Increasing the oxidation power of TCNQ by coordination of the fluorinated Lewis acid B(C6F5)3

The oxidation power of the cyanocarbon TCNQ (tetracyano-quinodimethane) can be significantly increased to approximately E = +0.9 V vs. Cp2Fe by coordination of up to four equivalents of the strong fluorinated Lewis acid B(C6F5)3. Thianthrene and tris(4-bromophenyl)amine were oxidized to the corresponding radical cations. Dianionic [TCNQ∙4 B(C6F5)3]2ꟷ was formed upon reduction with two equivalents of ferrocene or decamethylcobaltocene.

Synthesis and Excimer Formation Properties of Electroactive Polyamides Incorporated with 4,5-Diphenoxypyrene Units

A new dietherpyrene-cored diamine monomer, namely, 4,5-bis(4-aminophenoxy)pyrene, was successful synthesized and formed a series of electroactive polyamides with an aryloxy linkage in a polymer main chain and bearing pyrene chromophore as a pendent group using conventional one-pot polycondensation reactions with commercial aromatic/aliphatic dicarboxylic acids. The resulting polyamides exhibited good solubility in polar organic solvents and, further, can be made into transparent films. They had appropriate levels of thermal stability with moderately high glass-transition values. The dilute NMP solutions of these polyamides exhibited pyrene characteristic fluorescence and also showed a remarkable additional excimer emission peak centered at 475 nm. Electrochemical studies of these polymer films showed that these polyamides have both p- and n-dopable states as a result of the formation of radical cations and anions of the electroactive pyrene moieties.

The Effect of Thermal Treatment on Selected Properties and Content of Biologically Active Compounds in Potato Crisps

The aim of this study was to determine the effect of blanching and frying on selected properties of potato crisps of yellow- and purple-fleshed cultivars. The material used was yellow flesh cv. Ismena and purple flesh cv. Provita. Potato slices were blanched (1–5 min at 80–90 °C) and then fried (155–175 °C). The control sample was comprised of crisps that were not blanched. The fat content and color parameters were determined in crisps, while in defatted samples, the following were determined: the content of total polyphenols; antioxidant capacity, measured by the ability to scavenge the ABTS•+ radical cations (TEAC ABTS) and by the FRAP method; and the level of fluorescent intermediary compounds (FICs) and browning index (BI), as indicators of the progress of the Maillard reaction. The content of kynurenic acid (KYNA) was examined in the raw material, in slices, in the water after blanching and in the crisps. Blanching affected the fat absorption, with time being more critical than temperature. The color of crisps from yellow flesh potatoes after blanching lightened, while the color in the purple samples darkened. The content of total polyphenols was higher in purple crisps. Increasing the temperature and shortening the time of blanching increased the polyphenol content and the antioxidant capacity. Blanching decreased the level of FICs, while frying increased FICs. Higher BI values characterized the crisps from cv. Provita. Blanching reduced BI values by 50%, while frying at highest temperature increased these values. The content of KYNA in purple potatoes was almost three times higher than in yellow ones. Blanching and frying decreased the KYNA content in potatoes and fried crisps.

Conductive gold nanoparticles assembly linked through interaction between radical cations of ethylene- and propylene-3,4-dioxythiophene mixed tetramer thiolate

A conjugated mixed tetramer consisting of ethylenedioxythiophene (EDOT (E)) and propyrenedioxythiophene (ProDOT (P)) dimers (E2P2) with methylthio end-capping group at the EDOT side was directly introduced via a thiolate linker...

Electron Holes in G-Quadruplexes: The Role of Adenine Ending Groups

The study deals with four-stranded DNA structures (G-Quadruplexes), known to undergo ionization upon direct absorption of low-energy UV photons. Combining quantum chemistry calculations and time-resolved absorption spectroscopy with 266 nm excitation, it focuses on the electron holes generated in tetramolecular systems with adenine groups at the ends. Our computations show that the electron hole is placed in a single guanine site, whose location depends on the position of the adenines at the 3′ or 5′ ends. This position also affects significantly the electronic absorption spectrum of (G+)● radical cations. Their decay is highly anisotropic, composed of a fast process (<2 µs), followed by a slower one occurring in ~20 µs. On the one hand, they undergo deprotonation to (G-H2)● radicals and, on the other, they give rise to a reaction product absorbing in the 300–500 nm spectral domain.

More Than Carbazole Derivative Activates Room Temperature Ultralong Organic Phosphorescence of Benzoindole Derivative

Herein, we report four carbazole/1H-benzo[f]indole (Cz/Bd) derivatives with increasing Bd substitution (Bd number=0~3), which give a general mechanism for Bd-based ultralong organic phosphorescence. To physically isolate Cz and Bd, we synthesized Cz and Bd in the lab, separately. According to experimental results, we draw several important points. The first important point is that Bd and its derivatives commonly possess two groups of intrinsic phosphorescence bands, of which short-lifetime band at ~450 nm is assigned to the molecular phosphorescence of their neutral molecules and of which typical ultralong phosphorescence bands at 560 nm, 610 nm and 660 nm are assigned to their radical cations. Amazingly, PMMA films (1wt.%) of CNCzBdBr and CN2BdBr both demonstrate photo-activated room-temperature ultralong organic phosphorescence while this doesn’t happen to Bd and CN3Bd. The second important point is that activation of ultralong phosphorescence from Bd derivatives involves three factors: well dispersion with limited amount in matrix, generation of Bd derivatives’ radical cations and stabilizing radical cations mediated by matrix. Cz derivative can function as a matrix to activate (room temperature) ultralong organic phosphorescence of Bd derivative but its activation function can be replaced by other methods such as photo-activation. The third important point is that the photo-activated ultralong organic phosphorescence is closely related to molecular structure of Bd derivative and stability of its radical cation. The fourth important point is that for double-carbazole system with trace isomer its room temperature ultralong organic phosphorescence originates at least from synergistic effect of monosubstituted product and disubstituted product of Bd. Furthermore, it is discovered that several other matrixes can also activate room-temperature ultralong organic phosphorescence of Bd derivatives, further verifying the second important point. To our best knowledge, this study is a big breakthrough in ultralong organic phosphorescence and will probably open a new era for its development.

Resonance Raman Spectroscopy Investigation of the Interaction of Molecules Adsorbed on Solid Acid Surfaces

Many solid acids with very strong acid sites, as some zeolites, transition metal exchanged montmorillonites, sulfated metallic oxides, are known to have the oxidizing ability, which can be related to the catalytic activity of these materials. The interaction of these solid acids with aromatic molecules can give rise to several oxidation products. Intermediate species of aromatic molecules formed by interaction with strong solid acids had been reported, as radical cations, proving the oxidizing ability of the solids. Besides radical cations, charge transfer complexes between the solid acids and aromatic molecules can be formed. These radical cations and charge transfer complexes usually show absorption bands in the visible region, opening the possibility of studying these species by Resonance Raman Spectroscopy (RRS). Benzene and substituted benzenes, phenothiazine, t-stilbene, adsorbed on solid acids, are examples of molecules that had been investigated by RRS. Exciting the spectrum with suitable radiation makes it possible to observe the RRS of the species of interest even when its concentration is low, because of the preferential enhancement of the vibrational modes of the chromophore. A review of RRS studies of molecules adsorbed on solid acids is presented. RRS proved valuable in characterizing intermediate species as radical cations or charge transfer complexes formed on the solid acids.