ToF-SIMS study of selective anchoring of Ru(tpy)2 complexes on zirconium-phosphate functionalized oxide surfaces

Polypyridine-based ruthenium complexes are among the most interesting photoactive molecular systems, in virtue of a number of outstand-ing (photo)physicochemical properties. To exploit such properties in solid-state applications, such as molecular electronics, optoelectronics,and photovoltaics, tailored experimental strategies are needed for the anchoring of such complexes on surfaces. At the same time, thesestrategies need to be investigated and validated through precise monitoring of the surface composition. In this contribution, the authorsreport on the application of time-of-flight secondary ion mass spectrometry (ToF-SIMS) for studying the anchoring onto transparent(semi)conducting fluorine tin-doped oxide of the polypyridinic photoactive RuDT2. This molecule is characterized by an Ru(tpy)2core andtwo free terpyridinic units. The authors’approach involves the use of a surface priming strategy based on the chemistry of zirconium phos-phates and phosphonates (ZP-priming) to provide a platform for direct anchoring of RuDT2molecules at the oxide surface. Onto patternedZP-fluorine-doped tin oxide (FTO), the authors report selective anchoring of RuDT2only onto ZP domains, while no binding occurs ontobare FTO areas. The latter were shown to remain available for further functionalization using functional molecules containing phosphonicmoieties, and in the authors’case, a phosphonic derivative of rhodamine B (RhB-P) was used. ToF-SIMS imaging was intensively used tomonitor each reaction step and confirm the successful laterally resolved and selective adsorption of RuDT2and RhB-P onto ZP and bareFTO domains, respectively.