Coordination complexes dendrimers

By employing coordination complexes as branch points, dendrimers can be synthesized that contain metal ions throughout their structure. The repetitive unit of such dendrimers contains M-C, M-N, M-P, or M-S bonds [53,62]. The metal ions act as supramolecular glue [63], in which the complexation chemistry directs the assembly and structure of the dendrimer [53]. One of the synthetic procedures used to prepare organometallic dendrimers with coordination centers in every layer is based on a protection/deprotection procedure in which two complexes are used as dendritic building blocks wherein one acts as a metal and the other as a ligand [64,76]. 

Pt NMR spectra were employed to study the nature of Pt(bipy)22+ in aqueous alkaline solutions. The data were consistent with formation of a conformationally mobile pseudo-five-coordinate complex involving OH coordination.1079 The time dependence of Pt(II) complexation with poly(amid-oamine)dendrimers was established by 195Pt NMR spectroscopy.1080 The 2H and 13C NMR spectra for solutions of cA-[L2Pt 9-MeAd(-H) ]3(N03)3 show dissociation to a mononuclear species, e.g. cA-[L2Pt 9-MeAd(-H) ]+, where L... 

While several dendrimers based on redox active organic units or coordination complexes have been synthesized, their dynamical behavior is only beginning to be characterized. ... 

There are numerous examples of dendrimers and star polymers containing metal coordination complexes (253-259). The synthesis of polypsrridine ruthenium coordination complexes incorporating Fe and Co (113) has been established (255). A ruthenium star-shaped complex with a CpFe" "-coordinated arene as the core has also been reported (254). 

There are numerous examples of dendrimers and star polymers that contain metal coordination complexes based on pyridine ligands. There is also interest in the incorporation of more than one type of metal complex into these materials. Constable and coworkers have reported the synthesis of heptametallic complexes containing six peripheral ruthenium coordination complexes and a central iron or cobalt complex. Scheme 21 illustrates the reaction of 89 with either iron or cobalt complexes to produce the heptametallic dendrimer 90. A heptametallic star-shaped complex with a CpFe -coordinated arene as the core and ruthenium Aexa-pyridine complexes at the periphery has also been reported by Astruc. ... 

Self-assembly of aromatic dendron subunits has been tried by the design of coordination to multivalent metal cations (i.e., metal-cored dendrimer complexes). Several metal-cored dendrimer complexes have successfully exhibited luminescence by antenna effects. 

PBE dendrons bearing a focal bipyridine moiety have been demonstrated to coordinate to Ru + cations, exhibiting luminescence from the metal cation core by the excitation of the dendron subunits [28-30]. The terminal peripheral unit was examined (e.g., phenyl, naphthyl, 4-f-butylphenyl) to control the luminescence. The Ru +-cored dendrimer complexes are thought to be photo/redox-active, and photophysical properties, electrochemical behavior, and excited-state electron-transfer reactions are reported. 

Other complexes with phosphine sulfides are the three coordinate [Au (S-PPh2)2C(PPh2S) (PPh2Bun)],302 the /i4-phospha-l-thiethane compound [Fe3(CO)9(/i4-PS)(AuPPh3)2] (558),3 27 and the gold(I) dendrimers containing P=NP=NP=S or P=NP=S groups as (559).3028... 

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