Experimental and theoretical studies on pyrene-grafted polyoxometalate hybrid

Abstract

A novel pyrene covalently-attached polyoxometalate (POM) hybrid has been synthesized and fully characterized. The attractive electronic and photophysical properties of pyrene derivatives make the hybrid promising for studying and understanding electron transfer mechanisms in organic-functionalized POMs. The hybrid has an electronic absorption at 450 nm, indicating that there is a strong electronic interaction between the organic pyreneimido group and inorganic hexamolybdate cluster. The electron transfer mechanism of the as-prepared hybrid is illuminated via the combined studies of theoretical calculations and transient absorption spectroscopy. Time-dependent density functional theory studies revealed that the strong electronic absorption at the visible region mainly comes from the optically allowed π-π* transitions of the pyreneimido component (S(0) to S(2) transition). The electron transfer process from the excited pyreneimido moiety to the inorganic POM cluster is at the time scale of ~700 fs, which could be ascribed to the internal conversion of singlet excited states from S(2) state to S(1) state. This study provided a clear understanding of the mechanism governing the electron transfer process in organoimido derivatives of POMs. This result might offer a new route for the design of new charge transfer hybrid clusters of organic functionalized POMs and crucial guidance for their applications in optical and electrical devices.

Molecule-Based Water-Oxidation Catalysts (WOCs): Cluster-Size-Dependent Dye-Sensitized Polyoxometalates for Visible-Light-Driven O2 Evolution

“…The starting materials (TBA) 2 [Mo 6 O 19 ] and α-(TBA) 4 [Mo 8 O 26 ] were prepared according to the literature procedure4344. POM-1 ([Ru(C 12 N 2 H 8 ) 3 CH 3 OH][Mo 6 O 19 ]) was obtained as orange-red crystals in 10 days by slow diffusion of methanol solution of dichlorotris(1,10-phenanthroline) ruthenium (II) hydrate into DMF solution of (TBA) 2 [Mo 6 O 19 ].…”

Recent advances in organic‐based materials for resistive memory applications

“…POM molecules are a class of anionic metal‐oxide nanoclusters, which can achieve multiple stable metal‐centered redox states in a narrow potential range 196‐199 . Because of this multiredox behavior, POMs and their organic‐inorganic hybrid derivatives have become a new family of contenders for redox‐based resistive memory electronics 200‐206 …”

Synthesis and characterization of Lindqvist-type polyoxometalate–porphyrin copolymers

“…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]. The covalent approach offers several advantages; in particular it should enhance the directionality and the interaction between POMs and organic components such as ferrocenyl [19,20], pyrene and perylene [21][22][23], Ru and Ir complexes [22,24], and porphyrins [25][26][27].…”

“…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]. The covalent approach offers several advantages; in particular it should enhance the directionality and the interaction between POMs and organic components such as ferrocenyl [19,20], pyrene and perylene [21][22][23], Ru and Ir complexes [22,24], and porphyrins [25][26][27]. We reported the formation of a mixed POMporphyrin copolymer film with an Anderson type POM [MnMo 6 9À and ZnOEP, via an original electropolymerization/deposition process [29].…”