Polymers with Pendant Metal Complexes

Photovoltaic cells with the simple device structure ITO/polymer/C6o/Al were fabricated. The power conversion efficiencies of the devices fabricated 

The current-voltage characteristics of the ITO/polymer 22 and 23/C60/Al devices under illumination with simulated solar light (100 mW/cm2). 

---

Type II polymers with pendant metal complexes Polymers containing bipyridyl and terpyridyl metal-binding sites... 

Early examples of molecular wires concentrated on the polymer materials as a backbone with a pendant inorganic functionality. For example, Meyer et al. produced a series of polystyrene-based polymers with pendant MLCT complexes of Ru and Os (Fig. 3) [19]. The photophysical analysis of this class of polymers demonstrated that energy and electron transfer between different pendant groups was controlled to a large extent by the distance between the groups. Furthermore, the distance was found to depend more on the stoichiometric loading of the metal dications than the inherent structure of the polymer [81]. Several groups prepared... 

The coordination of metals to various other pendant sites present in block co-polymers has also been explored. For example, metal coordination to the olefinic groups present in the polybutadiene (PB) blocks of polystyrene-/ -polybutadiene (PS-/ -PB) diblock and PS- -PB-3-PS triblock copolymers has been reported.This was achieved by the reaction of PS-/ -PB with various metal complexes such as Fe3(CO)i2, [Rh(/r-Cl)(CO)2]2, PdCl2(NCMe)2, and PtCl2(NCMe)2 to afford materials with Fe-, Rh-, Pd-, and Pt-containing blocks. Intermolecular cross-linking was possible but solubility in organic solvents was maintained and micellization was observed in most cases. However, on solvent removal and drying, many of the polymers became insoluble. 

Polymers with pendant crown ethers show different selectivity from their monomers in complex formation with metal cations due to the ease of a 1 2 complex formation. They can be prepared either by the polymerization of the crown vinyl monomers or by the polymer reaction. The former method is preferable for studies on basic properties since it gives a regular polymer with pendant crown ether, however, the latter one is advantageous from an economic standpoint. 

A Co(IH) complex is inert in ligand-substitution reactions, and its uniform structure is thus maintained even in an aqueous solution. The reaction mechanism of a Co(III) complex in solution is well known, so that a pendant-type polymer-Co(IU) complex, e.g. 17,19, is one of the most suitable compounds for a quantitative study of the effects of a polymer ligand on the reactivity of a metal complex. The reactivities of the polymer-Co(III) complexes are discussed here kinetically and compared with those of the monomeric Co(III) complexes in the following reactions electron-transfer reactions between the polymer complexes and Fe(II) [Eqs. (5) and (6)], and the ligand-substitution reaction of the polymer-Co(III) complex with hydroxy ions or water [Eqs. (7) and (8)J. One of the electron-transfer reactions proceeds via... 

Coordination polymerization of dienes has progressed significantly within the last decade. Selective polymerization of 1,3-dienes is reinforced by conventional transition metal catalysts and by new organolanthanide catalysts. Nonconjugated dienes also polymerize selectively to produce polymers with cyclic units or vinyl pendant groups. Living polymerization of dienes has become common, which enabled preparation of block copolymers of dienes with alkenes and other monomers. Another new topic in this field is the polymerization of allenes and methylenecycloalkanes catalyzed by late transition metal complexes. These reactive dienes and derivatives provide polymers with novel structure as well as functionalized polymers. The precision polymerization of 1,2-, 1,3-, and l,n-dienes, achieved in recent years, will be developed to construct new polymer materials with olefin functionality. 

Redox metal centers can also be grafted on to the surface of silica, or on to the internal surface of a molecular sieve, by ligand displacement with pendant silanol groups [33]. Alternatively metal complexes can be tethered to silica or the internal surface of a molecular sieve via a spacer that is attached to the surface. This approach is analogous to the tethering of organic bases to solid surfaces referred to earlier. Metal complexes can also be attached to oxidatively stable organic polymers such as polybenzimidazole [34]. 

Industrial applications of metallocene catalysts are a recent development AU of them possess in their reaction center two aromatic rings, between which a complex bond holds a metal atom, in most cases zirconium. This type of catalysis produces polymers with exceptionally uniform structures. The chain lengths of the individual molecules closely approximate one another. The spatial structure is therefore well-defined. Polypropylene, for instance, is completely isotactic. It is even possible to produce polypropylene in which the pendant group orientation alternates between right and left. The resulting substance is known as a syndiotactic polypropylene (see above) [3]. 

Electropolymerization of Ru bipy complexes with pendant thiophene groups to form materials such as 7.16 as films on electrodes has also been explored [39]. The resultant polymers can possess appreciable redox conductivity (ca. 10 S cm" ). The overlap between the metal d orbitals and the p orbitals of the ligands can be tuned by alteration of the substitution pattern, and appreciable conductivities can thereby be achieved. 

Low molecular weight Schiff base complexes of many metals are well known and in the case of aromatic ligands these tend to have high thermal stability. Polymeric Schiff bases likewise have been well reported, and although many of these have the Schiff base appended as a substituent on a vinyl polymer backbone, others have the Schiff base residue as part of the mainchain. The latter continue to complex metals very well [140, 141] and one early paper reports the use of a Mn(II) polymeric complex in the aerobic oxidation of cumene at 30-100°C [142]. Indeed there is an implication in the paper that the polymer complex is stable to 200°C when complexed O2 tends to be liberated. Wohrle s group have also studied polymeric Schiff bases extensively, again mostly with pendant groups. However, they have reported a mainchain poly Schiff base [143], its complexation with Co(II), Ni(II) and Cu(II), and use of the supported complexes as catalysts in quadricyclane isomerisation to norbornadiene. 

---