Picosecond flash-photolysis of Ni(II)- and Ag(II)-porphyrins

Chirvonyi, V. S.; Джагаров, Б. М.; Timinskii, Yu.V.; Gurinovich, G. P.

doi:10.1016/0009-2614(80)80064-9

Cited by 48 publications

(42 citation statements)

References 12 publications

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“…It is a matter of debate whether the ͑d, d͒ excited state has singlet or triplet multiplicity. 50,59,60 Rodriguez and Holten did not observe any spectral changes attributable to intersystem crossing from the singlet state to the triplet state. 49 It is reasonable that the observed transient Raman bands arose from either ͑d, d͒ excited state, although the multiplicity has not been determined yet.…”

Section: A Electronic Relaxationmentioning

confidence: 91%

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Mizutani

Uesugi

Kitagawa

1999

The Journal of Chemical Physics

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The formation of a vibrationally excited photoproduct of nickel octaethylporphyrin (NiOEP) upon (π, π*) excitation and its subsequent vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy. Stokes Raman bands due to the photoproduct instantaneously appeared upon the photoexcitation. Their intensities decayed with a time constant of ∼300 ps, which indicates electronic relaxation from the (d, d) excited state (B1g) to the ground state (A1g), being consistent with the results of transient absorption measurements by Holten and co-workers [D. Kim, C. Kirmaier, and D. Holten, Chem. Phys. 75, 305 (1983); J. Rodriguez and D. Holten, J. Chem. Phys. 91, 3525 (1989)]. The Raman frequencies of NiOEP in the (d, d) excited state are shifted to lower frequencies compared to those of the ground state species, and it is reasonably interpreted by the core size expansion of the macrocycle by 0.05 Å upon the electron promotion from the dz2 to the dx2−y2 orbital. Anti-Stokes ν4 intensity in the vibrationally excited (d, d) state of NiOEP appeared promptly and decayed with time constants of 11±2 and 330±40 ps. The former is ascribed to vibrational relaxation, while the latter corresponds to the electronic relaxation from the (d, d) excited state to the electronic ground state. In contrast, the rise of anti-Stokes ν7 intensity was not instantaneous, but delayed by 2.6±0.5 ps, which indicates that intramolecular vibrational energy redistribution has not been completed in subpicosecond time regime. The peak position of the ν4 band shifted by nearly 5 cm−1 between 0 and 50 ps. The time constant for the shift of the ν4 band was 9.2±1.3 ps, which was close to that for the fast component of intensity decay of anti-Stokes bands. The ν4 band became narrower and symmetric as the delay time increases. These can be ascribed to intramolecular anharmonic coupling of the ν4 mode with the low frequency modes. The intra- and intermolecular vibrational energy relaxation in the metal excited state will be discussed.

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Section: A Electronic Relaxationmentioning

confidence: 91%

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Mizutani

Uesugi

Kitagawa

1999

The Journal of Chemical Physics

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“…При этом все π-электроны гема находились бы на низших заполненных оболочках. Подобные спектры наблюдались для ком-плексов порфиринов с Ni(II) и Cr(III) [13,[39][40][41][42].…”

Section: результаты и обсуждениеunclassified

Фотоиндуцированный разрыв связи Fe--O-=SUB=-2-=/SUB=- в гемоглобине: квантовый выход диссоциации, возбужденные электронные состояния и релаксационные безызлучательные процессы

