Localization/Delocalization of Charges in Bay-Linked Perylene Bisimides

Dynamics of reduced perylene bisimide cyclophane redox species by ultrafast spectroelectrochemistry

Charged molecules play essential roles in many natural and artificial functional processes, ranging from photosynthesis to photovoltaics to chemical reactions and more. It is often difficult to identify the optical dynamic properties of relevant redox species because they cannot be easily prepared, their spectra overlap, or they evolve on a femtosecond timescale. Here, we address these challenges by combining spectroelectrochemistry, ultrafast transient absorption spectroscopy, and suitable data analysis. We illustrate the method with the various redox species of a cyclophane composed of two perylene bisimide subunits. While singular-value decomposition is a well-established tool in the analysis of time-dependent spectra of a single molecular species, we here use it additionally to separate transient maps of individual redox species. This is relevant because at any specific applied electrochemical potential, several redox species coexist in the ensemble, and our procedure allows disentangling their spectroscopic response. In the second step, global analysis is then employed to retrieve the excited-state lifetimes and decay-associated difference spectra. Our approach is generally suitable for unraveling ultrafast dynamics in materials featuring charge-transfer processes.

Tetraazacoronenes and Their Dimers, Trimers and Tetramers

Tetraazacoronenes were synthesized from bay-functionalized tetraazaperylenes by Zr-mediated cyclization and four-fold Suzuki-Miyaura cross coupling. In the Zr-mediated approach, an η4 -cyclobutadiene-zirconium(IV) complex was isolated as an intermediate to cyclobutene-annulated derivatives. Using bis(pinacolatoboryl)vinyltrimethylsilane as a C2 building block gave the tetraazacoronene target compound along with the condensed azacoronene dimer as well as higher oligomers. The series of extended azacoronenes show highly resolved UV/Vis absorption bands with increased extinction coefficients for the extended aromatic cores and fluorescence quantum yields of up to 80 % at 659 nm.

A Symmetry-Broken Charge-Separated State in the Marcus Inverted Region

We report a long-lived charge-separated state in a chromophoric pair (DC-PDI₂ ) that uniquely integrates the advantages of fundamental processes of photosynthetic reaction centers: i) Symmetry-breaking charge-separation (SB-CS) and ii) Marcus-inverted-region dependence. The near-orthogonal bichromophoric DC-PDI₂ manifests an ultrafast evolution of the SB-CS state with a time constant of τ S B - C S ${{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ =0.35±0.02 ps and a slow charge recombination (CR) kinetics with τ C R ${{\tau }_{{\rm C}{\rm R}}}$ =4.09±0.01 ns in ACN. The rate constant of CR of DC-PDI₂ is 11 686 times slower than SB-CS in ACN, as the CR of the PDI radical ion-pair occurs in the deep inverted region of the Marcus parabola ( - Δ G C R ${{-{\rm \Delta }G}_{{\rm C}{\rm R}}}$ >λ). In contrast, an analogous benzyloxy (BnO)-substituted DC-BPDI₂ showcases a ≈10-fold accelerated CR kinetics with τ C R / τ S B - C S ${{\tau }_{{\rm C}{\rm R}}/{\tau }_{{\rm S}{\rm B}-{\rm C}{\rm S}}}$ lowering to ≈1536 in ACN, by virtue of a decreased CR driving force. The present investigation demonstrates a control of molecular engineering to tune the energetics and kinetics of the SB-CS material, which is essential for next-generation optoelectronic devices.

Isolation and Structural Characterization of Regioisomers of Dibrominated Terrylene Diimides

Diverse applications of rylenediimides are attributed to the accessibility of simple methodologies to obtain versatile halogenated precursors. Terrylene diimides are important molecular platforms to achieve materials with NIR absorption and emission. In this work, we present a simple synthesis for the hitherto unknown di- and tribromo-TDIs. Regioisomerically pure dibromo TDIs, including an elusive 1,14-derivative, could be successfully isolated and structurally characterized along with tribromo-TDI. The utility of these bromo derivatives has also been demonstrated with a redox anchoring.

