The Photo Physical Properties of Dendrimers Containing 1,4‐Dioxo‐3,6‐Diphenylpyrrolo[3,4‐c]pyrrole (DPP) as a Core

Abstract

Summary: The photophysical properties of dendrimers with 1,4‐dioxo‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole, also known as DPP, as a core were studied. DPP itself has a high quantum yield of fluorescence, as well as a high molar decadic absorption coefficient, ε (ε = 33 000 L · mol−1 · cm−1). The dendrimers, which differ by their substitution pattern, either at the nitrogen (DPPN) or at the carbon (DPPC), are studied in various solvents with different viscosity and solvent‐probe interaction and this for several generations and thus varying molecular volume. The stationary measurements show no difference in the absorption and emission spectra for the different generations nor a solvent‐effect. Single photon timing is used to determine the fluorescence lifetime, τ. For both dendrimers, the decay curves can be fitted to a mono‐exponential model. By means of fluorescence depolarization and fluorescence correlation spectroscopy, the hydrodynamic volumes (Vh) are determined. The results for both dendrimers as well as for both techniques are compared. The hydrodynamic radii of DPPN are similar when obtained by FCS compared with anisotropy. When the properties of the different dendrimers are compared, it can be shown that the hydrodynamic volumes of the first generation DPPC dendrimer are much larger compared to Vh of the DPPN dendrimers. The volumes for the third generation are comparable for both substitution patterns. magnified image

Improved Spectral Coverage and Fluorescence Quenching in Donor–acceptor Systems Involving Indolo[3‐2‐b]carbazole and Boron‐dipyrromethene or Diketopyrrolopyrrole

“…The redshift of the long wavelength absorption band and the fluorescence spectrum in toluene of polymer 2 suggests that, in analogy with triad 1 and polymer 1, the orbitals involved in this transition are to some extent delocalized between the ICZ and the DPP moieties, although to a smaller extent than in polymer 1. The less extensive delocalization, suggested by the smaller redshift of the absorption band versus that of DPP 1, is confirmed by the observation that while the average fluorescent rate constant of triad 1 and polymer 1 is much smaller than that of the corresponding BODIPY model compounds that of polymer 2 is close to the values that can be calculated for a diketopyrrolopyrrole (60). The broadening of the DPP-centered absorption band and the better vibrational fine structure of the fluorescence spectrum (compared to the absorption spectrum) suggest a change in molecular geometry, e.g.…”

“…The fluorescence rate constant <k f > calculated from the fluorescence decay time and the fluorescence quantum yield using Eq. (3) amounted to 2.7 9 10 8 s À1 , which is of the order of magnitude of the values observed for DPP (60).…”

Synthesis of diketopyrrolopyrrole (DPP) derivatives comprising bithiophene moieties

“…This method is derived from a modified literature procedure. 37,38 A solution of 3,6-bis(5 0 -bromo-4 0 -dodecyl-2,2 0 -bithiophen-5-yl)pyrrolo [3,4-c]pyrrole-1,4(2H,5H)-dione (13b) (0.4 mmol, 384 mg) and potassium carbonate (4 equiv, 1.6 mmol, 221 mg) in 12 ml anhydrous NMP was brought under argon atmosphere and was heated to 60 C. After 30 min at that temperature, 3 equiv of 1-(bromomethyl)-3,5-di-tert-butylbenzene (1.2 mmol, 340 mg) were added in one portion as a solution in 3 ml NMP (3,5-di-tert-butylbenzyl bromide is a white solid). The mixture was further mixed at 60 C during 2 h and then it was brought at 80 C and further stirred for 18.5 h. The mixture was cooled down to room temperature, washed with water (45 ml) and extracted with EtOAc (45 ml/30 ml/20 ml).…”

“…Derivative 4d was obtained from reaction of 3 with 3,5-bis-tert-butylbenzyl bromide (K 2 CO 3 , NMP, 140 C) in 74% yield. 37,38 Boc-protected DPP 4e was prepared from 3, N,N-dimethylaminopyridine (DMAP) and di-tert-butyl dicarbonate (THF, rt) in 68% yield. 9,22,39 Both DPPs (4d and 4e) were isolated by simple precipitation from MeOH and the bulky substituents render these DPP derivatives well soluble in organic solvents.…”

Poly(benzyl ether) dendrimers with strongly fluorescent distyrylbenzene cores as the fluorophores for peroxyoxalate chemiluminescence: insulating effect of dendritic structures on fluorescent sites

“…Although the reason is unclear at present, a variation in the fluorescence quantum yields with generation has been observed in another case of the Fréchet-type dendrimers with the fluorescent pyrrolopyrrole cores. 12 In the fluorescence excitation spectra, the small peaks in the shorter wavelength region at 285 nm increase with a generation increase (Figure 1). This is due to the singlet energy transfer from the dendron moieties to the core, 2, 3 and the efficiency of the energy Figure 1 and Table 1 transfer was estimated to be 0.16 for G3 by comparing the fluorescence quantum yields with excitation at 285 and 387 nm.…”