Electrochemically Enabled Intramolecular Aminooxygenation of Alkynes via Amidyl Radical Cyclization

An electrochemical synthesis of oxazol‐2‐ones and imidazol‐2‐ones has been developed via 5‐exo‐dig cyclization of propargylic carbamates‐ and ureas‐derived amidyl radicals. The electrosynthesis relies on the dual function of 2,2,6,6‐tetramethylpiperidin‐ 1‐yl)oxyl (TEMPO) as a redox mediator for amidyl radical formation and an oxygen atom donor. The reactions are conducted under mild conditions using a simple setup and provide convenient access to functionalized oxazol‐2‐ones and imidazol‐2‐ones from readily available materials.     

Luminescent Metallo‐Supramolecular Polymers

Luminescent metallo‐supramolecular polymers are a type of functional supramolecular architectures which integrates the advantages of emission, metal‐coordination, supramolecular chemistry as well as polymeric properties to realize advanced functions. Due to the abundant stimuli‐responsiveness of supramolecular assemblies and the light‐emitting properties, they have been widely applied as chemo‐sensors, light‐emitting devices, contrast agents for bio‐imaging, etc. In this review, we classify luminescent metallo‐supramolecular polymers based on the types of species (lanthanides, organometallic compounds, oligomer or polymer‐based ligands, small‐molecule‐based organic ligands) used to generate the luminescence and summarize recent developments of luminescent metallo‐supramolecular polymers. We mainly focus on the functions and applications of luminescent metallo‐supramolecular polymers and hope to give our reader a snapshot of research on luminescent metallo‐supramolecular polymers and encourage more scientists to devote into this promising area.     

The two-photon excitation cross section of 6MAP, a fluorescent adenine analogue

6MAP is a fluorescent analogue of adenine that undergoes Watson-Crick base pairing and base stacking in double-stranded DNA. The one-photon absorption spectrum of 6MAP is characterized by a maximum around 330 nm with moderate quantum yield fluorescence centered at about 420 nm. To take advantage of this probe for confocal and single-molecule microscopy, it would be advantageous to be able to excite the analogue via two photons. We report the first determination of the two-photon excitation cross section and spectrum for 6MAP from 614 to 700 nm. The power dependence of the fluorescence indicates that emission results from the absorption of two photons. The one-photon and two-photon emission line shapes are identical within experimental error. A study of the concentration dependence of the fluorescence yield for one-photon excitation shows no measurable quenching up to about 5 microM. The maximum in the two-photon excitation spectrum gives a two-photon cross section, delta(TPE), of 3.4 +/- 0.1 Goeppert-Mayer (G.M.) at 659 nm, which correlates well with the one-photon absorption maximum. This compares quite favorably with cross sections of various naturally fluorescent biological molecules such as flavins and nicotiamide. In addition, we have also obtained the two-photon-induced fluorescence emission spectrum of quinine sulfate. It is approximately the same as that for one-photon excitation, suggesting that two-photon excitation of quinine sulfate may be used for calibration purposes.     

Novel Pb(II), Zn(II), and Cd(II) coordination polymers constructed from ferrocenyl-substituted carboxylate and bipyridine-based ligands

Treatment of two kinds of ferrocenyl-substituted carboxylate ligands (3-ferrocenyl-2-crotonic acid, HOOC-CH=(CH(3))CFc (Fc=(eta(5)-C(5)H(5))Fe(eta(5)-C(5)H(4))) or O-ferrocecarbonyl benzoic acid, o-HOOCC(6)H(4)COFc with Pb(OAc)(2).3H(2)O, Zn(OAc)(2).2H(2)O, or Cd(OAc)(2).2H(2)O) resulted in four novel ferrocene-containing coordination polymers [[Pb(mu(2)-eta(2)-OOCCH=(CH(3))CFc)(2)].MeOH](n) (1), [[Zn(o-OOCC(6)H(4)COFc)(2)(4,4'-bipy)(H(2)O)(2)].2MeOH.2H(2)O](n) (4,4'-bipy = 4,4'-bipyridine) (2), [[Cd(o-OOCC(6)H(4)COFc)(2)(bpe)(MeOH)(2)].2H(2)O](n) (bpe = 1,2-bis(4-pyridyl)ethene) (3), and [Pb(o-OOCC(6)H(4)COFc)(eta(2)-o-OOCC(6)H(4)COFc)(bpe)](n)() (4). Their crystal structures have been characterized by single X-ray determinations. In polymer 1, Pb(II) ions are bridged by tridentate FcC(CH(3))=CHCOO(-) anions, forming an infinite chain [Pb(mu(2)-eta(2)-OOC=CH(CH(3))CFc)(2)](n). In polymers 2-4, there are three kinds of components, metal ions, o-FcCOC(6)H(4)COO(-) units, and organic bridging ligands. The bipyridine-based ligands connect metal ions leading to a one-dimensional chain with o-FcCOC(6)H(4)COO(-) units acting as monodentate or chelate ligands in the side chain. Such coordination polymers containing ferrocenyl-substituted carboxylate and bipyridine-based ligands are very rare. The solution-state differential pulse voltammetries of polymers 1-4 were determined. The results indicate that the half-wave potential of the ferrocenyl moieties is influenced by the Pb(II) ions in polymer 1 and strongly influenced by Zn(II), Cd(II), or Pb(II) ions in polymers 2-4. The thermal properties of the four polymers were also investigated.     

