Intramolecular Charge Transfer Complexes. 4. Poly(N-(2-hydroxyethyl)carbazolyl Acrylate-co-Picryl Methacrylate)

Abstract

Radical copolymerization of N-(2-hydroxyethyl)carbazolyl acry-late with picryl methacrylate takes place mainly through the inter-monomeric charge transfer complex (CTC) in dioxane solution. When the solvent is 1, 2-dichloroethane, concurrent chain transfer reactions arise. The copolymers obtained are intramolecular CTC. The charge transfer interaction depends on copolymer composition and conformation, and on the copolymerization solvent.     

Charge distribution in Mn(salen) complexes

The charge and spin distribution in manganese‐salen complexes were analyzed using different basis sets and density functionals. Five population analysis methods [Mulliken, Löwdin, Natural population analysis (NPA), atoms in molecules (AIM), and CHelpG] were used to characterize the charge distribution. Results show that NPA and AIM were the only methods capable of giving charges with the correct sign for all cases under study. According to the analysis of the natural charge and spin distributions, the salen ligand shows a complex behavior, counteracting the effect of the chloro and oxo ligands on the metal center. Furthermore, the presence of a chloride counter ion increases the oxo‐radical character of Oxo‐Mn(salen) complexes, which may play an important role in the rationalization of the catalytic properties of Mn(salen) complexes. © 2014 Wiley Periodicals, Inc.     

Charge Transfer Dissociation (CTD) Mass Spectrometry of Peptide Cations: Study of Charge State Effects and Side-Chain Losses

1+, 2+, and 3+ precursors of substance P and bradykinin were subjected to helium cation irradiation in a 3D ion trap mass spectrometer. Charge exchange with the helium cations produces a variety of fragment ions, the number and type of which are dependent on the charge state of the precursor ions. For 1+ peptide precursors, fragmentation is generally restricted to C?CO backbone bonds (a and x ions), whereas for 2+ and 3+ peptide precursors, all three backbone bonds (C?CO, C?N, and N?Cα) are cleaved. The type of backbone bond cleavage is indicative of possible dissociation channels involved in CTD process, including high-energy, kinetic-based, and ETD-like pathways. In addition to backbone cleavages, amino acid side-chain cleavages are observed in CTD, which are consistent with other high-energy and radical-mediated techniques. The unique dissociation pattern and supplementary information available from side-chain cleavages make CTD a potentially useful activation method for the structural study of gas-phase biomolecules.

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Sulphur substituted organotin compounds : VII. Charge transfer interactions of arylthiomethyl(triphenyl)tin compounds with tetracyanoethylene

Thermolysis of η²-benzoyl(phenyl)zirconocene yields the η²-benzophenonzirconocene complex 2, isolated as a dimer. 2 exhibits an ambivalent reactivity pattern. The formation of five-membered metallacycles from 2 and olefinic hydrocarbons possibly proceeds analogous to reactions of “normal” metalolefin π-complexes. However, both reactions with the electron-deficient olefins dimethylfumarate and -maleate and the behavior towards electrophilic and protic reagents as well as aromatic hydrocarbons might be interpreted in terms of a metallaoxirane-character of 2.     

Iron(III) 2,3-dihydroxyterephthalamides revisited. Charge effects on highly stable ferric complexes

A series of substituted 2,3-dihydroxyterephthalamides has been prepared and investigated by means of potentiometry, spectrophotometry and ¹H NMR spectroscopy at 25 °C. Proton association constants for the ligand and formation constants for the ferric complexes are as follows: 2,3-dihydroxy-N,N’-diethylterephthalamide, log β₀₁₁ = 10.83, log β₀₁₂ = 17.09, log β₁₁₀ = 17.27, log β₁₂₀ = 31.59, log β₁₃₀ = 42.67; 2,3-dihydroxy-N,N’-bis(2-hydroxyethyl)terephthalamide, log β₀₁₁ = 10.61, log β₀₁₂ = 16.66, log β₁₁₀ = 17.04, log β₁₂₀ = 31.0, log β₁₃₀ = 42.1; 2,3-dihydroxy-N,N’-bis(ethanesulfonate)terephthalamide disodium salt, log β₀₁₁ = 11.01, log β₀₁₂ = 17.48, log β₁₁₀ = 18.24, log β₁₂₀ = 31.72, log β₁₃₀ = 40.3; 2,3-dihydroxy-N,N’-bis(N,N-dimethylaminoethyl)terephthalamide dihydrobromide salt, log β₀₁₁ = 10.86, log β₀₁₂ = 20.10, log β₀₁₃ = 28.53, log β₀₁₄ = 33.92, log β₁₁₀ = 17.4, log β₁₂₀ = 32.5, log β₁₃₀ = 45.2. The equilibrium free metal ion concentrations (–log 〚Fe³⁺〛 = pM) of these ligands are compared and discussed.     

