Skip to main content
NCBI home page
ACS AuthorChoice logoLink to ACS AuthorChoice
. 2019 Jan 24;123(6):3433–3440. doi: 10.1021/acs.jpcc.8b12061

Excimer Formation in Carboxylic Acid-Functionalized Perylene Diimides Attached to Silicon Dioxide Nanoparticles

Jeffrey Gorman †, Raj Pandya †, Jesse R Allardice †, Michael B Price ‡, Timothy W Schmidt §, Richard H Friend †, Akshay Rao †, Nathaniel J L K Davis ‡,*
PMCID: PMC6428145  PMID: 30906497

Abstract

graphic file with name jp-2018-120619_0006.jpg

The creation of artificial light-harvesting complexes involves the ordered arrangement of chromophores in space. To guarantee efficient energy-transfer processes, organic dyes must be brought into close proximity, often leading to aggregation and the formation of excimer states. In recent years, the attachment of ligand-based chromophores to nanoparticles has also generated interest in relation to improved solar harvesting and spin-dependent electronic interactions such as singlet fission and upconversion. We explore the covalent attachment of two novel perylene-diimide (PDI) carboxylic acid ligands to silicon dioxide nanoparticles. This allows us to study electronic interactions between the ligands when attached to nanoparticles because these cannot couple to the wide band gap silicon dioxide. One of the synthesized PDI ligands has sterically hindering phenols in the bay position and undergoes minimal optical changes upon attachment, but the other forms an excimer state with a red-shifted and long-lived florescence. As such, molecular structure changes offer a method to tune weak and strong interactions between ligand layers on nanocrystal surfaces.

Introduction

To fully explore the versatility and functionality of solar energy, we need to create and characterize artificial light-harvesting systems that efficiently trap, transport, and convert solar energy to useable forms.1−3 These criteria are ensured in natural light-harvesting antenna systems by well-defined spatial arrangements of chromophores.4,5 The characterization of self-assemblies of organic chromophore dyes in nature has lead researchers to explore ways to exploit biomimetic supramolecular assemblies for tailored artificial photon processing, leading to functional molecular dye aggregates.1,6−10 As such, there is much interest in the self-assembly of organic dyes into highly organized aggregates with varying morphologies.11−18 Stabilization of these self-assembled superstructures is of great practical interest as it potentially improves aggregate stability, which in turn leads to improved light harvester functionality and longevity.

The performance of electronic and photonic processes in aromatic π–π stack materials depends strongly on the optical properties of the assembled chromophores.19−22 The exciton transport mechanisms in these materials23,24 can be understood according to a Frenkel exciton model where the electronic excitation is spread over many monomer units,1,25 which is similar to the quantum coherence found in natural photosynthetic systems.1,7 Organic dye chromophores have been used extensively in the fluorescence labeling of biomolecules. The standard approach of using a two-component system for wavelength shifting26 or fluorescence quenching27,28 via Förster resonance energy transfer (FRET)29 leads to complexities due to the multiple species involved. An alternative approach is to harness excimer emission from a single type of chromophore, which offers the advantages of a large stokes shift and long fluorescent lifetimes and potentially reduces background fluorescence at the desired detection wavelength, which is useful for time-resolved biosensing and bioimaging.30,31 As such, there is much interest in developing a clear understanding of the intramolecular processes that underlie excimer formation with the goal of eventually controlling them.

Perylene-diimides (PDIs) are one of the most heavily studied types of organic chromophores because of their range of hues from red to violet, their high molar absorptivity, their high photoluminescence quantum efficiency (PLQE), and their superior chemical, thermal, and photochemical stability.32−34 The tendency of PDIs to form self-assembled aggregates mean that they are versatile chromophores for the construction of novel functional supermolecular assemblies.34−36 By changing the functionality of both the imide and bay positions of the PDIs, various derivatives have been explored for applications in supramolecular assembly, liquid crystals, artificial light-harvesting systems, and organic photovoltaics.37,38 Aggregation can be decreased by functionalizing the diimide end-groups with bulky substituents that impede cofacial π–π interactions between the PDIs.34,39−41

Because of their extensive π-systems, at high concentrations, PDIs regularly form H or J aggregates,42 as well as excimer-like states.20,42−44 H-aggregates are characterized by face-on stacking, blue-shifted absorption, and quenched luminescence, whereas J aggregates form from edge-on stacking and have red-shifted luminescence.23,42 The role of the excimer state in PDIs has been extensively studied.20,45−49 The excimer-state emission generally comes from PDIs that exhibit H-aggregate formation facilitated by the addition of bulky groups attached to the imide positions of the PDI.44,48,50 Understanding the formation of these low-energy excimer states in molecular aggregates is of great interest11,51,52 as it could allow for increased functionality, stability, and device performance. The excimer state can act as an exciton trap site, decreasing the quantum yield or device performance if the trapping occurs at a faster rate than exciton diffusion,53,54 charge transfer, and transport.20,55

Recently, there has been an increase in research into the field of chromophore ligands attached to nanocrystal quantum dots56−59 or semiconductor scaffolds,60 in particular, the replacement of ligands that offer colloidal stability with ones that add additional optoelectronic properties. These ligands have potential applications for increased solar absorption, efficient transport of excitations, upconversion, and singlet fission.56−59 While studies of the interaction between the chromophores and the nanocrystal quantum dots directly lead to more potential applications, the growth of the field necessitates the study of the interactions between chromophores on the surface of nanoparticles (NPs) in the absence of the quantum dot interactions. We present a new method for the attachment of chromophores to small optically inert SiO2 NPs and study the interactions between two different PDI-based ligands. One of these ligands undergoes minimal optical changes upon attachment compared to the monomer form, whereas the other undergoes extensive aggregation and exhibits excimer-state emission. We find that steric hindrance is crucial to self-interaction in nanocrystal surface layers. This study presents a useful general methodology for characterizing interligand interactions for many other systems of interest.

