Two Rings Around One Ball: Stability and Charge Localization of [1 : 1] and [2 : 1] Complex Ions of [10]CPP and...

Area of Science:

• Supramolecular Chemistry
• Mass Spectrometry
• Computational Chemistry

Background:

• Noncovalent interactions are crucial in molecular recognition and self-assembly.
• Cycloparaphenylenes ([n]CPPs) are macrocyclic aromatic compounds with unique structural and electronic properties.
• Fullerenes (C60 and C70) are important carbon allotropes with diverse applications.

Purpose of the Study:

• To investigate the gas-phase chemistry of [10]cycloparaphenylene ([10]CPP) complexes with C60 and C70.
• To characterize the stability, charge distribution, and structural properties of these noncovalent complexes.
• To explore the formation and stability of novel [2:1] complexes.

Main Methods:

• Atmospheric pressure photoionization (APPI) and electrospray ionization (ESI) mass spectrometry.
• Energy-resolved collision-induced dissociation (ER-CID) for stability studies.
• Density Functional Theory (DFT) and molecular dynamics (MD) calculations.
• Isothermal titration calorimetry (ITC) for thermodynamic analysis.

Main Results:

• [1:1] [10]CPP⊃C60 and [10]CPP⊃C70 complexes observed as radical cations and anions.
• C70 complexes are more stable than C60 analogues.
• Radical cations are more stable than radical anions.
• Charge distribution differs between cationic ([10]CPP) and anionic (fullerene) complexes.
• Novel [2:1] ([10]CPP2⊃C60/70) complexes observed in gas phase and solution.
• [2:1] C70 complexes are more stable than C60 complexes.
• [2:1] complexes exhibit reduced stability compared to [1:1] complexes.

Conclusions:

• The gas-phase stability and charge distribution of [10]CPP-fullerene complexes are elucidated.
• C70 forms more stable complexes than C60.
• Novel [2:1] complexes offer new avenues for supramolecular assembly.
• Experimental and computational methods provide complementary insights into complex behavior.