Block Chromophores

Mono- or dinuclear platinum(II) complex capped with one or two [Pt(Bu3tpy)]+ units can be incorporated with Ln(hfac)3 units to produced a series of PtLn (Ln = Nd 88, Yb 89) and Pt2Ln (Ln = Nd 90, Yb 91) heteronuclear complexes [131]. With excitation at 350 nm L 550 nm, sensitized NIR lanthanide luminescence was detected in these Pt-Ln heteronuclear complexes with microsecond ranges of lifetimes, whereas Pt-based luminescence from the MLCT and LLCT states was mostly quenched. This reveals that fairly effective Pt Ln energy transfer is operating from the platinum(II) terpyridyl alkynyl chromophores to the lanthanide(III) centers. 

Veggel and coworkers [137, 138] first reported the use of ruthenium(II) tris(2,2 -bipyridine) complexes ([Ru(bpy)3] +) and ferrocene as light-harvesting chromophores for sensitization of NIR luminescence from Nd(III) and Yb(III) ions. The Ru-Ln complexes (Ln = Nd 104, Yb 105) resulted from incorporating [Ru(bpy)3] + with m-terphenyl-based lanthanide complexes. Upon excitation of the Ru(bpy)s chromophore absorption with visible light up to 500 nm, both Ru-Nd and Ru-Yb complexes exhibited typical NIR luminescence because of effective Ru Ln energy transfer with the rates of 1.1 x 10 s for Ru-Nd complex and 1.0 X 10 s for Ru—Yb species. 

Using functionalized DTPA- or cyclen-based ligands, Faulkner and coworkers, and other groups [ 139-143], described a series of kinetically stable Ln -M (M = Ru, Os, Re) heterobinu-clear or heterotrinuclear complexes 106-124, where the Ln(III) ion is bound in a DTPA-derived or cyclen-derived coordination environment and the Ru(bpy)2, Os(bpy)2, or Re(CO)3Cl unit 

Ward and coworkers [144-151] used a series of simple ruthenium(II) or osmium(II) complexes 127-136 containing cyanide and/or bpym to serve as precursors for fabrication of Ru-Ln or Os-Ln heteronuclear complexes. Reactions of these cyanide- and/or bpym-anions 

With a 1,10-phenanthroline functionalized P-diketone ligand, Ir2Ln (Ln = Nd 139, Er 140, Yb 141) heterotrinuclear complexes were recently prepared by Bian and Huang and cowork-ers in a stepwise approach [153, 154], in which the Ir(ppy)2 chromophore is chelated by 1,10-phenanthroline and the lanthanide bound to P-diketone and to nitrates. Upon irradiation 

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When one metal ion is used as a donor for sensitizing the emission of a second accepting metal ion, the characteristic lifetimes r of their excited states, which are related to their deactivation rates by r = k l, are affected by the metal-to-metal communication process. This situation can be simply modeled for the special case of an isolated d-f pair, in which the d-block chromophore (M) sensitizes the neighboring lanthanide ion (Ln) thanks to an energy transfer process described by the rate constant k 1 ". In absence of energy transfer, excited states of the two isolated chromophores decay with their intrinsic deactivation rates kxl and kLn, respectively, which provides eqs. (32) and (33) yielding eqs. (34) and (35) after integration ... 

The use of strongly absorbing d-block chromophores as sensitizers for the NIR emissions from lanthanide ions has attracted increasing attention since the first report by van Veggel and coworkers on the Nd + and Yb + luminescence sensitized by Ru(bpy)j+ and ferrocene in 2000. Subsequently, many d-block chromophores, based on related transition metals, such as R +, Ru +, Re+, Os +, Pd, Zn +, Cr +, and Co +, have been extensively studied in sensitizing the NIR emissions of lanthanide ions (i.e., Nd +,... 

Miscellaneous Disazo Dyes. Another group of disazo dyes is prepared by condensation of two identical or different aminoazo compounds commonly with phosgene, cyanuric chloride, or fumaryl dichloride, the fragments of which act as blocking groups between chromophores. 

In this way, many green azo dyes have been made by combining separate conjugated systems in the same molecule, eg, one yellow and the other blue. The blocking or the insulating group prevents the electronic interaction of one chromophore system with the second. Chloramine Fast Scarlet 4BS... 

We have studied two types of polymers that both belong to the second case those in which luminescent chromophores (typically K-coujugatcd oligomers) are separated by higher-energy-gap blocks (see Fig. 16-1 a) and those in which the chromophores are linked to each other in a non-coplanar way (sec Fig. 16-lb). 

Nanoscale Morphological Change of PS-b-P4VP Block Copolymer Films Induced by Site-Selective Doping of a Photoactive Chromophore... 

Direct and indirect competition formats, illustrated in Figure 1, are widely used for both qualitative and quantitative immunoassays. Direct competition immunoassays employ wells, tubes, beads, or membranes (supports) on to which antibodies have been coated and in which proteins such as bovine semm albumin, fish gelatin, or powdered milk have blocked nonspecific binding sites. Solutions containing analyte (test solution) and an analyte-enzyme conjugate are added, and the analyte and antibody are allowed to compete for the antibody binding sites. The system is washed, and enzyme substrates that are converted to a chromophore or fluorophore by the enzyme-tracer complex are added. Subsequent color or fluorescence development is inversely proportionate to the analyte concentration in the test solution. For this assay format, the proper orientation of the coated antibody is important, and anti-host IgG or protein A or protein G has been utilized to orient the antibody. Immunoassays developed for commercial purposes generally employ direct competition formats because of their simplicity and short assay times. The price for simplicity and short assay time is more complex development needed for a satisfactory incorporation of the label into the antibody or analyte without loss of sensitivity. 

The optical and electrochemical properties of porphyrins make these chromophores useful building blocks for the synthesis of electro- and photoactive polymers. Two types of linear polymers have been constructed using the self-assembly approach homo-polymeric assemblies and hetero- or shish kebab polymers. 

Dendritic molecules with electroactive units at either the focal point or core have been reported [92, 97]. There are, however, only a few examples of such moieties specifically pinned within cascade infrastructure. Our recent efforts in this direction [104-106] involve the incorporation of chromophoric 1,4-di-aminoanthraquinone (35) within the cascade infrastructure. Dendrimers based on a four-directional pentaerythritol core were synthesized using the extended 1 — 3 building block 36. A high dilution technique was applied to synthesize 36... 

Model analogs of the green type chromophore HBI have been chemically synthe-tized in different forms carrying blocking groups in place of the protein polypeptide chain [21, 24, 68, 69]. However, the covalent structure of HBI does not uniquely define its optical properties, because the molecule undergoes several protonation and conformational equilibria that directly affect its electronic structure. 

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