Influence of N-Substituents on Photovoltaic Properties of Singly Bay-Linked Dimeric Perylene Diimides

The influence of N-substituents on the photovoltaic properties of singly bay-linked perylene diimides (diPDIs) was systematically investigated to understand the aromatic-aliphatic balance, which is beneficial for achieving high device performance in organic photovoltaic (OPV) systems. The synthesis of various N-substituted diPDIs was successfully achieved using a newly developed one-step procedure, resulting in sufficiently high yields. Detailed investigations of seven variants of diPDIs demonstrated that the primary alkyl substituents, particularly the 2-ethylhexyl group, induce the self-organized growth of thin films with high crystallinity. This is beneficial for enhancing the device performance of bulk heterojunction (BHJ) systems. The results presented herein reveal the important roles of alkyl side chains as hydrophobic solubilizing auxiliaries or primary determinants in the control of the active layer nanomorphology. This offers a valuable guideline that is essential for developing high-performance organic semiconductor materials for future practical applications.

Elucidating π–π interaction-induced extension effect in sandwich phthalocyaninato compounds

π–π interaction-linked extension in the perpendicular direction to the monomers and corresponding effect on nonlinear optic properties have been clearly disclosed over the multiple-decker sandwich-type phthalocyaninato metal compounds.

Functional Block Copolymers Carrying One Double-Stranded Ladderphane and One Single-Stranded Block in a Facile Metathesis Cyclopolymerization Procedure

In order to improve the poor film-forming ability of polymeric ladderphane, di-block copolymers containing perylene diimide (PDI)-linked double-stranded poly(1,6-heptadiyne) ladderphane and branched alkyl side chains modified single-stranded poly(1,6-heptadiyne) were synthesized by metathesis cyclopolymerization (MCP) using Grubbs third-generation catalyst (Ru-III) in tetrahydrofuran solvent. The first block containing the ladderphane structure leads to higher thermal-stability, wider UV-vis absorption, lower LUMO level and ladderphane-induced rigidity and poor film-forming ability. The second block containing long alkyl chains is crucial for the guarantee of excellent film-forming ability. By comparing the effect of ladderphane structure on the resulted copolymers, single-stranded poly(1,6-heptadiyne) derivatives with PDI pedant were also processed. The structures of copolymers were proved by 1H NMR and gel permeation chromatography, electrochemical, photophysical, and thermal-stability performance were achieved by cyclic voltammetry (CV), UV-visible spectroscopy and thermogravimetric analysis (TGA) measurements. According to the experiment results, both copolymers possessed outstanding film-forming ability, which cannot be realized by small PDI molecules and oligomers. And they can serve as a superior candidate as for n-type materials, especially for their relatively wide range of light absorption (λ = 200~800 nm), and lower LUMO level (-4.3 and -4.0 eV).

One- and two-photon absorption properties of quadrupolar thiophene-based dyes with acceptors of varying strengths

The one-photon (1P) and two-photon (2P) absorption properties of three quadrupolar dyes, featuring thiophene as a donor and acceptors of varying strengths, are determined by a combination of experimental and computational methods employing the density functional theory (DFT). The emission shifts in different solvents are well reproduced by time-dependent DFT calculations with the linear response and state specific approaches in the framework of the polarizable continuum model. The calculations show that the energies of both 1P- and 2P-active states decrease with an increase of the strength of the acceptor. The 2P absorption cross-sections predicted by the response theory are accounted for by considering just one intermediate state (S1) in the sum-over-states formulation. For the chromophore featuring the stronger acceptor, the energetic positions of the 1P- and 2P-active states prevent the exploitation of the theoretically predicted very high 2P activity due to the competing 1P absorption into the S1 state.

