Document Detail


Predicting the Localized/Delocalized Character of Mixed-Valence Diquinone Radical Anions: Towards the Right Answer for the Right Reason.
MedLine Citation:
PMID:  23025699     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The Robin/Day class II/III mixed-valence character is established quantum-chemically for a series of mixed-valence diquinone radical anions. Particular emphasis is placed on the radical anion of tetrathiafulvalenedibenzoquinone, Q-TTF-Q, which has recently been used to evaluate constrained density functional approaches (CDFT) and new range hybrid functionals. Using a computational protocol based on hybrid functionals with 35-42% exact-exchange admixture and inclusion of solvent models during the structure optimization, it is demonstrated that a) Q-TTF-Q•-, 1, and the related diquinone radical anions 2-4 are all delocalized class III species in the gas phase and in nonpolar solvents, in contrast to previous assumptions; b) 1,4,5,8-anthracenetetraone radical anion, 2, remains class III in polar aprotic solvents, c) systems 1, 3 and 4 become class II, providing excellent agreement between computed and experimental intervalence charge-transfer excitations, thermal electron-transfer (ET) barriers and ESR hyperfine couplings. The direct conductor-like screening model for real solvents (D-COSMO-RS) allows the inclusion of specific hydrogen-bonding effects without the computational effort of molecular dynamics simulations and provides increased ET barriers, as well as a predicted incipient symmetry breaking for 2, due to hydrogen bonding in alcohol solvents. For the first time D-COSMO-RS optimizations in solvent mixtures have been evaluated. As previous computational studies of Q-TTF-Q•- neglected solvent effects during structure optimizations and obtained charge localization in gas-phase optimizations by CDFT or by exaggerated exact-exchange admixtures, they provided at best the right answer for the wrong reason.
Authors:
Manuel Renz; Martin Kaupp
Related Documents :
24454139 - 2-isopropyl-4-meth-oxy-5-methyl-phenyl acetate.
24281809 - Solvent-induced helical assembly and reversible chiroptical switching of chiral cyclic-...
24786409 - Metal levels in economically important bivalve species from turkey.
22733369 - Polycationic amphiphilic cyclodextrins as gene vectors: effect of the macrocyclic ring ...
23706059 - Deprotonation equilibrium of 5-tropolonediazonium salt strongly favors 1,2,5-tropoquino...
24647819 - Theoretical study of oxidation of monovacancies in hexagonal boron nitride (h-bn) sheet...
22259479 - Ethyl 1-(2-hy-droxy-eth-yl)-2-[2-(methyl-sulfan-yl)eth-yl]-1h-benzimidazole-5-carboxyl-...
23929759 - Synthesis of a silylium zwitterion.
20104339 - Markedly different cytotoxicity of the two enantiomers of c(2)-symmetrical ti(iv) pheno...
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-2
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  -     ISSN:  1520-5215     ISO Abbreviation:  J Phys Chem A     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-2     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  A Retrospective Analysis of Amniocenteses Performed for Advanced Maternal Age and Various Other Indi...
Next Document:  Identification of a conserved linear B-cell epitope in the M protein of porcine epidemic diarrhea vi...