Methods

All chemicals were purchased from Sigma-Aldrich and used as received.

Synthesis

Full synthetic details can be found in the Supporting Information.

Attachment of PDIs to Silicon Dioxide NPs

The surface of the silicon dioxide NPs (nanopowder, 10–20 nm particle size) was initially treated with (3-aminopropyl)triethoxysilane (APTES) 5% with 20 mg mL–1 NPs in toluene. The solution was left overnight, and the NPs were washed via flocculation with acetone (1:10 toluene/acetone) and centrifugation. The attachment of the PDI to the aminated silicon dioxide NPs was performed in chloroform with 1.1× molar equivalents of 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU) and 1× molar equivalents of N,N-diisopropylethylamine (DIPEA) compared to the PDI. The solution was left overnight, and the NPs were washed via flocculation with acetone and centrifugation.

Transmission Electron Microscopy

Transmission electron microscopy (TEM) samples were prepared by drop-casting an ca. 1 mg mL–1 silicon dioxide NP solution in octane on a TEM grid (200 mesh Cu, Agar Scientific). TEM measurements were conducted on a FEI Philips Tecnai 20 microscope, operating at 200 kV. Images were captured with a Gatan charge-coupled device (CCD) camera.

Steady-State Spectral Measurements

Absorption spectra were measured using a HP 8453 spectrophotometer. Dyes were dispersed in chloroform at a concentration of ca. 1 mg and a 1 cm path length was used. Photoluminescence measurements (1 mg in chloroform in a 1 mm cuvette) and powders including two-dimensional (2D) scans were measured on an Edinburgh Instruments FLS90 fluorimeter.

PLQE Measurements

Antenna complexes were placed in an integrating sphere and were photoexcited using a 405 or 532 nm continuous-wave laser. The laser and the emission signals were measured and quantified using a calibrated Andor iDus DU490A InGaAs detector for the determination of PLQE. PLQE was calculated as per de Mello et al.61

Transient Photoluminescence

To record the time-resolved emission scan or photoluminescence decay of the samples, time-correlated single-photon counting (TCSPC) was performed. Samples were excited with a pulsed laser (PicoQuant LDH400 40 MHz) at 375, 407, and 470 nm, with the resulting photoluminescence decay collected on a 500 mm focal length spectrograph (Princeton Instruments, SpectraPro2500i) with a cooled CCD camera. The instrument response was determined by scattering excitation light into the detector using a piece of frosted glass; a value of 265 ps was obtained. The excitation fluence for all samples was similar to that used in transient absorption measurements and maintained sufficiently low (∼6–12 μJ/cm2) to avoid nonlinear effects, for example, from exciton–exciton annihilation.

Picosecond Transient Absorption

The picosecond transient absorption (ps-TA) experiments were performed using an Yb-based amplified system (PHAROS, Light Conversion) providing 14.5 W at 1030 nm and 38 kHz repetition rate. The probe beam is generated by focusing a portion of the fundamental in a 4 mm YAG substrate and spans from 520 to 900 nm. The pump beam is generated by seeding a portion of the fundamental to a narrow band optical parametric oscillator (ORPHEUS-LYRA, Light Conversion). The pump pulse was set to 500 nm. The sample solutions were placed in 1 mm path length cuvettes (Helma). The pump and probe beams were focused to a size of 300 μm × 330 μm and 60 μm × 70 μm, respectively. The pump fluence was typically 45 μJ/cm2. The white light is delayed using a computer-controlled piezoelectric translation stage (Newport), and a sequence of probe pulses with and without the pump is generated using a chopper wheel (Thorlabs) on the pump beam. The probe pulse transmitted through the sample was detected by a silicon photodiode array camera (Stresing Entwicklungsbüro; visible monochromator 550 nm blazed grating).

Results and Discussion

To create our PDI ligands, we synthesize two different asymmetric PDIs with carboxylic acid functional groups. One imide substituent acts to increase the solubility of the perylene core, whereas the other offers the functionality. Having a long alkyl chain between the perylene core and the carboxylic acid ensures isolation of the spectral properties of the perylene core upon attachment to SiO2 NPs. PDI carboxylic acid ligands 4, a red PDI derivative, and 8, an orange PDI derivative, were synthesized as shown in Scheme 1. The orange PDI derivatives contain branched 7-tridecyl N-imide substituents to increase solubility and limit stacking, whereas the red PDI derivatives contain diisopropylphenyl N-imide chains to also give good solubility and limit stacking; tetraphenoxy substitution of the bay position induces torsion strain and further extends π-conjugation of the perylene core, resulting in the red-shifted absorption and emission.34

Scheme 1. Synthetic Reaction Scheme.

Scheme 1

Open in a new tab

(a) TsCl, Et3N, DCM, 0 °C, 3 h; then NaN3, DMF, 50 °C, 16 h, 60% over two steps; (b) CuSO4·5H2O, THPTA, HC≡CC(O)OEt, sodium l-ascorbate, THF/H2O, 50 °C, 1 h, 97%; (c) KOH, THF/H2O, 50 °C, 24 h, 88%; (d) TsCl, Et3N, DCM, 0 °C, 3 h; then NaN3, DMF, 50 °C, 16 h, 76% over two steps; (e) CuSO4·5H2O, THPTA, HC≡CC(O)OEt, sodium l-ascorbate, THF/H2O, 50 °C, 1 h, 97%; and (f) KOH, THF/H2O, 50 °C, 24 h, 78%.

