نتایج جستجو برای: π electron cloud
تعداد نتایج: 423554 فیلتر نتایج به سال:
Lone pair-π interaction is an important but less studied binding force. Generally, it is too weak to influence the physical properties of supramolecular systems. Herein we reported the first example exhibiting the impact of lone pair-π interactions on photochromic properties of naphthalene diimide based coordination networks. In three isostructural 1-D networks, [(DPNDI)ZnX2] (DPNDI = N,N-di(4-...
A new series of metal-free organic dyes containing pyrene and α-cyanoacrylic acid end groups and thiophene, bithiophene, thienylbenzene or thienylfluorene π-linkers were synthesized and characterized by absorption, emission and electrochemical measurements. Time-dependent density functional theoretical calculations were also performed to unravel the nature of the absorption induced electronic e...
Understanding electron transport across π-stacked systems can help to elucidate the role of intermolecular tunneling in molecular junctions and potentially with the design of high-efficiency molecular devices. Here we show how conjugation length and substituent groups influence the electron transport and thermoelectric response in the π-stacked structures by investigating five representative st...
Non-covalent π-π interactions are central to chemical and biological processes, yet the full understanding of their origin that would unite the simplicity of empirical approaches with the accuracy of quantum calculations is still missing. Here we employ a quantum-mechanical Hamiltonian model for van der Waals interactions, to demonstrate that intermolecular electron correlation in large supramo...
Luminescent silver cluster-based coordination polymers composed of Ag10 or Ag12 cluster cores and multidentate pyridine linkers were synthesized as well luminescent polymorphic silver(I)-based polymers. It was found that these exhibit highly sensitive luminescence quenching effect to nitrobenzene, attributed the π–π stacking interactions between nitrobenzene electron-withdrawing character nitro...
Aromatic π-π stacking interactions are ubiquitous in nature, medicinal chemistry and materials sciences. They play a crucial role in the stacking of nucleobases, thus stabilising the DNA double helix. The following paper describes a series of chimeric DNA-polycyclic aromatic hydrocarbon (PAH) hybrids. The PAH building blocks are electron-rich pyrene and electron-poor perylenediimide (PDI), and ...
The electron cloud in positron storage rings is pinched when a bunch passes by. For short bunches, the radiation due to acceleration of electrons of the cloud is coherent. Detection of such radiation can be used to measure the density of the cloud. The estimate of the power and the time structure of the radiated signal is given in this paper. ∗Work supported by Department of Energy contract DE–...
Carbonyl-carbonyl (C=O···C'=O') interactions are ubiquitous in both small and large molecular systems. This interaction involves delocalization of a lone pair (n) of a donor oxygen into the antibonding orbital (π*) of an acceptor carbonyl group. Analyses of high-resolution protein structures suggest that these carbonyl-carbonyl interactions prefer to occur in pairs, that is, one donor per accep...
Recent nonthermal X-ray and γ-ray observations, attributed to electron emission processes, for the first time give an experimental confirmation that electrons are accelerated on SNR shocks up to the energy ∼ 10 eV. We have no direct observational confirmations about proton acceleration by SNR. Different models of γ-emission from SNRs predict different emission mechanisms as dominating. Only π o...
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