence: 99%

Phenothiazine Photosensitizers for Onium Salt Photoinitiated Cationic Polymerization

Gomurashvili

Crivello

2003

ACS Symposium Series

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“…Next, we explore the creation of hybrid gels that respond to light. , This is done by using a type of molecule called a photoacid generator (PAG). When an aqueous solution of a PAG is exposed to ultraviolet (UV) light, the molecules decompose to form acidic species, thereby lowering the pH of the system. − Thus, PAGs can be used to convert a pH-sensitive system to one that instead responds to light. The application of PAGs in the light-tunable self-assembly of surfactants and polymers was pioneered in our lab , and has also been used by others. − In the present case, we use PAGs in conjunction with the above pH-sensitive anionic/nonionic hybrid gel.…”

Section: Results and Discussionmentioning

confidence: 99%

Smart Hydrogel-Based Valves Inspired by the Stomata in Plants

Gargava

Arya

Raghavan

2016

ACS Appl. Mater. Interfaces

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We report the design of hydrogels that can act as "smart" valves or membranes. Each hydrogel is engineered with a pore (about 1 cm long and <1 mm thick) that remains closed under ambient conditions but opens under specific conditions. Our design is inspired by the stomatal valves in plant leaves, which regulate the movement of water and gases in and out of the leaves. The design features two different gels, active and passive, which are attached concentrically to form a disc-shaped hybrid film. The pore is created in the central active gel, and the conditions for opening the pore can be tuned based on the chemistry of this gel. For example, if the active gel is made from N-isopropylacrylamide (NIPA), the actuation of the pore depends on the temperature of water relative to 32 °C, which is the lower-critical solution temperature (LCST) of NIPA. The concentric design of our hybrid provides directionality to the volumetric transition of the active gel, i.e., it ensures that the pore opens as the active gel shrinks. In turn, contact with hot water (T > 32 °C) opens the pore and allows the water to pass through the gel. Conversely, the pore remains closed when the water is cold (T < 32 °C). The gel thereby acts as a "smart" valve that is able to regulate the flow of solvent depending on its properties. We have extended the concept to other stimuli that can cause gel-swelling transitions including solvent composition, pH, and light. Additionally, when two different gel-based valves are arranged in series, the assembly acts as a logical "AND" gate, i.e., water flows through the valve-combination only if it simultaneously satisfies two distinct conditions (such as its pH being below a critical value and its temperature being above a critical value).

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“…As shown by the photograph in Figure , the initial mixture is a low-viscosity sol. When exposed to UV light for 45 min, the PAG gets photolyzed, releasing acid (H + ). − The acid reacts with the insoluble CaCO 3 particles to generate free Ca 2+ ions, which cross-link the alginate chains into a gel network. , The resulting alginate gel is strong enough to hold its weight in the inverted vial (Figure ); note also the stirring bar trapped in the gel…”

Section: Resultsmentioning

confidence: 99%

“…The concept in this case was to combine the nanoparticles with an amphiphilic stabilizer and a photoacid generator (PAG). PAGs are commercially available molecules that have been used for a long time in the microelectronics industry. − Their distinctive property is that they get photolyzed by UV light to form an acidic moiety. − In our system, the photolysis of the PAG caused the pH to drop by about 3 units, and in turn, the charges on the edges of the clay nanoparticles switched from negative to positive . This charge reversal drove the initially separated particles to cluster into a gel network …”

Section: Introductionmentioning

confidence: 90%

Light-Activated Ionic Gelation of Common Biopolymers

Javvaji¹,

Baradwaj²,

Payne

et al. 2011

Langmuir

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Biopolymers such as alginate and pectin are well known for their ability to undergo gelation upon addition of multivalent cations such as calcium (Ca(2+)). Here, we report a simple way to activate such ionic gelation by UV irradiation. Our approach involves combining an insoluble salt of the cation (e.g., calcium carbonate, CaCO(3)) with an aqueous solution of the polymer (e.g., alginate) along with a third component, a photoacid generator (PAG). Upon UV irradiation, the PAG dissociates to release H(+) ions, which react with the CaCO(3) to generate free Ca(2+). In turn, the Ca(2+) ions cross-link the alginate chains into a physical network, thereby resulting in a hydrogel. Dynamic rheological experiments confirm the elastic character of the alginate gel, and the gel modulus is shown to be tunable via the irradiation time as well as the PAG and alginate concentrations. The above approach is easily extended to other biopolymers such as pectin. Using this approach, a photoresponse can be imparted to conventional biopolymers without the need for any chemical modification of the molecules. Photoresponsive alginate gels may be useful in creating biomaterials or tissue mimics. As a step toward potential applications, we demonstrate the ability to photopattern a thin film of alginate gel onto a glass substrate under mild conditions.

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Photolysis of ((3-(Trimethylsilyl)propoxy)phenyl)phenyliodonium Salts in the Presence of 1-Naphthol and 1-Methoxynaphthalene

Cited by 25 publications

References 24 publications

Phenothiazine Photosensitizers for Onium Salt Photoinitiated Cationic Polymerization

Phenothiazine Photosensitizers for Onium Salt Photoinitiated Cationic Polymerization

Smart Hydrogel-Based Valves Inspired by the Stomata in Plants

Light-Activated Ionic Gelation of Common Biopolymers

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