The synthesis of the red PDI 4 began from previously reported62 alcohol-functionalized tetraphenoxy bay-substituted PDI 1. Single-step Jones oxidation of the alcohol to an acid was prohibited owing to additional hydrolysis of the imide positions. Instead, 1 was substituted with an azide to give 2 in two steps. Copper-catalyzed azide–alkyne cycloaddition (CuAAC) with ethyl propiolate yielded ester 3 in near unity followed by base-mediated deprotection to give 4 in near-quantitative yield. The orange PDI 6(62) was converted in a similar manner to yield the acid 8.

The optical properties of the synthesized PDI carboxylic acids (4 and 8) in solution exhibit absorption and emission spectra similar to model symmetrical PDIs with similar core structures33,41,63(Figure 1a). Photoluminescent quantum yields of the synthesized red 4 and orange 8 PDIs in chloroform were measured to be 95 and 90%, respectively, with luminescence lifetimes of 5.5 and 4.3 ns, respectively.

Figure 1.

Figure 1

Open in a new tab

Attachment of PDIs to SiO2 NPs. (a) Extinction coefficients and emission (under 500 nm excitation) of the synthesized PDI carboxylic acids. (b) Reaction diagram of the created PDI-coated SiO2 NPs: CHCl3, DIPEA, HBTU, RT, 12 h.

To attach the ligands to the surface of a NP, 15 nm SiO2 NPs were amine-functionalized via the addition of APTES in dichloromethane (DCM).64 The PDI ligands 4 and 8 were amide-coupled to amine-functionalized NPs using HBTU and DIPEA (Figure 1b). The NPs were then washed extensively via flocculation with acetone/centrifugation and redispersal to remove any unbound PDI. These PDI-attached NPs exhibited strong absorption and luminescence compared to the unfunctionalized SiO2 beads (Figure S1). The TEM images of the resulting particles (Figure S2) showed no structural difference between the PDI-attached and the clean SiO2 beads. However, the functionalized SiO2 NPs had higher colloidal stability in organic solvents (toluene and chloroform) as the PDI-coated particles would stay dispersed in solution for >8 h compared to the unfunctionalized SiO2 NPs that settled after 1 h. We assign this to the increased colloidal stability offered via the bulky attached ligands. Note that the SiO2 particles aggregate together upon drying, as seen in Figure S2, as such all measurements were performed in solution.

We see only minimal subtle shift in the absorption spectra upon attachment (Figure S3). In particular, the vibronic structure of the orange PDI’s absorption band changes, with a decrease in the strength of the 0,0 subband relative to the others. This difference is completely consistent with the effects of moderate aggregation and will be discussed later.39 By using the measured extinction coefficients of the PDI carboxylic acids and a known weight of SiO2 NPs, the attachment density of the PDIs to the SiO2 surface was calculated. The packing density of the red PDI on the SiO2 NPs was found to be 0.32 per nm2, whereas that of the orange PDI was found to be 1.0 per nm2 (assuming spherical SiO2 NPs with a Gaussian distribution between 10 and 20 nm). This gives attachments to the NPs of around 715 orange PDIs or 225 red PDIs. This difference is most likely the result of steric hindrance by the phenol substituents in the bay positions of the red PDI, preventing the higher loadings seen in the orange PDI NPs.

The difference in loading has a direct effect on the photoluminescence from the PDI NPs (Figure 2). The red PDI NPs show a very similar emission spectrum to the free monomer though we note the appearance of a second peak in its emission at 650 nm that appears to be vibronic in nature. However, the orange PDI NP shows a large red shift and broadened emission. The PLQEs of the red and orange PDI NPs were 18.5 and 6.5%, respectively. 2D excitation/emission scans (Figure 2c,d) do show that we only have a single species emitting in our NP systems, as at all excitation wavelengths (300–600 nm), they exhibit similar emission spectra.

Figure 2.

Figure 2

Open in a new tab

Absorption and emission data. (a) Absorption and emission of an orange PDI NP. (b) Absorption and emission of a red PDI NP. (c) 2D emission/excitation of an orange PDI NP. (d) 2D emission/excitation of an orange PDI NP.

To understand the nature of the intramolecular interactions within our PDI NPs, we perform time-resolved photoluminescence measurements using TCSPC. Upon attachment to the SiO2 NP, the red PDI shows no significant change in lifetime (5.5 ns unattached vs 5.6 ns with SiO2) and a very minimal red shift (Figures 3b,d and S4). It is worth noting that the decrease in PLQE associated with the red PDI upon attachment may be attributed to localized dark states which decrease the PLQE but do not change the measured emission lifetime. As such, we assign these observations to minimal aggregation of the red PDI monomer attached to the surface of the SiO2 NP. Compared to the unattached orange PDI 8, the attached orange PDI NP broadened and the red-shifted emission is longer-lived, 8.4 ns compared to 4.3 ns (Figures 3a,c and S4). In the first few 100 ps, there also appears to be a red shift in the spectra, indicating an energy transfer process to the lower-lying species. This long-lived red-shifted emission is characteristic of excimer emission in PDIs.17,30,31,45,46,54 On the basis of the measured PLQEs and lifetimes, we calculate a 30-fold decrease in the intrinsic radiative rate of the excimeric species compared to the unattached orange PDI 8, along with a 5-fold increase in the nonradiative rate. A similar but less drastic trend is seen with the red PDI NPs (Table S1). This is indicative of the H-aggregate behavior36—where the radiative transition moments of the aggregated molecules partially cancel each other, thus increasing the lifetime of spontaneous emission.

Figure 3.

Figure 3

Open in a new tab

Transient photoluminescence of PDI monomers (4 and 8) compared to PDI NPs. (a) Transient photoluminescence of the orange PDI monomer 8 in chloroform. (b) Transient photoluminescence of the red PDI monomer 4 in chloroform. (c) Transient photoluminescence of orange PDI NPs in chloroform. (d) Transient photoluminescence of red PDI NPs in chloroform.

