Roman Münnich

Improving the photocatalytic activity of air-cleaning nanomaterials by synthetic variation of binding-site geometries in Porphyrazine/TiO₂-Hybrids

Organic/inorganic hybrid materials derived from porphyrazines (Pz) and oxidic semiconductors like TiO₂ are of interest for a broad range of applications, among them solar energy conversion¹ and photocatalysis.² The functionality and efficiency of these hybrid materials are intimately coupled to the relative binding geometry between Pz and the oxide surface and hence a definite control over the parameters governing the interaction is of general interest. It has already been shown that peripheral polyphenylation of dibenzoquinoxalino-Pz is a conceivable way for shielding the photophysically active core from environmental impact.³ We are now developing this concept further and introduce anchoring groups to oxidic nanoparticles in a regiospecific manner around the dendritic polyphenyl shell embedding the Pz (Fig. 1).

With regiochemical variations of the anchoring group positions we will be able to control the relative binding angle and the distance between the Pz core and the oxide surface (Fig. 2).

Particulary in the area of photocatalysis, the pronounced photosensitizing ability of the Pz offers exciting possibilities. In hybrid materials of Pz and TiO₂ the photocatalytic activity (i.e. the photoinduced generation of active oxygen species) of the inorganic component in the UV can be complemented by the visible-light induced singlet oxygen (¹O₂) generation of the organic dye.

The development of such hybrid materials will demonstrate how the control of relative binding site geometries can influence the photocatalytic activity and the suitability of these hybrids for a desired „dual pathway photocatalysis“ (Fig. 3).

[1] Md. K. Nazeeruddin, R. Humphry-Baker, M. Grätzel, D. Wöhrle, G. Schnurpfeil, G. Schneider,
      A. Hirth, N. Trombach, J. Porphyrins Phthalocyanines1999, 3, 230.
[2] A. E. H. Machado, M. D. França, V. Velani, G. A. Magnino, H. M. M. Velani, F. S. Freitas,
      P. S. Müller, C. Sattler, M. Schmücker, Int. J. Photoenergy2008, 482373.
[3] P. Löser, A. Winzenburg, R. Faust, Chem. Commun.2013, 49, 9413.
 

Deep-cavity subporphyrazines with extended π-perimeters, R. Münnich, P. Löser, A. Winzenburg, R. Faust, J. Porphyrins Phthalocyanines 2016, 8, 11, 1277-1283.
DOI: 10.1142/S1088424616501078
 

R. Münnich, A. Winzenburg, R. Faust
“Controlling Binding Site Geometries to Oxidic Nanoparticles with Polyphenyl-Substituted Porphyrazines“, 8th International Conference on Porphyrins and Phthalocyanines (ICPP-8), Istanbul, Juni 22-27, 2014.

R. Münnich, A. Winzenburg, R. Faust
“Controlling Binding Site Geometries to Oxidic Nanoparticles with Polyphenyl-Substituted Porphyrazines“, ORCHEM 2014, 19th Lecture Conference Liebig Vereinigung für Organische Chemie, Weimar, September 15-17, 2014.

 R. Münnich, A. Winzenburg, R. Faust
“Controlling Binding Site Geometries to Oxidic Nanoparticles with Polyphenyl-Substituted Porphyrazines“, CINSaT Herbstkolloquium, Kassel, Oktober 15, 2014.

 R. Münnich, R. Faust
“Influence of Binding Site Geometries on Nanoparticle Size in Porphyrazine/TiO2-Hybrids“, CINSaT Frühjahrskolloquium, Friedrichroda, Februar 25-26, 2016.

R. Münnich, R. Faust
“Subporphyrazine/TiO₂-Hybrids for Dual Pathway Photocatalysis“, 9th International Conference on Porphyrins and Phthalocyanines (ICPP-9), Nanjing China, Juli 03-08, 2016.

R. Münnich, R. Faust
“Subporphyrazine/TiO₂-Hybrids for Dual Pathway Photocatalysis“, CINSaT Herbstkolloquium, Kassel, Oktober 19, 2016.