Джагаров

Lepeshkevich

Панарин

et al. 2018

Журнал Технической Физики

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Поступила в редакцию 21.02.2018 г.Методом лазерной кинетической наносекундной спектроскопии проведены исследования бимолекулярной рекомбинации молекулярного кислорода с гемоглобином человека при возбуждении в различных спек-тральных диапазонах. Получены принципиально отличные результаты: наличие достаточно эффективной фотодиссоциации при возбуждении в Q-полосу ππ * -природы и практически полное ее отсутствие при возбуждении в полосу, расположенную в ближней ИК области и соответствующую переносу электрона с порфириновой a 2u -орбитали на смешанную орбиталь, образованную из d-орбитали железа и свободной π-орбитали молекулярного кислорода. Анализ этих данных совместно с данными, полученными ранее с привлечением техники нано-, пико-и фемтосекундной спектроскопии, позволил описать механизм и динамику реакции фотодиссоциации и релаксационных внутригемовых процессов. ВведениеОбнаруженная в 1957 г.[1] реакция фотодиссоциации оксигемоглобина (фотоиндуцированный разрыв связи Fe-O 2 ), а затем аналогичная реакция для оксимио-глобина и по сей день остается предметом много-численных исследований с привлечением различных теоретических и экспериментальных подходов . Установление механизма, квантовой эффективности и динамики этой реакции, которая реализуется при важ-нейшем физиологическом процессе -дыхании, пред-ставляется крайне необходимым для понимания при-роды связи гемового железа с молекулярным кисло-родом. Необходимо также отметить, что отсутствует полное понимание того, как при встрече молекулы дез-оксигемоглобина Hb (основное состояние квинтетное, S = 2) с молекулой O 2 (основное состояние триплет-ное, S = 1) образуется связь Fe-O 2 в оксигемоглобине HbO 2 , основное состояние которого является синглет-ным (S = 0). Окончательно не решен вопрос, какова электронная природа этой связи. В литературе обсужда-ются три варианта связи: 1) Fe(II) (S = 1)−O 2 (S = 1), 2) Fe(II) (S = 0)− 1 O 2 (S = 0), 3) Fe(III)−O − 2 ; в послед-нем случае Fe находится в ферри-форме и связывается с супероксидным анион-радикалом [23,24]. Возникают также определенные сложности при выяснении причин темнового разрыва связи Fe-O 2 в гемоглобине. Кро-ме того, выяснение детального механизма диссоциации оксигемоглобина необходимо для понимания подобных реакций, которые происходят в комплексах гемоглобина с другими малыми лигандами NO и CO, также вовлечен-ными в важнейшие физиологические процессы. Очевид-но, что выяснение механизма ассоциации/диссоциации гемоглобина и O 2 может и должно оказаться необходи-мым для установления законов, управляющих нелиней-ным кооперативным взаимодействием биомакромолекул с различными лигандами.Цель настоящей работы заключалась в установлении механизмов и динамики как собственно фотодиссоциа-ции оксигемоглобина, так и конкурирующих с ней пер-вичных фотофизических релаксационных внутригемо-вых процессов. При этом основная задача заключалась в установлении природы возбужденного электронного фотодиссоциирующего состояния.В настоящей работе представлены результаты, по-лученные методом лазерного наносекундного фотолиза при воз...

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“…Indeed, the (d,d) nature of this transient species is confirmed by both TA and RR data. First, its absorption profile ( Figure 3B) is typical for the 3 B 1g excited state of 4-coordinate Ni porphyrins, [30][31][32][33][34] which exhibits a clear red shift from the corresponding ground-state absorption profile, in keeping approximately the same shape. Second, the lifetime of the longlived transient species is also typical for the 3 B 1g excited (d,d) state of 4-coordinate Ni porphyrins.…”

Section: Ni(tmpy-p4) In Poly(dg-dc) 2 Ni(tmpy-p4mentioning

confidence: 99%

“…The properties of the lowest and long-lived (d,d) excited state (hundreds of ps), presumably a ( 3 B 1g ) triplet state, have already been settled for non-water-soluble Ni(II) porphyrins. [19][20][21][29][30][31][32][33][34][35][36][37][38][39][40][41] The nature of the short-lived transient species (lifetime e10 ps) is still currently under debate. Earlier studies proposed that this transient species may originate from different excited electronic states, 1 Q (π,π*), 29 3 T 1 (π,π*), 30,31 or 1 B 1g (d,d).…”

