Tunneling versus Hopping in Mixed-Valence Oligo-p-phenylenevinylene Polychlorinated Bis(triphenylmethyl) Radical Anions

Organic solids and polymers that absorb in the near-infrared (NIR) region (1000–2000 nm) represent a class of emerging materials and show a great potential for use in photonics and telecommunications. The radical anions of stacked aromatic imides, fused phorphyrin arrays, polythiophenes, sandwich-type lanthanide bisphthalocyanines, semiquinones, and mixed-valence dinuclear metal complexes are a few known examples of NIR-absorbing organic materials. Most of these NIR-absorbing materials are also electro- chemically active or electrochromic (EC). This brief review covers several types of NIR-absorbing organic materials and discusses their potential for applications in EC variable optical attenuators (VOAs).

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Mixed valence radical anions of 4,4″-dinitro-p-terphenyl and its aza derivatives as models for electronic communication in conducting polymers

Journal of Photochemistry and Photobiology A Chemistry ◽

10.1016/j.jphotochem.2019.02.037 ◽

2019 ◽

Vol 376 ◽

pp. 140-145 ◽

Cited By ~ 1

Author(s):

João P. Telo ◽

M. Fernanda N.N. Carvalho

Keyword(s):

Conducting Polymers ◽

Electronic Communication ◽

Mixed Valence ◽

Radical Anions

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Resonance Raman spectroscopic study of solvent-dependent coexistence of localized and delocalized dinitroaromatic radical anions

Canadian Journal of Chemistry ◽

10.1139/cjc-2014-0058 ◽

2014 ◽

Vol 92 (10) ◽

pp. 940-947 ◽

Cited By ~ 2

Author(s):

Ryan M. Hoekstra ◽

Yen-Ting Chen ◽

Matthew D. Kiesz ◽

João P. Telo ◽

Rachel M. Stephenson ◽

...

Keyword(s):

Broad Band ◽

Mixed Valence ◽

Resonance Raman ◽

Reorganization Energy ◽

Class Ii ◽

Radical Anions ◽

Class Iii ◽

Excitation Energies ◽

Absorption Region ◽

Stretch Mode

Optical absorption spectra of three dinitroaromatic radical anions, 2,7-dinitro-9,9-dimethylfluorene (1•−), 4,4′-dinitrobiphenyl (2•−), and 4,4′-dinitrotolane (3•−) in solvents THF, HMPA, and MeCN show both an unresolved broad band characteristic of charge-localized mixed valence species (Robin-Day classification Class II), and a vibronically structured band of the delocalized species (Class III). With decreasing solvent reorganization energy, a greater portion of the compounds become charge-delocalized. In particular, 1•− with the greatest coupling, is almost entirely composed of the delocalized species in all solvents. An intense Raman mode is used to identify the charge-bearing unit as the nitrobenzene moiety. Resonance Raman profiles are utilized to gain detailed information of vibrational modes. The out-of-phase ring lengthening stretch mode is observed to be enhanced at higher excitation energies, corresponding to the absorption band of the Class II species, while the in-phase ring lengthening stretch mode, a totally symmetric vibration, is most strongly enhanced in the absorption region of the Class III species. Resonance Raman profiles support the solvent-dependent coexistence of Class II and Class III molecules of the same chemical composition.

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Interpretation of Mixed-Valence Compound Optical Spectra Near the Class II/III Border: Dinitrobiphenyl and Dinitrophenanthrene Radical Anions

The Journal of Physical Chemistry A ◽

10.1021/jp807602k ◽

2008 ◽

Vol 112 (49) ◽

pp. 12622-12628 ◽

Cited By ~ 26

Author(s):

Stephen F. Nelsen ◽

Kevin P. Schultz ◽

João P. Telo

Keyword(s):

Mixed Valence ◽

Class Ii ◽

Optical Spectra ◽

Radical Anions ◽

Mixed Valence Compound

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Mixed valence complexes involving MM quadruple bonds (M=Mo or W)

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2007.2143 ◽

2007 ◽

Vol 366 (1862) ◽

pp. 101-112 ◽

Cited By ~ 13

Author(s):

Malcolm H Chisholm

Keyword(s):

Mixed Valence ◽

Electronic Coupling ◽

Organic Radical ◽

Radical Anions ◽

Class Iii ◽

Mixed Valency ◽

Bridging Ligand ◽

Quadruple Bond ◽

Redox Active ◽

Quadruple Bonds

The MM quadruple bond of configuration MM σ 2 π 4 δ 2 is redox active and in many ways ideally suited for studies of mixed valency when two or more such centres are linked by a bridging ligand. In this account, the mechanism of electronic coupling is examined for complexes of the type [L 3 M 2 bridgeM 2 L 3 ] 0/+ where L, a pivalate; bridge, a dicarboxylate or related ligand and M, Mo or W. The represented examples allow us to probe electronic factors close to the class II/III border and readily distinguish between electron and hole transfer in the superexchange mechanism. The potential for mixed valence organic radical anions mediated by the M 2 centre is also raised and one specific example of class III behaviour is described.

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