SAMs phthalocyanins

Bocian, Lindsey and co-workers studied sandwich complex nanocapacitors comprised of porphyrin and phthalocyanine ligands separated by lanthanide metals [133]. A triple-decker sandwich of phthalocyanine-Eu-phthalocyanine-Eu-porphy-rin, with two phenylethynyl linker wires from the porphyrin, potentially has up to nine accessible oxidation states (—4 to +4). SAMs of monomers, dimers, trimers, and oligomers of this sandwich, anchored at one or both ends by thioacetyl groups, gave charge densities up to 10 10 mol cm-2, electron-transfer rates up to 105 electrons s-1, and charge-dissipation half-lives in the 10-50 s range. 

Figure 5.45 (a) Molecular structures of the thiol-terminated phthalocyanine compounds reported by Russell and co-workers [77]. (b) Schematic of the experimental configuration used for evanescent wave excitation and emission detection at Pc SAMs, including a gas flow-through cell. Reprinted with permission from T. R. E. Simpson, D. J. Revell, M. J. Cook and D. A. Russell, Langmuir, 13, 460 (1997). Copyright (1997) American Chemical Society... 

Li, Z, Lieberman M, Hill W (2001) XPS and SERS study of silicon phthalocyanine mono-layers Umbrella vs octopus design strategies for formation of oriented SAMs. Langmuir 17( 16) 4887—4894... 

Mashazi PN, Ozoemena K I, Maree DM, Nyokong T (2006) Self-assembled monolayers (SAMs) of cobalt tetra carboxylic acid chloride phthalocyanine covalently attached onto a preformed mercaptoethanol SAM A novel method. Electrochim Acta 51(17) 3489—3494... 

Li et al. [47] fabricated SAMs of ruthenium phthalocyanine (RuPc) on a silver substrate precoated with an SAM of 4-mercaptopyridine (PySH) or l,4-bis[2-(4-pyridyl)ethenyl]-benzene (BPENB). SERS spectroscopy was used to explore the structure and orientation of the self-assembled films, and they successfully observed Raman bands due to vibrational modes of the pigment molecules in the composite films in the SERS spectra. 

Ozoemena, K., R Westbroek, and T. Nyokong (2002). Cychc voltammetric studies of octabutylthiophthalocyaninatocobalt(n) and its self-assembled monolayers (SAMs) on gold electrode. J. Porphyrins Phthalocyanines 6, 98-106. 

ITO Chemisorption of small redox-active molecules on ITO can be used to probe changes in electrochemically activity of ITO surface as a function of surface pretreatment [314-316, 326]. The modification of ITO surface with electroactive small molecules such as Fc(COOH)2 and 3-T7VA provides for better wettability of organic layers to the polar ITO surface and enhanced electrical contact between ITO and copper phthalocyanine (CuPc) layers in multilayer excitonic organic EL and PV technologies [316]. Ferrocene terminated SAMs (Fc-SAMs) [326] are one of the most studied redox-active two dimensional aggregates on metal surfaces [630]. 

Fig. 23 Phthalocyanine alkanethiols synthesised by Russell et al. and schematic representation of the possible orientation of the phthalocyanine SAMs on the gold substrate [172-174]...

To investigate the heterogeneous ET rates in phthalocyanine SAMs a series of monomers, dimers, trimers and oligomers of triple-decker eu-... 

Another interesting application is to use phthalocyanines as a hole-injection layer in organic light-emitting diodes (OLEDs). Zhu et al. demonstrated that a SAM of phthalocyanine thiol (HS-Pc) may act as a hole injection material in OLEDs (Fig. 42). The insertion of a SAM of HS-Pc between the Au anode and the hole-transport layers enhances the hole injection, which in-... 

Fig. 1 a Schematic representation of a SAM of a sulfur containing Pc on Au, b attachment of a simple Pc to a preformed SAM, ME (mercaptoethanol), TAClPc (tetraacid chloride phthalocya-nine). Reproduced with permission from Ref. [7], c formation of SAM using single-walled carbon nanombes (SWCNTs) attached to iron phthalocyanine, peripherally tetra-substimted with diethylaminoethane-thiol, adapted from Ref. [8]. The highlighted area represent Au electrode... 

XPS can be used to characterize the modified surfaces [43]. XPS has been used to analyze thin films containing azide groups fi om as early as 1989 [44, 45]. For the SAM formation using aryl- or alkyl-thio (SR) phthalocyanines, the question as to whether the R group remains intact following SAM formation was resolved using XPS, Fig. 10, which showed that some RS bond remains intact [46]. 

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