Coherent intermolecular proton transfer in the acid–base reaction of excited state pyranine

2017 ◽  
Vol 19 (28) ◽  
pp. 18243-18251 ◽  
Author(s):  
Wooseok Heo ◽  
Nizam Uddin ◽  
Jae Woo Park ◽  
Young Min Rhee ◽  
Cheol Ho Choi ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Acid Base ◽  
Acidic Proton ◽  
Intermolecular Proton Transfer

The acidic proton in pyranine is transferred coherently to acetate through the stretching motion of the whole molecule.

scholarly journals A Solvent-Mediated Excited-State Intermolecular Proton Transfer Fluorescent Probe for Fe3+ Sensing and Cell Imaging

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 516
Author(s):  
You Qian ◽  
Fuchun Gong ◽  
Jiguang Li ◽  
Pan Ma ◽  
Hanming Zhu ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Fluorescent Probe ◽  
Cell Imaging ◽  
Cyano Group ◽  
Proton Donor ◽  
Cell Permeability ◽  
One Pot ◽  
Intermolecular Proton Transfer ◽  
Synthesis Strategy

Constructing excited-state intermolecular proton transfer (ESIPT-e) fluorophores represents significant challenges due to the harsh requirement of bearing a proton donor-acceptor (D-A) system and their matching proton donating-accepting ability in the same molecule. Herein, we synthesized a new-type ESIPT-e fluorophor (2-APC) using the “four-component one-pot” reaction. By the installing of a cyano-group on pyridine scaffold, the proton donating ability of -NH2 was greatly enhanced, enabling 2-APC to undergo ESIPT-e process. Surprisingly, 2-APC exhibited dual-emissions in protic solvents ethanol and normal fluorescence in aprotic solvents, which is vastly different from that of conventional ESIPT-a dyes. The ESIPT emission can be obviously suppressed by Fe3+ due to the coordination reaction of Fe3+ with the A-D system in 2-APC. From this basis, a highly sensitive and selective method was established using 2-APC as a fluorescent probe, which offers the sensitive detection of Fe3+ ranging from 0 to 13 μM with the detection limit of 7.5 nM. The recovery study of spiked Fe3+ measured by the probe showed satisfactory results (97.2103.4%) with the reasonable RSD ranging from 3.1 to 3.8%. Moreover, 2-APC can also exhibit aggregation-induced effect in poor solvent or solid-state, eliciting strong red fluorescence. 2-APC was also applied to cell-imaging, exhibiting good cell-permeability, biocompatibility and color rendering. This multi-mode emission of 2-APC is significant departure from that of conventional extended p-conjugated systems and ESIPT dyes based on a flat and rigid molecular design. The “one-pot synthesis” strategy for the construction of ESIPT molecules pioneered a new route to achieve tricolor-emissive fluorophores.

Excited state acid–base equilibrium of tyrosine

1978 ◽  
Vol 56 (9) ◽  
pp. 1238-1245 ◽  
Author(s):  
David Michael Rayner ◽  
Donald Theodore Krajcarski ◽  
Arthur Gustav Szabo
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Quantum Yields ◽  
Acid Base ◽  
Large Shift ◽  
Fluorescence Quantum Yields ◽  
Base Equilibrium ◽  
Tyrosine Fluorescence ◽  
Acid Base Equilibrium ◽  
Buffer Base

Fluorescence attributable to the tyrosinate form of the amino acid tyrosine, previously only observed at pH > pK(S0) = 10.3 where tyrosinate exists in the ground state, has been observed at neutral pH in the presence of high buffer base concentrations. This observation is consistent with the large shift in pK(Sl) predicted from absorption measurements and confirms that proton transfer is indeed a mechanism by which carboxylate ions quench tyrosine fluorescence. The dependence of the fluorescence quantum yields of tyrosine and tyrosinate on pH does not fit a simple excited state acid–base equilibrium model but a more complicated system where carboxylate is also capable of simultaneously quenching tyrosine fluorescence by a mechanism not involving proton transfer. Kinetic analysis of the system allows calculation of pK(S1) = 4.2 for tyrosine. The quantum yield of tyrosinate fluorescence can be appreciably higher than that normally measured at alkaline pH where a separate quenching mechanism must operate. These results have significance in the interpretation of the fluorescence properties of proteins.

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.

Ultrafast Excited-State Intermolecular Proton Transfer in Indigo Oligomer

2019 ◽  
Vol 123 (30) ◽  
pp. 6463-6471
Author(s):  
Xuemei He ◽  
Fan Yang ◽  
Shuang Li ◽  
Xiaoxiao He ◽  
Anchi Yu ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Intermolecular Proton Transfer

Photochemistry of Pheomelanin Building Blocks and Model Chromophores: Excited-State Intra- and Intermolecular Proton Transfer

2014 ◽  
Vol 5 (12) ◽  
pp. 2094-2100 ◽  
Author(s):  
Amal El Nahhas ◽  
Torbjörn Pascher ◽  
Loredana Leone ◽  
Lucia Panzella ◽  
Alessandra Napolitano ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Building Blocks ◽  
Intermolecular Proton Transfer

Ultrafast Excited-State Intermolecular Proton Transfer of Cyanine Fluorochrome Dyes

2011 ◽  
Vol 116 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Naama Karton-Lifshin ◽  
Itay Presiado ◽  
Yuval Erez ◽  
Rinat Gepshtein ◽  
Doron Shabat ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Intermolecular Proton Transfer
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