Naphthalene diimide group

Mechanically responsive n-n interactions have also been utilized in supramo-lecular polymers, where n-n stacking between electronically complementary (i.e., electron-rich and electron-poor) n-conjugated groups has been utilized to achieve supramolecular polymerization [57-60]. For example, pairs of naphthalene diimide groups that were introduced into the backbone and termini of polymer PI (Fig. 13) bind to pyrene moieties that were introduced to both ends of polymer P2. 

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. 

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. 

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

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. 

Alkyl substituted versions of naphthalene tetracarboxylic diimide (NTCDI, 46b) showed mobilities of 0.16 cmW s (R = octyl, 46c), 0.01 cmW s (R = dodecyl, 46d), and 5 x 10 3 cmW s (R = octadecyl, 46e) when measured under vacuum, but no observable electron mobility when measured in ambient. The incorporation of fiuoroalkyl groups on the side chains stabilizes NTCDI thin films and allows for n-channel operation under ambient conditions. Mobilities as high as 0.03 cmW s were obtained for 46f and 0.06 cmW s for 46g with on/off ratios on the order of... 

Polyquinoxalines (11) are another group of ladder polymers. They differ from polyimidazopyrrolones by the presence of a fused six-membered cyclic diimide structure. A possible synthetic route for polyquinoxalines involves the reaction of 1,4,5,8-naphthalene tetracarboxylic acid with aromatic tetra-amines in polyphosphoric acid (PEA) at temperatures up to 220°C. 

It has been possible to prepare [2]catenanes by simply using neutral n-n stacking interactions. Sanders reported the use of crown ether macrocycle 40 containing two electron-rich naphthalene units, which could interact with 2 equivalents of an electron-poor aromatic diimide unit 41 that is appended with terminal acetylene groups to allow... 

Attractive interactions between electronically complementary aromatic tt-systems have been widely exploited in supramolecular chemistry since the first reports of their potential in this field some 30 years ago. More recently, work by Colquhoun, Hayes, and coworkers has demonstrated that such interactions can also be exploited in the design of healable polymer blends, whereby electron-rich pyrenyl end-groups intercalate into designed chain-folds in polyimides derived from naphthalene-1,4,5,8-tetra-carboxylic dianhydride. Initial computational and spectroscopic studies on model compounds showed that a chain-fold comprising two diimide units linked by a triethylenedioxy chain provided the ideal geometry for... 

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