Metalloporphyrin Assemblies on Pyridine-Functionalized Titanium Dioxide

Abstract

Porphyrin adsorption on TiO2 nanoparticles has been achieved for multiple porphyrins, and in mixed porphyrin assemblies, via axial ligation to surface-bound pyridine anchored by either para carboxylic or phosphonic functionalizations. Homogenous assemblies were prepared and characterized, while mixed metalloporphyrin assemblies were demonstrated by controlling the concentration ratios of respective porphyrins in the modifying solution. Evaluation of the assemblies using spectroscopic techniques and electrochemistry confirms high porphyrin retention, while exhibiting their surface bound optical and electrochemical properties. A thorough study is discussed where several metalloporphyrins have been evaluated (Ru(CO)OEP, Ru(CO)TPP, and ZnTPP) for relative comparisons and relationships to pyridyl axial binding strengths. The systematic study evaluates multiple background cases using either H2TPP, TiO2 modification with benzoic acid, or unmodified TiO2 to confirm the high affinity of Ru and Zn porphyrins for surface-anchored pyridyl sites. The simple method of step-by-step coordinative anchoring of porphyrins to TiO2 using small, commercially available molecules is highly adaptable for use in dye-sensitized solar cells (DSSC) where intimate contact between the absorbing dye and the semiconductor is required. DSSC devices with novel mixed porphyrin assemblies were shown to give higher power performance than DSSCs utilizing sensitization with only one type of porphyrin.

Porphyrins as Active Components for Electrochemical and Photoelectrochemical Devices

“…TiO 2 nanoparticles were functionalized with isonicotinic acid and then covered with arrays of the metal porphyrins Ru(CO)OEP, Ru(CO)TPP and ZnTPP. 256 The ligation of the dye was achieved both in a stepwise fashion and through simultaneous metalloporphyrin adsorption, in different ratios. Such multimetalloporphyrin systems showed improved photovoltaic performance with respect to that of DSSC devices composed of only one of the considered porphyrins.…”

Comparative study of the anchorage and the catalytic properties of nanoporous TiO2 films modified with ruthenium (II) and rhenium (I) carbonyl complexes

“…The photovoltaic cells based on titanium dioxide are wellknown for its high-efficiency in dye-sensitized solar cells since Grätzel and co-workers incorporated dinitrogenated ruthenium (II) complexes onto the TiO 2 surface [1][2][3]. TiO 2 surfaces as rutile or anatase-like forms have a skeleton of titanium and oxygen atoms spatially distributed [4,5] providing a high number of Ti-OH groups on the solid surface [6,7], which allows linking of organometallic compounds and organic chains for the preparation of hybrid materials [8][9][10]. On the other hand, the controlled manufacture of dye-sensitized TiO 2 structures at the nanometric scale allows either promote or suppress the recombination of electron and hole pairs upon UV-visible light excitation, conferring to TiO 2 -based materials an increasing interest within renewable energy and environment fields as well as in nanotechnology [1][2][3][4][5]8,9].…”

Thermal behavior and the solvent effects ofρ-Methoxy Tetraphenylporphyrin (TOMPP), Copper Porphyrin (CuTOMPP), and Nitroporphyrin (CuTOMPP-NO2)

“…PDT is also used for destroy unwanted tissues such as tumors [12], new blood vessels [13], and atherosclerotic plaques [14]. An extra stable porphyrin occurs by complexation with transition metal ions explained by the macrocyclic effect [15]. Porphyrins and their derivatives have well-known technological applications.…”