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Tyulyaeva, E. Yu.; Ломова, Т. Н.

doi:10.1023/a:1011348027437

Cited by 8 publications

(4 citation statements)

References 7 publications

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“…Compounds 1-6 can be prepared either via the classical acidified condensation [28][29][30] or via the 2-step, 1-pot synthetic protocols [31,32]. The latter procedure has been used in the recent preparation of 1, 2 and 4 [33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, EPR and DFT calculations of rare Ag(II)porphyrins and the crystal structure of [Zn(II)tetrakis(4-bromo-2-thiophene)porphyrin]

Ghazzali¹,

Abu‐Youssef²,

Larsson³

et al. 2008

Inorganic Chemistry Communications

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Section: Introductionmentioning

confidence: 99%

Synthesis, EPR and DFT calculations of rare Ag(II)porphyrins and the crystal structure of [Zn(II)tetrakis(4-bromo-2-thiophene)porphyrin]

Ghazzali¹,

Abu‐Youssef²,

Larsson³

et al. 2008

Inorganic Chemistry Communications

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“…The model systems often consist of two moieties, acceptor and donor of the energy and/or electrons, kept at a fixed distance from each other by a spatial separator that either mediates the transfer reactions or not. In some systems, gold(III) porphyrins have been used due to their good stability and suitable redox properties, ,,,, making them excellent as electron acceptors in electron-transfer reactions. The gold(III) porphyrins can act as electron acceptors either in the ground state or in the first excited triplet state (electron hole donor).…”

Section: Introductionmentioning

confidence: 99%

Triplet Photophysics of Gold(III) Porphyrins

et al. 2005

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Gold porphyrins are often used as electron-accepting chromophores in donor-acceptor complexes for the study of photoinduced electron transfer, and they can also be involved in triplet-triplet energy-transfer interactions with other chromophores. Since the lowest excited singlet state is very short-lived (240 fs), the triplet state is usually the starting point for the transfer reactions, and it is therefore crucial to understand its photophysics. The triplet state of various gold porphyrins has been reported to have a lifetime of around 1.5 ns at room temperature and to have a biexponential decay both in emission and in transient absorption with decay times of around 10 and 100 micros at 80 K. In this paper, the triplet photophysics of two gold porphyrins (Au(III) 5,15-bis(3,5-di-tert-butylphenyl)-2,8,12,18-tetraethyl-3,7,13,17-tetramethylporphyrin and Au(III) 5,10,15,20-tetra(3,5-di-tert-butylphenyl)porphyrin) are studied by steady-state and time-resolved absorption and emission spectroscopy over a wide temperature range (4-300 K). The study reveals the existence of a dark state with an approximate lifetime of 50 ns, which was not previously observed. This state acts as an intermediate between the short-lived singlet and the triplet state manifold. In addition, we present DFT calculations, in which the core electrons of the central metal were replaced by a pseudopotential to account for the relativistic effects, which suggest that the lowest excited singlet state is an optically forbidden ligand-to-metal charge-transfer (LMCT) state. This LMCT state is an obvious candidate for the experimentally observed dark state, and it is shown to dictate the photophysical properties of gold porphyrins by acting as a gate for triplet state formation versus direct return to the ground state.

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“…This fact is most likely associated with a steric factor, specifically, the Er atom in (Br)ErPc stronger deviates from the plane of the coordinated nitrogen atoms of the macrocyclic ligand because of the hindrances from the bulkier Br atom. Characteristically, lanthanides with a lower atomic number (and, consequently, a larger covalent radius) do not exhibit such effect, and axial chloride complexes are less stable than bromide and, all the more, acetate ones [6,27,28]. This is especially related to gadolinium complexes [(X)GdPc] [6], whose stability along the series Cl > Br > > AcO varies 24.4 times.…”

Section: Complexmentioning

confidence: 99%

Axial ligands and (acido) (phthalocyaninato) lanthanides(III) stability on examples of erbium and lutetium

Ломова

2015

Russ J Gen Chem

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The results of a spectrophotometric study of the dissociation kinetics of the coordination centre in (phthalocyaninato) erbium(III) and lutetium(II), (X)LnPc (X = Cl, Br, AcO) in ethanol in the presence of acetic acid are reported. The kinetic equations, the numerical values of reaction rate constants and dependences of the letter on the temperature were determined by the method of excessive concentrations. The stoichiometric mechanism of the complexes dissociation and the nature of the limiting elementary reaction were substantiated and the role of axial ligands in the reaction mechanism was revealed using spectral data and the quasiequilibrium principle to describe kinetic regularities. The resulting data can help in the use of erbium and lutetium phthalocyanines as precursors in the synthesis of higher stoichiometry complexes.It was previously shown that the equatorial (macrocyclic) and axial ligands in metal porphyrins (MP) and metal phthalocyanines (MPc) with a mixedligand coordination sphere and the metal cation having the formal charge >2, not only are bound to the central atom with different strengths, but also exert a cis effect on each other, thereby affecting the reactivity [1-6]. Higher stoichiometry complexes, where the axial positions are occupied by one or even two porphyrin/ phthalocyanine ligands, specifically, sandwich complexes are the most stable and widespread form in the case of rare earth metals having a large radius and high coordination numbers. Such complexes exhibit nonlinear optical, magnetic, electrochromic, and other practically important properties [7-16] provoking a growing interest in the synthesis of new compounds of this class. Among recent achievements, the synthesis of four-and six-membered sandwich complexes containing a flexible spacer (clamshell complexes)[17] or a cadmium ion as one of the central ions [18] are worth mentioning. Even though sandwich complexes of rare-earth metals are much more stable than 1 : 1 complexes with an axial acido ligand (X) LnP, (X)LnPc [19], the search for ways to enhance stability of the latter complexes and the study of their properties are continued. According to [20,21], chloride and acetate axial complexes of (porphyrinato) gadolinium(III), europium(III), and thulium(III) complexes are paramagnetics, and in external magnetic fields of up to 1 T at 15-25°С they exhibit magnetocaloric properties which are much dependent on the nature of the axial ligand. (AcO)GdTPP (TPP is 5,10,15,20-tetraphenyl-21H,23H-porphine dianion) shows a high magnetocaloric effect which compares with that of lanthanum manganite doped with silver ions [22] and implies that acidoporphyrin complexes of rare-earth metals hold promise for application in solid-state refrigerators and hyperthermia therapy.In view of the aforesaid, it is quite obvious that the studying the influence of the nature of axial ligands on the stability of (phthalocyaninato) rare earth complexes is an urgent task. In the present work we synthesized erbium(III) and lutetium(III) phthalocyanines of t...

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Cited by 8 publications

References 7 publications

Synthesis, EPR and DFT calculations of rare Ag(II)porphyrins and the crystal structure of [Zn(II)tetrakis(4-bromo-2-thiophene)porphyrin]

Synthesis, EPR and DFT calculations of rare Ag(II)porphyrins and the crystal structure of [Zn(II)tetrakis(4-bromo-2-thiophene)porphyrin]

Triplet Photophysics of Gold(III) Porphyrins

Axial ligands and (acido) (phthalocyaninato) lanthanides(III) stability on examples of erbium and lutetium

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