Selective deposition of rod-like phthalocyanine aggregates on Au surfaces patterned with a combination of microcontact printing and electropolymerization

Patterned thin films of a unique phthalocyanine (Pc), (2,3,9,10,16,17,23,24-oktakis((2-benzyloxy)ethoxy)phthalocyaninato) copper (1), are created by means of capillary flow of chloroform solutions into micrometer-dimension hydrophobic/hydrophilic channels. These channels are created by a combination of microcontact printing of octadecylmercaptan (C₁₈-SH) layers on gold, creating a hydrophobic channel bottom, and oxidative electropolymerization of m-aminophenol (at pH 4), creating hydrophilic channel walls (microcontact printing/electropolymerization, μCP-EP). The polyphenoxide channel walls grow perpendicular to the substrate plane, with excellent retention of structure to thicknesses (ca. 30 nm) far exceeding the height of the C₁₈-self-assembled monolayer (SAM). Doping of the C₁₈-SAM layers with small percentages of 1-phenyldodecane provides for efficient wetting of the channel bottoms with solutions of 1, consistent with recent studies, which have shown the need for phenyl-termination of substrates surfaces to create coherent rod-like aggregate structures. These optimized channels provide for excellent capillary flow conditions for chloroform solutions of 1, yielding 10 μm width Pc films with thicknesses exceeding the height of the polyphenoxide channel walls by up to 10×. We also present evidence for formation of birefringent (ordered) material near the hydrophilic walls.