Electrochemically Driven, Ni-Catalyzed Aryl Amination: Scope, Mechanism, and Applications.

C-N cross-coupling is one of the most valuable and widespread transformations in organic synthesis. Largely dominated by Pd- and Cu-based catalytic systems, it has proven to be a staple transformation for those in both academia and industry. The current study presents the development and mechanistic understanding of an electrochemically driven, Ni-catalyzed method for achieving this reaction of high strategic importance. Through a series of electrochemical, computational, kinetic, and empirical experiments, the key mechanistic features of this reaction have been unraveled, leading to a second generation set of conditions that is applicable to a broad range of aryl halides and amine nucleophiles including complex examples on oligopeptides, medicinally relevant heterocycles, natural products, and sugars. Full disclosure of the current limitations and procedures for both batch and flow scale-ups (100 g) are also described.

Electrochemical behavior of palmatine and its sensitive determination based on an electrochemically reduced L-methionine functionalized graphene oxide modified electrode.

A new and sensitive voltammetric sensor for palmatine, based on an electrochemically reduced L-methionine functionalized graphene oxide modified glassy carbon electrode (L-Met-ERGO/GCE), is reported. The electrochemical characteristics of palmatine at the proposed sensor were studied systematically and some dynamic parameters were calculated for the first time. A reasonable reaction mechanism for palmatine on the L-Met-ERGO/GCE electrode was proposed and discussed, and this could be a reference for the pharmacological action of palmatine in clinical study. Under optimized conditions, the peak current had a linear relationship with palmatine concentration in the range of 1 × 10(-7) to 5 × 10(-5) mol L(-1) with a detection limit of 6 × 10(-8) mol L(-1). Additionally, the proposed method was also used to detect palmatine in human urine samples, medicinal tablets and the Chinese herb Fibraurea recisa Pierre with satisfactory results.

Physical mechanism of the photoinduced charge transfer in multibranched compounds during one- and two-photon absorption.

The physical mechanism of the photoinduced charge transfer of D-A-type multibranched compounds with 1,3,5-triazine as the core are studied. The molecular configuration of the new 1,3,5-triazine derivative appears as the strip-type, V-type and triangular-axis-type with an increase in the number of branches, where the charge is transferred in each branch from tail dimethylamine to center 1,3,5-triazine. One-photon absorption (OPA) and two-photon absorption (TPA) gradually increase due to the enhancement of the commonality of the system plane and of the charge transfer path. The triangular-axis-type molecule is highly symmetrical, which causes the first and second excited states to be degenerate; the charge transfer occurs in the dual- and triple-chain of the first excited state and in the single-chain of the second excited state.

Physical mechanism of special type photoinduced charge transfer in one-photon and two-photon absorption of Mobius rings.

In this work, the monomers and dimers of the Mobius ring were studied using density functional theory (DFT), symmetric matching perturbation theory (SAPT) and various excited state wave function analysis methods. The one-photon and two-photon absorption and their charge transfer excitation characteristics of the Mobius ring were qualitatively and quantitatively analyzed. The exchange-related induced super-exchange charge transfer, charge sequence transfer and local excitation-enhanced charge transfer were analyzed and discussed. The relationship between the super-exchange action and the transition distance and the degree of electron hole density separation is obtained. A mechanism to enhance charge transfer excitation was discovered during the two-photon transition.

Photoinduced Charge Transfer in Push/Pull Systems of Two-Photon Absorption.

A series of stilbene derivatives have been constructed by modifying the stilbene systems with different H, CN, NH2, NMe2, and NO2 groups. In a vacuum, it was found that a redshift in the ultraviolet-visible spectrum occurred because of the enhancement of the donor/acceptor capabilities of this group, with the order of redshift being NO2 > NMe2 > CN > NH2 > H. For stilbene molecular systems, the peak of two-photon absorption (TPA) observed in the simulated spectra should be attributed to two transitions that are contributed by two excited states with similar energy. In the case of derivatives, such a transition is separated by energy, and two TPA peaks can be clearly observed (derivatives containing NO2 and NMe2 groups have two TPA peaks), where the magnitude of the separation is directly related to the intensity of the peripheral group. In addition, the S1 state is the intermediate state in the TPA transitions to both of the final excited states.

Optical Properties of Artemisinin and Its Derivatives.

Artemisinin and its derivatives are of great research value in biology. In this work, we study their chiral and optical properties. The multidimensional multifunction analysis method is used to analyze the linear and nonlinear optical processes (one-photon and two-photon absorption: OPA and TPA), electronic circular dichroism (ECD), and Raman optical activity (ROA) mechanisms under light excitation. Transition dipole moments (TDMs) and charge difference density (CDD) are used to describe the electromagnetic interaction between ECD and ROA when a substance is excited by light. The theoretical research results of the study show that the dioxygen atoms provide an intermediary for the transfer between charges and also enhance the role of the TDMs. This generalized chiral theory can not only explain the traditional sources of chirality but also distinguish whether the molecule has chirality when the chiral center is not obvious. By analyzing ROA and different vibration modes, we can clearly observe that each part of the molecule responds differently when excited.

The Dependence of Implicit Solvent Model Parameters and Electronic Absorption Spectra and Photoinduced Charge Transfer.

In this work, the relationship between multiple solvent parameters and charge transfer index was analyzed by multi-factor multi-variate partial least squares regression (PLSR). The charge transfer of the molecule is visualized by the analysis of the excited state wave function. Hydrogen bond basicity and surface tension can significantly affect charge transfer by studying the solvation model parameters and charge transfer index. Finally, a method in which a solvent regulates charge transfer strength and migration length is proposed.

Modular radical cross-coupling with sulfones enables access to sp3-rich (fluoro)alkylated scaffolds.

Cross-coupling chemistry is widely applied to carbon-carbon bond formation in the synthesis of medicines, agrochemicals, and other functional materials. Recently, single-electron-induced variants of this reaction class have proven particularly useful in the formation of C(sp2)-C(sp3) linkages, although certain compound classes have remained a challenge. Here, we report the use of sulfones to activate the alkyl coupling partner in nickel-catalyzed radical cross-coupling with aryl zinc reagents. This method's tolerance of fluoroalkyl substituents proved particularly advantageous for the streamlined preparation of pharmaceutically oriented fluorinated scaffolds that previously required multiple steps, toxic reagents, and nonmodular retrosynthetic blueprints. Five specific sulfone reagents facilitate the rapid assembly of a vast set of compounds, many of which contain challenging fluorination patterns.

Electrochemical behavior of tectoridin and its sensitive determination based on L-arginine modified electrode.

A simple, inexpensive and highly sensitive voltammetric method for the determination of tectoridin was developed using a poly(L-Arginine) modified electrode. The redox character of tectoridin at proposed electrode was studied systematically and some dynamic parameters were calculated for the first time. A reasonable reaction mechanism of tectoridin on the poly(L-Arginine)/GCE was also dicussed and proposed, which could be a reference for the pharmacological action of tectoridin in clinical study. And the electroanalytical method for determination of tectoridin was established by differential pulse voltammograms (DPV). Under optimum conditions, the response peak currents were linear relationship with tectoridin concentrations in the range of 5.0×10(-8)-2.0×10(-6) mol L(-1) with a detection limit of 4.0×10(-8) mol L(-1). Therefore, the high sensitivity for tectoridin sensing at the proposed electrode was achieved, and the proposed method could also be used to detect tectoridin in the Chinese medicinal herb Blackberrylily with satisfactory results.