The orange PDI exhibits a significant quenching of the photoluminescence quantum yield and red-shifting of emission on attachment to SiO2 NPs. A similar behavior has been observed in other PDI or acene systems upon aggregation, with the PL quenching attributed to excimer formation, charge transfer, or singlet fission.65−69 To examine the origin of this in PDI-orange–SiO2 NP composites, we carried out ps-TA spectroscopy.

The transient absorption spectrum in Figure 4 shows three main features: a positive band between 550 and 650 nm, a broad negative signal, 600–900 nm, and a sharp negative peak at 700 nm that rapidly decays. We overlay the steady-state absorption and emission spectra with the transient spectral dynamics (the region around 600 nm is cut due to an experimental artifact) in Figure 4b. The positive band consists of a combination of ground-state bleach and stimulated emission (near 550 nm). The broad negative signal (600–900 nm) corresponds to a photoinduced absorption (PIA) which is additionally overlaid with a sharp PIA peak at 700 nm. Within ∼2 ps, this sharp 700 nm PIA peak decays, as does the ground-state bleach/stimulated emission, and the broad PIA signal out to 900 nm rises.

Figure 4.

Figure 4

Open in a new tab

ps-TA spectra of the PDI-orange–glass composite. (a) Transient absorption spectrum of the PDI-orange–glass NP composite, following photoexcitation at 500 nm. The Δ/T signal is plotted as functions of probe wavelength and time delay between the pump and probe, where ΔT is the change in the transmission of the sample with/without the pump pulse and T is the transmission without the pump pulse. The positive signal between 500 and 600 nm corresponds to an overlap of the ground-state bleach and stimulated emission, and the broad negative signal is due PIA. (b) We overlap the TA spectrum at various time slices with the steady-state absorption (dark red) and emission (pink) spectra of the PDI–NP composites. The spectrum around 600 nm has been removed due to an experimental artifact. (c) Kinetics associated with GSB (550 nm), singlet PIA (705 nm), and broad excimer PIA (sampled at 840–850 nm) of the PDI–glass NP composites. The singlet PIA sits on top of the broad excimer PIA and disappears within 2000 fs, corresponding to a reduction in the GSB.

These observations, combined with the transient photoluminescence measurements, are consistent with a rapid evolution of photoexcited singlet excitons to excimers. Upon photoexcitation, an initial excited singlet exciton population (characterized by the sharp 700 nm PIA peak70 and enhanced stimulated emission) evolves in ∼2 ps to a different state with a broad PIA that persists and is the dominant species out to ∼1 ns, which is the timescale at which the broad emissive species is observed in the transient PL. [We note that triplet signals would be observed as sharp PIA peaks70 (similar to the singlet signals), but we do not see any evidence for this, only transfer from the initial sharp singlet PIA to the broad excimeric PIA.]

Thus, in the orange PDI SiO2 NP system, we are confident in assigning the red-shifted, long-lived, low PLQE emission with no absorption shift, to that of an excimer.23,24 Because of the large overlap between the PDI absorption and emission spectrum, rapid energy migration through the ligands is expected. The self-Förster radius,29 the distance at which 50% of all excitations lead to energy transfer from the one molecule to a like molecule was calculated, based on the absorbance and emission spectrum and the PLQE of our PDI monomers (4 and 8) in chloroform, to be 1.52 and 1.66 nm for the orange and red PDIs, respectively (the orientation factor was assumed to be 2/3). As the distance between PDIs on the SiO2 NPs is 1 nm for the orange PDIs and 1.8 nm for the red PDIs, it is likely that FRET strongly outcompetes monomer emission for the orange PDI systems and competes with monomer emission in the red system as the distance is close to that of the Förster radius. It is also worth noting that the hexyl alkyl chain linker is relatively flexible, which could allow some molecules to sit closer together. Over the time scale of monomer luminescence decay, the excitation should be able to sample a large number of sites, finding an aggregated or excimer forming site. The difference in luminescence properties of the PDI NPs is likely not solely due to the increased FRET efficiency but also to the fact that the red PDI has a more isolated luminophore core due to the out-of-plane phenols, which makes it less sensitive to microenvironments, aggregation, and the formation of excimer states.62,63 Migration of this excited state ends when the excitation reaches a site capable of excimer formation, which is more likely in the orange PDI NPs.

Conclusions

We present the synthesis of two novel PDI carboxylic acid derivatives for the use as chromophore ligands. These PDIs were covalently attached to the surface of SiO2 NPs. Where the perylene red derivative with its sterically hindering bay substituent phenol groups underwent only minor aggregation, the orange PDI was found to form excimer states with long-lived red-shifted emission. This work represents an initial study into the photophysical and aggregation effects of chromophore ligands when brought into close proximity as they attach to the surface of NPs. As such, this work represents an important study in the context of the rise of chromophore ligand nanocrystal systems.

Acknowledgments

J.G., R.P., J.R.A., A.R., and N.J.L.K.D. acknowledge funding from the EPSRC and the Winton Program for the Physics of sustainability. N.J.L.K.D. thanks the Ernest Oppenheimer Trust for a research fellowship. The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 670405). The data underlying this publication can be found at https://www.repository.cam.ac.uk/handle/1810/288077.

Supporting Information Available

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpcc.8b12061.

  • Digital images of the PDI NPs; TEM images of the PDI NPs; absorption and emission spectra of the attached and unattached PDIs; transient photoluminescent decays at peak emission of the attached and unattached PDIs; calculated radiative and nonradiative luminescence rates; and synthetic details of molecules 2, 3, 4, 6, 7, and 8 (PDF)

The authors declare no competing financial interest.

