Ligand-lanthanide hybridization

This PCR -> hybridization -> DELFIA type of assay can be performed in a multi-color format. Samiotaki et al. (1997) reported this type of assay using seven different hybridization probes, which are three singly-labeled probes (labeled with Eu, Tb, and Sm), three doubly-labeled probes (labeled with Eu and Tb, Eu and Sm, and Tb and Sm), and one triply-labeled probe (labeled with Eu, Tb, and Sm) (see table 5 and scheme 15 for the chelate ligand). After PCR amplification, the PCR product was allowed to hybridize with one of the seven hybridization probes, washed, detected lanthanide ions by DELFIA , and washed. This cycle was repeated for the remaining six hybridization probes. This procedure enabled detection and identification of seven types of human papilloma virus in one single assay. 

New luminescent hybrid mesoporous material was prepared by covalent anchoring rare earth complex onto MCM-41 by a postsynthesis approach. The monomer (referred to here as PABI) which plays double roles, i.e., as a ligand for lanthanide ion and as an organic functional molecule to modify MCM-41 is synthesized and characterized by H NMR and MS. The fluorescence spectra show clearly that the hybrid mesoporous material possesses excellent luminescence characteristics. The hybrid mesoporous material retains the structure of MCM-41 after modification. 

Some lanthanide alkyl complexes can induce intramolecular C-H bond activation via metalation of the ligand with elimination of CH4 or SiMc4 under suitable conditions [63-65]. A representative example of the sp -hybridized C-H activation is presented in Figure 8.15 [65]. 

An intruiging approach to site-selective RNA cleavage was reported by Kuzuya et al. [130]. In contrast to the previons examples, in this system the metal complex is free in solution (not localized). Site-selective activation for hydrolysis at single positions in a target RNA strand is achieved by covalent attachment of an acridine moiety to the template DNA strand, which canses local perturbation in the hybridized RNA strand opposite this position [131]. RNA strand scission is very site-specific for the localized perturbation (Fig. 9b). This approach was optimized for various metal ions inclnding Ca and Mg % transition metal ions, and lanthanide ions [132, 133]. Two sites in a single RNA conld be activated by incorporation of two acridines in the DNA template [134], and the rate of the process was further enhanced by the attachment of a ligand for Lu in close proximity to the acridine activator [135]. 

Shen and Holzapfel [190] and Wang and Bulou [191,192] have considered a covalency model that combines the central field and symmetry restricted covalency models. The approach incorporates the effects of nuclear screening and hybridization of ligand orbitals with 4f orbitals. When the radial 4f wavefunc-tions of the central field covalency model (instead of the free ion 4f wavefunc-tions) are used in the formation of lanthanide centered molecular orbitals, we obtain... 

Pope SJA, Coe BJ, Faulkner S, Bichenkova EV, Yu X, Douglas KT (2004) Self-assembly of hetero-bimetallic d-f hybrid complexes sensitization of lanthanide luminescence by d-block metal-to-ligand charge-transfer excited states. J Am Chem Soc 126 9490-9491... 

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