Intermolecular Domino Reaction of Two Aryl Iodides Involving Two C?H Functionalizations

A palladium‐catalyzed intermolecular cross‐coupling of two aryl iodides is reported, giving polycyclic ring systems with a high level of convergence and efficiency.     

Enhanced slow light propagation in photonic crystal waveguides using angular properties of scatter elements

Applicability of the angular properties of scatter elements as a tool to achieve improved slow light performance with small group velocity dispersion and large bandwidth in photonic crystal waveguides is investigated. A polyatomic photonic crystal waveguide, including two scatter elements with different geometrical shapes in each primitive cell, is proposed to investigate the feasibility of our method. Numerical results show that a versatile control of the dispersion relation of slow light modes, with large normalized delay-bandwidth products ranging from 0.2085 to 0.3394, can be obtained using a unique geometrical parameter.     

MIXED-CONVECTION HEAT AND MASS TRANSFER IN A FULLY DEVELOPED HORIZONTAL CHANNEL FLOW

An experimental study of mixed-convection heat and mass transfer flow of a CuS0₄ + H₂S0₄ + H₂O solution in a horizontal channel is performed by using an electrochemical system. Unstable temperature and concentration gradients imposed by a heated cathodic bottom initiate an ascending (secondary) flow of light boundary-layer fluid into the freestream. To visualize the flow, the shadowgraph technique is used. Electrical measurements are used to obtain mass transfer rates and to infer a Sherwood number. The ranges of the parameters studied in the present work for the square channel are Pr = 5-7, Sc = 1,700-2,300, Re = 100-1,000, Gr_m= 1.27 X 10⁶ and Gr_ab = 4.06 × 10⁶-2.4S × 10⁷.     

Electrochemical behavior of organosoluble gold nanoclusters and its application

Journal of Solid State Electrochemistry - This contribution described the electrochemical study of organosoluble gold nanoclusters (AuNCs).The AuNCs were characterized with UV-vis absorption...     

Polymeric ytterbium(ii) complex with pyridyl amido ligands

The reaction of potassium pyridyl amido ligand {L = [N(R)(2-C5H3N-6-Me)]–, R = CH2But} with YbI2(thf)2 afforded the linear polymeric complex [K0.5(L)3YbiiK0.5]n, which was characterized by X-ray structure analysis.     

Presodiation Strategies for the Promotion of Sodium-Based Energy Storage Systems

Nowadays sodium-based energy storage systems (Na-based ESSs) have been widely researched as it possesses the possibility to replace traditional energy storage media to become next generation energy storage system. However, due to the irreversible loss of sodium ions in the first cycle, development of Na-based ESSs is limited. Presodiation, as a strategy of adding excess sodium ions to the system in advance, accomplishes the enhancement of electrochemical performance. In this minireview, different presodiation strategies applied in sodium-based energy storage systems will be summarized in detail, their functions and corresponding mechanisms will be discussed as well. Furthermore, the current novel application of presodiation method in other aspects of Na-based ESSs will be mentioned additionally. At last, in the view of present research status of presodiation, issues that can be mitigated are put forward and guidelines are given on how to deliberate in-depth presodiation technology in the future, dedicating to promote the further development of Na-based ESSs.