Supplementary Material

jp8b12061_si_001.pdf (1.2MB, pdf)

References

  1. Scholes G. D.; Fleming G. R.; Olaya-Castro A.; van Grondelle R. Lessons from Nature about Solar Light Harvesting. Nat. Chem. 2011, 3, 763–774. 10.1038/nchem.1145. [DOI] [PubMed] [Google Scholar]
  2. Melkozernov A. N.; Barber J.; Blankenship R. E. Light Harvesting in Photosystem I Supercomplexes†,‡. Biochemistry 2006, 45, 331–345. 10.1021/bi051932o. [DOI] [PubMed] [Google Scholar]
  3. Gust D.; Moore T. A.; Moore A. L. Mimicking Photosynthetic Solar Energy Transduction. Acc. Chem. Res. 2001, 34, 40–48. 10.1021/ar9801301. [DOI] [PubMed] [Google Scholar]
  4. Hu X.; Schulten K. How Nature Harvests Sunlight. Phys. Today 1997, 50, 28–34. 10.1063/1.881879. [DOI] [Google Scholar]
  5. Horton P.; Ruban A. V.; Walters R. G. Regulation of Light Harvesting in Green Plants. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1996, 47, 655–684. 10.1146/annurev.arplant.47.1.655. [DOI] [PubMed] [Google Scholar]
  6. Sung J.; Kim P.; Fimmel B.; Würthner F.; Kim D. Direct Observation of Ultrafast Coherent Exciton Dynamics in Helical π-Stacks of Self-Assembled Perylene Bisimides. Nat. Commun. 2015, 6, 8646. 10.1038/ncomms9646. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. McGaughey G. B.; Gagné M.; Rappé A. K. π-Stacking Interactions. J. Biol. Chem. 1998, 273, 15458–15463. 10.1074/jbc.273.25.15458. [DOI] [PubMed] [Google Scholar]
  8. Whitesides G. M.; Boncheva M. Beyond Molecules: Self-Assembly of Mesoscopic and Macroscopic Components. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 4769–4774. 10.1073/pnas.082065899. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Davis N. J. L. K.; MacQueen R. W.; Jones S. T. E.; Orofino-Pena C.; Cortizo-Lacalle D.; Taylor R. G. D.; Credgington D.; Skabara P. J.; Greenham N. C. Star-shaped fluorene-BODIPY oligomers: versatile donor-acceptor systems for luminescent solar concentrators. J. Mater. Chem. C 2017, 5, 1952–1962. 10.1039/c6tc05298c. [DOI] [Google Scholar]
  10. Pandya R.; MacQueen R. W.; Rao A.; Davis N. J. L. K. Simple and Robust Panchromatic Light Harvesting Antenna Composites via FRET Engineering in Solid State Host Matrices. J. Phys. Chem. C 2018, 122, 22330–22338. 10.1021/acs.jpcc.8b07998. [DOI] [Google Scholar]
  11. Wasielewski M. R. Self-Assembly Strategies for Integrating Light Harvesting and Charge Separation in Artificial Photosynthetic Systems. Acc. Chem. Res. 2009, 42, 1910–1921. 10.1021/ar9001735. [DOI] [PubMed] [Google Scholar]
  12. Ziessel R.; Harriman A. Artificial Light-Harvesting Antennae: Electronic Energy Transfer by Way of Molecular Funnels. Chem. Commun. 2011, 47, 611–631. 10.1039/c0cc02687e. [DOI] [PubMed] [Google Scholar]
  13. Choi M.-S.; Yamazaki T.; Yamazaki I.; Aida T. Bioinspired Molecular Design of Light-Harvesting Multiporphyrin Arrays. Angew. Chem., Int. Ed. 2003, 43, 150–158. 10.1002/anie.200301665. [DOI] [PubMed] [Google Scholar]
  14. Imahori H. Giant Multiporphyrin Arrays as Artificial Light-Harvesting Antennas. J. Phys. Chem. B 2004, 108, 6130–6143. 10.1021/jp038036b. [DOI] [PubMed] [Google Scholar]
  15. Calzaferri G.; Huber S.; Maas H.; Minkowski C. Host-Guest Antenna Materials. Angew. Chem., Int. Ed. 2003, 42, 3732–3758. 10.1002/anie.200300570. [DOI] [PubMed] [Google Scholar]
  16. Webber S. E. Photon-Harvesting Polymers. Chem. Rev. 1990, 90, 1469–1482. 10.1021/cr00106a005. [DOI] [Google Scholar]
  17. Schwartz E.; Palermo V.; Finlayson C. E.; Huang Y.-S.; Otten M. B. J.; Liscio A.; Trapani S.; González-Valls I.; Brocorens P.; Cornelissen J. J. L. M.; et al. ″Helter-Skelter-Like″ Perylene Polyisocyanopeptides. Chem.—Eur. J. 2009, 15, 2536–2547. 10.1002/chem.200801746. [DOI] [PubMed] [Google Scholar]
  18. Adeyemi O. O.; Malinovskii V. L.; Biner S. M.; Calzaferri G.; Häner R. Photon Harvesting by Excimer-Forming Multichromophores. Chem. Commun. 2012, 48, 9589. 10.1039/c2cc34183b. [DOI] [PubMed] [Google Scholar]
  19. Struijk C. W.; Sieval A. B.; Dakhorst J. E. J.; van Dijk M.; Kimkes P.; Koehorst R. B. M.; Donker H.; Schaafsma T. J.; Picken S. J.; van de Craats A. M.; et al. Liquid Crystalline Perylene Diimides: Architecture and Charge Carrier Mobilities. J. Am. Chem. Soc. 2000, 122, 11057–11066. 10.1021/ja000991g. [DOI] [Google Scholar]
