Naphthalene diimides

Generation of o-QM Tethered to Naphthalene Diimides by Mild Activation... 

Di Antonio, M. Doria, F. Mella, M. Merli, D. Profumo, A. Freccero, M. Novel naphthalene diimides as activatable precursors of bisalkylating agents, by reduction and base catalysis. J. Org. Chem. 2007, 72, 8354—8360. 

Oxidative repair is not a unique feature of our Rh(III) complexes. We also demonstrated efficient long-range repair using a covalently tethered naphthalene diimide intercalator (li /0 1.9 V vs NHE) [151]. An intercalated ethidium derivative was ineffective at dimer repair, consistent with the fact that the reduction potential of Et is significantly below the potential of the dimer. Thymine dimer repair by a series of anthraquinone derivatives was also evaluated [151]. Despite the fact that the excited triplets are of sufficient potential to oxidize the thymine dimer ( 3 -/0 1.9 V vs NHE), the anthraquinone derivatives were unable to effect repair [152]. We attribute the lack of repair by these anthraquinone derivatives to their particularly short-lived singlet states anthraquinone derivatives that do not rapidly interconvert to the excited triplet state are indeed effective at thymine dimer repair [151]. These observations suggest that interaction of the dimer with the singlet state may be essential for repair. 

Scheme 8 Naphthalene diimide (18), pyrazinonaphthalimide (19), and bis pyrazino-naphthalimide derivatives (20, 21).

Near-infrared (NIR) absorption spectroscopy has been used to characterize the delocalized re-stacks on electronic conducting dendrimers by Miller and coworkers [47-49]. These dendrimers were prepared by peripherally modifying PAMAM dendrimers with cationically substituted naphthalene diimides, and then reduced with one electron per imide group to convert each imide into its anion radical. The re-stacking of these radical anions on these dendrimer surfaces was indicated by an absorbance band beyond 2000 nm in the NIR spectra. 

Quite differently, Pleux et al. tested a series of three different organic dyads comprising a perylene monoimide (PMI) dye linked to a naphthalene diimide (NDI) or C60 for application in NiO-based DSSCs (Fig. 18.7) [117]. They corroborated a cascade electron flow from the valance band of NiO to PMI and, finally, to C60. Transient absorption measurements in the nanosecond time regime revealed that the presence of C60 extends the charge-separated state lifetime compared to just PMI. This fact enhanced the device efficiencies up to values of 0.04 and 0.06% when CoII/m and P/Ij electrolytes were utilized, respectively. More striking than the efficiencies is the remarkable incident photon-to-current efficiency spectrum, which features values of around 57% associated to photocurrent densities of 1.88 mA/cm2. 

An example of the difficulties encountered when trying to fabricate an ohmic electrode, able to sustain a space-charge-limited current, is the recent work of the Neher group [179]. The authors deposited barium as an electron injection cathode on top of an electron transporting polymer based on a naphthalene diimide core whose LUMO is as low as 4 eV below vacuum level. Although the Fermi level of barium should be above the LUMO of the polymer, the electron current is. 

The intercalation of polycyclic aromatic compounds into duplex DNA structures was used to develop nucleic acid-based electrochemical sensors.66 For example, the bis-ferrocene-tethered naphthalene diimide (16) was used as a redox-active intercalator to probe DNA hybridization.67 The thiolated probe was assembled on a Au electrode, and the formation of the duplex DNA with the complementary analyte nucleic acid was probed by the intercalation of (16) into the double-stranded nucleic acid structure and by following the voltammetric response of the ferrocene units (Fig. 12.17a). The method enabled the analysis of the target DNA with a sensitivity that corresponded to ca. 1 x 10-20mol. 

Fig. 6.47 G2 PAMAM dendrimer with three different cationic naphthalene diimide end groups (according to Miller, Tomalia et al.)...

Scheme 11.1 General synthetic approach to symmetric and asymmetric naphthalene diimides.

However, produced a neutral [2]catenane (Scheme 11.5) [lib] bearing a mechanically interlocked bis-NDI macrocycle in 53% yield. This yield is far more attractive for a bis-NDI macrocycle than the 10% yield originally obtained in macrocycles [30a]. This approach involved an oxidative coupling of two acetylenic naphthalene diimides in the presence of crown ether. The efficiency of the catenation can be attributed to the crown ether component acting as a permanent template for the forming cyclophane. 

Figure 6.17 Differential-pulse voltammograms for the ferrocenyl naphthalene diimide indicator at the fiTlVmodified electrode before (curve a) and after (curve b) hybridization with dA2o- Also shown is the chemical structure of the indicator. (Reproduced with permission from Ref. 72.)...

The naphthalene diimide electroactive unit was used to functionalize poly(amidoamine) dendrimers up to the sixth generation [134]. Compound 66 illustrates the first-generation dendrimer, containing six peripheral diimide units in the sixth generation dendrimer the peripheral units number 192. Cyclic voltamme-... 

Dendrimer 67 contains two naphthalene diimide electroactive units in the core [137]. Electrochemical investigation in DMF showed the presence of two reversible bielectronic reduction processes at the potential typically featured by other naphthalene diimide-containing compounds. Thus, the two units behave independently and can be readily accessed from the electrode surface. The lack of encapsulating... 

Various fluorinated aromatic nucleobases have been synthesised for PNA. As is found with similar fluorinated aromatic bases in DNA (section 1.3.3), they behave as universal bases with complementary DNA. PNA with a terminal 9-aminoacridine has been prepared to examine binding of monovalent ions. A Tio PNA oligomer was found to be sensitive to increasing the concentration of K(f) ions, but the presence of the terminal acridine significantly reduced the sensitivity. The incorporation of naphthalene diimide at the N-terminus of PNA stabilises DNA-PNA duplexes, whilst the bis-functionalised PNA (31) not only stabilises the duplex with DNA but also can be used to photocrosslink to DNA. The presence of the phosphonium ion in (31) aids mitochondrial location of the PNA. 

Other electroactive groups incorporated in gold-thiol monolayers include tetrathiaful-valene365 and fullerene393. Miller and coworkers prepared thiol-derivatized oligoimides with naphthalene diimide electroactive groups. Electron transfer to each electroactive function was observed394,395. 

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