Unusual Absorption Spectra Found for Some Phthalocyaninatozinc(II) Complexes Bearing Dendritic Substituents at α Positions

Kasuga, Kuninobu; Matsuura, Noriyuki; Inoue, Koji; Handa, Makoto; Sugimori, Tamotsu; Nakata, Makoto

doi:10.1246/cl.2002.352

Cited by 30 publications

(17 citation statements)

References 20 publications

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“…This band cannot be assigned to aggregational processes since a decrease in intensity along with a broadening of the major Q-band and the appearance of adsorption band in the more short-wave region are usually observed in the case of aggregation. A similar extra band, termed the X-band, was previously observed for substituted PcZn in nonpolar and slightly polar solvents such as benzene and chloroform and also in THF [12,13]. The appearance of an X-band may be attributed to distortions of the pyrazinoporphyrazine macrocycle in the Styr 8 PyzPzZn complex, which lower the molecular symmetry.…”

supporting

confidence: 67%

Effect of styryl substituents introduced into the periphery of pyrazinoporphyrazine macrocycle on the spectral and luminescence properties of complexes

Tomachinskaya

Tretyakova

2007

Theor Exp Chem

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A synthesis is reported for a new pyrazinoporphyrazine complex containing eight styryl fragments on the periphery of the macrocycle, namely, zinc tetrakis-2, 3-{5,6-bis[(E)-2-(4-methylphenyl)vinyl]pyrazino}-porphyrazine. The introduction of styryl substituents into the macrocycle leads to a significant bathochromic shift of the Q-band in the electronic absorption spectrum and to an increase in the fluorescence quantum yield.The unique properties of porphyrins, phthalocyanines, and their aza analogs have been studied over recent decades. These compounds have found use in many areas of science and technology: from engineering (catalysis, light-conducting materials, etc.) to medicine (photodynamic therapy) [1]. Zinc(II) phthalocyanine complexes display photosensitizing properties [2-4] but their tendency to aggregate in solution significantly reduces their photosensitizing capacity [2,5]. The introduction of various substituents in the periphery of the macrocycle has a significant effect on the properties of the phthalocyanine system [6,7]. On the other hand, porphyrazines, which, similar to phthalocyanines, are derivatives of the tetraazaporphyrin skeleton, have been studied much less extensively although they possess no less interesting spectral and photophysical properties [8,9]. Pyrazine dyes, which have interesting spectral and optical properties, have found use in emitters for electroluminescent devices, fluorescent materials, and materials for the transformation and storage of solar energy [10,11].In the present work, we synthesized new macrocyclic porphyrazine compounds, in which styryl fragments have been introduced onto the periphery of the macrocycle, and studied the spectral and luminescence properties of these compounds in nonaqueous solutions. EXPERIMENTALThe IR spectra were taken at 4000-200 cm -1 on a Specord M-80 spectrophotometer for KBr pellets. The PMR spectra were taken on a Varian spectrometer at 300 MHz for solutions in DMSO-d 6 and CDCl 3 using TMS as the internal standard. The electronic absorption spectra were taken on a Specord M-40 spectrophotometer in quartz cells, l = 10 mm, c = 10 -6 -10 -5 mol/L with dimethylsulfoxide (DMSO), pyridine (Py), dimethylformamide (DMF), tetrahydrofuran (THF), dichloromethane, benzene, or 1,2,4-trichlorobenzene (TCB) as the solvent.0040-5760/07/4302-0125

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supporting

confidence: 67%

Effect of styryl substituents introduced into the periphery of pyrazinoporphyrazine macrocycle on the spectral and luminescence properties of complexes

Tomachinskaya

Tretyakova

2007

Theor Exp Chem

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“…This is different from the tetra-β-substituted analogues which are usually a mixture of different isomers [28]. Special aggregation properties in solution have been revealed exclusively for these tetra-α-substituted compounds due to the special steric hindrance of the α-substituents [29]. However, the aggregation behavior of this kind of compound at the air-water interface is not yet studied.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional “nano-ring and nano-crystal” morphologies in Langmuir monolayer of phthalocyaninato nickel complexes

