Strong Closed-Shell Interactions in Inorganic Chemistry

Pyykkö, Pekka

doi:10.1021/cr940396v

Cited by 2,349 publications

(1,792 citation statements)

References 453 publications

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“…The MP2 results are likely to be more reliable than the BP86 results, since they include also the weak interaction effects, and we thus conclude that the supersystem is energetically lower than the two constituents. (It is known that the MP2 method rather exaggerates the dispersion energies, compared to a CCSD(T) limit for the same basis [16,17].) A larger basis, which cannot be used at present, would be expected to strengthen the interaction [16].…”

Section: Resultsmentioning

confidence: 99%

“…(It is known that the MP2 method rather exaggerates the dispersion energies, compared to a CCSD(T) limit for the same basis [16,17].) A larger basis, which cannot be used at present, would be expected to strengthen the interaction [16]. Concerning the zero-point vibrational energy (ZPVE) corrections to the interaction energy, they were found to be negligible (0.4 kJ/mol) at the BP86 level.…”

Section: Resultsmentioning

confidence: 99%

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Pocket and antipocket conformations for the CH₄@C₈₄ endohedral fullerene

Rehaman

Gagliardi

Pyykkö

2006

Int J of Quantum Chemistry

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ABSTRACT:The endohedral fullerene CH 4 @C 84 has been studied using density functional theory (DFT) and second-order Møller-Plesset perturbation theory (MP2). In addition to the structure with a COH bond of CH 4 in a tetrahedral pocket conformation, we find an alternative minimum, very close in energy (6.3-9.5 kJ/mol higher according to the level of theory), with the methane inverted, which we call the antipocket conformation. Computed IR spectra are reported for CH 4 @C 84 and also for the reference system CH 4 @C 60 . The calculated vibrational levels, in a harmonic approximation, reveal close-lying translational, librational, and shell-vibrational modes. The results are also presented for the isoelectronic species NH 4 ϩ @C 60 .

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Pocket and antipocket conformations for the CH₄@C₈₄ endohedral fullerene

Rehaman

Gagliardi

Pyykkö

2006

Int J of Quantum Chemistry

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“…Ying and co-workers proposed that d 10 -d 10 metallophilic interaction was the reason for Hg 2+ binding to AuNCs [114,120].…”

Section: Reactive Quenchersmentioning

confidence: 99%

DNA-stabilized, fluorescent, metal nanoclusters for biosensor development

Liu

2014

TrAC Trends in Analytical Chemistry

196

141

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In the past decade, fluorescent silver, gold and copper nanoclusters (Ag, Au and CuNCs) have emerged as a new class of signaling moiety for biosensor development. Compared to semiconductor quantum dots, metal NCs have less toxicity concerns and can be more easily conjugated to biopolymers. Due to their extremely small size, these NCs need a stabilizing ligand. Many polymers, proteins and nucleic acids have been reported to stabilize NCs. In particular, many DNA sequences produce highly fluorescence NCs. Coupling these DNA stabilizers with other sequences such as aptamers has generated a large number of biosensors. In this review, the synthesis of DNA and nucleotide-templated NCs is first summarized; their chemical interactions are also discussed. In the second part, the properties of NCs such as fluorescence quantum yield, emission wavelength and lifetime, structure and photostability are briefly reviewed. In the last part, various sensor design strategies using these NCs are categorized into the following four classes: 1) fluorescence de-quenching; 2) generation of templating DNA sequences to produce NCs; 3) change of nearby environment; and 4) reacting with heavy metal ions or other quenchers. Finally, the future trends in this field are discussed.

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“…In the physics literature, it is customary to call the stronger bonds "front bonds" and to call the weaker bonds "back bonds." [37][38][39] Because the back bonds formally correspond to closed-shell interactions, chemists call them "secondary" bonds, [40][41][42][43] or donor-acceptor interactions, 44 or, sometimes, hypervalent or 3-center bonds, where the distinction is only quantitative, if any. 42 Importantly, the secondary bonds are stronger than van der Waals interaction and are directional, similarly to their strictly-covalent counterparts.…”

Section: Ppσ-bonded Semiconductors: the Role Of The Secondary Ppσmentioning

confidence: 99%

Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network

Zhugayevych

Lubchenko

2010

The Journal of Chemical Physics

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Semiconductor glasses exhibit many unique optical and electronic anomalies. We have put forth a semi-phenomenological scenario (J. Chem. Phys. 132, 044508 (2010)) in which several of these anomalies arise from deep midgap electronic states residing on high-strain regions intrinsic to the activated transport above the glass transition. Here we demonstrate at the molecular level how this scenario is realized in an important class of semiconductor glasses, namely chalcogen and pnictogen containing alloys. Both the glass itself and the intrinsic electronic midgap states emerge as a result of the formation of a network composed of σ-bonded atomic p-orbitals that are only weakly hybridized. Despite a large number of weak bonds, these ppσ-networks are stable with respect to competing types of bonding, while exhibiting a high degree of structural degeneracy. The stability is rationalized with the help of a hereby proposed structural model, by which ppσ-networks are symmetry-broken and distorted versions of a high symmetry structure. The latter structure exhibits exact octahedral coordination and is fully covalently-bonded. The present approach provides a microscopic route to a fully consistent description of the electronic and structural excitations in vitreous semiconductors.

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Strong Closed-Shell Interactions in Inorganic Chemistry

Cited by 2,349 publications

References 453 publications

Pocket and antipocket conformations for the CH₄@C₈₄ endohedral fullerene

Pocket and antipocket conformations for the CH₄@C₈₄ endohedral fullerene

DNA-stabilized, fluorescent, metal nanoclusters for biosensor development

Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network

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Strong Closed-Shell Interactions in Inorganic Chemistry

Cited by 2,349 publications

References 453 publications

Pocket and antipocket conformations for the CH4@C84 endohedral fullerene

Pocket and antipocket conformations for the CH4@C84 endohedral fullerene

DNA-stabilized, fluorescent, metal nanoclusters for biosensor development

Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network

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Product

Resources

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Pocket and antipocket conformations for the CH₄@C₈₄ endohedral fullerene

Pocket and antipocket conformations for the CH₄@C₈₄ endohedral fullerene