Controlling the Transport Properties of Gold Nanotubule Membranes Using Chemisorbed Thiols

We have developed a new class of synthetic membranes that consist of a porous polymeric support that contains an ensemble of gold nanotubules that span the complete thickness of the support membrane. The support is a commercially available microporous polycarbonate filter with cylindrical nanoscopic pores. The gold nanotubules are prepared via electroless deposition of Au onto the pore walls; that is, the pores act as templates for the nanotubules. We have shown that by controlling the Au deposition time, Au nanotubules that have effective inside diameters of molecular dimensions (<1 nm) can be prepared. Hence, these membranes are a new class of molecular sieves. In addition, because the tubules are composed of gold, well-known Au-thiol chemistry can be used to change the chemical environment within the tubules. This paper reviews recent research on using chemisorbed thiols to control the transport properties of Au nanotubule membranes. The use of both electrical neutral thiols to introduce chemical-transport selectivity and charged thiols to introduce ion-transport selectivity is reviewed.