Coordination polymers double-stranded

In this report, both the structure-based and source-based nomenclature rules are extended to regular double-strand (ladder and spiro) organic polymers. Biopolymers, however, such as DNA are not considered here. Rules for quasi-single-strand coordination polymers, resembling spiro polymers yet not covalently bonded, are not included. 

Ikeda M, Tanaka Y, Hasegawa T, Fumsho Y, Yashima E. Construction of double-stranded metaUosupramolecular polymers with a controlled heUcity by combination of salt bridges and metal coordination. J Am Chem Soc 2006 128 6806-6807. 

The role of zinc in the enzymes listed in Table 12 is very often that of a strong Lewis acid, in which substrates are coordinated, polarized and hence activated. In other cases, zinc may play a regulatory, structural or template role. Zinc may also have a structural function in other biological molecules, for example in the unwinding and subsequent rewinding of the double-stranded polymers involved in replication and transcriptional processes. There is also evidence for a role for zinc in the stabilization of membranes and cell walls.463 The high concentrations of zinc in certain snake venoms reflect the presence in the venom of proteolytic enzymes and hemorrhagic toxins that all require zinc for activity.464... 

Several metal-organic polymers assembled by dithioether ligands, which are functionalized by heteroelements such as O, N, or Si in the spacer unit, have been recently described and reacted with Cu(I) salts. For example, the 2D square-grid coordination polymer 37 incorporating the 16-membered dithiaoxa crown-ether L37 has been prepared by a self-assembly process involving the interaction of the dithiaoxa macrocycle with CuCN (Scheme 17) the parallel reaction of the dithiaoxa crown-ether with Cul afforded the ID double-stranded coordination polymer 37 . This example demonstrates, how the nature of the counterion can control the form of the network.157... 

The potential for RNA to act as a catalyst is dictated by its structure as a linear polymer of the four common ribonucleotides. Like DNA, RNA can form double stranded, antiparallel helices via traditional Watson-Crick base pairing. However, the backbone of nucleic acid is highly flexible and RNA can form complex tertiary structures that often involve non-Watson-Crick base pairing to create active site crevices for catalysis. The phosphodiester backbone is charged negatively and interacts electrostatically as well as by direct coordination with solution divalent cations. Ribose, purines, and pyrimidine bases contain both H-bond donors and acceptors that help stabilize higher-order stmcture and provide for substrate positioning, as well as participate in active site interactions. 

Structure-based nomenclature can also be used when the CRU backbone has no carbon atoms. An example is the polymer traditionally named poly(dimethylsiloxane) , which on the basis of structure would be named poly(oxydimethylsilylene) or poly(oxydimethylsilanediyl) . This nomenclature method has also been applied to inorganic and coordination polymers and to double-strand (ladder and spiro) organic polymers."... 

Ikeda, M., Tanabe, Y, Hasegawa, T. et al. (2006) Construction of double-stranded metaUo-supramolecular polymers with a controlled helicity by combination of salt bridges and metal coordination. Journal of the American Chemical Society, 128,6806-6807 Furusho, Y., Tanabe, Y. and Yashima, E. (2006) Double helix-to-double helix transformation, using platinum(II) acetylide complexes as surrogate linkers. Organic Letters, 8, 2583-2586 Furusho, Y. and Yashima, E. (2007) Molecular design and synthesis of artificial double helices. Chemical Record, 7, 1-11. 

In the linear copper(I) coordinated polymer two helices are found. These are single stranded, one is left handed and one right handed with the methoxy substituents pointing outside the helix. A comparison with the copper(I) based double stranded helicates reported by Lehn and co-workers is schematically shown in figure 9. 

There is another interesting system that exploits the same FRET mechanism, to obtain in this case fluorescence amplification, but based on the addition of a non-bound second fluorophore. Bin Liu and Yusong Wang [127] have immobilized a DNA strand on monodispersed silica nanoparticles (1(X) nm in diameter) and then hybridized it with a fluorescein labelled complementary DNA engineered to induce in the final double strand three pairs of T-T mismatches that are specific coordination sites for mercury ions. After incubation with metal ions and thermal washing, a cationic conjugated polymer was added. This last component was selected in order... 

International Union of Pure and Applied Chemistry (1985b) Nomenclature of regular double-strand and quasi-single-strand inorganic and coordination polymers (Recommendations 1984). Pure Appl Chem 57 149-168... 

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