TY - JOUR
T1 - Photochromism of dihydroindolizines. Part 16
T2 - Tuning of the photophysical behavior of photochromic dihydroindolizines in solution and in polymeric thin film
AU - Ahmed, Saleh A.
AU - Hozien, Zeinab A.
AU - Abdel-Wahab, Aboel Magd A.
AU - Al-Raqa, Shaya Y.
AU - Al-Simaree, Abdulrahman A.
AU - Moussa, Ziad
AU - Al-Amri, Saleh N.
AU - Messali, Mouslim
AU - Soliman, Ahmed S.
AU - Dürr, Heinz
N1 - Funding Information:
S.A.A. is highly indebted to the University of Saarland and Alexander von Humboldt foundation (AvH), Germany for their financial support of this work and their chemicals and instrumentation donations. Also, the authors are highly indebted to Taibah University and the deanship of scientific research for the partially support of this work through the funded project no. 479/430.
PY - 2011/9/16
Y1 - 2011/9/16
N2 - In this work, photochromic materials based on the dihydroindolizine (DHI) system were synthesized in multistep reactions using chemical and photochemical methods. Some of the synthesized photochromic dihydroindolizine derivatives were substituted on the fluorene (region A) and pyridazine (region C) moieties in order to provide the appropriate functionality for optimal tuning of the photochromic properties of the system. Irradiation of the photochromic DHIs with polychromatic light led to ring opened colored betaines, which underwent thermal 1,5-electrocyclization. The red to green colored betaines produced after UV irradiation returned back through 1,5-electrocyclization to the corresponding DHIs with different rate constants depending on the substituents in both fluorene and pyridazine regions. The kinetic measurements of the thermal 1,5-electrocyclization under different temperatures that ranged from -10 to 25 °C showed that the half-lives of the colored betaines fall in the second to hours domain. Interestingly, these materials showed a very good photochromic behavior not only in solution but also in the PMMA matrix. Irradiation of a slide prepared by the deep-coating method led to the formation of the colored betaine and the kinetics of the thermally reversible 1,5-electrocyclization and the AFM image of the film has been recorded. Indeed, the chemical and thermal stability of the investigated betaines in polymer (PMMA) will render such species useful for a plethora of new of applications.
AB - In this work, photochromic materials based on the dihydroindolizine (DHI) system were synthesized in multistep reactions using chemical and photochemical methods. Some of the synthesized photochromic dihydroindolizine derivatives were substituted on the fluorene (region A) and pyridazine (region C) moieties in order to provide the appropriate functionality for optimal tuning of the photochromic properties of the system. Irradiation of the photochromic DHIs with polychromatic light led to ring opened colored betaines, which underwent thermal 1,5-electrocyclization. The red to green colored betaines produced after UV irradiation returned back through 1,5-electrocyclization to the corresponding DHIs with different rate constants depending on the substituents in both fluorene and pyridazine regions. The kinetic measurements of the thermal 1,5-electrocyclization under different temperatures that ranged from -10 to 25 °C showed that the half-lives of the colored betaines fall in the second to hours domain. Interestingly, these materials showed a very good photochromic behavior not only in solution but also in the PMMA matrix. Irradiation of a slide prepared by the deep-coating method led to the formation of the colored betaine and the kinetics of the thermally reversible 1,5-electrocyclization and the AFM image of the film has been recorded. Indeed, the chemical and thermal stability of the investigated betaines in polymer (PMMA) will render such species useful for a plethora of new of applications.
KW - 1,5-Electrocylization
KW - Dihydroindolizines
KW - Half-lives
KW - Kinetics
KW - Photochromism
KW - Solid thin film
KW - Temperature dependence
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U2 - 10.1016/j.tet.2011.06.092
DO - 10.1016/j.tet.2011.06.092
M3 - Article
AN - SCOPUS:80051690449
SN - 0040-4020
VL - 67
SP - 7173
EP - 7184
JO - Tetrahedron
JF - Tetrahedron
IS - 37
ER -