Infrared and nuclear magnetic resonance studies of some tin phthalocyanines and hemiporphyrazines

Sutton, L. E.; Kenney, Malcolm E.

doi:10.1021/ic50056a023

Cited by 32 publications

(10 citation statements)

References 3 publications

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“…When coordinated to metals, the two nitrogen atoms from the isoindole moieties bind more tightly to the metal while the pyridine units retain much of their original character. 22,23 Previous studies have focused on the synthesis of metallohemiporphyrazines (HpMX n ) where the Hp ligand carries a −2o r−1 charge in complexes containing Pb(II), 1…”

Section: Synthesis and Structures Unlike Porphyrins Andmentioning

confidence: 99%

Excitonic Luminescence of Hemiporphyrazines

et al. 2012

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Metal-free hemiporphyrazine (HpH2) is a notoriously insoluble material possessing interesting photophysical properties. Here we report the synthesis, structure, and photophysical properties of an octahedral zinc trans-ditriflate hemiporphyrazine complex "HpH2Zn(OTf)2" that contains a neutral hemiporphyrazine ligand. The photophysical properties of hemiporphyrazine are largely unaffected by introduction of zinc(II) triflate, but a dramatic increase in solubility is observed. HpH2Zn(OTf)2 therefore provides a convenient model system to evaluate the impact of aggregation on the photophysical properties of hemiporphyrazine. Soluble aggregates and crystalline materials containing planar hemiporphyrazines exhibit relatively strong absorbance of visible light (450-600 nm) and red luminescence (600-700 nm). Hemiporphyrazine monohydrate (HpH2·H2O), in contrast, has a nonplanar "saddleshaped" conformation that exhibits very little absorbance of visible light in solution or in the solid state. Upon photoexcitation at 380 nm, HpH2Zn(OTf)2 and HpH2 exhibit multiwavelength emissions centered at 450 and 650 nm. Emissions at 450 nm are highly anisotropic, while emissions at 650 nm are fully depolarized with respect to a plane-polarized excitation source. Taken together, our results suggest that excitonic coupling of aggregated and crystalline hemiporphyrazines results in increased absorbance and emission of visible light from S0 S1 transitions that are usually symmetry forbidden in isolated species. In contrast to previously proposed theories involving excited-state intramolecular proton transfer, we propose that the multiple-wavelength luminescent emissions of HpH2Zn(OTf)2 and HpH2 are due to emissive S1 and S2 states in aggregated and crystalline hemiporphyrazines. These results may provide a better understanding of the nonlinear optical properties of these materials in solution and in the solid state.

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Section: Synthesis and Structures Unlike Porphyrins Andmentioning

confidence: 99%

Excitonic Luminescence of Hemiporphyrazines

et al. 2012

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“…Early NMR and IR studies on germanium and tin hemiporphyrazines proved the low degree of π-electron delocalization of the Hp ring and the high asymmetry of its ligand core, i.e., the isoindole nitrogens bound to the metal much more strongly than the pyridine ones. , As a consequence of this, metallohemiporphyrazinates, unlike phthalocyaninates, show an unusual tendency toward axial ligation (even with metals of d 8 −d 10 configuration like nickel, copper, or zinc, for which stable four-coordinated complexes would be expected) giving rise to 1:1 or 1:2 adducts with H 2 O, hydrohalic acids and pyridine . Thus, reaction of the metallic acetates with the free base 2 in boiling DMF yields the anhydrous (Ni 2+ , Cu 2+ ) or the monohydrated (Co 2+ , Zn 2+ ) derivatives, whereas reaction of the corresponding metallic halides affords MHp(HX), for Zn 2+ , or MHp(HX) 2 , for Ni 2+ , Co 2+ , and Cu 2+ .…”

Section: Synthesismentioning

confidence: 99%

“…The reaction of metallomacrocycles with bidentate ligands to give “shish-kebab” polymers has been widely applied in the case of the related phthalocyanines. ,3d, Polymers consisting of stacked MHp units (M = Si, Ge, Sn) and O 2- as bridging ligand are generally prepared by starting from the monomeric dichlorocomplexes MHpCl 2 . Alkaline hydrolysis of these compounds leads to the corresponding dihydroxides MHp(OH) 2 , which afford the polymers [MHpO] n upon thermal treatment. ,, Reaction of the mentioned dihydroxy complexes with bifunctional alcohols or bisphenols also leads to “shish-kebab” polymers . The related [FeHpO] n ( 5 ) is accessible by treating H 2 Hp with iron(II) acetate in hot nitrobenzene, whereby the solvent acts as oxidizing agent 18d…”

Section: Synthesismentioning

confidence: 99%

Hemiporphyrazines as Targets for the Preparation of Molecular Materials: Synthesis and Physical Properties

Fernández‐Lázaro¹,

Torres²,

Hauschel³

et al. 1998

Chem. Rev.

143

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“…-d[Br03-]/df = [ka2/4fcc][Br03-]2m2 (7) A direct implication is that at a given temperature and hydrogen ion concentration, all reducing agents subject to the considerable restraints outlined above should yield identical second-order rate parameters. This feature has in fact been observed with Np(V) and large excesses of Ce(III) or Mn(II) in 3 M sulfuric acid.…”

Section: Discussionmentioning

confidence: 99%

Kinetic study of the reduction of bromate ion by neptunium(V) in perchlorate solution

Knight¹,

Thompson²

1973

Inorg. Chem.

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The empirical form of the rate law for the reaction 4Np(V) + Br(V) = 4Np(VI) + Br(I) at 25°in perchloric acid-lithium perchlorate solutions is -d[Br(V)] /dt = k0 [Br(V)]2 [H+]1 •51. This expression adequately correlates the kinetic data from 10 to 90% reaction over a large range of initial reactant concentrations. At least one induction period is observed. A complex reaction scheme is proposed in which the rate parameter is identified as [fca2[H+]2/4&Co]/[l + (&Cl/fcCo)[H*] ], where k& is the rate constant for the reaction between brómate ion and a bromous acid intermediate, and kC(¡ and kc are rate constants of parallel paths for the disproportionation of the same intermediate. Comparisons with other systems in which brómate ion is reduced by weak one-electron reductants are made.H202 ,17 and Br~,7 however, the sole fate of the bromous acid appears to be reduction to hypobromous acid.Clearly, the demonstration of the validity of the full reaction scheme (a)-(c) proposed for these intriguing systems will require considerable additional investigation. The present study, because of its apparent simplicity, will hopefully provide a foundation on which further results can be added.

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Infrared and nuclear magnetic resonance studies of some tin phthalocyanines and hemiporphyrazines

Cited by 32 publications

References 3 publications

Excitonic Luminescence of Hemiporphyrazines

Excitonic Luminescence of Hemiporphyrazines

Hemiporphyrazines as Targets for the Preparation of Molecular Materials: Synthesis and Physical Properties

Kinetic study of the reduction of bromate ion by neptunium(V) in perchlorate solution

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