ChemInform Abstract: Water‐Soluble Disulfonated Aromatic Ketones (I) and (IV) ‐ Photophysical and Photochemical Properties.

Kronfeld, K.‐P.; Timpe, H.‐J.

doi:10.1002/chin.198908055

Cited by 3 publications

(17 citation statements)

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“…The experimental 9 and theoretical spectra in Figures 5 and 6 show a tail in the 300−350 nm wavelength range. Calculations show that this structure can be allocated to the 3 (π H π L *) absorption spectrum. The most intense peak in this region with an oscillator strength of ∼0.04 (see Table 4) corresponds to T 1 → T 15/16 excitation.…”

Section: ■ Results and Discussionmentioning

confidence: 95%

“…For TX dissolved in polar−protic solvents, the chimeric behavior requires the presence of isoenergetically positioned 1 (π H π L *) and 3 (n O π L *) electronic states. 1 In order to 3 (n O π L *) states (see below), the spectrum of the relaxed 1 (π H π L *) state is not available in the experiment. The negative peak at around 390−400 nm (390 nm in the experiment 9 ) represents the ground-state bleach.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Because τ ISC is the reciprocal of the sum of these two rate constants, k ISC and k ReISC , the larger of the two is the determining factor. k ReISC being the rate constant for the (π H π L *) ⇝ 3 (n O π L *) (SOME = 15.6 cm −1a ) 3 (n O π L *) ⇝ 1 (π H π L *) (SOME cm =17.32 −1b ) 1.9 × 10 6 6.7 × 10 6 2 × 10 5 4 × 10 10 7 × 10 10 7 × 10 10 6 × 10 10 298 K 2.9 × 10 9 2.7 × 10 6 8.9 × 10 6 3 × 10 5 4 × 10 10 7 × 10 10 7 × 10 10 6 × 10 10 323 K 3.3 × 10 9 5.4 × 10 6 1.6 × 10 7 8 × 10 5 4 × 10 10 7 × 10 10 7 × 10 10 6 × 10 10 a SOME calculated at the 1 (π H π L *) minimum in vacuum. b SOME calculated at the 3 (π O π L *) minimum in vacuum.…”

Section: ■ Conclusionmentioning

confidence: 99%

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Chimeric Behavior of Excited Thioxanthone in Protic Solvents: II. Theory

et al. 2014

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The chimeric behavior of thioxanthone in protic solvents has been investigated employing computational chemistry methods. In particular, methanol and 2,2,2-trifluoroethanol have been chosen in this study. The solvent environment has been modeled using microsolvation in combination with a conductor-like screening model. The vertical excitation spectrum within the same solvent is seen to depend on the number of specific bonds formed between the chromophore and the solvent molecules. Two different models have been discussed in this work, namely, one and two H-bond models. In particular, the formation of the second H-bond causes the energy gap between the πHπL* and nOπL* states to increase further. Excited-state absorption spectra for the photophysically relevant electronic states have been theoretically determined for comparison with the time-resolved spectra recorded experimentally [Villnow, T.; Ryseck, G.; Rai-Constapel, V.; Marian, C. M.; Gilch, P. J. Phys. Chem. A 2014]. The equilibration of the 1(πHπL*) and 3(nOπL*) states holds responsible for the chimeric behavior. This equilibrium sets in with a calculated time constant of 23 ps in methanol and 14 ps in TFE (5 and 10 ps in experiment, respectively). The radiative decay from the optically bright 1(πHπL*) state is computed to occur with a time constant of 25 ns in both solvents (14–25 ns in experiment).

