No abstract

Homogeneous catalytic oxidations of cyclohexene by transition‐metal‐substituted phosphotungstates [PW11M(L)O39]m− (PW11M, M=CoII, CuII, FeIII, NiII, MnII, L=H2O or absence) with hydrogen peroxide in acetonitrile were experimentally studied. The catalytic activities of allylic oxidation were found to strongly depend on the transition metals, and PW11Co showed the highest activity. The product distribution and the catalyst stability were dominated by mole ratio of hydrogen peroxide to PW11M, whereby low or high mole ratios led to stable structure of PW11M and predominant formation of allylic oxidation products or decomposition of PW11M, respectively. Different from the activation of the allylic C−H bond by radicals, the oxidation of C=C double bond was based on tungsten‐peroxo species. A reaction mechanism composed of radical and nonradical processes was proposed from NMR, EPR, and kinetic data, to describe the reaction pathways of cyclohexene oxidation.

Digital PCR (dPCR) surpasses the performance of earlier PCR formats because of highly precise, absolute quantification and other unique merits. A simple thermocycling approach and durable microcarrier are of great value for dPCR advancement and application. Herein, a near‐infrared (NIR) controlled thermocycling approach by embedding magnetic graphene oxide (GO) composite into the agarose microcarriers is developed. The core‐shell composite is constructed by sequentially encapsulating GO and silica outside the magnetic nanocores. Benefiting from these additives, the resultant composite agarose gains appealing features as light‐driven temperature changing, switchable gel–sol phase transforming, biocompatibility, and magnetic traction. By further emulsifying into droplets via the microfluidics method, the influence of typical parameters including material loading amount, laser intensity, and droplet diameter at various ranges is investigated for assembling microcarriers with different responsiveness. Then a paradigm of the NIR program can be easily tailored for PCR thermocycling. Finally, the feasibility of the approach is verified by detecting statistically diluted Klebsiella pneumoniae DNA samples, from 0.1 to 2 copies per drop. It is anticipated that this method has promising prospects for dPCR‐based and other temperature‐controlled applications.