نتایج جستجو برای: π electron cloud

تعداد نتایج: 423554  

Journal: :Dalton transactions 2015
Jian-Jun Liu Ying-Fang Guan Yong Chen Mei-Jin Lin Chang-Cang Huang Wen-Xin Dai

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-...

Journal: :Physical chemistry chemical physics : PCCP 2011
Abhishek Baheti Chuan-Pei Lee K R Justin Thomas Kuo-Chuan Ho

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...

Journal: :Faraday discussions 2014
Qian Li Gemma C Solomon

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...

2017
Jan Hermann Dario Alfè Alexandre Tkatchenko

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...

Journal: :Chemistry: A European Journal 2023

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...

2014
Christian B Winiger Simon M Langenegger Oleg Khorev Robert Häner

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 ...

2004
S. Heifets

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–...

Journal: :Chemical communications 2013
Amit Choudhary Charles G Fry Kimberli J Kamer Ronald T Raines

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...

2001
O. PETRUK

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...

Journal: :Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 2007

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