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The mechanisms of three cascade reactions between N -methylindole and sulfonylazides via Huisgen cycloaddition were investigated using density functional theory, and the polarized continuum model (PCM) was applied to simulate the solvent effects. Fukui functions and dual descriptor have been employed to assess the atomic reactivity. With respect to these three reactions, each has two possible reaction pathways (I and II). The calculated results show that singlet O 2 plays a crucial role in the oxidative dehydrogenation process in the first reaction between 2-imine indole and p-tosylazide (TsN 3 ), when the reaction occurs without O 2 but with N 2 , two pathways via the processes of breaking two covalent bonds, followed by 1,2-H shift and N 2 removal (or by N 2 removal and 1,2-H shift) exist. Water molecule plays an important role in the H-shift process in the third reaction of the methyl substituted N -methylindole with TsN 3 . Our results demonstrated that these reactions can take place at certain condition, in good agreement with the experimental observation. The understanding of the competitive pathways for Huisgen cycloaddition of N -methylindole and sulfonylazides can provide valuable insights into related reactions. [ABSTRACT FROM AUTHOR]

Context: The reaction between Na and HF is a typical harpooning reaction which is of great interest due to its significance in understanding the elementary chemical reaction kinetics. This work aims to investigate the detailed reaction mechanisms of sodium with hydrogen fluoride and the adsorption of HF on the resultant NaF as well as the (NaF)4 tetramer. The results suggest that the reaction between Na and HF leads to the formation of sodium fluoride salt NaF and hydrogen gas. Na interacts with HF to form a complex HF···Na, and then the approaching of F atom of HF to Na results in a transition state H···F···Na. Accompanied by the broken of H-F bond, the bond forms between F and Na atoms as NaF, then the product NaF is yielded due to the removal of H atom. The resultant NaF can further form (NaF)4 tetramer. The interaction of NaF with HF leads to the complex NaF···HF; the form I as well as II of (NaF)4 can interact with HF to produce two complexes (i.e., (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF), but the form III of (NaF)4 can interact with HF to produce only one complex (NaF)4(III)···HF. These complexes were explored in terms of noncovalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analyses. NCI analyses confirm the existences of attractive interactions in the complexes HF···Na, NaF···HF, (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF, and (NaF)4(III)···HF. QTAIM analyses suggest that the F···Na interaction forms in the HF···Na complex while the F···H hydrogen bonds form in NaF···HF, (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF, and (NaF)4(III)···HF complexes. Natural bond orbital (NBO) analyses were also applied to analyze the intermolecular donor-acceptor orbital interactions in these complexes. These results would provide valuable insight into the chemical reaction of Na and HF and the adsorption interaction between sodium fluoride salt and HF. Methods: The calculations were carried out at the M06-L/6-311++G(2d,2p) level of theory which were performed using the Gaussian16 program. Intrinsic reaction coordinate (IRC) calculations were carried out at the same level of theory to confirm that the obtained transition state was true. The molecular surface electrostatic potential (MSEP) was employed to understand how the complex forms. Quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) analysis was used to know the topology parameters at bond critical points (BCPs) and intermolecular interactions in the complex and intermediate. The topology parameters and the BCP plots were obtained by the Multiwfn software. [ABSTRACT FROM AUTHOR]

Design and engineering of highly efficient emitting materials with assembly-induced luminescence, such as room-temperature phosphorescence (RTP) and aggregation-induced emission (AIE), have stimulated extensive efforts. Here, we propose a new strategy to obtain size-controlled Eu3+-complex nanoparticles (Eu-NPs) with self-assembly-induced luminescence (SAIL) characteristics without encapsulation or hybridization. Compared with previous RTP or AIE materials, the SAIL phenomena of increased luminescence intensity and lifetime in aqueous solution for the proposed Eu-NPs are due to the combined effect of self-assembly in confining the molecular motion and shielding the water quenching. As proof of concept, we also show that this system can be further applied in bioimaging, temperature measurement and HClO sensing. The SAIL activity of the rare-earth (RE) system proposed here offers a further step forward on the roadmap for the development of RE light conversion systems and their integration in bioimaging and therapy applications. [ABSTRACT FROM AUTHOR]

Carbon monoxide can interact with two dihalogen molecules XY (X, Y = Cl, Br) in the form of X(Y)⋯C OX(Y)⋯C O⋯X(Y)X(Y) trimeric complex, and their nature and characteristics were investigated at MP2/aug-cc-pVDZ level without and with counterpoise method, together with single point calculations at CCSD(T)/aug-cc-pVDZ level. The optimized geometries, stretching modes and interaction energies of a series of X(Y)⋯C OX(Y)⋯C O⋯X(Y)X(Y) trimeric complexes were obtained and discussed. The cooperativity in these complexes was evaluated. EDA analyses reveal that the electrostatic interaction is the dominant net driving force in each trimer, but the contributions of other interactions like exchange, dispersion and polarization interactions are also important. QTAIM and NCI analyses confirm the existence of attractive halogen-bonding interactions. Additionally, EDDMF analysis was employed for the component dimers of these trimers, which indicates that the formation of halogen-bonding interactions is closely related to the charge shift and the rearrangement of electronic density in the formation of these complexes. The results would provide valuable insight into for these linear halogen bonds. [ABSTRACT FROM AUTHOR]

The equilibrium geometries, growth patterns, stabilities, and electronic properties of bimetallic BeSi ( n = 1-11) clusters are systematically investigated at the B3LYP/6-311G(d) level of theory. Harmonic vibrational analysis has been performed to assure that the optimized geometries are stable. The optimized results suggest that the three-dimensional structures are observed for the most stable isomers of BeSi clusters when n > 2. The calculated vertical ionization potential for the lowest-energy isomers are comparable to the experimental values of Si. According to the averaged binding energy, fragmentation energy, second-order energy difference and HOMO-LUMO gaps calculations, we identify that the BeSi and BeSi clusters are more stable, and Be atoms doping enhance the chemical reactivity of the Si host. The natural population and natural electron configuration analyses indicate that the Be atoms possess positive charge at n = 1-5 but negative charge at n = 6-11. The chemical hardness of BeSi clusters show three local maxima at n = 2, 5, and 9, whereas three local minima are found for the corresponding chemical potential, meaning these clusters are more stable than their neighboring cluster sizes. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]