Formation and Photocatalytic Properties of Nanocomposite Films Containing Both Tetracobalt Dawson-Derived Sandwich Polyanions and Tetracationic Porphyrins

Abstract

Films based on electrostatic interactions between tetracationic zinc porphyrins, ZnOEP(py)(4)(4+) or ZnTMePyP(4+), and the tetracobalt Dawson-derived sandwich polyanion αββα-[Co(4)(H(2)O)(2)(P(2)W(15)O(56))(2)](16-) are formed by the so-called layer-by-layer method. These films have been characterized by UV-visible absorption spectroscopy, atomic force microscopy and electrochemistry. The composition of the film was measured by X-ray photoelectron spectrum (XPS). The XPS data confirm the presence of the expected elements. The photocatalytic properties of these films have been also studied for the reduction of silver and gold ions. Indeed, in these systems, porphyrins can be excited by visible light and then play the role of photosensitizers able to give electrons to POM known to be good catalysts. Silver nanowires and gold nanosheets have been obtained.

Unoccupied states in Cu and Zn octaethyl-porphyrin and phthalocyanine

“…Cu and Zn phthalocyanines (Pc) have been used as a light absorber or emitter in a variety of opto-electronic devices, such as organic light emitting diodes and dye-sensitized solar cells, [1][2][3][4][5] as well as photocatalytic devices. 6 They also are part of molecular donor-acceptor assemblies that serve as prototype structures for real solar cells. 5,[7][8][9][10] Therefore there has been a long-standing interest in their energy level structure using both theory and various spectroscopic methods.…”

Gadolinium polytungstate nanoclusters: a new theranostic with ultrasmall size and versatile properties for dual-modal MR/CT imaging and photothermal therapy/radiotherapy of cancer

“…Many heteroatoms can be incorporated into a POM framework, including Gd, Mn and Cu, to impart various properties. [36][37][38][39] These nanoclusters can then be used in biomedical, [40][41][42][43][44][45][46][47][48][49] analytical, [50][51][52][53][54] magnetic, [55][56][57][58][59][60] optical 61,62 and catalytic applications. [63][64][65][66][67] For example, paramagnetic rare earth elements such as Gd 3+ can be easily incorporated into polytungstate (a type of POM) structures to form new molecules.…”

Synthesis and characterization of Lindqvist-type polyoxometalate–porphyrin copolymers

“…To expand the practical application range, their association to a lightharvesting antenna is yet necessary, since POMs themselves are mainly photoactive in the UV part of the solar spectrum. In most POM-dye materials reported in the literature, the hybrids were assembled via electrostatic interactions [5][6][7][8][9][10][11][12][13].…”

“…Peng reported the synthesis of an Fe(terpyridine) 2 -Lindqvist molybdate coordination polymer [18]. Ruhlmann and Hasenknopf reported systems with either axial coordination of polyoxometalate-grafted pyridyl groups to the metal ions in [Ru(CO)TPP] (TPP = tetraphenylporphyrin) or [ZnTPP] [15], or porphyrin-grafted pyridyl groups to a-[MSiW 11 O 39 ] 6À Keggintype POMs (M = Co 2+ and Ni 2+ ) [17]. There is a growing number of examples of covalently attached dyes on POMs in the literature [19][20][21][22][23][24][25][26][27][28].…”