Using carboxyl functionalized porphyrin and phthalocyanine as building blocks and alkane derivatives as coadsorbates, two-dimensional hydrogen-bonded networks were formed on graphite surface and observed by scanning tunneling microscopy. The configuration of the hydrogen bonding in the 2-D structure of 5,10,-15,20-tetrakis (4-carboxylphenyl)-21H,23H-porphyrin (TCPP) is found to be different from that in the 3-D structure in bulk crystal. The difference of these structures from that expected from the bulk crystal is attributed to the effect of minimization of surface free energy in the 2-D system, which leads to close packing symmetry of molecules on the substrate.

It is demonstrated in this paper, using alkyl-substituted phthalocyanine as an example of functionalized phthalocyanines, the modular assembling behavior was observed in the formation of single molecular array structures. The driving force is considered to be van der Waals interaction. This study also suggests the possibility of further investigation on the assembling behavior of general types of phthalocyanine as well as other planar molecules.

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Using scanning tunnelling microscopy (STM) and x-ray diffraction (XRD), the assembling behaviour of substituted phthalocyanine and porphyrin on both hydrophobic and hydrophilic surfaces was investigated. Copper (II) 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (denoted as CuPcOC8) and 21,23-dihydro-5,10,15,20-tetrakis[4-(tetradecyloxy)phenyl]porphyrin (TTPP) molecules adsorb stably on a highly oriented pyrolytic graphite (HOPG) surface, yielding high-resolution STM images. The results illustrate that alkyl molecular anchors can be used as a generalized approach for immobilization of organic molecules on hydrophobic surfaces. The XRD results show that on a hydrophilic substrate CuPcOC8 and TTPP form completely different assembled structures from those on a HOPG surface, which indicates that the polarity of the substrate has substantial effects on the assembling behaviour of organic molecules.

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Epitaxial thin films of PrBa 2 (Cu 0.8 Al 0.2) 3 O 7 have been vacuum deposited by rf sputtering on the LaAlO 3 substrates. Though electrically much more resistive, these Al-substituted films are all of orthorhombic structure and epitaxial quality on various oxide substrates, much like YBa 2 Cu 3 O 7 and PrBa 2 Cu 3 O 7 grown under similar conditions. The samples appeared to be shiny and dark as observed with the naked eye, but their electrical resistivity, (T), ranged from ϳ1 ⍀ cm at room temperature to about six orders of magnitude higher at Tϳ30 K. From the (T) functional for both the target and the films, which, by and large, follows Mott's T Ϫ1/4 law with their own relevant material constants, we believe that the mechanism of electrical conduction was mainly through variable range hopping. This suggests that the substitution of Al has caused extensive localization of charge carriers. The localization radius is ϳ0.2 nm while the hopping distance is ϳ3-9 nm.