東京大学 · 化学
Arpita Varadwaj教授の研究室は、分子内および分子間の非共有結合相互作用に注目し、特にハロゲン結合やポスト遷移金属結合、窒素族元素結合(pnictogen bond)など、電子状態に基づく新しい結合種の発見と定義を主眼としています。特に、フッ素原子の外側表面に局在する正電荷的サイトが、他の分子の負電荷部位とどのように引力的相互作用を形成するかを、高精度の電子構造計算(DFT、MP2、CCSD(T)など)を用いて解明しています。また、C60カイロ内に閉じ込められた水分子の挙動や、孤立した負性ルイス塩基同士の相互作用など、極めて微細な電子的相互作用のメカニズムを量子化学的手法で解明しています。
Figures are computed from collected data and may differ slightly.
Can two sites of positive electrostatic potential localized on the outer surfaces of two halogen atoms (and especially fluorine) in different molecular domains attract each other to form a non-covalent engagement? The answer, perhaps counterintuitive, is <i>yes</i> as shown here using the electronic structures and binding energies of the interactions for a series of 22 binary complexes formed between identical or different atomic domains in similar or related halogen-substituted molecules contai
The definition of the term “tetrel bond” and instances of its occurance in chemical systems are proposed based on the evidence documented in the current literature.
Based on an experimental observation, it has been controversially suggested in a study (Kurotobi et al., Science 2011, 33, 613) that a single molecule of water can completely be localized within the subnano-space inside the fullerene C(60) cage and, that neither the H atoms nor the O lone-pairs are linked, either via hydrogen bonding or through dative bonding, with the interior C-framework of the C(60) cage. To resolve the controversy, electronic structure calculations were performed by using th
It has been demonstrated in several instances that the 0.001 a.u. (electrons per bohr3) isodensity mapped electrostatic surface potentials on the fluorines along the outermost extensions of the CF covalent bonds in tetrafluoromethane (CF4) are entirely negative, they are thereby unable to engage in σhole bonding interactions with the negative sites on another molecules. In this study, we have attempted at resolving this controversy by performing various high-level electronic structure calculati
This article proposes a definition for the term “pnictogen bond” and lists its donors, acceptors, and characteristic features. These may be invoked to identify this specific subset of the inter- and intramolecular interactions formed by elements of Group 15 which possess an electrophilic site in a molecular entity.
The study presents the possibility for the formation of attractive intermolecular interactions between various entirely negative Lewis bases, leading to the formation of the thirteen isolated binary complexes examined.
Coulomb's law states that like charges repel, and unlike charges attract. However, it has recently been theoretically revealed that two similarly charged conducting spheres will almost always attract each other when both are in close proximity. Using multiscale first principles calculations, we illustrate practical examples of several intermolecular complexes that are formed by the consequences of attraction between positive atomic sites of similar or dissimilar electrostatic surface potential o
Methylammonium lead iodide (CH<sub>3</sub> NH<sub>3</sub> PbI<sub>3</sub> ) perovskite compound has produced a remarkable breakthrough in the photovoltaic history of solar cell technology because of its outstanding device-based performance as a light-harvesting semiconductor. Whereas the experimental and theoretical studies of this system in the solid state have been numerously reported in the last 4 years, its fundamental cluster physics is yet to be exploited. To this end, this study has perfo
We examine the equilibrium structure and properties of six fully or partially fluorinated hydrocarbons and several of their binary complexes using computational methods. In the monomers, the electrostatic surface of the fluorine is predicted to be either entirely negative or weakly positive. However, its lateral sites are always negative. This enables the fluorine to display an anisotropic distribution of charge density on its electrostatic surface. While this is the electrostatic surface scenar
A relationship between reported experimental band gaps (solid) and DFT-calculated binding energies (gas) is established, for the first time, for each of the four ten-membered lead (or tin) trihalide perovskite solar cell semiconductor series examined in this study, including CH<sub>3</sub> NH<sub>3</sub> PbY<sub>3</sub> , CsPbY<sub>3</sub> , CH<sub>3</sub> NH<sub>3</sub> SnY<sub>3</sub> and CsSnY<sub>3</sub> (Y=I<sub>(3-x)</sub> Br<sub>x=1-3</sub> , I<sub>(3-x)</sub> Cl<sub>x=1-3</sub> , Br<sub>
The pnictogen bond, a somewhat overlooked supramolecular chemical synthon known since the middle of the last century, is one of the promising types of non-covalent interactions yet to be fully understood by recognizing and exploiting its properties for the rational design of novel functional materials. Its bonding modes, energy profiles, vibrational structures and charge density topologies, among others, have yet to be comprehensively delineated, both theoretically and experimentally. In this ov
A set of six binary complexes that feature iodine-centered halogen bonding, extracted from structures deposited in the Cambridge Structure Database, has been examined computationally using density functional theory calculations with the M06-2X global hybrid, and dispersion corrected B3LYP-D3 and B97-D3, to determine their equilibrium geometries, binding energies and electronic properties. The results show that gas phase calculations are very informative in evaluating what occurs in the solid sta
A stibium bond, i.e., a non-covalent interaction formed by covalently or coordinately bound antimony, occurs in chemical systems when there is evidence of a net attractive interaction between the electrophilic region associated with an antimony atom and a nucleophile in another, or the same molecular entity. This is a pnictogen bond and are likely formed by the elements of the pnictogen family, Group 15, of the periodic table, and is an inter- or intra-molecular non-covalent interaction. This ov
In chemical systems, the arsenic-centered pnictogen bond, or simply the arsenic bond, occurs when there is evidence of a net attractive interaction between the electrophilic region associated with a covalently or coordinately bound arsenic atom in a molecular entity and a nucleophile in another or the same molecular entity. It is the third member of the family of pnictogen bonds formed by the third atom of the pnictogen family, Group 15 of the periodic table, and is an inter- or intramolecular n
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