Peculiarity of Hexamethylenetetratellurafulvalene (HMTTeF) Charge Transfer Complexes of Donor-Acceptor (D-A) Type

The complex formation of hexamethylenetetratellurafulvalene (HMTTeF) with 28 kinds of organic electron acceptors yielded 31 charge transfer (CT) complexes. The infrared and ultra-violet-visible-near-infrared spectra of the complexes were examined to study the ionicity of their ground states in solid. A plot of CT transition energies and the difference of redox potentials; ΔE(DA) of donor (D) and acceptor (A) molecules indicated that four complexes have a neutral ground state. Four other complexes exhibit characteristic features of a fully ionic ground state based on the vibrational spectra. Notably, the HCBD, F₄TCNQ and DDQ complexes indicate both a relatively low first CT band and high conductivity in a solid in spite of the fully ionic character being very plausible. Twenty-three complexes having a partially ionic ground state have a CT band below 4×10 cm⁻¹ and are highly conductive. The preparation of good single crystals of the HMTTeF complexes for structural analysis was only successful with Et₂TCNQ and BTDA-TCNQ, which have the structure of DA alternately stacking. These two complexes indicate high conductivities in spite of their disadvantageous packing manner. The intermolecular interactions are found to be strongly enhanced by both the bulky molecular orbital of HMTTeF and the decreased on-site Coulomb repulsion in the HMTTeF complexes. These two factors in particular seem to prevent both the fully ionic and the DA alternating HMTTeF complexes from becoming insulators, even though the redox parameters and the crystal structures predict them to be insulating.     

Bridge-Length-Dependent Intramolecular Charge Transfer in Bis(dianisylamino)-Terminated Oligo(p-phenylene)s

Radical cations of bis(dianisylamino)-terminated oligo(p-phenylene)s (OPPs) with up to five phenyl moieties were characterized by means of UV/Vis-NIR and variable-temperature ESR spectroscopy to investigate the bridge-length-dependence on intramolecular charge/spin self-exchange between two nitrogen redox-active centers. Additionally, a comparative study between bis(dianisylamine)-based mixed-valence (MV) radical cations connected by p-terphenylene and hexa-peri-hexabenzocoronene (HBC) π-bridging units also provided information on the influence of extended π-conjugation over the OPP-bridge due to the planarization between adjacent phenylene units on the strength of electronic coupling. The present study on a homologous series of organic MV systems clarifies the attenuation factor through the OPP-bridge and the linear relationship between the electrochemical potential splitting and the electronic coupling in the region of intermediate-to-weak electronic coupling regime.     

Charge carrier photogeneration and transport in poly(methyl-phenylsilylene)

Optical excitations in poly(methyl-phenylsilylene) can be realized within the framework of a chemical bond in the polymer backbone or a side group skeleton. A charge transfer of the electron from the main chain to a side group is necessary to form stable ion-pairs. Dissociation of the ion-pairs can be described in terms of the Onsager theory of geminate recombination. The photogeneration efficiency can be improved by an electron acceptor doping. The charge carrier transport is influenced by two factors: delocalized movement inside the conjugated domains and intra- and interchain hopping. The electrostatic interactions of polar additives with polarons influence the polaron binding energy and the charge hopping.     

Charge transport properties of tris(8-hydroxyquinolinato)aluminum(III): why it is an electron transporter

The charge transport properties of mer-tris(8-hydroxyquinolinato)aluminum(III) (mer-Alq), which is the most widely used electron transport material in OLED, were investigated by quantum chemistry calculations within the framework of the charge hopping model and Marcus electron transfer theory. Internal reorganization energies of 0.276 and 0.242 eV were calculated by the DFT-B3LYP method employing a 6-31 G* basis set for the electrons lambdai(e) and holes lambdai(h), respectively. The relative distances and orientations of Alq molecules in amorphous film were simulated by those in the beta-phase. The intermolecular charge-transfer integrals, Hda(h) and Hda(e), along all 14 hopping pathways were then calculated by the Koopmans Theorem in conjunction with the Hartree-Fock method employing a 6-31 G* basis set as well as by the direct coupling method. The results showed that there were some Hda(e) that were 1 order of magnitude larger than any Hda(h), because hopping pathways with effective overlaps of LUMOs can occur and, thus, large Hda(e). On the other hand, effective overlap of HOMO was absent in all pathways, resulting in a relatively small Hda(h). This difference in the magnitudes of Hda(e) and Hda(h) would predict a 2 orders of magnitude difference in the electron-transfer rate constants and account for the observed 2 orders of magnitude difference in the mobilities of electrons and holes.