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RISS 인기검색어
- 검색키워드
- 저자 : Madridejos, Jenica Marie L. (검색결과 3 건)
- 무료
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- 유료
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Size-dependent conformational change in halogen–π interaction: from benzene to graphene
Kim, Dong Yeon,Madridejos, Jenica Marie L.,Ha, Miran,Kim, Jun-Hyeong,Yang, David ChangMo,Baig, Chunggi,Kim, Kwang S. The Royal Society of Chemistry 2017 Chemical communications Vol.53 No.45
<P>Diatomic halogen molecules X-2 (X = Cl/Br) favor the edge-to-face conformation on benzene with significant electrostatic interaction via halogen bonding. In contrast, they favor the stacked conformation on graphene with negligible electrostatic interaction. As the aromatic ring expands, the inner facial side becomes almost electrostatically neutral. On coronene, the two conformations are compatible.</P>
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Anisotropic and amphoteric characteristics of diverse carbenes
Kim, Dong Yeon,Yang, D. ChangMo,Madridejos, Jenica Marie L.,Hajibabaei, Amir,Baig, Chunggi,Kim, Kwang S. The Royal Society of Chemistry 2018 Physical chemistry chemical physics Vol.20 No.20
<P>Despite its key importance in carbene chemistry, the amphoteric (<I>i.e.</I>, both nucleophilic and electrophilic) behavior of the divalent carbon atom (:C) in carbenes is not well understood. The electrostatic potential (EP) around :C is often incorrectly described by simple isotropic atomic charges (particularly, as in singlet CF2); therefore, it should be described by the multipole model, which can illustrate both negative and positive EPs, favoring the positively and negatively charged species that are often present around :C. This amphotericity is much stronger in the singlet state, which has more conspicuous anisotropic charge distribution than the triplet state; this is validated by the complexation structures of carbenes interacting with Na<SUP>+</SUP>, Cl<SUP>−</SUP>, H2O, and Ag<SUP>+</SUP>. From the study of diverse carbenes [including CH2, CLi2/CNa2, CBe2/CMg2, CF2/CCl2, C(BH2)2/C(AlH2)2, C(CH3)2/C(SiH3)2, C(NH2)2/C(PH2)2, cyclic systems of C(CH2)2/C(CH)2, C(BHCH)2, C(CH2CH)2/C(CHCH)2, and C(NHCH)2/C(NCH)2], we elucidate the relationships between the electron configurations, electron accepting/donating strengths of atoms attached to :C, π conjugation, singlet-triplet energy gaps, anisotropic hard wall radii, anisotropic electrostatic potentials, and amphotericities of carbenes, which are vital to carbene chemistry. The (σ<SUP>2</SUP>, π<SUP>2</SUP> or σπ) electronic configuration associated with :C on the :CA2 plane (where A is an adjacent atom) in singlet and triplet carbenes largely governs the amphoteric behaviors along the :C tip and :C face-on directions. The :C tip and :C face-on sites of σ<SUP>2</SUP> singlet carbenes tend to show negative and positive EPs, favoring nucleophiles and electrophiles, respectively; meanwhile, those of π<SUP>2</SUP> singlet carbenes, such as very highly π-conjugated 5-membered cyclic C(NCH)2, tend to show the opposite behavior. Open-shell σπ singlet (such as highly π-conjugated 5-membered cyclic C(CHCH)2) and triplet carbenes show less anisotropic and amphoteric behaviors.</P>
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Youn, Il Seung,Kim, Dong Yeon,Cho, Woo Jong,Madridejos, Jenica Marie L.,Lee, Han Myoung,Kołaski, Maciej,Lee, Joonho,Baig, Chunggi,Shin, Seung Koo,Filatov, Michael,Kim, Kwang S. American Chemical Society 2016 The Journal of physical chemistry A Vol.120 No.46
<P>Various types of interactions between halogen (X) and pi moiety (X-pi interaction) including halogen bonding play important roles in forming the structures of biological, supramolecular, and nanomaterial systems containing halogens and aromatic rings. Furthermore, halogen molecules such as X-2 and CX4 (X = Cl/Br) can be intercalated in graphite and bilayer graphene for doping and graphene functionalization/modification. Due to the X-pi interactions, though recently highly studied, their structures are still hardly predictable. Here, using the coupled-cluster with single, double, and noniterative triple excitations (CCSD(T)), the Moller-Plesset second-order perturbation theory (MP2), and various flavors of density functional theory (DFT) methods, we study complexes of benzene (Bz) with halogen-containing molecules X-2 and CX4 (X = Cl/Br) and analyze various components of the interaction energy using symmetry adapted perturbation theory (SAPT). As for the lowest energy conformers (S1), X-2-Bz is found to have the T-shaped structure where the electropositive X atom-end of X-2 is pointing to the electronegative midpoint of CC bond of the Bz ring, and CX4-Bz has the stacked structure. In addition to this CX4 Bz (S1), other low energy conformers of X-2-Bz (S2/S3) and CX4-Bz (S2) are stabilized primarily by the dispersion interaction, whereas the electrostatic interaction is substantial. Most of the density functionals show noticeable deviations from the CCSD(T) complete basis set (CBS) limit binding energies, especially in the case of strongly halogen-bonded conformers of X-2-Bz (S1), whereas the deviations are relatively small for CX4-Bz where the dispersion is more important. The halogen bond shows highly anisotropic electron density around halogen atoms and the DFT results are very sensitive to basis set. The unsatisfactory performance of many density functionals could be mainly due to less accurate exchange. This is evidenced from the good performance by the dispersion corrected hybrid and double hybrid functionals. B2GP-PLYP-D3 and PBE0-TS (Tkatchenko-Scheffler)/D3 are well suited to describe the X-pi interactions adequately, close to the CCSD(T)/CBS binding energies (within similar to 1 kJ/mol). This understanding would be useful to study diverse X-pi interaction driven structures such as halogen containing compounds intercalated between 2-dimensional layers.</P>
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