Very Efficient Generation of Quinone Methides through Excited State Intramolecular Proton Transfer to a Carbon Atom

2012 ◽  
Vol 18 (34) ◽  
pp. 10617-10623 ◽  
Author(s):  
Nikola Basarić ◽  
Nađa Došlić ◽  
Jakov Ivković ◽  
Yu-Hsuan Wang ◽  
Momir Mališ ◽  
...  
Keyword(s):  
Excited State ◽  
Carbon Atom ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Quinone Methides ◽  
Efficient Generation

Excited state intramolecular proton transfer in 1-hydroxypyrene

2011 ◽  
Vol 89 (3) ◽  
pp. 433-440 ◽  
Author(s):  
Matthew Lukeman ◽  
Misty-Dawn Burns ◽  
Peter Wan
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Quinone Methide ◽  
Acid Base ◽  
Quinone Methides ◽  
Marked Enhancement ◽  
Theoretical Predictions ◽  
Important Pathway ◽  
Acetonitrile Solutions

1-Hydroxypyrene (1) shows unusual acid–base chemistry in its singlet excited state. Whereas most hydroxyarenes experience a marked enhancement in their acidity when excited, and rapidly deprotonate to give the corresponding phenolate anion, this is not an important pathway for 1, despite theoretical predictions that 1 should experience enhanced acidity as well. In this work, we demonstrate that 1 undergoes a competing excited state intramolecular proton transfer from the OH to carbon atoms at the 3, 6, and 8 positions of the pyrene ring to give quinone methide intermediates. When the reaction is carried out in D2O, reversion of these quinone methides to starting material results in replacement of the ring hydrogens with deuterium, providing a convenient handle to follow the reaction with NMR spectroscopy and mass spectrometry. The quantum yield for the reaction is 0.025 and appears to not be strongly dependent on the water content when aqueous acetonitrile solutions are used. 1-(2-Hydroxyphenyl)pyrene (19) was prepared and studied and shows similar reactivity to 1.

Competing photodehydration and excited-state intramolecular proton transfer (ESIPT) in adamantyl derivatives of 2-phenylphenols

2011 ◽  
Vol 89 (2) ◽  
pp. 221-234 ◽  
Author(s):  
Nikola Basarić ◽  
Nikola Cindro ◽  
Yunyan Hou ◽  
Ivana Žabčić ◽  
Kata Mlinarić-Majerski ◽  
...  
Keyword(s):  
Excited State ◽  
Carbon Atom ◽  
Proton Transfer ◽  
Phenyl Ring ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Intramolecular Proton Transfer ◽  
Hydroxyl Group ◽  
Quantum Yields

2-Phenylphenol derivatives strategically substituted with a hydroxyadamantyl substituent were synthesized and their photochemical reactivity was investigated. Derivatives 9 and 10 undergo competitive excited-state intramolecular proton transfer (ESIPT) from the phenol to the carbon atom of the adjacent phenyl ring and formal ESPT from the phenol to the hydroxyl group coupled with dehydration. These two processes (both via S1) give rise to two classes of quinone methides (QMs) that revert to starting material or react with nucleophiles, respectively. ESIPT to carbon atoms was studied by performing photolyses in the presence of D2O, whereupon deuterium incorporation to the adjacent phenyl ring was observed ([Formula: see text] = 0.1–0.2). The competing formal ESPT and dehydration takes place with quantum yields that are an order of magnitude lower and was studied by isolation of photomethanolysis products. Derivative 8 did not undergo ESIPT to carbon atom. Owing to the presence of an intramolecular H bond, an efficient ESIPT from the phenol to the hydroxyl group coupled with dehydration gives a QM that efficiently undergoes electrocyclization (overall [Formula: see text] = 0.33), to give chroman 16. In addition, spiro[adamantane-2,9′-(4′-hydroxy)fluorene] (12) undergoes ESIPT, unlike the previously reported unreactive parent 2-hydroxyfluorene. The reactive singlet excited states of the prepared biphenyl and fluorene molecules were characterized by fluorescence spectroscopy, whereas laser flash photolysis (LFP) was performed to characterize the longer lived QM intermediates.

Observation of excited state proton transfer reactions in 2-phenylphenol and 2-phenyl-1-naphthol and formation of quinone methide species

2015 ◽  
Vol 17 (14) ◽  
pp. 9205-9211 ◽  
Author(s):  
Jiani Ma ◽  
Xiting Zhang ◽  
Nikola Basarić ◽  
Peter Wan ◽  
David Lee Phillips
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Transient Absorption ◽  
Intramolecular Proton Transfer ◽  
Quinone Methide ◽  
Transfer Reactions ◽  
Quinone Methides ◽  
Time Resolved ◽  
Excited State Proton Transfer ◽  
Proton Transfer Reactions

Excited state intramolecular proton transfer from a phenol (naphthol) to a carbon atom of the adjacent aromatic ring and formation of quinone methides was studied by femtosecond time-resolved transient absorption.

scholarly journals An enhanced sampling QM/AMOEBA approach: The case of the excited state intramolecular proton transfer in solvated 3-hydroxyflavone

2021 ◽  
Vol 154 (18) ◽  
pp. 184107
Author(s):  
Michele Nottoli ◽  
Mattia Bondanza ◽  
Filippo Lipparini ◽  
Benedetta Mennucci
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Enhanced Sampling

scholarly journals The development of aryl-substituted 2-phenylimidazo[1,2-a]pyridines (PIP) with various colors of excited-state intramolecular proton transfer (ESIPT) luminescence in the solid state

2016 ◽  
Vol 4 (16) ◽  
pp. 3599-3606 ◽  
Author(s):  
Toshiki Mutai ◽  
Tatsuya Ohkawa ◽  
Hideaki Shono ◽  
Koji Araki
Keyword(s):  
Excited State ◽  
Solid State ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Aryl Group ◽  
Red Emission ◽  
Wide Range

The color of ESIPT luminescence of HPIP is tuned in a wide range by the introduction of aryl group(s), and thus a series of PIPs showing blue to red emission is realized.

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