Selenolate as an alternative to thiolate as the anchoring group in monomolecular self-assembly on gold and silver surfaces

Selenolate is frequently considered an alternative to thiolate to serve as an anchoring group (AG) for the formation of self-assembled monolayers (SAMs) on coinage metal substrates. There is, however, still a lot of controversy about the advantages and disadvantages of this AG. Here, we review the current state of the field, considering the basic types of selenolate SAMs on Au(111) and Ag(111) substrates. Recent experimental data, discussed in the review, allowed to clarify key questions such as the strength of the selenolate–Au(Ag) bond, the thermal stability of selenolate SAMs, and their charge transport properties. In addition, further issues, such as the odd–even effects, the strengths of consecutive bonds along the molecular framework, the chemical and electrochemical stability of selenolate SAMs, and their reaction toward electron irradiation, are discussed. It is concluded that, in most cases, selenolate SAMs can be used on the same basis as their thiolate counterparts, with clear advantages in terms of molecular order for aromatic and hybrid monolayers on Au(111) and much higher stability toward photooxidation in molecular junctions. These and other properties are prerequisites for the broad application of selenolate SAMs in molecular and organic electronics and other fields involving surface engineering of coinage metal substrates.