Photochromism of Asymmetrical Diarylethenes with a Pyrrole Unit: Effects of Aromatic Stabilization Energies of Aryl Rings

2013 ◽  
Vol 15 (5) ◽  
pp. 980-983 ◽  
Author(s):  
Gang Liu ◽  
Shouzhi Pu ◽  
Renjie Wang
2017 ◽  
Vol 41 (9) ◽  
pp. 3619-3633 ◽  
Author(s):  
Vaibhav A. Dixit ◽  
William R. F. Goundry ◽  
Simone Tomasi

Novel five-membered azaboroles are aromatic, stable under neutral conditions, isomer stabilization energy is explained using σ-bond and aromatic stabilization energies.


Tetrahedron ◽  
2017 ◽  
Vol 73 (45) ◽  
pp. 6479-6485 ◽  
Author(s):  
Huitao Xu ◽  
Shasha Wei ◽  
Congbin Fan ◽  
Gang Liu ◽  
Shouzhi Pu

2002 ◽  
Vol 4 (17) ◽  
pp. 2873-2876 ◽  
Author(s):  
Paul von Ragué Schleyer ◽  
Frank Pühlhofer

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Maria ◽  
Khurshid Ayub

Aromaticities of five membered heterocycles, containing up to three heteroatoms, are quantified through the dimethyldihydropyrene (DHP) probe. Bond fixation caused by the fusion of heterocycles to the dimethyldihydropyrene nucleus (DHPN) was measured by changes in the1H NMR chemical shifts (magnetic) and bond lengths alterations (structural criterion). Chemical shifts of dihydropyrenes were calculated at GIAO HF/6-31G(d)//B3LYP/6-31+G(d). For1H NMR chemical shift analysis, two nonaromatic reference models are studied. Among the studied heterocycles, pyrazole and triazole are about 80–85% aromatic relative to benzene, through both magnetic and geometric criteria. Thiazole and oxazoles are found least aromatic where quantitative estimates of aromaticities are about 34–42%, relative to benzene. These quantitative estimates of aromaticities of five membered heterocycles are also comparable to those from aromatic stabilization energies. The quantification of aromaticity through energetic, magnetic, and structural criteria can deliver the similar inferences provided that suitable reference systems are chosen.


2015 ◽  
Vol 33 (7) ◽  
pp. 785-791 ◽  
Author(s):  
Zhiyuan Sun ◽  
Congcong Zhang ◽  
Hui Li ◽  
Congbin Fan ◽  
Gang Liu ◽  
...  

2004 ◽  
Vol 03 (02) ◽  
pp. 145-153 ◽  
Author(s):  
PABLO R. DUCHOWICZ ◽  
EDUARDO A. CASTRO

Aromatic stabilization energies (ASE) for a set of 29 five-membered heteroaromatic compounds are calculated using molecular descriptors such as magnetic susceptibility exaltation (Λ), nucleus-independent chemical shifts (NICS), and electrotopological indices (EI) via linear, quadratic and cubic fitting polynomials. Theoretical estimations compare fairly well with experimental data when three variables multilinear regression equations are employed.


1981 ◽  
Vol 46 (3) ◽  
pp. 740-747 ◽  
Author(s):  
Jiří Krechl ◽  
Josef Kuthan

The CNDO/2 method has been used for evaluation of energy relations between some configurations of 1-methyl-1,4-dihydronicotinamide (I) - acetaldehyde (II) supermolecule. Stabilization energies have been estimated for formation of the configuration type A,B and C, the energetically most favourable situation corresponding to the formulas IIIa and IIIb. Characters of some MO's and CNDO/2 and INDO electron distributions are discussed with respect to biochemical aspects of the interaction of NADH and acetaldehyde.


2011 ◽  
Vol 135 (13) ◽  
pp. 134118 ◽  
Author(s):  
Katarzyna Walczak ◽  
Joachim Friedrich ◽  
Michael Dolg

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