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Synthesis of π-Ring-Fused Porphyrin(2.1.1.1)s and Their Rh(I) Complexes
Yuting Dong1, Fan Wu2, Tao Zhang1
1School of Chemistry and Chemical Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China.
Inorganic Chemistry
|August 6, 2024
Summary
Researchers synthesized novel, stable expanded porphyrins and their Rh(I) complexes. These molecules exhibit nonaromaticity due to unique chair-shaped conformations, confirmed by various spectroscopic and structural analyses.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Coordination Chemistry
Background:
- Expanded porphyrins are macrocyclic compounds with unique electronic and photophysical properties.
- Understanding the relationship between molecular conformation and aromaticity is crucial in macrocyclic chemistry.
Purpose of the Study:
- To synthesize and characterize novel, stable, and simplest expanded porphyrins, specifically π-ring-fused porphyrin(2.1.1.1)s.
- To investigate the effect of Rh(I) complexation on the molecular conformation and electronic properties of these expanded porphyrins.
- To determine the aromaticity of the synthesized compounds.
Main Methods:
- Synthesis of π-ring-fused porphyrin(2.1.1.1)s and their Rh(I) complexes.
- X-ray crystallography for structural determination.
- Nuclear Magnetic Resonance (NMR) spectroscopy for structural and electronic analysis.
- Nuclear Independent Chemical Shift (NICS) and Anisotropy of Calculated Induced current Density (ACID) calculations to assess aromaticity.
Main Results:
- First-time synthesis of stable and simplest expanded porphyrins (porphyrin(2.1.1.1)s) and their Rh(I) complexes.
- Free base porphyrin(2.1.1.1)s adopt chair-shaped conformations.
- Rh(CO)2 insertion leads to more twisted molecular conformations.
- NMR, X-ray, NICS, and ACID data collectively confirm the nonaromatic nature of these molecules due to their conformations.
- Protonation and Rh(I) coordination result in red-shifted absorptions in the near-infrared (NIR) region.
Conclusions:
- The synthesized porphyrin(2.1.1.1)s and their Rh(I) complexes represent a new class of stable expanded porphyrins.
- The chair-shaped conformations are responsible for the nonaromaticity of these systems.
- Coordination and protonation induce significant changes in electronic properties, leading to NIR absorptions.
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