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Section: ■ Results and Discussionmentioning

confidence: 95%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

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Chimeric Behavior of Excited Thioxanthone in Protic Solvents: II. Theory

et al. 2014

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“…Microfluidic Fabrication of pNIPAAm−pAAm Core−Shell Microgels. A p(AAm-co-DMMIAAm) solution with a concentration of 100 g L −1 containing 10 mmol L −1 of the triplet photosensitizer sodium 2,7-thioxanthonedisulfonate, prepared according to Kronfeld and Timpe, 54 was used to encapsulate the p(NIPAAm-co-BIS) core microgels. The microfluidic device and the tubing were wrapped in aluminum foil to prevent gelation of the p(AAm-co-DMMIAAm) solution by ambient light.…”

Section: Methodsmentioning

confidence: 99%

Core–Shell Microgels with Switchable Elasticity at Constant Interfacial Interaction

Seuß

Schmolke

Drechsler

et al. 2016

ACS Appl. Mater. Interfaces

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Hydrogels based on poly(N-isopropylacrylamide) (pNIPAAm) exhibit a thermo-reversible volume phase transition from swollen to deswollen states. This change of the hydrogel volume is accompanied by changes of the hydrogel elastic and Young's moduli and of the hydrogel interfacial interactions. To decouple these parameters from one another, we present a class of submillimeter sized hydrogel particles that consist of a thermosensitive pNIPAAm core wrapped by a nonthermosensitive polyacrylamide (pAAm) shell, each templated by droplet-based microfluidics. When the microgel core deswells upon increase of the temperature to above 34 °C, the shell is stretched and dragged to follow this deswelling into the microgel interior, resulting in an increase of the microgel surficial Young's modulus. However, as the surface interactions of the pAAm shell are independent of temperature at around 34 °C, they do not considerably change during the pNIPAAm-core volume phase transition. This feature makes these core-shell microgels a promising platform to be used as building blocks to assemble soft materials with rationally and independently tunable mechanics.

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“…In order to obtain evidence for the formation of the triplet state in the photoreactivity of CYA, we used another energy acceptor substrate instead of oxygen. Acrylamide has largely been employed for this purpose in the literature (24,25). The laser excitation at 266 nm of an argon-saturated aqueous 1.4 · 10 )2 2.7 · 10 ) 4 1.8 · 10 )2 <10 ) 5 2.7 · 10 )2 solution of the mixture acrylamide (2.0 · 10 )3 mol L )1 ) and CYA (1.1 · 10 )4 mol L )1 ) at pH = 5.4 led to a rapid decay of the absorbance at 275 nm, indicating that an energy transfer process is efficiently operating and that the triplet excited state was formed upon excitation of CYA.…”

Section: Laser Flash Photolysis Studiesmentioning

confidence: 99%

Reaction Pathways for the Photodegradation of the Organophosphorus Cyanophos in Aqueous Solutions

Ménager¹,

Pilichowski²,

Sarakha³

2010

Photochem & Photobiology

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Photodegradation in aqueous solutions is an important pathway for many agrochemicals such as pesticides. In the present work, the photochemical transformation of cyanophos (CYA) was investigated in aqueous solutions using UV light within the 254-313 nm range as well as solar light. The study was performed in order to have a deep insight into the mechanistic pathways for the photochemical disappearance of CYA. Upon UV irradiation of an aerated solution of CYA, the degradation quantum yield was found equal to 1.8 x 10(-2). It is independent of the excitation wavelength but varies with oxygen concentration. It increased by a factor of 2 from oxygen-saturated to oxygen-free solution. Photosensitized experiments were performed using acrylamide and hydroquinone as energy acceptor and energy donor substrates, respectively. They show that both singlet and triplet excited states were involved in the photochemical behavior of CYA. The laser flash photolysis experiments clearly showed the involvement of the triplet excited state which was efficiently quenched by molecular oxygen and acrylamide with the rate constants 1.97 x 10(9) and 2.71 x 10(9) mol(-1) L s(-1), respectively. The photoproducts structures were proposed according to the mass spectral data using the LC/MS technique. The analytical study shows that various processes such as hydrolysis, homolytic bond dissociations and Photo-Fries process occur.

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ChemInform Abstract: Water‐Soluble Disulfonated Aromatic Ketones (I) and (IV) ‐ Photophysical and Photochemical Properties.

Cited by 3 publications

References 1 publication

Chimeric Behavior of Excited Thioxanthone in Protic Solvents: II. Theory

Chimeric Behavior of Excited Thioxanthone in Protic Solvents: II. Theory

Core–Shell Microgels with Switchable Elasticity at Constant Interfacial Interaction

Reaction Pathways for the Photodegradation of the Organophosphorus Cyanophos in Aqueous Solutions

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