  20. Chen Z.; Stepanenko V.; Dehm V.; Prins P.; Siebbeles L. D. A.; Seibt J.; Marquetand P.; Engel V.; Würthner F. Photoluminescence and Conductivity of Self-Assembled π-π Stacks of Perylene Bisimide Dyes. Chem.—Eur. J. 2007, 13, 436–449. 10.1002/chem.200600889. [DOI] [PubMed] [Google Scholar]
  21. Horowitz G.; Kouki F.; Spearman P.; Fichou D.; Nogues C.; Pan X.; Garnier F. Evidence for N-Type Conduction in a Perylene Tetracarboxylic Diimide Derivative. Adv. Mater. 1996, 8, 242–245. 10.1002/adma.19960080312. [DOI] [Google Scholar]
  22. Fechtenko A.; Mu K.; Moons E.; Friend R. H.; Mackenzie J. D. Self-Organized Discotic Liquid Crystals for High-Efficiency Organic Photovoltaics. Science 2001, 293, 1119–1122. 10.1126/science.293.5532.1119. [DOI] [PubMed] [Google Scholar]
  23. Spano F. C. The spectral signatures of Frenkel polarons in H- and J-aggregates. Acc. Chem. Res. 2010, 43, 429–439. 10.1021/ar900233v. [DOI] [PubMed] [Google Scholar]
  24. Scholes G. D.; Rumbles G. Erratum: Excitons in nanoscale systems. Nat. Mater. 2006, 5, 920. 10.1038/nmat1756. [DOI] [PubMed] [Google Scholar]
  25. McRae E. G.; Kasha M. Enhancement of Phosphorescence Ability upon Aggregation of Dye Molecules. J. Chem. Phys. 1958, 28, 721–722. 10.1063/1.1744225. [DOI] [Google Scholar]
  26. Tyagi S.; Marras S. A. E.; Kramer F. R. Wavelength-Shifting Molecular Beacons. Nat. Biotechnol. 2000, 18, 1191–1196. 10.1038/81192. [DOI] [PubMed] [Google Scholar]
  27. Tyagi S.; Kramer F. R. Molecular Beacons: Probes That Fluoresce Upon Hybridization. Nat. Biotechnol. 1996, 14, 303–308. 10.1038/nbt0396-303. [DOI] [PubMed] [Google Scholar]
  28. Bouquin N.; Malinovskii V. L.; Häner R. Highly Efficient Quenching of Excimer Fluorescence by Perylene Diimide in DNA. Chem. Commun. 2008, 1974. 10.1039/b802193g. [DOI] [PubMed] [Google Scholar]
  29. Förster T. Transfer Mechanisms of Electronic Excitation. Discuss. Faraday Soc. 1959, 27, 7–17. 10.1039/df9592700007. [DOI] [Google Scholar]
  30. Wang Y.; Chen J.; Chen Y.; Li W.; Yu C. Polymer-Induced Perylene Probe Excimer Formation and Selective Sensing of DNA Methyltransferase Activity through the Monomer-Excimer Transition. Anal. Chem. 2014, 86, 4371–4378. 10.1021/ac500195u. [DOI] [PubMed] [Google Scholar]
  31. Wang K.-R.; Yang Z.-B.; Li X.-L. High Excimer-State Emission of Perylene Bisimides and Recognition of Latent Fingerprints. Chem.—Eur. J. 2015, 21, 5680–5684. 10.1002/chem.201406447. [DOI] [PubMed] [Google Scholar]
  32. Neuteboom E. E.; Meskers S. C. J.; Meijer E. W.; Janssen R. A. J. Photoluminescence of Self-Organized Perylene Bisimide Polymers. Macromol. Chem. Phys. 2004, 205, 217–222. 10.1002/macp.200300044. [DOI] [Google Scholar]
  33. Würthner F.; Sautter A.; Schilling J. Synthesis of Diazadibenzoperylenes and Characterization of Their Structural, Optical, Redox, and Coordination Properties. J. Org. Chem. 2002, 67, 3037–3044. 10.1021/jo011133l. [DOI] [PubMed] [Google Scholar]
  34. Würthner F. Perylene Bisimide Dyes as Versatile Building Blocks for Functional Supramolecular Architectures. Chem. Commun. 2004, 1564–1579. 10.1039/b401630k. [DOI] [PubMed] [Google Scholar]
  35. Würthner F.; Chen Z.; Dehm V.; Stepanenko V. One-Dimensional Luminescent Nanoaggregates of Perylene Bisimides. Chem. Commun. 2006, 1188. 10.1039/b517020f. [DOI] [PubMed] [Google Scholar]
  36. Yasarapudi V. B.; Frazer L.; Webb J. E. A.; Gallaher J. K.; Macmillan A.; Falber A.; Thordarson P.; Schmidt T. W. Competing Energy Transfer Pathways in a Five-Chromophore Perylene Array. J. Phys. Chem. C 2018, 122, 13937–13943. 10.1021/acs.jpcc.8b01084. [DOI] [Google Scholar]
  37. Elemans J. A. A. W.; van Hameren R.; Nolte R. J. M.; Rowan A. E. Molecular Materials by Self-Assembly of Porphyrins, Phthalocyanines, and Perylenes. Adv. Mater. 2006, 18, 1251–1266. 10.1002/adma.200502498. [DOI] [Google Scholar]
  38. Huang C.; Barlow S.; Marder S. R. Perylene-3,4,9,10-Tetracarboxylic Acid Diimides: Synthesis, Physical Properties, and Use in Organic Electronics. J. Org. Chem. 2011, 76, 2386–2407. 10.1021/jo2001963. [DOI] [PubMed] [Google Scholar]
  39. Ford W. E.; Kamat P. V. Photochemistry of 3,4,9,10-perylenetetracarboxylic dianhydride dyes. 3. Singlet and triplet excited-state properties of the bis(2,5-di-tert-butylphenyl)imide derivative. J. Phys. Chem. 1987, 91, 6373–6380. 10.1021/j100309a012. [DOI] [Google Scholar]
