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Gael, V. I.; Kuz'mitskii, V. A.; Соловьев, К. Н.

doi:10.1023/a:1004112102893

Cited by 8 publications

(14 citation statements)

References 18 publications

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“…The size of this angle depends on the force of the interaction with ions in the complex [2,4]. Therefore the long-wavelength shift of the bands in the electronic absorption spectrum in formation of the H 4 P 2+ ⋅2I -complex is probably caused by an increase in the tilt angle θ of the pyrrole rings, i.e., it is due to an increase in the degree of distortion of the tetrapyrrole macrocycle upon complexation, which is consistent with the results of quantum chemical calculations [15].…”

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confidence: 85%

“…In fact, for the H 4 P 2+ ⋅2Br -complex, the broadening of the bands in the absorption spectrum is less, and there is practically no broadening for the H 4 P 2+ ⋅2Cl -complex [9]. We know that formation of the diprotonated form of porphyrins is accompanied by saddle-shaped out-of-plane distortions of the conformation of the tetrapyrrole macrocycle [2,4,15]. Mutual repulsion of the four protons in the ring of the porphyrin macrocycle leads to the pyrrole rings (while remaining practically planar) "pulling out" from the average plane of the macrocycle so that two opposite nitrogen atoms lie on the one side of the macrocycle while two lie on the other side.…”

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confidence: 99%

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Halide ion determination from luminescence of the diprotonated form of porphyrin

et al. 2007

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We have studied quenching of the fluorescence of the diprotonated form of 3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin by iodide ions in solutions. We have established that there is both static quenching of fluorescence when nonfluorescent complexes are formed with the iodide ions, as a result of an internal heavy atom effect, and also dynamic diffusion-controlled quenching. Based on analysis of the dependences of the fluorescence intensity and fluorescence lifetime on the iodide ion concentration in solution, we suggest using the diprotonated form of this porphyrin as the base compound for designing a fluorescent molecular receptor for halide ions.Key words: porphyrin, acid-base equilibria, diprotonated form, quenching of fluorescence, halide ion, heavy atom effect.Introduction. Design of new, efficient methods for detecting chemical compounds in various media by using molecular sensors is an important problem in modern science [1]. The physicochemical properties of a compound used as the source of the analytical signal, indicating recognition of a specific substrate, are very important characteristics determining the operating efficiency on the whole of any chemical sensor. The method for transduction of the primary chemical signal to the analytical signal directly used for diagnostics is also important, since it determines how easy it is to manufacture and how convenient it is to use the sensor. The optical method for conversion of the analytical signal is one of the most attractive approaches for a number of reasons. First of all, it can make possible design of remote detection methods, and consequently the measurements are inherently safe; this approach makes real-time measurements relatively simple to set up, etc.Representatives of the class of tetrapyrrole compounds can be used as converters of the primary analytical signal to the optical response of the sensor. They have rather intense fluorescence and/or phosphorescence, which can be used for these purposes. Furthermore, these compounds can also be used as the source of the analytical signal. One of the problems which can be solved using tetrapyrrole compounds is detection of anions in solutions. We know that the protonated forms of tetrapyrrole compounds can form adducts with anions of acids in which the anions form hydrogen bonds with positively charged protons of the porphyrin ring [2][3][4]. We should point out that porphyrins with an expanded macrocycle can also form complexes with anions: sapphyrins, anthraphyrins, rubyrins, etc. [5], which have recently been actively studied with the aim of using them as the basis for designing anion-sensitive materials [5][6][7][8].Recently [9] studies were conducted with the aim of studying the possibility of using protonated porphyrins as receptors for halide ions (Hal -) [9]. The monoprotonated and diprotonated forms of 3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin were directly titrated with solutions of halide salts, and it was established that in the solutions, the stable complexes H 3 P + ⋅Hal...

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confidence: 85%

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confidence: 99%

Halide ion determination from luminescence of the diprotonated form of porphyrin

et al. 2007

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“…The molecular structure of H 4 P 2+ . 2Xcomplexes with halide ions was the subject of numerous experimental and theoretical investigations [1,3,[6][7][8][9][10][11][12][13][14]. It was shown [1] that Clions are symmetrically aligned exactly at the porphyrin macrocycle symmetry axis at two sides of the porphyrin plane.…”

Section: Binding Of Halides At Diprotonated Macrocycle Hostmentioning

confidence: 99%

“…Large efforts have been made in the elucidation of the molecular conformation [1,3,[6][7][8][9][10][11][12][13][14], acid-base equilibria involved [15-19 and references therein], ground and excited state properties [2,13,[18][19][20][21][22] of the diprotonated porphyrins. Essential progress has been achieved in this area.…”

