TY - JOUR
T1 - Ultrafast excited-state intermolecular proton transfer of cyanine fluorochrome dyes
AU - Karton-Lifshin, Naama
AU - Presiado, Itay
AU - Erez, Yuval
AU - Gepshtein, Rinat
AU - Shabat, Doron
AU - Huppert, Dan
PY - 2012/1/12
Y1 - 2012/1/12
N2 - Steady-state and time-resolved emission spectroscopy techniques were employed to study the excited-state proton transfer (ESPT) to water and D 2O from QCy7, a recently synthesized near-infrared (NIR)-emissive dye with a fluorescence band maximum at 700 nm. We found that the ESPT rate constant, k PT, of QCy7 excited from its protonated form, ROH, is ∼1.5 × 10 12 s -1. This is the highest ever reported value in the literature thus far, and it is comparable to the reciprocal of the longest solvation dynamics time component in water, τ S = 0.8 ps. We found a kinetic isotope effect (KIE) on the ESPT rate of ∼1.7. This value is lower than that of weaker photoacids, which usually have KIE value of ∼3, but comparable to the KIE on proton diffusion in water of ∼1.45, for which the average time of proton transfer between adjacent water molecules is similar to that of QCy7.
AB - Steady-state and time-resolved emission spectroscopy techniques were employed to study the excited-state proton transfer (ESPT) to water and D 2O from QCy7, a recently synthesized near-infrared (NIR)-emissive dye with a fluorescence band maximum at 700 nm. We found that the ESPT rate constant, k PT, of QCy7 excited from its protonated form, ROH, is ∼1.5 × 10 12 s -1. This is the highest ever reported value in the literature thus far, and it is comparable to the reciprocal of the longest solvation dynamics time component in water, τ S = 0.8 ps. We found a kinetic isotope effect (KIE) on the ESPT rate of ∼1.7. This value is lower than that of weaker photoacids, which usually have KIE value of ∼3, but comparable to the KIE on proton diffusion in water of ∼1.45, for which the average time of proton transfer between adjacent water molecules is similar to that of QCy7.
UR - https://www.scopus.com/pages/publications/84855862353
U2 - 10.1021/jp2095856
DO - 10.1021/jp2095856
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AN - SCOPUS:84855862353
SN - 1089-5639
VL - 116
SP - 85
EP - 92
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 1
ER -