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Feng F, Lee SH, Cho SW, Kömürlü S, McCarley TD, Roitberg A, Kleiman VD, Schanze KS. Conjugated polyelectrolyte dendrimers: aggregation, photophysics, and amplified quenching. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:16679-16691. [PMID: 22970824 DOI: 10.1021/la303641m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Conjugated polyelectrolyte dendrimers (CPDs) are monodisperse macromolecules that feature a fully π-conjugated dendrimer core surrounded on the periphery by ionic solubilizing groups. CPDs are soluble in water and polar organic solvents, and they exhibit photophysics characteristic of the π-conjugated chromophores comprising the dendrimer core. Here we describe the synthesis and photophysical characterization of series of three generations of CPDs based on a phenylene ethynylene repeat unit structure that is surrounded by an array of anionic sodium carboxylate groups. Molecular dynamics simulations indicate that the first-generation CPD is flat while the second- and third-generation CPDs adopt oblate structures. Photophysical studies, including absorption, fluorescence spectroscopy, and lifetimes, show that the ester protected precursor dendrimers exhibit highly efficient blue fluorescence in THF solution emanating from the phenylene ethynylene chromophore that is in the dendrimer core. By contrast, the water-soluble CPDs have much lower fluorescence quantum yields and the absorption and fluorescence spectra exhibit features of strong chromophore-chromophore interactions. The results are interpreted as suggesting that the CPDs exist as dimer or multimer aggregates, even in very dilute solution. Fluorescence quenching of the anionic CPDs with the dication electron acceptor N,N'-dimethylviologen (MV(2+)) is very efficient, with Stern-Volmer quenching constants (K(SV)) increasing with generation number. The third-generation CPD exhibits highly efficient amplified quenching, with K(SV) ∼ 5 × 10(6) M(-1).
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Affiliation(s)
- Fude Feng
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
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Abdallah D, Whelan J, Dust JM, Hoz S, Buncel E. Energy Transfer in the Azobenzene−Naphthalene Light Harvesting System. J Phys Chem A 2009; 113:6640-7. [DOI: 10.1021/jp901596t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dalia Abdallah
- Department of Chemistry, Queen’s University, Kingston, ON, K7L 3N6 Canada, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, K7K 7B4 Canada, Departments of Chemistry and Environmental Science, Sir Wilfred Grenfell College (SWGC), Memorial University of Newfoundland, Corner Brook, Newfoundland and Labrador, A2H 6P9 Canada, and Department of Chemistry, Bar Ilan University, Ramat-Gan, Israel
| | - Jamie Whelan
- Department of Chemistry, Queen’s University, Kingston, ON, K7L 3N6 Canada, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, K7K 7B4 Canada, Departments of Chemistry and Environmental Science, Sir Wilfred Grenfell College (SWGC), Memorial University of Newfoundland, Corner Brook, Newfoundland and Labrador, A2H 6P9 Canada, and Department of Chemistry, Bar Ilan University, Ramat-Gan, Israel
| | - Julian M. Dust
- Department of Chemistry, Queen’s University, Kingston, ON, K7L 3N6 Canada, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, K7K 7B4 Canada, Departments of Chemistry and Environmental Science, Sir Wilfred Grenfell College (SWGC), Memorial University of Newfoundland, Corner Brook, Newfoundland and Labrador, A2H 6P9 Canada, and Department of Chemistry, Bar Ilan University, Ramat-Gan, Israel
| | - Shmaryahu Hoz
- Department of Chemistry, Queen’s University, Kingston, ON, K7L 3N6 Canada, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, K7K 7B4 Canada, Departments of Chemistry and Environmental Science, Sir Wilfred Grenfell College (SWGC), Memorial University of Newfoundland, Corner Brook, Newfoundland and Labrador, A2H 6P9 Canada, and Department of Chemistry, Bar Ilan University, Ramat-Gan, Israel
| | - Erwin Buncel
- Department of Chemistry, Queen’s University, Kingston, ON, K7L 3N6 Canada, Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, ON, K7K 7B4 Canada, Departments of Chemistry and Environmental Science, Sir Wilfred Grenfell College (SWGC), Memorial University of Newfoundland, Corner Brook, Newfoundland and Labrador, A2H 6P9 Canada, and Department of Chemistry, Bar Ilan University, Ramat-Gan, Israel
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Abstract
The development of nanotechnology using organic materials is one of the most intellectually and commercially exciting stories of our times. Advances in synthetic chemistry and in methods for the investigation and manipulation of individual molecules and small ensembles of molecules have produced major advances in the field of organic nanomaterials. The new insights into the optical and electronic properties of molecules obtained by means of single-molecule spectroscopy and scanning probe microscopy have spurred chemists to conceive and make novel molecular and supramolecular designs. Methods have also been sought to exploit the properties of these materials in optoelectronic devices, and prototypes and models for new nanoscale devices have been demonstrated. This Review aims to show how the interaction between synthetic chemistry and spectroscopy has driven the field of organic nanomaterials forward towards the ultimate goal of new technology.
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Affiliation(s)
- Andrew C Grimsdale
- Max-Planck-Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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Hofkens J, Cotlet M, Vosch T, Tinnefeld P, Weston KD, Ego C, Grimsdale A, Müllen K, Beljonne D, Brédas JL, Jordens S, Schweitzer G, Sauer M, De Schryver F. Revealing competitive Forster-type resonance energy-transfer pathways in single bichromophoric molecules. Proc Natl Acad Sci U S A 2003; 100:13146-51. [PMID: 14583594 PMCID: PMC263731 DOI: 10.1073/pnas.2235805100] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2003] [Indexed: 11/18/2022] Open
Abstract
We demonstrate measurements of the efficiency of competing Förster-type energy-transfer pathways in single bichromophoric systems by monitoring simultaneously the fluorescence intensity, fluorescence lifetime, and the number of independent emitters with time. Peryleneimide end-capped fluorene trimers, hexamers, and polymers with interchromophore distances of 3.4, 5.9, and on average 42 nm, respectively, served as bichromophoric systems. Because of different energy-transfer efficiencies, variations in the interchromophore distance enable the switching between homo-energy transfer (energy hopping), singlet-singlet annihilation, and singlet-triplet annihilation. The data suggest that similar energy-transfer pathways have to be considered in the analysis of single-molecule trajectories of donor/acceptor pairs as well as in natural and synthetic multichromophoric systems such as light-harvesting antennas, oligomeric fluorescent proteins, and dendrimers. Here we report selectively visualization of different energy-transfer pathways taking place between identical fluorophores in individual bichromophoric molecules.
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Affiliation(s)
- Johan Hofkens
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200 F, 3001 Heverlee, Belgium.
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