  40. Syebold G.; Wagenblast G. New Perylene and Violanthrone Dyestuffs for Fluorescent Collectors. Dyes Pigm. 1989, 11, 303–317. 10.1016/0143-7208(89)85048-x. [DOI] [Google Scholar]
  41. Langhals H.; Ismael R.; Yürük O. Persistent Fluorescence of Perylene Dyes by Steric Inhibition of Aggregation. Tetrahedron 2000, 56, 5435–5441. 10.1016/s0040-4020(00)00452-x. [DOI] [Google Scholar]
  42. Würthner F.; Kaiser T. E.; Saha-Möller C. R. J-Aggregates: From Serendipitous Discovery to Supramolecular Engineering of Functional Dye Materials. Angew. Chem., Int. Ed. 2011, 50, 3376–3410. 10.1002/anie.201002307. [DOI] [PubMed] [Google Scholar]
  43. Yagai S.; Seki T.; Karatsu T.; Kitamura A.; Würthner F. Transformation from H- to J-Aggregated Perylene Bisimide Dyes by Complexation with Cyanurates. Angew. Chem., Int. Ed. 2008, 47, 3367–3371. 10.1002/anie.200705385. [DOI] [PubMed] [Google Scholar]
  44. Yoo H.; Yang J.; Yousef A.; Wasielewski M. R.; Kim D. Excimer Formation Dynamics of Intramolecular π-Stacked Perylenediimides Probed by Single-Molecule Fluorescence Spectroscopy. J. Am. Chem. Soc. 2010, 132, 3939–3944. 10.1021/ja910724x. [DOI] [PubMed] [Google Scholar]
  45. Brown K. E.; Salamant W. A.; Shoer L. E.; Young R. M.; Wasielewski M. R. Direct Observation of Ultrafast Excimer Formation in Covalent Perylenediimide Dimers Using Near-Infrared Transient Absorption Spectroscopy. J. Phys. Chem. Lett. 2014, 5, 2588–2593. 10.1021/jz5011797. [DOI] [PubMed] [Google Scholar]
  46. Giaimo J. M.; Lockard J. V.; Sinks L. E.; Scott A. M.; Wilson T. M.; Wasielewski M. R. Excited Singlet States of Covalently Bound, Cofacial Dimers and Trimers of Perylene-3,4:9,10-Bis(Dicarboximide)S. J. Phys. Chem. A 2008, 112, 2322–2330. 10.1021/jp710847q. [DOI] [PubMed] [Google Scholar]
  47. Lefler K. M.; Brown K. E.; Salamant W. A.; Dyar S. M.; Knowles K. E.; Wasielewski M. R. Triplet State Formation in Photoexcited Slip-Stacked Perylene-3,4:9,10-bis(dicarboximide) Dimers on a Xanthene Scaffold. J. Phys. Chem. A 2013, 117, 10333–10345. 10.1021/jp4083008. [DOI] [PubMed] [Google Scholar]
  48. Fink R. F.; Seibt J.; Engel V.; Renz M.; Kaupp M.; Lochbrunner S.; Zhao H.-M.; Pfister J.; Würthner F.; Engels B. Exciton Trapping in π-Conjugated Materials: A Quantum-Chemistry-Based Protocol Applied to Perylene Bisimide Dye Aggregates. J. Am. Chem. Soc. 2008, 130, 12858–12859. 10.1021/ja804331b. [DOI] [PubMed] [Google Scholar]
  49. Schubert A.; Settels V.; Liu W.; Würthner F.; Meier C.; Fink R. F.; Schindlbeck S.; Lochbrunner S.; Engels B.; Engel V. Ultrafast Exciton Self-Trapping upon Geometry Deformation in Perylene-Based Molecular Aggregates. J. Phys. Chem. Lett. 2013, 4, 792–796. 10.1021/jz4000752. [DOI] [PubMed] [Google Scholar]
  50. Zhang X.; Chen Z.; Würthner F. Morphology Control of Fluorescent Nanoaggregates by Co-Self-Assembly of Wedge- and Dumbbell-Shaped Amphiphilic Perylene Bisimides. J. Am. Chem. Soc. 2007, 129, 4886–4887. 10.1021/ja070994u. [DOI] [PubMed] [Google Scholar]
  51. McHale J. L. Hierarchal Light-Harvesting Aggregates and Their Potential for Solar Energy Applications. J. Phys. Chem. Lett. 2012, 3, 587–597. 10.1021/jz3000678. [DOI] [PubMed] [Google Scholar]
  52. Yasarapudi V. B.; Frazer L.; Davis N. J. L. K.; Booker E. P.; Macmillan A.; Gallaher J. K.; Roberts D.; Perrier S.; Schmidt T. W. Optimization of Energy Transfer in a Polymer Composite with Perylene Chromophores. J. Mater. Chem. C 2018, 6, 7333–7342. 10.1039/c8tc02457j. [DOI] [Google Scholar]
  53. Ye T.; Singh R.; Butt H.-J.; Floudas G.; Keivanidis P. E. Effect of Local and Global Structural Order on the Performance of Perylene Diimide Excimeric Solar Cells. ACS Appl. Mater. Interfaces 2013, 5, 11844–11857. 10.1021/am4035416. [DOI] [PubMed] [Google Scholar]
  54. Lim J. M.; Kim P.; Yoon M.-C.; Sung J.; Dehm V.; Chen Z.; Würthner F.; Kim D. Exciton delocalization and dynamics in helical π-stacks of self-assembled perylene bisimides. Chem. Sci. 2013, 4, 388–397. 10.1039/c2sc21178e. [DOI] [Google Scholar]
