Ternary Porphyrinato Hf^IV and Zr^IV Polyoxometalate Complexes

Abstract

We report a facile, high yield synthesis and characterization of discrete, ternary porphyrin-metalpolyoxometalate (Por-M-POM) complexes where a group (IV) transition metal ion is bound both to the porphyrin core and to the lacunary site of a Keggin POM, PW 11 O 39 −7 . The remarkably robust complexes exploit the fact that Hf(IV) and Zr(IV) are 7-8 coordinate and reside outside the plane of the porphyrin macrocycle, thus enabling the simultaneous coordination to mesotetraphenylporphyrin (TPP) or meso-tetra(4-pyridyl)porphyrin (TPyP) and to the defect site in the Keggin framework. This architecture couples the photonic properties of the porphyrin to the POM because the metal ion is incorporated into both frameworks. Thus the ternary complexes can serve as a basis for the characterization of Hf(IV) and Zr(IV) porphyrins bound to oxide surfaces via the group (IV) metal ions. The Hf(Por) and Zr(Por) bind strongly to TiO 2 nanoparticles and indium tin oxide (ITO) surfaces, but significantly less binds to crystalline SiO 2 or TiO 2 surfaces. Together, the strong binding of the metalloporphyrins to the POM, nanoparticles, and the ITO surfaces, and paucity of binding to crystalline surfaces, suggests that the 3-4 open coordination sites on the Hf(Por) and Zr(Por) are predominantly bound at surface defect sites.

Hafnium (IV) and zirconium (IV) porphyrinoid diacetate complexes as new dyes for solar cells

“…[4,5]. For example, after stirring the slurry of 30 mg Ti02 nanoparticles (5 nm, anatase nanocrystalas) with a 0.…”

“…and the corresponding derivatives with two cr, S04 -and HP04 -2 were already synthesized in our lab according to literature methods. [4] Control molecules TPP, ZnTPP, were purchased from Frontier Scientific.…”

“…Since, POMs are regarded as good models for defect sites on oxide surfaces, structure of Por-M POM ternary complex leads to idea that binding of these Por derivatives to the oxide is possible. The anchoring mode of the sensitizer to the oxide (tetrapyridylporphyrin)-Hf(IV) (PW11039) ternary complex, [4] and bottom: tetra tert-butylphenyporphryin Hf(IV) dimer bridged by two sulfate ions. [5] semiconductor plays a very important role in trapping and injecting electrons into the conduction band of the oxide material.…”

Synthesis and characterization of Lindqvist-type polyoxometalate–porphyrin copolymers

“…Some POM-porphyrin coordination complexes were also reported [14][15][16][17]. Peng reported the synthesis of an Fe(terpyridine) 2 -Lindqvist molybdate coordination polymer [18].…”

A copper–cyclen coordination complex associated with a polyoxometalate anion: Synthesis, crystal structure and electrochemistry of [Cu(cyclen)(MeCN)][W6O19]

“…Structural, topological and electronic diversities are the key aspects of the chemistry associated with POM anions [15][16][17][18]. Inorganic solids, based on POM counter anions and supramolecular and/or coordination complexes of crown ethers [19][20][21][22][23][24][25][26][27][28] or porphyrins [29] as cations, have drawn considerable interest in contemporary research as new functional materials, in addition to the separation aspect. However, no structurally characterized coordination complexes of the aza-crown ethers associated with a POM counter anion have been demonstrated yet in literature [30].…”