Inter- and Intramolecular Interactions of Polymers as Studied by Fluorescence Spectroscopy. I. Exciplex Formation of a Polyester with a Terephthalate Main Chain Having a Pendant ι -Carbazylbutyl Group

1975 ◽  
Vol 8 (3) ◽  
pp. 280-283 ◽  
Author(s):  
Shigeo Tazuke ◽  
Yuziro Matsuyama
Keyword(s):  
Fluorescence Spectroscopy ◽  
Main Chain ◽  
Intramolecular Interactions ◽  
Exciplex Formation

Aromatic Polyimides Containing Main-Chain Diphenylaminofluorene–Benzothiazole Motif: Fluorescence Quenching, Two-Photon Properties, and Exciplex Formation in a Solid State

2011 ◽  
Vol 44 (18) ◽  
pp. 7194-7206 ◽  
Author(s):  
Matthew J. Dalton ◽  
Ramamurthi Kannan ◽  
Joy E. Haley ◽  
Guang S. He ◽  
Daniel G. McLean ◽  
...  
Keyword(s):  
Solid State ◽  
Fluorescence Quenching ◽  
Main Chain ◽  
Aromatic Polyimides ◽  
Two Photon ◽  
Exciplex Formation

scholarly journals Modeling and characterization of exciplexes in photoredox CO2 reduction: Insights from quantum chemistry and fluorescence spectroscopy

2021 ◽  
Author(s):  
Kareesa Kron ◽  
Jonathan Ryan Hunt ◽  
Jahan Dawlaty ◽  
Shaama Mallikarjun Sharada
Keyword(s):  
Excited State ◽  
Fluorescence Spectroscopy ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Co2 Reduction ◽  
Energy Decomposition Analysis ◽  
Emission Frequency ◽  
Exciplex Formation ◽  
Exciplex Emission

Interactions between excited state arenes and amines can lead to the formation of structures with distinct emission behavior. These excited state complexes or exciplexes can reduce the ability of the arene to participate in other reactions, such as CO2 reduction, or increase the likelihood of degradation via Birch reduction. Exciplex geometries are necessary to understand photophysical behavior and probe degradation pathways but are challenging to calculate. We establish a detailed computational protocol for calculation, verification, and characterization of exciplexes. Using fluorescence spectroscopy, we first demonstrate the formation of exciplexes between excited state oligo-(p-phenylene) (OPP), shown to successfully carry out CO2 reduction, and triethylamine (TEA). Time-dependent density functional theory (TDDFT) is employed to optimize the geometries of these exciplexes, which are validated by comparing both emission energies and their solvatochromism with experiment. Excited state energy decomposition analysis confirms the predominant role played by charge transfer interactions in the red-shift of emissions relative to the isolated excited state OPP*. We find that although the exciplex emission frequency depends strongly on solvent dielectric, the extent of charge separation in an exciplex does not. Our results also suggest that the formation of solvent-separated ionic radical states upon complete electron transfer competes with exciplex formation in higher dielectric solvents, thereby leading to reduced exciplex emission intensities in fluorescence experiments.

scholarly journals Self-Structuring in Water of Polyamidoamino Acids with Hydrophobic Side Chains Deriving from Natural α-Amino Acids

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1261 ◽  
Author(s):  
Federica Lazzari ◽  
Amedea Manfredi ◽  
Jenny Alongi ◽  
Raniero Mendichi ◽  
Fabio Ganazzoli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Main Chain ◽  
Intramolecular Interactions ◽  
Wavelength Interval ◽  
Acid Base ◽  
Repeat Units ◽  
Inflection Points ◽  
Ph Dependent ◽  
Selective Interactions ◽  
Base Properties

This paper reports on synthesis, acid-base properties and self-structuring in water of chiral polyamidoamino acids (PAACs) obtained by polyaddition of N,N′-methylenebisacrylamide with l-alanine, l-valine and l-leucine (M-l-Ala, M-l-Val, M-l-Leu) with potential for selective interactions with biomolecules. The polymers maintained the acid-base properties of amino acids. In water, the circular dichroism spectra of PAACs revealed pH-dependent structuring in the range 3–11 and in the wavelength interval 200–280 nm. Taking as reference the values at pH 3, the differential molar ellipticities were plotted in the pH interval 3–11. Sigmoidal curves were obtained presenting inflection points at pH 8.1, 6.8 and 7.3 for M-l-Ala, M-l-Val and M-l-Leu, respectively, corresponding to the amine half-ionization. Theoretical modeling showed that PAACs assumed stable folded conformations. Intramolecular interactions led to transoid arrangements of the main chain reminiscent of protein hairpin motif. Oligomers with ten repeat units had simulated gyration radii consistent with the hydrodynamic radii obtained by dynamic light scattering.

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