Identity and yield of positive charge centers in irradiated chloro hydrocarbon liquids and the rates of their interaction with solute molecules

Ying, Wang; Tria, John J.; Dorfman, Leon M.

doi:10.1021/j100478a005

Cited by 35 publications

(19 citation statements)

References 1 publication

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“…For example, radiolysis of methylene chloride yields reactive radical species such as RCl • . [38][39][40][41][42] In oxygenated solutions, • CH 2 Cl reacts with O 2 to generate CH 2 ClOO • , which also acts as an oxidative species. The reaction between 1 and CH 2 ClOO • is expected to yield the radical cation of the dye.…”

Section: Resultsmentioning

confidence: 99%

Photochemistry of Squaraine Dyes: Excited Triplet State and Redox Properties of Crown Ether Squaraines

Sauvé¹,

Kamat²,

Thomas³

et al. 1996

J. Phys. Chem.

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The excited state and redox properties of three crown-ether derivatives of squaraines have been studied. Direct laser excitation of these dyes leads to the formation of excited triplets, dye radical cations and anions, via a biphotonic photoionization mechanism. All these transient species absorb strongly in the visible region. The triplet states of these dyes generated via triplet-triplet energy transfer from 3 (1-pyrenecarboxaldehyde)* and 3 C 60 * photosensitizers also produce dye radical cations and anions via a self-quenching process. The bimolecular rate constants for the self-quenching process are in the range of (0.5-1.9) × 10 9 M -1 s -1 . The redox properties of these dyes have been investigated by electrochemical, spectroelectrochemical, and radiolytic methods. They exhibit two reversible oxidations in the potential range of 0.7-1.2 V vs SCE. The spectral features of electrochemically generated one electron oxidation product (λ max ) 680 nm) match those of dye radical cations produced by photochemical and radiolytic methods.

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Section: Resultsmentioning

confidence: 99%

Photochemistry of Squaraine Dyes: Excited Triplet State and Redox Properties of Crown Ether Squaraines

Sauvé¹,

Kamat²,

Thomas³

et al. 1996

J. Phys. Chem.

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“…It is pertinent to note similar pulsed radiolysis studies in 1,2 dichloromethane (10). Again inclusion of a low ionization potential solute in the irradiated solvent produces the solute radical cation, which appeared at a very rapid rate and beyond the measurement time of the system.…”

Section: Introductionmentioning

confidence: 88%

“…Radiolytic studies (9–16) show that the positive hole is very labile in both solid and liquid CCl 4 and ionizes solutes (RH) hosted by this solvent.…”

Section: Introductionmentioning

confidence: 99%

The Laser Two-photon Photolysis of Liquid Carbon Tetrachloride†

Zhang

Thomas

2006

Photochem Photobiol

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The two-photon photolysis of liquid CCl4 with 25 ps pulses of 266 nm light has been studied and compared with similar studies with high energy radiation. Both neutral and ionic species are produced from excited states and ionization. The emphasis of the study is on the ionic processes, while some data related to excited states and free radicals are presented. In both radiolysis and photolysis, a solvent separated charged pair, CCl3+ // Cl-, exhibiting a lambda(max) at 475 nm, is observed that exhibits a total growth over 38 to 100 ps. Solutes with ionization potentials less than that of CCl4 (11.47 eV) reduce the yield of the 475 nm species producing radical cations of the solute. The efficiency of this process is about 10-fold larger in radiolysis compared with photolysis. Analysis of the data suggest that the lower energy of two-photon photolysis produces a charge pair CCl4+ // CCl4-, which decays in about 3 ps to CCl4+ // Cl-. This species then decays to CCl3+ // Cl-. The lifetime of the growth of the 475 nm is measured as 46 ps. These studies clearly show areas where radiolysis and photolysis can be quite similar and also areas where the vast difference in excitation energy introduces stark differences in the observed radiation and photoinduced chemistry.

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“…at 720 nm) [39] and PMDI radical anion (e PMDI C À = 41 700 m À1 cm À1 at 720 nm) [25] were employed. Rate constants (k) for the various processes were obtained from F and t F values by using standard equations.…”

mentioning

confidence: 99%

An Anthracene‐Appended β‐Cyclodextrin‐Based Dyad: Study of Self‐Assembly and Photoinduced Electron‐Transfer Processes

Balan

Gopidas

2007

Chemistry A European J

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The self-assembly of a beta-cyclodextrin (beta-CD)-based supramolecular dyad is reported, in which the donor anthracene moiety is covalently linked to the smaller rim of the beta-CD and the acceptor pyromellitic diimide (PMDI) is encapsulated within the beta-CD cavity. Encapsulation of the PMDI into the beta-CD cavity was studied by a variety of techniques, which suggested that PMDI is encapsulated so as to position the aromatic part at the centre of the cavity with the 2-propyl end at the narrower rim among the overhanging primary OH groups and the N-ethylpyridinium end situated at the wider rim exposed to water. Photoinduced electron transfer (PET) in the system was studied by fluorescence quenching and laser flash photolysis techniques. At [PMDI]<10(-4) M, the equilibrium is in favour of the free molecules, and under these conditions fluorescence quenching is negligible and diffusion-mediated electron transfer involving the triplet excited state of anthracene predominates. At higher concentrations of PMDI, the equilibrium is largely in favour of the supramolecular dyad and intra-ensemble PET processes predominate. The experimentally determined electron-transfer rate constant agrees very well with that calculated by using the Marcus equation. It was observed that a fraction of the ion pairs survived for more than 200 micros.

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Identity and yield of positive charge centers in irradiated chloro hydrocarbon liquids and the rates of their interaction with solute molecules

Cited by 35 publications

References 1 publication

Photochemistry of Squaraine Dyes: Excited Triplet State and Redox Properties of Crown Ether Squaraines

Photochemistry of Squaraine Dyes: Excited Triplet State and Redox Properties of Crown Ether Squaraines

The Laser Two-photon Photolysis of Liquid Carbon Tetrachloride†

An Anthracene‐Appended β‐Cyclodextrin‐Based Dyad: Study of Self‐Assembly and Photoinduced Electron‐Transfer Processes

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