skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Synthesis, Spectroscopic Properties, and Metalation of 3-Alkoxybenziporphyrins
A series of 5-alkoxy-1,3-benzenedicarbaldehydes and related dimers were prepared in three steps from dimethyl 5-hydroxyisophthalate. Acid catalyzed condensation of the dialdehydes with a tripyrrane dicarboxylic acid, followed by oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, afforded good yields of 3-alkoxybenziporphyrins, although dimeric tetraaldehydes failed to give isolatable porphyrinoid products. Proton NMR spectroscopy gave no indication of an aromatic ring current, but addition of trifluoroacetic acid resulted in the formation of dications that exhibited weakly diatropic characteristics. Spectroscopic titration with TFA demonstrated that stepwise protonation took place, generating monocationic and dicationic species. 3-Alkoxybenziporphyrins reacted with nickel(II) or palladium(II) acetate to give the related nickel(II) or palladium(II) complexes. These stable organometallic derivatives showed increased diatropic properties that were most pronounced for the palladium(II) complexes. These unique porphyrinoids provide further insights into the properties of benziporphyrins.  more » « less
Award ID(s):
2247214
PAR ID:
10527186
Author(s) / Creator(s):
;
Publisher / Repository:
MDPI
Date Published:
Journal Name:
Molecules
Volume:
29
Issue:
8
ISSN:
1420-3049
Page Range / eLocation ID:
1903
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, The Journal of Organic Chemistry)
    cid catalyzed condensation of N-alkyltripyrranes with trialdehydes derived from 1,3-cyclopentadiene or methyl-1,3-cyclopentadiene, followed by oxidation with aqueous ferric chloride solutions, gave 23-alkyl-21- carbaporphyrin-2-carbaldehydes in 22−27% yield together with weakly aromatic oxycarbaporphyrins. The carbaporphyrins reacted with palladium(II) acetate or nickel(II) acetate to give organometallic complexes but in both cases alkyl group migration took place to generate 21-alkyl derivatives. Although this type of reactivity had been observed previously for palladium complexes, this is the first time the phenomenon has been seen in nickel(II) carbaporphyrins. Reactions with nickel(II) acetate in refluxing DMF for longer time periods primarily led to decomposition but unusual byproducts were identified. These could be obtained in higher yields by reacting the carbaporphyrin aldehydes with 5 equiv of (bis(trifluoroacetoxy)iodo)benzene in the presence of grade 3 alumina. Decarbonylation and oxidation generate a trioxocyclopentane moiety that is embedded in the porphyrinoid macrocycle. The new system has strongly aromatic properties that are evident from the proton NMR spectra, nucleus independent chemical shift (NICS) calculations and anisotropy of induced ring current plots. 
    more » « less
  2. ; (, Organic & Biomolecular Chemistry)
    null (Ed.)
    Neo-confused porphyrins (neo-CPs), porphyrin isomers with a 1,3-connected pyrrolic subunit, are aromatic structures with a CNNN coordination core. Previously, examples of neo-CPs with fused benzo units or electron-withdrawing ester substituents have been described. In this paper, two new examples of neo-CPs are reported that lack a fused aromatic unit or an ester moiety, but instead have a bromo or phenyl substituent on the neo-confused ring. Acid-catalyzed condensation of suitably substituted 1,2′-dipyrrylmethane dialdehydes with a 2,2′-dipyrrylmethane, followed by oxidation with aqueous ferric chloride solutions, afforded the neo-CPs in 40–45% yield. These porphyrin analogues had slightly reduced diatropic ring currents and slowly decomposed in solution. The related palladium( ii ) and nickel( ii ) complexes proved to be very unstable, even though the diatropicity of the macrocycle was enhanced. This study shows that stabilizing substituents are necessary for investigations into this class of porphyrinoids. Attempts to prepare imidazole versions of neo-CPs were unsuccessful. 
    more » « less
  3. ; (, Organometallics)
    Isolable sulfonium-ylide stabilized palladium carbene complexes were synthesized through palladium(II)-induced cyclization of 1,2-alkynylarylsulfanes. X-ray crystallographic analysis characterized the maintenance of a palladium +2 oxidation state, with carbene-carbon–palladium bond lengths of 1.95 Å, indicating partial double bond character. These endocyclic sulfonium ylide carbenes represent the first characterized and/or isolable examples of this ligand class; such groups were previously proposed as reaction intermediates during cyclization–carbonylation reactions. A variety of palladium(II) complexes bearing sulfonium ylide carbene ligands, with differing substituents, were synthesized and the structure and stability of these complexes in solution were analyzed by 1H and 13C NMR spectroscopy, revealing reversibility and a stability dependence on substituents. The chirality of the sulfur heteroatom and the overall properties these ligands provide a potential electronic and steric alternative to existing carbene ligands, which could facilitate the future development of complementary metal-based reactivity. 
    more » « less
  4. ; ; ; ; (, Journal of Porphyrins and Phthalocyanines)
    The proton NMR spectra for free base 22-hydroxybenziporphyrins show that they favor antiaromatic keto-tautomers (22-oxybenziporphyrins) in solution. Protonation affords weakly diatropic dications, while metalation produces nonaromatic nickel(II), copper(II) and palladium(II) complexes. 
    more » « less
  5. ; ; ; ; ; ; ; (, Chemistry – A European Journal)
    Abstract The preparation of radicals with intense and redox‐switchable absorption beyond 1000 nm is a long‐standing challenge in the chemistry of functional dyes. Here we report the preparation of a series of unprecedented stable neutral nickel(II) and copper(II) complexes of “Manitoba dipyrromethenes” (MB‐DIPYs) in which the organic chromophore is present in the radical‐anion state. The new stable radicals have an intense absorption atλmax∼1300 nm and can be either oxidized to regular [MII(MB‐DIPY)]+(M=Cu or Ni) or reduced to [MII(MB‐DIPY)]−compounds. The radical nature of the stable [MII(MB‐DIPY)] complexes was confirmed by EPR spectroscopy with additional insight into their electronic structure obtained by UV‐Vis spectroscopy, electro‐ and spectroelectrochemistry, magnetic measurements, and X‐ray crystallography. The electronic structures and spectroscopic properties of the radical‐based chromophores were also probed by density functional theory (DFT) and time‐dependent DFT (TDDFT) calculations. These nickel(II) and copper(II) complexes represent the first stable radical compounds with a MB‐DIPY ligand. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email