Modulating the Photochemistry of Bipyridylic Compounds by Symmetric Substitutions

Ortiz-Sánchez, Juan Manuel; Gelabert, Ricard; Moreno, Miquel; Lluch, José M.

doi:10.1002/cphc.201000596

Cited by 7 publications

(5 citation statements)

References 60 publications

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“…Because of the large size of the p conjugated system in BSP, a systematic CASSCF study would need a far too large active space requiring an unattainable amount of computational resources. Very recently 45,46 the same strategy has been successfully used to analyze a series of bipyridyl derivatives.…”

Section: Theoretical Resultsmentioning

confidence: 99%

Photo-deactivation pathways of a double H-bonded photochromic Schiff base investigated by combined theoretical calculations and experimental time-resolved studies

Randino

Ziółek

Gelabert

et al. 2011

Phys. Chem. Chem. Phys.

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The photophysics of N,N'-bis(salicylidene)-p-phenylenediamine (BSP) is analyzed both theoretically and experimentally. The alternative intramolecular proton-transfer reactions lead to three different tautomers. We performed DFT and TDDFT calculations to analyze the topography of the reactions connecting the three tautomers. Deactivation paths through a Conical Intersection (CI) region are also analyzed to explain the low fluorescence quantum yield of the phototautomers. The complex molecular structure of BSP provides a large number of deactivation paths, almost all of them energetically available following the initial photoexcitation. Femtosecond (fs) time-resolved emission studies in solution and flash photolysis experiments (nano to millisecond regime) were performed to get detailed information on the time domain of the full photocycle. The picture that emerges by combining theoretical and experimental results shows a very fast (less than 100 fs) photoinduced single proton transfer process leading to a phototautomer where a single proton has moved. This species may deactivate through a low-energy CI leading in about 20 ps to a rotameric form in the ground state that has a lifetime of several tens of microseconds in solution. This process competes with another deactivation path taking place prior to the proton-transfer reaction which involves a low-energy CI leading to a rotamer of the enol structure. In the flash photolysis studies, the rotamer of the enol structure was directly identified by the positive transient absorption band in the 250-260 nm and its lifetime in n-hexane (10 ms) is almost 3 orders of magnitude longer than the lifetime of the photochrome (around 40 μs). Our findings do not exclude a double proton transfer reaction in the excited enol form to give a tautomer in less than 100 fs during the first (impulsive) phase of the reaction which reverts back to the photoproducts of the simple proton transfer in 1-3 ps.

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Section: Theoretical Resultsmentioning

confidence: 99%

Photo-deactivation pathways of a double H-bonded photochromic Schiff base investigated by combined theoretical calculations and experimental time-resolved studies

Randino

Ziółek

Gelabert

et al. 2011

Phys. Chem. Chem. Phys.

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“…Recent quantum modelings were done for SA and they showed that ESIPT occurs from a planar enol* which gives a planar cis-keto*. This planar cis-keto* is not stable and undergos out-of-plane torsion which is the precursor of cis−trans isomerization to the trans-keto photoproduct . Thus one hypothesis for the two fluorescent cis-keto* is a planar and a nonplanar isomer or different nonplanar isomers.…”

Section: Resultsmentioning

confidence: 99%

Comparative Investigation of Ultrafast Photoinduced Processes in Salicylidene-Aminopyridine in Solution and Solid State

et al. 2009

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Photodynamics and excited-state intramolecular proton transfer (ESIPT) of N-(3,5-ditert-butylsalicylidene)-4-aminopyridine (4P) and N-(3,5-ditert-butylsalicylidene)-2-aminopyridine (2P) are studied by steady-state and transient optical spectroscopy in solution and solid state (microcrystalline powder). These two compounds are representative of anils Classes A and B, respectively. The results confirm that in solution both compounds have a similar dynamic behavior: upon excitation at 390 nm, ESIPT leads to different cis-keto* fluorescent species which relax to the photochromic trans-keto photoproduct within a few tens of picoseconds. Furthermore, for the first time, picosecond data are recorded for the two classes of anils in the solid state: in 2P, two cis-keto* fluorescent excited state species (23 and 250 ps lifetime) are relaxing exclusively to the cis-keto ground state, whereas in 4P, a single cis-keto* fluorescent species is observed which leads to the trans-keto photoproduct in 250 ps via an intermediate metastable species. † Part of the "Hiroshi Masuhara Festschrift".

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“…Among them, the family of aromatic Schiff bases is to be highlighted because the photochromism in these compounds is produced through an ESIPT process. [22,23] Recently, interest in photochromic systems has suddenly increased because of the intriguing possibility of using them as molecular optical switches or photomemory devices. The use of organic molecules for the future realization of digital processors and storage media at the miniaturized level is at present a hot topic in applied science.…”

Section: Introductionmentioning

confidence: 99%

Bipyridyl Derivatives as Photomemory Devices: A Comparative Electronic‐Structure Study

Ortiz-Sánchez

Gelabert

Moreno

et al. 2010

Chemistry A European J

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The two isoelectronic bipyridyl derivatives [2,2'-bipyridyl]-3,3'-diamine (BP(NH(2))(2)) and [2,2'-bipyridyl]-3,3'-diol (BP(OH)(2)) are experimentally known to undergo very different excited-state double proton transfer processes that result in fluorescence quantum yields that differ by four orders of magnitude. Such differences have been theoretically explained in terms of topographical features in the potential energy surface and the likely presence of conical intersections. The hypothetical hybrid compound [2,2'-bipyridyl]-3-amin-3'-ol (BP(OH)(NH(2))) presents intermediate photochemical features of its "ancestors". In this report we analyze the photochemical properties of a whole family of "dark" (not fluorescent) states that can be accessed from each bipyridyl derivative upon irradiation of light of a given wavelength and their potential application as photomemory devices. In the light of our density functional theory (DFT), time-dependent DFT (TDDFT), and complete active space self-consistent field (CASSCF) calculations, BP(NH(2))(2) is the more likely candidate to become a photomemory device.

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Modulating the Photochemistry of Bipyridylic Compounds by Symmetric Substitutions

Cited by 7 publications

References 60 publications

Photo-deactivation pathways of a double H-bonded photochromic Schiff base investigated by combined theoretical calculations and experimental time-resolved studies

Photo-deactivation pathways of a double H-bonded photochromic Schiff base investigated by combined theoretical calculations and experimental time-resolved studies

Comparative Investigation of Ultrafast Photoinduced Processes in Salicylidene-Aminopyridine in Solution and Solid State

Bipyridyl Derivatives as Photomemory Devices: A Comparative Electronic‐Structure Study

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