Valence‐Bond Resonance Structures for a Triplet State

1960 ◽  
Vol 33 (3) ◽  
pp. 663-664 ◽  
Author(s):  
A. D. McLachlan
Keyword(s):  
Triplet State ◽  
Valence Bond ◽  
Resonance Structures

Aromaticity of Pyrene and Its Cyclopentafused CongenersResonance and NICS Criteria. An Ab Initio Valence Bond Analysis in Terms of Kekulé Resonance Structures

2001 ◽  
Vol 105 (15) ◽  
pp. 3838-3845 ◽  
Author(s):  
Remco W. A. Havenith ◽  
Joop H. van Lenthe ◽  
Fokke Dijkstra ◽  
Leonardus W. Jenneskens
Keyword(s):  
Ab Initio ◽  
Valence Bond ◽  
Resonance Structures

scholarly journals ZZ Polynomials for Isomers of (5,6)-Fullerenes Cn with n = 20–50

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1483 ◽  
Author(s):  
Henryk A. Witek ◽  
Jin-Su Kang
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Topological Analysis ◽  
Valence Bond ◽  
Topological Invariants ◽  
Kekulé Structures ◽  
Resonance Structures ◽  
Clar Number ◽  
Benchmark Data ◽  
Clar Structures

A compilation of ZZ polynomials (aka Zhang–Zhang polynomials or Clar covering polynomials) for all isomers of small (5,6)-fullerenes Cn with n = 20–50 is presented. The ZZ polynomials concisely summarize the most important topological invariants of the fullerene isomers: the number of Kekulé structures K, the Clar number Cl, the first Herndon number h1, the total number of Clar covers C, and the number of Clar structures. The presented results should be useful as benchmark data for designing algorithms and computer programs aiming at topological analysis of fullerenes and at generation of resonance structures for valence-bond quantum-chemical calculations.

Investigating the Resonance in Nitric Acid and the Nitrate Anion Based on a Modern Bonding Analysis

2018 ◽  
Vol 71 (4) ◽  
pp. 227 ◽  
Author(s):  
Malte Fugel ◽  
Florian Kleemiss ◽  
Lorraine A. Malaspina ◽  
Rumpa Pal ◽  
Peter R. Spackman ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Double Bond ◽  
Theoretical Calculations ◽  
Valence Bond ◽  
Nbo Analysis ◽  
Nitrate Anion ◽  
Resonance Structures ◽  
Bonding Analysis ◽  
Experimental Electron Density ◽  
Bond Character

The nitrate anion, NO3−, is often regarded as a textbook example for the very fundamental concept of resonance. Usually, three equivalent resonance structures with one N–O double bond and two N–O single bonds are considered. Consequently, each of the three N–O bonds should have a partial double bond character. In this study, we analyse the resonance in NO3− in comparison with the related species HNO3 and FNO3 by applying a combination of the Quantum Theory of Atoms in Molecules (QTAIM), a natural bond orbital (NBO) analysis, the electron localizability indicator (ELI), and valence bond (VB) calculations. Despite the fundamental importance of nitrate salts and nitric acid for the environment, chemistry, and industry, a bonding analysis is absent from the literature so far. The classical resonance structures are clearly reflected by the bond analysis tools, but are not the only contributions to the bonding situation. The resonance in HNO3 and FNO3 is greatly perturbed by the hydrogen and fluorine atoms. In addition to theoretical calculations, experimental electron density and wave function refinements were carried out on a KNO3 crystal.

A nitroreductase-activatable near-infrared theranostic photosensitizer for photodynamic therapy under mild hypoxia

2020 ◽  
Vol 56 (43) ◽  
pp. 5819-5822
Author(s):  
Jing Zheng ◽  
Yongzhuo Liu ◽  
Fengling Song ◽  
Long Jiao ◽  
Yingnan Wu ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Triplet State ◽  
Near Infrared ◽  
Mild Hypoxia

In this study, a near-infrared (NIR) theranostic photosensitizer was developed based on a heptamethine aminocyanine dye with a long-lived triplet state.

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