Monolayer and aggregate formation of a modified phthalocyanine on mica determined by a delicate balance of surface interactions

► Phthalocyanine modified with ether tails forms a monolayer on mica substrates. ► Surface X-ray diffraction and AFM show an ordered layer on a dried mica surface. ► The monolayer orders on K+ and Na+ terminated but not on H3O+ covered mica faces. ► In contact with water the molecules do not order, but aggregate at the surface.