Metal coordination polymers benzimidazoles

When benzimidazole acts as a corrosion inhibitor for copper this involves formation of a coordination polymer which results from aerial oxidation of the initial benzimidazole-Cu" complex to give a film of bis-benzimidazolatocopper + (51) on the metal surface <89JCS(P2)33>. 

Polymers containing benzimidazole units in their backbones have also been used in the synthesis of coordination metallopolymers (159-162). Osmium and ruthenium coordinated polymers with bipyridine ligands have been prepared (159,160). These polymers (72, 73) possessed metal-metal interactions through their conjugated backbones. Communication between the ruthenium centers of 72 increased by deprotonating the imidazole protons (160). The osmium coordinated polymer (73) showed two reduction waves separated by 0.32 V, indicative of strong cnmmimication between the Os centers (159). 

Polymers 250 and 251, formed by coordination of Ru11 complexes to the preformed 2,6-poly(bis(benzimidazol-2-yl)pyridine), showed a strong enhancement of absorption and photosensitivity in the visible region relative to the unmetalated polymer.141 The metalated polymers, with ca. 90% of the coordination sites occupied, showed an inherent viscosity of 1.8 dLg-1. Although the polymers have low conductivities (ca. 10 10Scm-1), they exhibited higher photocurrents than the organic precursor polymer. 

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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