Linking molecules to metal surfaces with covalent bonds

Area of Science:

• Molecular electronics
• Surface chemistry
• Organic chemistry

Background:

• Covalent linkage between organic molecules and metal electrodes is crucial for developing stable and conductive molecular junctions.
• Understanding the surface chemistry and reaction mechanisms at the molecular and atomic level is essential for advancing molecular electronics.
• Chemical reactions provide versatile tools for designing molecular circuitry and probing interfacial properties.

Purpose of the Study:

• To review and showcase various methods for forming covalent organic/metal contacts.
• To highlight strategies for creating robust and highly-conducting molecular junctions.
• To discuss the insights gained into surface chemistry and reaction mechanisms through these covalent bonding approaches.

Main Methods:

• Transmetalation reactions using organostannanes and boronic acids.
• Electrochemical redox approaches involving diazonium terminal groups, amines, and imine radicals.
• Novel strategies including C(sp2)-C(sp2) bond cleavage in cycloparaphenylenes and established thiol/acetylene chemistry.

Main Results:

• Formation of C-Au and N-Au bonds with gold electrodes via transmetalation and electrochemical methods.
• Successful C-Au bond formation through C(sp2)-C(sp2) bond cleavage in cycloparaphenylenes.
• Established methods for S-Au, S-Ag, C-Au, and C-Ag bond formation using thiol and acetylene groups.

Conclusions:

• Covalent organic/metal linkages are key to robust molecular junctions.
• Diverse chemical and electrochemical strategies enable precise control over interfacial bond formation.
• These methods offer significant potential for molecular electronics and detailed surface chemistry investigations.