Photochemical and Photophysical Studies of and in Bulk Polymers

Abraham, Shibu; Weiss, Richard G.

doi:10.1002/9781118095300.ch11

Cited by 2 publications

(1 citation statement)

References 179 publications

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“…Reviews should be consulted to comprehend the opportunities and limitations involved in the use of these media. [3,7,[111][112][113][114][115][116][117] Amongst the solid surfaces considerable control on excited state reactions have been achieved in zeolites which are easier to handle and commercially available at modest cost; even large pore zeolites (MCMs) can be easily synthesized. Availability of zeolites with varying internal structures and dimensions has attracted a number of groups to explore them as reaction 4 media.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular photochemistry concepts highlighted with select examples

Ramamurthy

Mondal

2015

Journal of Photochemistry and Photobiology C: Photochemistry Re

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‗Supramolecular Photochemistry' (SP) deals with a study of the properties of molecules in their excited states where the medium plays a significant role. While ‗Molecular Photochemistry' (MP) deals with studies in isotropic solution, the SP deals with reactant molecules that interact weakly with their surroundings. The surroundings in general are highly organized assemblies such as crystals, liquid crystals, micelles, hostguest structures etc. The behavior of exited molecules in SP unlike in isotropic solution is controlled not only by their inherent electronic and steric properties but also by the immediate surroundings. The weak interactions that control the chemistry include van der Walls, hydrophobic, C-H-, - and several types of hydrogen bonds. In this review the uniqueness of SP compared to MP is highlighted with examples chosen from reactions in crystals, micelles and host-guest assemblies. In spite of distinctly different structures (crystals, micelles etc.) the influence of the medium could be understood on the basis of a model developed by G. M. J. Schmidt for photoreactions in crystals. The principles of reaction cavity model are briefly outlined in this review. There are a few important features that are specific to SP. For example, highly reactive molecules and intermediates could be stabilized in a confined environment; they enable phosphorescence to be observed at room temperature and favor chiral induction in photochemical reactions. Using such examples the uniqueness of SP is highlighted. The future of SP depends on developing efficient and unique catalytic photoreactions using easily available reaction ‗containers'. In addition, their value in artificial photosynthesis should be established for SP to occupy a center stage in the future.

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Section: Introductionmentioning

confidence: 99%

Supramolecular photochemistry concepts highlighted with select examples

Ramamurthy

Mondal

2015

Journal of Photochemistry and Photobiology C: Photochemistry Re

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Modulation of the Photophysical Properties of Pyrene by the Microstructures of Five Poly(alkyl methacrylate)s Over a Broad Temperature Range

Atvars

Abraham

Hill

et al. 2013

Photochem & Photobiology

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Pyrene fluorescence spectra have been recorded in five poly(alkyl methacrylate)s (where alkyl is ethyl butyl, isobutyl, cyclohexyl and hexadecyl) over a 20-400 K temperature range. The changes in the position and the full width at half maximum (FWHM) of the 0-0 emission band (peak I) have been correlated with the structural characteristics of the alkyl groups in the different relaxation regimes of the polymers to assess the degree of coupling of the excited singlet states with the polymer cybotactic regions. Data treatment of the peak I positions using an electron-phonon model indicates that longitudinal optical modes are involved, and that the magnitude of coupling depends on the polymer structure and follows the same trend as the glass transition temperatures. The same spectral parameters have been correlated also with "hole" free volumes from positron annihilation spectroscopy over temperature ranges which span the glass or melting transitions of the polymers. Reasons why free volume and FWHM measurements follow the same trends, and other aspects of the systems, are discussed.

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Photochemical and Photophysical Studies of and in Bulk Polymers

Cited by 2 publications

References 179 publications

Supramolecular photochemistry concepts highlighted with select examples

Supramolecular photochemistry concepts highlighted with select examples

Modulation of the Photophysical Properties of Pyrene by the Microstructures of Five Poly(alkyl methacrylate)s Over a Broad Temperature Range

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