ChemInform Abstract: Mechanism of Intramolecular Excited-State Proton Transfer and Relaxation Processes in the Ground and Excited States of 3-Hydroxyflavone and Related Compounds.

ChemInform ◽  
1987 ◽  
Vol 18 (10) ◽  
Author(s):  
M. ITOH ◽  
Y. FUJIWARA ◽  
M. SUMITANI ◽  
K. YOSHIHARA
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Excited States ◽  
Relaxation Processes ◽  
Excited State Proton Transfer ◽  
Related Compounds

Excited-State Proton Transfer: Molecules in a Hurry to Get Rid of Antiaromaticity

2019 ◽  
Author(s):  
Chia-Hua Wu ◽  
Lucas Karas ◽  
Henrik Ottosson ◽  
Judy Wu
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Chemical Shifts ◽  
Proton Relay ◽  
Proton Transfers ◽  
Bifunctional Compounds ◽  
Excited State Proton Transfer ◽  
Derivatives Of ◽  
Related Compounds

<p>Baird’s rule explains why and when excited-state proton transfer (ESPT) reactions happen in organic compounds. Bifunctional compounds that are [4<i>n</i>+2] π-aromatic in the ground state, become [4<i>n</i>+2] π-antiaromatic in the first <sup>1</sup>ππ* states, and proton transfer (either<i>inter-</i>or <i>intra-</i>molecularly) helps relieve excited-state antiaromaticity. Computed nucleus independent chemical shifts (NICS) for several ESPT examples (including excited-state intramolecular proton transfers (ESIPT), biprotonic transfers, dynamic catalyzed transfers, and proton relay transfers) document the important role of excited-state antiaromaticity. <i>o-</i>Salicylic acid undergoes ESPT only in the “antiaromatic” S<sub>1</sub>(<sup>1</sup>ππ*) state, but not in the “aromatic” S<sub>2</sub>(<sup>1</sup>ππ*) state. Stokes’ shifts of structurally-related compounds (<i>e.g.</i>, derivatives of 2-(2-hydroxyphenyl)benzoxazole and hydrogen-bonded complexes of 2-aminopyridine with pro tic substrates) vary depending on the antiaromaticity of the photoinduced tautomers. Remarkably, Baird’s rule predicts the effect of light on hydrogen bond strengths; hydrogen bonds that enhance (and reduce) excited-state antiaromaticity in compounds become weakened (and strengthened) upon photoexcitation.</p>

Excited state proton transfer in amino- and hydroxy-phenyl heteroazoles and related compounds

1997 ◽  
Vol 72-74 ◽  
pp. 513-514 ◽  
Author(s):  
K. Kuldová ◽  
Y. Eichen ◽  
P. Emele ◽  
H.P. Trommsdorff
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Excited State Proton Transfer ◽  
Related Compounds

scholarly journals Excited-state proton transfer relieves antiaromaticity in molecules

2019 ◽  
Vol 116 (41) ◽  
pp. 20303-20308 ◽  
Author(s):  
Chia-Hua Wu ◽  
Lucas José Karas ◽  
Henrik Ottosson ◽  
Judy I-Chia Wu
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Chemical Shifts ◽  
Proton Relay ◽  
Proton Transfers ◽  
Bifunctional Compounds ◽  
Excited State Proton Transfer ◽  
Derivatives Of ◽  
Related Compounds

Baird’s rule explains why and when excited-state proton transfer (ESPT) reactions happen in organic compounds. Bifunctional compounds that are [4n + 2] π-aromatic in the ground state, become [4n + 2] π-antiaromatic in the first 1ππ* states, and proton transfer (either inter- or intramolecularly) helps relieve excited-state antiaromaticity. Computed nucleus-independent chemical shifts (NICS) for several ESPT examples (including excited-state intramolecular proton transfers (ESIPT), biprotonic transfers, dynamic catalyzed transfers, and proton relay transfers) document the important role of excited-state antiaromaticity. o-Salicylic acid undergoes ESPT only in the “antiaromatic” S1 (1ππ*) state, but not in the “aromatic” S2 (1ππ*) state. Stokes’ shifts of structurally related compounds [e.g., derivatives of 2-(2-hydroxyphenyl)benzoxazole and hydrogen-bonded complexes of 2-aminopyridine with protic substrates] vary depending on the antiaromaticity of the photoinduced tautomers. Remarkably, Baird’s rule predicts the effect of light on hydrogen bond strengths; hydrogen bonds that enhance (and reduce) excited-state antiaromaticity in compounds become weakened (and strengthened) upon photoexcitation.

Excited-State Proton Transfer: Molecules in a Hurry to Get Rid of Antiaromaticity

2019 ◽  
Author(s):  
Chia-Hua Wu ◽  
Lucas Karas ◽  
Henrik Ottosson ◽  
Judy Wu
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Chemical Shifts ◽  
Proton Relay ◽  
Proton Transfers ◽  
Bifunctional Compounds ◽  
Excited State Proton Transfer ◽  
Derivatives Of ◽  
Related Compounds

<p>Baird’s rule explains why and when excited-state proton transfer (ESPT) reactions happen in organic compounds. Bifunctional compounds that are [4<i>n</i>+2] π-aromatic in the ground state, become [4<i>n</i>+2] π-antiaromatic in the first <sup>1</sup>ππ* states, and proton transfer (either<i>inter-</i>or <i>intra-</i>molecularly) helps relieve excited-state antiaromaticity. Computed nucleus independent chemical shifts (NICS) for several ESPT examples (including excited-state intramolecular proton transfers (ESIPT), biprotonic transfers, dynamic catalyzed transfers, and proton relay transfers) document the important role of excited-state antiaromaticity. <i>o-</i>Salicylic acid undergoes ESPT only in the “antiaromatic” S<sub>1</sub>(<sup>1</sup>ππ*) state, but not in the “aromatic” S<sub>2</sub>(<sup>1</sup>ππ*) state. Stokes’ shifts of structurally-related compounds (<i>e.g.</i>, derivatives of 2-(2-hydroxyphenyl)benzoxazole and hydrogen-bonded complexes of 2-aminopyridine with pro tic substrates) vary depending on the antiaromaticity of the photoinduced tautomers. Remarkably, Baird’s rule predicts the effect of light on hydrogen bond strengths; hydrogen bonds that enhance (and reduce) excited-state antiaromaticity in compounds become weakened (and strengthened) upon photoexcitation.</p>

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