Section: Introductionmentioning

confidence: 99%

Tetrapyrrolic compounds as hosts for binding of halides and alkali metal cations

Kruk

Старухин

Мамардашвили

et al. 2009

J. Porphyrins Phthalocyanines

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In this paper the binding of halides and alkali metal cations with porphyrin hosts is reported. The halide ions are complexed with diprotonated porphyrin macrocycle with high affinity and stable complexes of 1:1 and 1:2 structures with halide ions are formed. Strong (up to 300 times) quenching of the porphyrin fluorescence has been found upon the titration of porphyrin solutions with iodide ions. It was established that both static quenching upon formation of the non-fluorescent complex and dynamic diffusion-controlled quenching took place. It is shown that the halide ions binding isotherms can be linearized with double-logarithmic plots. The alkali metal cations are trapped with mono-mesoarylporphyrins containing a conformationally mobile complexing polyether fragment on the benzene ring with a terminal pyridine ring. The alkali metal cation binding constant depends on the polyether chain length. The five-membered (n = 5) polyether chain provides very high binding selectivity for potassium over lithium or sodium. The potassium complexation constants 3.6 × 10 5 and 7.2 × 10 4 M -1 have been obtained for Zn 2+ complex and diprotonated porphyrin, respectively. For signaling of the alkali cation complexation, it is proposed to use the binding between the terminal pyridine ring with either the Lewis acidic site (chelated Zn 2+ ion) or the diprotonated macrocycle core (H 4 P 2+ ) acting as salt bridging site.

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“…The non-coplanarity of the phenyl rings of the H 2 TPhP molecule with the porphyrin plane is enhanced in H 4 TPhP 2+ and is responsible for the long-wavelength shift of the absorption bands, which is not compensated by the hypsochromic shift due to diprotonation of the center of the molecule. This question is considered quantum mechanically in [29].…”

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confidence: 99%

Electronic spectra of cationic forms of meso-tetrapropylporphin in a nanoporous silicate gel matrix

et al. 2006

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ev UDC 535.37We have studied the fluorescence and fluorescence excitation spectra at 300 K, 77 K, and 4.2 K for silicate gel matrices colored with meso-tetrapropylporphin by impregnation of the matrix with a solution of the pigment. Comparison of the data obtained with the absorption spectra in acidified solutions and analysis of the low-temperature fine-structure vibronic spectra, and also taking into account data obtained earlier for octaethylporphin in a xerogel showed formation of two cationic forms of meso-tetrapropylporphin in the gel matrix: the short-wavelength form has a dicationic structure, while the long-wavelength form has a monocationic structure. We have traced out the correlations of the vibrational structure in the spectra of the dicationic form with data for the porphin dication, and we have drawn a number of conclusions concerning the normal vibrational modes that are active in the vibronic fluorescence and absorption spectra of the studied cationic forms. Using the AM1 semiempirical quantum chemical method, we optimized the geometry of the mesotetrapropylporphin dication: the most stable of the possible conformers is the dication structure with saddleshaped macrocycle nonplanarity.Introduction. The elevated mechanical strength, radiation resistance, transparency in the visible and UV regions of the spectrum, easily controlled porosity, and also pronounced capillary effect that are characteristic of nanoporous silicate gel matrices explain the considerable interest in them as new functional nanostructured materials promising for use in nanoelectronics, optoelectronics, and microelectronics. The broad possibilities for varying the final physicochemical properties of gel systems are determined by the specific sol-gel synthesis conditions for the nanoporous materials (choice of chemical structure for the starting metal alkoxides, change in concentration of reaction components, variation of the pH by using a set of acid-base catalysts, synthesis temperature, gel drying conditions, etc.). The range of possible practical applications of such inorganic gel materials is considerably expanded because they can be colored by organic polyatomic molecules (the latter is possible since sol-gel synthesis is carried out at temperatures close to room temperature). Such new molecular impurity inorganic materials show promise for use as laser active media [1], photosensitive materials for optical storage and data processing [2], optical limiters [3], sensors [4], etc.Inorganic gel matrices can hold different classes of molecules in their pores. However, there is special interest in molecules in the porphyrin class, especially due to the expanding range of their practical applications [5]. In a number of papers, it has been shown (see, for example, [6-10]), that for free-base porphyrins incorporated into a tetraethoxysilane (TEOS) gel matrix, protonation of the central nitrogen atoms occurs, i.e., cationic forms are formed. The reason for this is the presence of hydroxyl groups on the surface of nanopores in the g...

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Cited by 8 publications

References 18 publications

Halide ion determination from luminescence of the diprotonated form of porphyrin

Halide ion determination from luminescence of the diprotonated form of porphyrin

Tetrapyrrolic compounds as hosts for binding of halides and alkali metal cations

Electronic spectra of cationic forms of meso-tetrapropylporphin in a nanoporous silicate gel matrix

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