Phenols ( I ) are extremely relevant chemical functionalities in natural, synthetic and industrial chemistry. Their corresponding electron-rich anions, namely phenolates ( I ), are characterized by interesting physicochemical properties that can be drastically altered upon light excitation. Specifically, phenolates ( I ) become strong reducing agents in the excited state and are able to generate reactive radicals from suitable precursors via single-electron transfer processes. Thus, these species can photochemically trigger strategic bond-forming reactions, including their direct aromatic C−H functionalization. Moreover, substituted phenolate anions can act as photocatalysts to enable synthetically useful organic transformations. An alternative mechanistic manifold is represented by the ability of phenolate derivatives I to form ground state electron donor-acceptor (EDA) complexes with electron-poor radical sources. These complementary scenarios have paved the way for the development of a wide range of relevant organic reactions. In this Minireview, we present the main examples of this research field, and give insight on emerging trends in phenols photocatalysis towards richer organic synthesis. 相似文献
The degradation of SF6 and SF5 organyls by S F and S C bond‐activation reactions at [{Rh(μ‐H)(dippp)}2] under mild conditions is reported. Fluorido and thiolato species were identified as products or intermediates, and were characterized by X‐ray diffraction analysis and multinuclear NMR spectroscopy. An unprecedented cyclic process for the conversion of the potent greenhouse gas SF6 into H2S was developed. 相似文献
Electron-donating corroles (Cor) were integrated with electron-accepting phthalocyanines (Pc) to afford two different non-covalent Cor ⋅ Pc systems. At the forefront was the coordination between a 10-meso-pyridine Cor and a ZnPc. The complexation was corroborated in a combination of NMR, absorption, and fluorescence assays, and revealed association with binding constants as high as 106 m −1. Steady-state and time-resolved spectroscopies evidenced that regardless of exciting Cor or Pc, the charge-separated state evolved efficiently in both cases, followed by a slow charge-recombination to reinstate the ground state. The introduction of non-covalent linkages between Cor and Pc induces sizeable differences in the context of light harvesting and transfer of charges when compared with covalently linked Cor-Pc conjugates. 相似文献
The charge renormalization in planar and spherical charged lipidic aqueous interfaces has been investigated by means of thermodynamic and electrokinetic measurements. We analyzed the behavior of mixed DOTAP/DOPE monolayers at the air-electrolyte solution interface and DOTAP/DOPE liposomes 100 nm in size dispersed in an aqueous phase of varying ionic strength. For the two systems, we have compared the "effective" surface charge derived from the measurements of surface potential and zeta-potential to the "bare" charge based on the stoichiometry of the lipid mixture investigated. The results confirm that a strong charge renormalization occurs, whose strength depends on the geometry of the mesoscopic system. The dependence of the "effective" charge on the "bare" charge is discussed in light of an analytical approximation based on the Poisson-Boltzmann equation recently proposed. 相似文献
Poly(amido‐amine)s carrying primary amino groups as side substituents have been obtained by polyaddition of N‐triphenylmethyl‐monosubstituted 1,2‐diaminoethane (TPHMAE) to 2,2‐bisacrylamido acetic acid or 1,4‐bisacryloylpiperazine and subsequent removal of the protecting triphenylmethyl group by treating the resultant polymers with aqueous hydrochloric acid. Soluble polymers can be also obtained directly by the polyaddition of monoprotonated 1,2‐diaminoethane to 2,2‐bisacrylamido acetic acid in the presence of a limited amount of added acetic or hydrochloric acid. The resultant polymers are of a higher molecular weight than the corresponding ones prepared from TPHMAE. By adding a limited amount of N‐triphenylmethyl‐monosubstituted 1,2‐diaminoethane to the monomer mixtures leading to poly(amido‐amine)s with a recognised potential as nonviral vectors, such as ISA 23 and ISA 1, a controlled number of pendant primary amino groups have been introduced. By this procedure, ISA 23 and ISA 1 become suitable as polymer carriers for carboxylated drugs as well as amenable to the labelling techniques by fluorescent probes commonly employed for proteins.
The behaviour under electron impact of six 1,1-bis(benzenesulphonyl)cyclioalkanes and of 1-phenyl-1-(benzensesulphaonyl)cyclopropane has been studied in detail with the aid of exact mass measurements, linked scans for metastable ion analysis, collisional spectroscopy and kinetic energy release measurements. The molecular ions of these compounds undergo a sulphone-sulphinate rearrangement with alkyl group migration on oxygen, in analogy with what is found for simple monosulphones and, in general, their fragmentation resembles that of mono-sulphonyl compounds. Loss of SO2 from the molecular ion is observed for all substrates, but only in the case of 1, 1-bis(benzenesulphonyl)cyclopropane is this followed by loss of the second SO2 unit; the first loss of SO2 is probably accompanied by rearrangement since the fragmentation pattern of [M ? SO2]+˙ ions from this compound is different than that of the isobaric molecular ions of 1-phenyl-1-(benzenesulphonyl)cyclopropane. 相似文献
Photonuclear activation with 18 and 35 MeV bremsstrahlung beams and gamma ray spectrometry has been used to determine the
concentrations of 14 elements in human hair. A careful study of interferences made possible a nondestructive analysis with
practical limits of detection between 0.1 and 100 μg·g.
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Synthesis and Structure of Tetrafluoroaurates(III) MI[AuF4] with MI = Li, Rb Single crystal investigations on Rb[AuF4], light yellow, confirm the tetragonal unit cell (K[BrF4]-type) with a = 618.2(1) and c = 1191(1) pm, Z = 4, space group I 4/mcm-D (No. 140). Li[AuF4], light yellow too, crystallizes monoclinic with a = 485.32(7), b = 634.29(8), c = 1004.43(13) pm, β = 92.759(12), Z = 4; space group P 2/c-C (No. 13). The structure of Li[AuF4] is related to the Rb[AuF4]-type of structure. 相似文献