Section: Introductionmentioning

confidence: 99%

Excited States of Water-Soluble Metal Porphyrins as Microenvironmental Probes for DNA and DNA-Model Compounds: Time-Resolved Transient Absorption and Resonance Raman Studies of Ni(TMpy-P4) in [Poly(dG-dC)]₂and [Poly(dA-dT)]₂

Galievsky¹,

Chirvony²,

Kruglik³

et al. 1996

J. Phys. Chem.

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The dynamics and mechanisms of photoexcitation relaxation of the water-soluble cationic metalloporphyrin nickel(II) 5,10,15,20-tetrakis[4-(N-methylpyridyl)]porphyrin (Ni(TMpy-P4)) bound to DNA-model polynucleotides, i.e. poly(dG-dC) 2 and poly(dA-dT) 2 , and free in a mere phosphate buffer, have been studied in detail by using time-resolved picosecond transient absorption (TA) and nanosecond resonance Raman (RR) spectroscopies. For the Ni(TMpy-P4)-poly(dG-dC) 2 complex, double-exponential kinetics of relaxation has been found, with time constants of e10 and 350 (20 ps, and absolute absorption spectra have been reconstructed from experimentally measured difference spectra. The long-lived transient species has been assigned to the excited intramolecular metal-centered (d,d) state 3 B 1g of the 4-coordinate Ni porphyrin intercalated between G-C base pairs. Transient RR spectra originating from this state have also been obtained and discussed. A much more complicated process of excitation relaxation has been found for the Ni(TMpy-P4)-poly(dA-dT) 2 complex, where at least four relaxation components can be separated with time constants of e10, ∼100, ∼450 ps, and .1 ns. Our studies support the existence of at least two types of Ni(TMpy-P4) interaction with poly(dA-dT) 2 , each having its own kinetics of TA decay and transient RR spectra. Both TA and RR sets of data show that a major part of Ni porphyrin molecules yields a photophysical behavior typical for a 4-coordinate species, the excited (d,d) state 3 B 1g playing the key role in relaxation processes, while a minor part of Ni(TMpy-P4) also participates in axial ligand binding/release photoprocesses. Comparative analysis of transient RR spectra of Ni(TMpy-P4) bound to the AT sequence and free in a phosphate buffer shows that no 6-coordinate 3 B 1g (L) 2 transient species is photogenerated in the complex with poly(dA-dT) 2 , and therefore, axial coordination of only one extra-ligand molecule (most probably from the surrounding water solution) to the porphyrin central Ni ion is proposed to explain the experimental results. Possible processes of Ni(TMpy-P4) binding to poly(dA-dT) 2 are discussed on the basis of the current photophysical data.

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Picosecond flash-photolysis of Ni(II)- and Ag(II)-porphyrins

Cited by 48 publications

References 12 publications

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Excited States of Water-Soluble Metal Porphyrins as Microenvironmental Probes for DNA and DNA-Model Compounds: Time-Resolved Transient Absorption and Resonance Raman Studies of Ni(TMpy-P4) in [Poly(dG-dC)]₂and [Poly(dA-dT)]₂

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Picosecond flash-photolysis of Ni(II)- and Ag(II)-porphyrins

Cited by 48 publications

References 12 publications

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Intramolecular vibrational energy redistribution and intermolecular energy transfer in the (d, d) excited state of nickel octaethylporphyrin

Excited States of Water-Soluble Metal Porphyrins as Microenvironmental Probes for DNA and DNA-Model Compounds: Time-Resolved Transient Absorption and Resonance Raman Studies of Ni(TMpy-P4) in [Poly(dG-dC)]2and [Poly(dA-dT)]2

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Excited States of Water-Soluble Metal Porphyrins as Microenvironmental Probes for DNA and DNA-Model Compounds: Time-Resolved Transient Absorption and Resonance Raman Studies of Ni(TMpy-P4) in [Poly(dG-dC)]₂and [Poly(dA-dT)]₂