Liu

Bian

et al. 2006

Journal of Colloid and Interface Science

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“…The spectra for each of the Zn Pcs were measured in CH 2 Cl 2 ‐EtOH mixtures, and the aggregation properties were monitored as a function of EtOH content. In order to obtain comparable data between the pure CH 2 Cl 2 solutions and those that contained EtOH, it was necessary to add 0.1% pyridine to all solutions to prevent EtOH coordination that can affect the intensity of the Q‐band 32 …”

Section: Resultsmentioning

confidence: 99%

“…Determination of the dimerization constants for the metallated zinc Pcs 4a‐4f and 10 was performed following the same procedure as the unmetallated compounds with CH 2 Cl 2 ‐EtOH mixtures as solvent. Pyridine (0.1%) was added to the solutions of zinc Pcs to prevent the coordination of ethanol to the zinc atom 32 . For all compounds, negligible K d values were determined in solutions containing up to 30% ethanol (Table 2, Fig.…”

Section: Resultsmentioning

confidence: 99%

“…These attempts have been met with ranging degrees of success. McKeown and coworkers, 20–24 Ng and coworkers, 25–28 Kobayashi and coworkers, 29,30 and Kasuga and coworkers 31,32 have studied the placement of bulky groups along the periphery of Pc chromophores or as axial substituents. Four peripheral dendritic substituents, unless coupled with electrostatic repulsion, 25,26,29,30 are ineffective at preventing Pc self‐association, even up to third‐generation dendrimers 20–24 .…”

Section: Introductionmentioning

confidence: 99%

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Solution and Thin‐Film Aggregation Studies of Octasubstituted Dendritic Phthalocyanines

Kernag¹,

McGrath²

2009

Israel Journal of Chemistry

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The synthesis and solution and thin‐film characterization of eight octasubstituted dendritic phthalocyanines (Pcs) and their zinc complexes are reported. The Pc chromophore was substituted in the 2,3,9,10,16,17,23,24‐positions with three generations of benzylaryl ether dendrons with either a benzyl (3a‐3c) or 3,5‐di‐t‐butylbenzyl periphery (3d‐3f). Visible spectra in solution (CH2Cl2‐EtOH mixtures, toluene, THF, dioxane, acetone, and EtOAc) indicated a varying degree of chromophore aggregation that depended on solvent, dendrimer generation, and whether the Pc was metallated. Variable‐concentration visible spectroscopic studies were analyzed using a nonlinear least‐squares fitting procedure giving Kd values. These values further quantitated the observations that the t‐butyl‐substituted den‐drimers 3d‐3f were all less prone to aggregation in solution than the unsubstituted dendrimers 3a‐3c, with a monotonic decrease in Kd across the series 3a → 3b → 3c → 3d → 3e → 3f. Second‐generation t‐butyl‐substituted dendrimer 3f showed little to no aggregation in all solvents studied. Thin‐film studies indicated that the largest members of the two dendrimer groups, third‐generation 3c and second‐generation 3f, were largely monomeric as evidenced by split Q‐bands, similar to that seen in dilute CH2Cl2 solution when deposited via spin‐coating onto glass slides. The metallated zinc Pcs 4a‐4f all exhibited significantly less tendency toward aggregation in both solution and thin‐films than their unmetallated analogues.

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Unusual Absorption Spectra Found for Some Phthalocyaninatozinc(II) Complexes Bearing Dendritic Substituents at α Positions

Abstract: Phthalocyaninatozinc(II) complexes bearing dendritic substituents have been prepared. It was found that their generation number and positions on the phthalocyanine ring caused unusual absorption and emission spectral features.

Cited by 30 publications

References 20 publications

Effect of styryl substituents introduced into the periphery of pyrazinoporphyrazine macrocycle on the spectral and luminescence properties of complexes

Effect of styryl substituents introduced into the periphery of pyrazinoporphyrazine macrocycle on the spectral and luminescence properties of complexes

Two-dimensional “nano-ring and nano-crystal” morphologies in Langmuir monolayer of phthalocyaninato nickel complexes

Solution and Thin‐Film Aggregation Studies of Octasubstituted Dendritic Phthalocyanines

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