Conjugated polymers coordination complexes

Conjugated polymers coordinated to chromium tricarbonyl were reported in 1989 134 xhese polymers were formed through a palladium-catalyzed cross-coupling reaction of T)%dichloroarene chromium tricarbonyl complexes with organostannane reagents, as shown in scheme 22. 

The nature of Dexter triplet energy transfer between bonded systems of a red phosphorescent Ir + complex and a conjugated polymer, polyfluorene, has been investigated in electrophosphorescence OLEDs . Red-emitting phosphorescence has been described based on the [Ir(btp)2(acac)j fragment attached either directly (spacerless) or through a —(CH2)8— chain (octamethylene-tethered) at the 9-position of a 9-octylfluorene host. Xu and coworkers reported that an efficient red EP with CIE chromaticity coordinates X = 0.69, y = 0.29, independent on current density, was obtained from [Ir(acac)(btfmp)2] doped devices. The EL spectrum has a maximum at 648 nm. A maximum external quantum efficiency of 9.6%, at current density of 0.125 mAcm, and a maximum luminance of 4200 cdm , at 7 = 552 mAcm , have been obtained. 

As with other polymers, the metal complex may be part of the polymer backbone, or attached to the backbone by a conjugated linker. Investigations into the conjugated polymers have been assisted by studies of model complexes.44 Polythiophenes incorporating organometallic complexes are discussed first, followed by those incorporating other coordination complexes with bipyridine, terpyridine, Schiff base, and other ligands. 

The past seven years have seen significant advances in the preparation of coordination polymers. A vast assortment of conjugated polymers has been prepared that incorporate bpy, phen, and other polydentate ligands. Complexation to metal ions affords new polymeric materials with properties modified by the presence of the transition metal. 

The TT-conjugated polymers or oligomers are able to serve as redox-active 7C-conju-gated ligands with coordination capability towards transition metals as described above. Few papers have been published on the complexation behavior of the redox-active Tt-conjugated polymers. Multi-coordination to -conjugated polymers possessing relevant redox function is likely to provide multi-redox systems. 

The difference in the ratio is accounted for as follows. Two coordination sites are available with Pd(OAc)2 or PdCl2(MeCN)2, but the complex 3 bearing the tri-dentate ligand has only one free coordination site. A cross-linked polyaniline network complex 4 is considered to be formed in the former case. On the contrary, the latter complexation affords the single-strand conjugated complex 5. Thus, a hybrid system composed of transition metals and 7C-conjugated polymers is controlled structurally (Fig. 3.11). 

A photoactive metal center is introduced in these systems. The ruthenium bipyridyl complexes are coordinated to the emeraldine base to form the corresponding polymer complexes as described above." The incorporation of the ruthenium centers to the pyridyl backbone has been also reported to give the ruthenium complexes Conjugated ruthenium bipyridine complexes thus obtained are evaluated to be photorefractive materials. Other transition metal complexes can be employed to form the corresponding polymer complexes. The pyridine unit is replaced by bithienyl, 1,4-diazabutadiene, ethylene, benzimidazole or thiazole. ... 

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