  55. Howard I. A.; Laquai F.; Keivanidis P. E.; Friend R. H.; Greenham N. C. Perylene Tetracarboxydiimide as an Electron Acceptor in Organic Solar Cells: A Study of Charge Generation and Recombination. J. Phys. Chem. C 2009, 113, 21225–21232. 10.1021/jp907633g. [DOI] [Google Scholar]
  56. Huang Z.; Li X.; Yip B. D.; Rubalcava J. M.; Bardeen C. J.; Tang M. L. Nanocrystal Size and Quantum Yield in the Upconversion of Green to Violet Light with CdSe and Anthracene Derivatives. Chem. Mater. 2015, 27, 7503–7507. 10.1021/acs.chemmater.5b03731. [DOI] [Google Scholar]
  57. Huang Z.; Tang M. L. Designing Transmitter Ligands That Mediate Energy Transfer between Semiconductor Nanocrystals and Molecules. J. Am. Chem. Soc. 2017, 139, 9412–9418. 10.1021/jacs.6b08783. [DOI] [PubMed] [Google Scholar]
  58. Mongin C.; Garakyaraghi S.; Razgoniaeva N.; Zamkov M.; Castellano F. N. Direct Observation of Triplet Energy Transfer from Semiconductor Nanocrystals. Science 2016, 351, 369–372. 10.1126/science.aad6378. [DOI] [PubMed] [Google Scholar]
  59. Davis N. J. L. K.; Allardice J. R.; Xiao J.; Petty A. J. II; Greenham N. C.; Anthony J. E.; Rao A. Singlet Fission and Triplet Transfer to PbS Quantum Dots in TIPS-Tetracene Carboxylic Acid Ligands. J. Phys. Chem. Lett. 2018, 9, 1454–1460. 10.1021/acs.jpclett.8b00099. [DOI] [PubMed] [Google Scholar]
  60. Banerjee T.; Hill S. P.; Hermosilla-Palacios M. A.; Piercy B. D.; Haney J.; Casale B.; DePrince A. E.; Losego M. D.; Kleiman V. D.; Hanson K. Diphenylisobenzofuran Bound to Nanocrystalline Metal Oxides: Excimer Formation, Singlet Fission, Electron Injection, and Low Energy Sensitization. J. Phys. Chem. C 2018, 122, 28478–28490. 10.1021/acs.jpcc.8b08599. [DOI] [Google Scholar]
  61. de Mello J. C.; Wittmann H. F.; Friend R. H. An Improved Experimental Determination of External Photoluminescence Quantum Efficiency. Adv. Mater. 1997, 9, 230–232. 10.1002/adma.19970090308. [DOI] [Google Scholar]
  62. Davis N. J. L. K.; MacQueen R. W.; Roberts D. A.; Danos A.; Dehn S.; Perrier S.; Schmidt T. W. Energy Transfer in Pendant Perylene Diimide Copolymers. J. Mater. Chem. C 2016, 4, 8270–8275. 10.1039/c6tc02555b. [DOI] [Google Scholar]
  63. Würthner F. Perylene Bisimide Dyes as Versatile Building Blocks for Functional Supramolecular Architectures. Chem. Commun. 2004, 1564–1579. 10.1039/b401630k. [DOI] [PubMed] [Google Scholar]
  64. Pasternack R. M.; Rivillon Amy S.; Chabal Y. J. Attachment of 3-(Aminopropyl)Triethoxysilane on Silicon Oxide Surfaces: Dependence on Solution Temperature. Langmuir 2008, 24, 12963–12971. 10.1021/la8024827. [DOI] [PubMed] [Google Scholar]
  65. Le A. K.; Bender J. A.; Arias D. H.; Cotton D. E.; Johnson J. C.; Roberts S. T. Singlet Fission Involves an Interplay between Energetic Driving Force and Electronic Coupling in Perylenediimide Films. J. Am. Chem. Soc. 2018, 140, 814–826. 10.1021/jacs.7b11888. [DOI] [PubMed] [Google Scholar]
  66. Manikowski H.; Wróbel D.; Lewandowska K.; Graja A. Charge Transfer in PDI-Derived Systems Studied with Light-Induced Electron Spin Resonance. Synth. Met. 2007, 157, 363–367. 10.1016/j.synthmet.2007.04.003. [DOI] [Google Scholar]
  67. Ley D.; Guzman C. X.; Adolfsson K. H.; Scott A. M.; Braunschweig A. B. Cooperatively Assembling Donor-Acceptor Superstructures Direct Energy into an Emergent Charge Separated State. J. Am. Chem. Soc. 2014, 136, 7809–7812. 10.1021/ja5015053. [DOI] [PubMed] [Google Scholar]
  68. Le A. K.; Bender J. A.; Roberts S. T. Slow Singlet Fission Observed in a Polycrystalline Perylenediimide Thin Film. J. Phys. Chem. Lett. 2016, 7, 4922–4928. 10.1021/acs.jpclett.6b02320. [DOI] [PubMed] [Google Scholar]
  69. Dover C. B.; Gallaher J. K.; Frazer L.; Tapping P. C.; Petty A. J.; Crossley M. J.; Anthony J. E.; Kee T. W.; Schmidt T. W. Endothermic Singlet Fission Is Hindered by Excimer Formation. Nat. Chem. 2018, 10, 305–310. 10.1038/nchem.2926. [DOI] [PubMed] [Google Scholar]
  70. Tilley A. J.; Pensack R. D.; Lee T. S.; Djukic B.; Scholes G. D.; Seferos D. S. Ultrafast Triplet Formation in Thionated Perylene Diimides. J. Phys. Chem. C 2014, 118, 9996–10004. 10.1021/jp503708d. [DOI] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

jp8b12061_si_001.pdf (1.2MB, pdf)

Articles from The Journal of Physical Chemistry. C, Nanomaterials and Interfaces are provided here courtesy of American Chemical Society

RESOURCES