Bridged polymeric phthalocyanines

Knothe, G. (1993). Isomerism and symmetry of bridged polymeric phthalocyanines. Macromol. Theor. Simul. 2, 503-516. 

Polymeric phthalocyanine, which possess a higher stability compared to the monomers, can be obtained by combining a phthalocyanine with a polymer, The linking of the polymeric chain can occur at the central metal atom, the phenyl rings, through bridging or attachment 1o a polymeric chain. 

A connectivity of 1 is given for side chain metal-containing polymers as 1 in which the metal complex is connected via one bond to the main chain [11]. Additional examples for other connectivities are (Fig. 1-8) connectivity 2 in metal(yne)s 2 [12] connectivity 3 in arsenic(III) sulfide 3 connectivity 4 in a polymeric methyl rhenium oxide of the formula Ho.5[(CH3)o.92Re03] co 4 [13] or polymeric phthalocyanines 5 [14] connectivity 8 in lanthanide complexes of bis(tetradendate) Schiff base bridging ligands 6 [15]. 

The cofacially stacked polymeric phthalocyanines can exhibit high electrical conductivities in either the undoped or the doped state (Table 7-1) [166,168,170]. For comparison, low molecular weight phthalocyanines MPc or naphthalocyanines MNc (M = Fe, Cu, Co, Ni, Zn) exhibit values between a = 10 and 10 S cm V For undoped polymers. Table 7-1 shows that polymerization through cyano- and tetrazine-bridging is particularly effective in increasing the conductivity. This effect can be ascribed to the existence of additional interactions (Ti-orbital interactions through the bonds) [170,194]. 

Low molecular weight phthalocyanines are prepared by cyclotetramerization of unsubstituted or substituted phthalic acid derivatives such as phthalonitrile in the presence of suitable metals. If bifunetional tetracarbonitriles are employed, polymeric phthalocyanines 56 and 57 are obtained [equations (22) and (23)] 1,2,4,5-tetracyano-benzene, oxyalkyleneoxy-, oxyaryleneoxy- [239-242], tetrathio- or dioxadithia-bridged [243], bisphthalonitriles and tetracarboxylic acid derivatives such as 1,2,4,5-benzenetetra-carboxylic acid dianhydride [244-246]. The reactions of the carbonitriles were carried out in bulk in the presence of a metal at T= 200-400 °C. Dark-blue till black-coloured polymers insoluble in any organic solvent were obtained. Recently the synthesis of the... 

Rhodium phthalocyanines - In view of the current interest in polymeric bridged phthalocyanines [110], Rh(III) phthalocyanines with trans-bidentate ligands were synthesized. RhCl(Pc)L (obtained from o-cyanobenzamide) [290] appears to strongly hold its chloride ligand. Action of ligands L, namely pyridine,... 

Recently, Wynne and co-workers [1,2] and Marks and co-workers [3-6] described the synthesis and characterization of inorganic-organic polymers, in which a metallic or pseudometallic element alternates with a linear-chain bridging atom, like oxygen or fluorine. The metallic or pseudometallic element is usually the centr atom of a phthalocyanine system, and the bridge-stacked polymeric structure is rigid. These derivatives are electrical conductors after iodine oxidation. 

Electrodes modified with films obtained from polymerization of CoTAPc (cobalt tetraamino phthalocyanine) show two waves for the reduction of O2. At low polarizations two-electron reduction waves are observed with the formation of peroxide and a four-electron reduction to form water is observed at higher polarizations It is not clear why these polymeric films can promote the four-electron pathway. It can be argued that within the polymeric films Co atoms belonging to different MN4 units become separated by the ideal distance for O2 to bind to two cobalt centers forming a bridge. However there are no detailed studies of the structures of these polymeric films to clarify this point. A similar behavior has been observed with adsorbed layers of vitamin B12 where a four-electron reduction mechanism is observed at high polarizations " . In all these cases, it is likely that O2 interacts with one single site at the time and vitamin B12 is still able to promote four-electron reduction process. 

To date Si, Sn and Co have been used as central atoms in polymeric liquid crystalline phthalocyanines. Oxide and cyanide served as bridging ligands. 

Fig. 6 Impedance plots of gold electrodes coated with (a) polymerized nickel(II)tetrakisben-zylmercaptophthalocyanine in the O-Ni-O oxo bridged form (polyNi(OH)TBMPC/Au) and (b) polymerized nickel(II)-tetrakisdodecyl-mercapto-phthalocyanine in the O-Ni-O oxo bridged form (polyNi(OH)TDMPc/Au) in 0.1 M NaOH. Numbers in the curves are the polymerization cycles. Reproduced with permission from Ref. [9] Fig. 5...

---