Helical orbitals and circular currents in linear carbon wires

Area of Science:

• Quantum Chemistry
• Molecular Electronics
• Organic Synthesis

Background:

• Disubstituted odd-carbon cumulenes feature near-degenerate helical π-orbitals.
• These molecules are chiral, possessing orbitals of both helicities.
• Splitting these degenerate orbitals is crucial for observable electronic effects.

Purpose of the Study:

• To investigate strategies for splitting helical molecular orbitals in odd-carbon cumulenes.
• To explore the control of electron transport and circular currents using molecular chirality.
• To predict experimental single-molecule conductance behaviors.

Main Methods:

• Utilizing pyramidalized single-faced π-donors, specifically amine substituents.
• Analyzing the electronic structure and helical orbital properties.
• Examining coherent electron transport via Landauer transmission.

Main Results:

• Amine substituents effectively split the helical molecular orbitals.
• Chirality induced by substituents allows systematic control over frontier orbital helicity.
• Two distinct modes of single-molecule conductance are predicted.
• Strong circular currents are observed, controllable by molecular conformation.
• Circular currents exhibit ring-reversal linked to quantum interference.

Conclusions:

• Odd-carbon cumulenes with controlled helical orbitals are promising for molecular electronics.
• Amine substituents offer a viable method for manipulating electronic properties.
• The findings provide a foundation for designing novel molecular wires with tunable transport characteristics.