Incarceration strongly increases the rate of the thermal decomposition of diazirine 1 to yield carbene 2. The increase of the inner phase rate is rationalized by a stabilization of the transition state through dispersion interactions between the breaking C−N bonds and one of the highly polarizable arene rings of the surrounding host 3.
Raman and infrared spectra of trimethylsulfonium dicyanamide [(CH(3))(3)SN(CN)(2)] are reported and accurately reproduced by DFT methods (B3LYP and B3PW91), MP2, and MP3, and to a lesser extent by the RHF method. The (CH(3))(3)SN(CN)(2) ionic liquid forms two isomeric dimers that are of cyclic structure, one of which is 13 kcal/mol lower in energy than the other. Both isomeric cyclic pairs (versions 1 and 2), [(CH(3))(3)SN(CN)(2)](2), have the potential to further combine and form a common structure containing four pairs of (CH(3))(3)SN(CN)(2). This structure can then conceivably undergo a stacking procedure to form extended ionic liquid nanotubes of eight ionic liquids, [(CH(3))(3)SN(CN)(2)](8). The possible formation of gas phase ionic liquid clusters of two, four, and eight trimethylsulfonium dicyanamide ionic liquids is supported by highly exergonic free energy changes obtained from B3LYP/(6-311+G(d,p)) density functional calculations.
Supramolecular ferrocene-fullerene constructs in which the donor, ferrocene linked to a benzo-18-crown-6 entity (Fc-crown), was self-assembled with the acceptor, fullerene bearing one or two alkyl ammonium ions (NH 3 + -C 60 ), yielding dyads or a triad, respectively. The newly formed conjugates were characterized by spectroscopic (fluorescence, electospray ionization-mass, and 1 H NMR) and electrochemical methods. The adopted crown ether-alkyl ammonium ion binding strategy resulting in stable donor-acceptor conjugates was also supported by the computational studies performed at the DFT B3LYP/3-21G(*) level in addition to the binding constants obtained from fluorescence quenching studies. The experimentally calculated freeenergy changes indicated exothermic light-induced charge-separation process. Accordingly, efficient photoinduced charge-separation processes were confirmed by the combination of the time-resolved fluorescence and nanosecond transient absorption spectral measurements. The rates of charge recombination were found to be 2-3 orders of magnitude lower, yielding radical ion-pairs, Fc + -crown/NH 3 + -C 60 •with lifetimes in the 10-240 ns range. Generally, by increasing the donor-acceptor distance, a decrease in both k CS and k CR was observed for the supramolecular ferrocene-fullerene dyads; that is, the lifetimes of Fc + -crown/NH 3 + -C 60 •changed from 10 to 165 ns. However, for the triad, involving two ferrocene donors of varying donoracceptor distances, the k CR originating from the far-side located ferrocene was found to be 240 ns while the k CR from the near-side located ferrocene was faster than the time duration of the nanosecond laser pulse (6 ns).
The use of chlorotrityl resins for the immobilization of amines is sometimes deterred by the lengthy process of loading the reactants on the resins and product decomposition caused by the reactive chlorotrityl group in the presence of 1% TFA as a cleavage agent. Here, we report improved methods developed for selective and efficient loading of aminobenzoic acid derivatives on chlorotrityl resins and for cleavage of aniline-containing products from the resins without decomposition. These methods led to the synthesis of a library of 144 discrete chemicals as potential farnesyltransferase inhibitors (FTIs) using IRORI's radio-frequency-encoded sorting technique and to the study of the applicability of the bivalence approach to the development of FTIs.
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