Organic linkers

Fig. 13. Schematic illustration of metal-organic molecular squares, assembled from linear organic linkers and 90° metal units (left), linear metal units and organic comers (middle), or linear metal units and 90° metal units (113). The latter two classes have several inner-cavity binding sites and thus fit the definition of metalated container molecules.

Large molecular weight compounds are unlikely to react with DNA or other chromosomal material and therefore a genotoxicity evaluation may be of little value. However, genotoxicity studies may provide useful information about the safety of products containing organic linkers. 

In this section, the structural features of PBs and related compounds are discussed following the nature of the organic linker. Special attention is focused on the factors that govern the presence, or not, of P-B interactions. 

Higher molecular weight polymers (40,000-50,000) have been reported from condensation reactions between monomer 6.15 and various silanediols, as illustrated in reaction (6).2 Polymer 6.16 can be melt-fabricated into films or fibers, which probably reflects the presence of roughly 100 repeating units per chain. However, the separation of the ferrocenyl units by the organic linker groups reduces the influence of the organometallic component. 

Scheme 3.3 Methods for synthesising the crown ethers (R - V are organic linker groups).

This theoretically established distance dependence has been verified in several homogeneous series of dyads containing modular organic linkers of variable length [22, 30-32],... 

An example of a porous framework that is isoreticular, but not isostructural, with MOF-5 is MOF-177, which incorporates the extended organic linker 1,3,5-benzenetribenzoate (BTB). The framework of crystalline MOF-177, Zn40(BTB)2- (DEF)i5(H20)3, where DEF = diethyl formamide, has an ordered structure with an estimated surface area of4,500 m2 g-1, which greatly exceeds those of zeolite Y (904 m2g 1) and carbon (2,030 m2 g-1). 

Fig. 9 Schematic representation of coordination polymers and extended inorganic hybrids (a) and (b) show 1-D and 2-D coordination polymers, respectively, while (c) shows a system that has inorganic connectivity in two dimensions and is connected in the third dimension by organic linkers.

Human-type protein analog consisting of natural amino acid Human-type protein analog containing nonnatural amino acid Bioconjugate of human-type protein and other protein Bioconjugate of human-type protein and organic linker... 

Examination of genotoxicity of pharmaceuticals is required to assess the interaction of the drug with DNA. These studies are generally not applicable to immunotoxins. Unlike chemotherapeutics that cause cell death through DNA interaction, immunotoxins mediate cell death by preventing protein synthesis. However, immunotoxins use a linker to connect the toxin to the antibody that may need to be examined if it is an organic linker and has the ability to bind DNA (per ICH S6). The majority of immunotoxins use either a nonreducible thioether linker for intact toxins or a disulfide bond for A chains and ribosome-inactivating proteins and do not interact with DNA. 

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