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Rectangular-shaped expanded phthalocyanines with two central metal atoms
Osamu Matsushita1, Valentina M Derkacheva, Atsuya Muranaka
1Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Journal of the American Chemical Society
|February 10, 2012
Summary
Synthesized novel expanded phthalocyanines with two central metal ions (Mo or W) exhibit a unique 22-π-electron conjugation system, satisfying aromaticity rules. These advanced materials show electronic absorption bands extending into the near-infrared region.
Area of Science:
- Inorganic Chemistry
- Materials Science
- Supramolecular Chemistry
Background:
- Phthalocyanines (Pcs) are macrocyclic compounds with diverse applications.
- Expanding the Pc core can tune electronic and optical properties.
- Synthesis of novel Pc congeners is crucial for developing advanced materials.
Purpose of the Study:
- To synthesize and characterize novel ring-expanded phthalocyanine (Pc) congeners.
- To investigate the structural, electronic, and optical properties of these new Pc systems.
- To explore the aromaticity and conjugation within the expanded Pc framework.
Main Methods:
- Synthesis of expanded Pc congeners using urea.
- Characterization via electrochemistry, mass spectrometry (MS), IR, electron paramagnetic resonance (EPR), NMR, electronic absorption, and magnetic circular dichroism (MCD) spectroscopies.
- X-ray diffraction analysis for structural determination.
Main Results:
- Successful synthesis of expanded Pc congeners with Mo or W central metal ions.
- X-ray structures reveal rectangular C(2v) symmetry and specific coordination of central metal atoms.
- Electronic absorption bands observed in the 1200-1500 nm region, explained by Gouterman's four-orbital theory.
- Evidence for a heteroaromatic 22-π-electron conjugation system, satisfying Hückel's rule.
Conclusions:
- The synthesized ring-expanded Pcs possess a stable heteroaromatic 22-π-electron system.
- These findings contribute to understanding structure-property relationships in advanced phthalocyanine systems.
- The novel Pc congeners hold potential for applications in materials science and electronics.
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