“Helter‐Skelter‐Like” Perylene Polyisocyanopeptides

Abstract

Exciton migration! Spectroscopic analyses and extensive molecular dynamics studies revealed a well-defined 4(1) helix in which the perylene molecules (see figure) form four "helter-skelter-like" overlapping pathways along which excitons and electrons can rapidly migrate.We report on a combined experimental and computational investigation on the synthesis and thorough characterization of the structure of perylene-functionalized polyisocyanides. Spectroscopic analyses and extensive molecular dynamics studies revealed a well defined 4(1) helix in which the perylene molecules form four "helter skelter-like" overlapping pathways along which excitons and electrons can rapidly migrate. The well-defined polymer scaffold stabilized by hydrogen bonding, to which the chromophores are attached, accounts for the precise architectural definition, and molecular stiffness observed for these molecules. Molecular-dynamics studies showed that the chirality present in these polymers is expressed in the formation of stable right-handed helices. The formation of chiral supramolecular structures is further supported by the measured and calculated bisignated Cotton effect. The structural definition of the chromophores aligned in one direction along the backbone is highlighted by the extremely efficient exciton migration rates and charge densities measured with Transient Absorption Spectroscopy.

Photophysical studies of poly-isocyanopeptide based photovoltaic blends

“…However, the chiral integrity and extreme rigidity of this molecule in a wide range of media, has been previously characterized by CD (see Schwartz et al [5]) and, most pertinently, in pery-PIC/P3HT blends in a paper by Palermo et al [18] It is therefore considered that the weight of the previous evidence on this matter is sufficiently convincing. We note that, whilst both having a predominantly hydrophilic character, the surface energies of the spectrosil substrates used for optical measurements may be somewhat different from the PEDOT:PSSplanarised substrates used for device work.…”

“…[2][3][4][5] The particular batch used in these experiments had a mean molecular weight of 9 × 10 5 g/mol, corresponding to an inferred mean chain length of around 180 nm. Regioregular poly(3-hexylthiophene) (P3HT) was purchased from Plextronics ("Plexcore HP", lot #05-10192).…”

“…The perylene units are arranged into chiral "helter-skelter" arrays, which do not form the kind of crystalline molecular aggregates often seen with perylene derivatives, but rather the units overlap continuously along the chain. [5] The resulting polymer is highly rigid, with persistence lengths of up to 76 nm, within an overall supramolecular structure of several hundred nanometers length. The chemical structure and bonding structure of the perylene-substituted polyisocyanide (pery-PIC) material are shown in Figure 1(a) and (b) respectively.…”

Energy transfer in pendant perylene diimide copolymers

“…While previous research has focused on utilising the π-π interactions of perylene monomers for supramolecular assembles that display exciton transport, [30][31][32][33] the use of polymers as a spatial scaffold with controlled inter-chromophore spacing for organising dye molecules is one potential method of allowing higher PDI concentrations without aggregation. Incorporating a low concentration emitter species enables FRET and minimises reabsorption losses.…”

Electronic Transport Properties of Ensembles of Perylene‐Substituted Poly‐isocyanopeptide Arrays

“…These polymeric systems have been synthesized via a nickel catalyzed polymerization reaction of isocyanide monomers, as described in detail elsewhere. [16][17][18] The polymer chains are ultra-stiff, as shown by a persistence length as high as 76 nm, and can have a contour length exceeding 12 mm. [19] The side chains of this polymers can be functionalized with various moieties such as carboxyl units, thiophene [20] or perylene-bis(dicarboximide) (PDI), [21,22] thereby offering control of spatial position over hundreds of nanometers.…”