A charge iteration-corrected extended-Hückel study of the electronic and spectroscopic properties of conjugated heterocycles

Castevens, Charles M.

doi:10.1007/s00214-008-0444-5

Cited by 4 publications

(3 citation statements)

References 54 publications

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“…The compounds containing 4 pyrroles have attracted increased attention in materials sciences because of their biological and pharmaceutical activities. Over the years, porphyrins ( Pr ) are well‐known compounds containing 4 modified pyrroles with the linkage of methine (═CH–) and has been studied experimentally and theoretically because of their extensive application in biology and optical power limiting . Pr are highly conjugated macrocycles, highly colored, and aromatic.…”

Section: Introductionmentioning

confidence: 99%

“…Over the years, porphyrins (Pr) are well-known compounds containing 4 modified pyrroles with the linkage of methine (═CH-) and has been studied experimentally and theoretically because of their extensive application in biology and optical power limiting. [4][5][6][7][8][9][10] Pr are highly conjugated macrocycles, highly colored, and aromatic. Designing new Pr analogues has attracted considerable interest for understanding and extending the characteristics of Pr.…”

Section: Introductionmentioning

confidence: 99%

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A density functional theory investigation of the stability, aromaticity, and photophysical behavior for the highly conjugated macrocycles containing 4 pyrroles

Wei

Bai

Xia

et al. 2016

J of Physical Organic Chem

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Porphyrin (Pr), porphycene (Pc), and [22]porphyrin(2.2.2.2) (P[22]) have been theoretically investigated. We design 2 highly conjugated macrocycles containing 4 pyrroles with different linkage bridges, which are named for 4 pyrrole (Pf) and methylene‐dipyrrolidine (Pm), as the theoretical model so as to investigate the stability, aromaticity, and photophysical behavior of these porphyrin derivatives, and the influence of getting or losing electron to the neutral molecule. The geometric structures of the molecules are optimized by density functional theory method. The absorptions are calculated by the time‐dependent density functional theory method. Based on the optimized structures, the nucleus‐independent chemical shifts (NICS) are calculated. The molecule with negative NICS value possesses larger highest occupied molecular orbital (HOMO)‐lowest occupied molecular orbital (LUMO) gap than that with positive NICS value, the molecule with bigger positive NICS value possesses smaller HOMO‐LUMO gap, and the molecule with bigger negative NICS value (in absolute value) possesses bigger HOMO‐LUMO gap. The current density indicates that the π‐electron delocalization is more effective in Pr and Pc than in Pf, Pm, and P[22] and corresponds to the stability of molecules. The absorptions of the molecules are all in the UV‐visible and infrared regions. The major transitions for most of the molecules are all from HOMO to LUMO. Compared with Pf2−, Pr2−, Pc2−, and P[22]2−, Pm2− shows distinctive photophysical properties, which is due to the reduced HOMO‐LUMO gap, structural distortion, and strong antiaromaticity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A density functional theory investigation of the stability, aromaticity, and photophysical behavior for the highly conjugated macrocycles containing 4 pyrroles

Wei

Bai

Xia

et al. 2016

J of Physical Organic Chem

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“…[23][24][25][26][27] Porphyrins belong to highly conjugated macrocycles being composed of four modified pyrrole subunits with the linkage of methine bridges (=CH-) between α carbon atoms. Porphyrins are aromatic on the magnetic criterion.…”

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confidence: 99%

Theoretical Analysis on Molecular Magnetic Properties of N-Confused Porphyrins and Its Derivatives

Wei¹,

Bai²,

Xia³

et al. 2012

Bulletin of the Korean Chemical Society

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We have theoretically investigated the magnetic properties of N-confused porphyrin (NCP), tetraphenyl-Nconfused porphyrin (TPNCP) and their substituted derivatives with O, S and Se heteroatoms (2ONCP, 2STPNCP, 2SeNCP, 2OTPNCP, etc.) by using DFT method. In the minimum energy structures of the 2OTPNCP, the two couples opposite phenyl substitutes are staggered. In the case of TPNCP, 2STPNCP and 2SeTPNCP, two phenyls being respectively close to or opposite to N-confused pyrrole are found to be pointed the same direction, whilst others are in the opposite direction. Based on the equilibrium structures, the 1 H chemical shifts and nucleus-independent chemical shifts (NICS) are calculated in this paper. The π current density being induced by the tridimensional perpendicular magnetic field transmits the inner section of the pyrrole segments for NCP and TPNCP. As for their substituted derivatives with O, S and Se atoms, the current path passes through the outer section of the two heterorings. The NICS values at the ring critical points of the heterorings are much lower (in absolute value) than those of which is at the center of an isolated pyrrole molecule. The 1 H NMR for β H atoms of the heterorings decreases from O, S to with Se.

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Study on the interaction between urea and cellulose by combining solid-state 13C CP/MAS NMR and extended Hückel charges

Song

et al. 2014

Cellulose

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A charge iteration-corrected extended-Hückel study of the electronic and spectroscopic properties of conjugated heterocycles

Cited by 4 publications

References 54 publications

A density functional theory investigation of the stability, aromaticity, and photophysical behavior for the highly conjugated macrocycles containing 4 pyrroles

A density functional theory investigation of the stability, aromaticity, and photophysical behavior for the highly conjugated macrocycles containing 4 pyrroles

Theoretical Analysis on Molecular Magnetic Properties of N-Confused Porphyrins and Its Derivatives

Study on the interaction between urea and cellulose by combining solid-state 13C CP/MAS NMR and extended Hückel charges

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