A series of 4-(X)-substituted naphthalimides (X ) ethenylFc, ethynylFc, piperidinyl, ethenylpiperidinyl, ethenylpyrrolidinyl) with ferrocenyl headgroups (R ) Fc(CH 2 ) n , n ) 1, 5, 11) and analogous ethenylFc, ethynylFc, and ethynylFc # (Fc # ) octamethylferrocenyl) compounds with a methyl headgroup have been investigated. These are the first 4-enamine-1,8-naphthalimides to be reported. Spectrochemical properties for all compounds are presented and the X-ray structures of 4-piperidinyl and 4-ethynylferrocenyl derivatives described. This series of donor-acceptor derivatives allows a correlation between the degree of internal charge separation, UV-vis and emission properties, and mediation by the organometallic redox couple. Charge separation increases in the order 4-amino , 4-CdCamino = 4-CtCFc = 4-CdCFc < 4-CtCFc # . The unsaturated spacer is the key influence on both λ flu and φ f , but λ flu is independent of the headgroup due to the imide node. In contrast, φ f shows a "distance" effect for the ferrocenyl headgroup, and as a result φ f can be "tuned"; dyads with the Fc(CH 2 ) 11 headgroup have φ f > 0.2. Solvatochromism data gives an excited state dipole of ∼8 D. An EPR study of radical anions provides a description of the SOMO. Through-space interaction between the ferrocenyl headgroup and the charge-separated excited state may account for some of the trends in EPR and φ f . In general, emission is decreased upon oxidation to the ferrocenium analogues.

The stereoisomers of a series of dinuclear ruthenium(ii) complexes [{Ru(phen)(2)}(2)(micro-BL)](4+) (phen = 1,10-phenanthroline) with flexible bridging ligands (BL) bb2 {1,2-bis[4(4'-methyl-2,2'-bipyridyl)]ethane}, bb5 {1,5-bis[4(4'-methyl-2,2'-bipyridyl)]pentane}, bb7 {1,7-bis[4(4'-methyl-2,2'-bipyridyl)]heptane}, and bb10 {1,10-bis[4(4'-methyl-2,2'-bipyridyl)]decane} have been synthesised. Their binding to a control dodecanucleotide, d(CCGGAATTCCGG)(2), and a tridecanucleotide, d(CCGAGAATTCCGG)(2), which contains a single adenine bulge have been studied using fluorescence displacement assays involving intercalating and groove-binding dyes, equilibrium dialysis and binding affinity chromatography. The fluorescence intercalator displacement (FID) assay indicated that LambdaLambda-[{Ru(phen)(2)}(2)(micro-bb7)](4+) had the greatest binding affinity with all the oligonucleotides, whereas an analogous fluorescence technique using a minor-groove binding dye, equilibrium dialysis and affinity binding chromatography showed that DeltaDelta-[{Ru(phen)(2)}(2)(micro-bb7)](4+) had the strongest binding. An (1)H NMR study of the binding of the DeltaDelta-enantiomer of [{Ru(phen)(2)}(2)(micro-bb7)](4+) to d(CCGAGAATTCCGG)(2) confirmed the selectivity of the metal complex for the bulge site and provided the basis for an energy-minimised binding model of the dinuclear ruthenium complex with the single adenine bulge containing trinucleotide. The binding model demonstrated the ability of the flexibly-linked complex to follow the curvature of the DNA minor groove.

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