Synthesis, photophysical and electronic properties of tetra-donor- or acceptor-substituted ortho-perylenes displaying four reversible oxidations or reductions

Via regioselective Ir-catalyzed C-H borylation and subsequent reactions (i.e., via Br4-Per or (BF3K)4-Per intermediates), we have introduced strong π-donors and acceptors at the 2,5,8,11-positions of perylene leading to unusual properties. Thus, incorporation of four donor diphenylamine (DPA) or four acceptor Bmes2 (mes = 2,4,6-Me3C6H2) moieties yields novel compounds which can be reversibly oxidized or reduced four times, respectively, an unprecedented behavior for monomeric perylene derivatives. Spectroelectrochemical measurements show NIR absorptions up to 3000 nm for the mono-cation radical of (DPA)4-Per and a strong electronic coupling over the perylene bridge was observed indicative of fully delocalized Robin-Day Class III behavior. Both (DPA)4-Per and (Bmes2)4-Per derivatives possess unusually long intrinsic singlet lifetimes (τ 0), e.g., 94 ns for the former one. The compounds are emissive in solution, thin films, and the solid state, with apparent Stokes shifts that are exceptionally large for perylene derivatives. Transient absorption measurements on (DPA)4-Per reveal an additional excited state, with a long lifetime of 500 μs, which sensitizes singlet oxygen effectively.

Tetrahydroxy-Perylene Bisimide Embedded in a Zinc Oxide Thin Film as an Electron-Transporting Layer for High-Performance Non-Fullerene Organic Solar Cells

By introduction of four hydroxy (HO) groups into the two perylene bisimide (PBI) bay areas, new HO‐PBI ligands were obtained which upon deprotonation can complex Zn^II ions and photosensitize semiconductive zinc oxide thin films. Such coordination is beneficial for dispersing PBI photosensitizer molecules evenly into metal oxide films to fabricate organic–inorganic hybrid interlayers for organic solar cells. Supported by the photoconductive effect of the ZnO:HO‐PBI hybrid interlayers, improved electron collection and transportation is achieved in fullerene and non‐fullerene polymer solar cell devices, leading to remarkable power conversion efficiencies of up to 15.95 % for a non‐fullerene based organic solar cell.

Formation of the Charge-Localized Dimer Radical Cation of 2-Ethyl-9,10-dimethoxyanthracene in Solution Phase

Although dimer radical ions of aromatic molecules in the liquid-solution phase have been intensely studied, the understanding of charge-localized dimers, in which the extra charge is localized in a single monomer unit instead of being shared between two monomer units, is still elusive. In this study, the formation of a charge-localized dimer radical cation of 2-ethyl-9,10-dimethoxyanthracene (DMA), (DMA)₂ ^.+ is investigated by transient absorption (TA) and time-resolved resonance Raman (TR³ ) spectroscopic methods combined with a pulse radiolysis technique. Visible- and near-IR TA signals in highly concentrated DMA solutions supported the formation of non-covalent (DMA)₂ ^.+ by association of DMA and DMA^.+ . TR³ spectra obtained from 30 ns to 300 μs time delays showed that the major bands are quite similar to those of DMA except for small transient bands, even at 30 ns time delay, suggesting that the positive charge of non-covalent (DMA)₂ ^.+ is localized in a single monomer unit. From DFT calculations for (DMA)₂ ^.+ , our TR³ spectra showed the best agreement with the calculated Raman spectrum of charge-localized edge-to-face T-shaped (DMA)₂ ^.+ , termed DT^.+ , although the charge-delocalized asymmetric π-stacked face-to-face (DMA)₂ ^.+ , termed DF3^.+ , is the most stable structure of (DMA)₂ ^.+ according to the energetics from DFT calculations. The calculated potential energy curves for the association between DMA^.+ and DMA showed that DT^.+ is likely to be efficiently formed and contribute significantly to the TR³ spectra as a result of the permanent charge-induced Coulombic interactions and a dynamic equilibrium between charge localized and delocalized structures.

Synthesis and characterisation of rylene diimide dimers using molecular handcuffs

Mechanically interlocked handcuffs provide a strategy to study rylene diimide dimers and to investigate their electronic and magnetic properties.

A strategy for positioning, and loosely connecting, molecules in close proximity using mechanically interlocked handcuffs is described. The strategy is demonstrated using rylene diimides, creating dimeric structures in which two components are linked through pillar[5]arene/imidazolium rotaxanes. Investigation of the resulting molecules demonstrates intriguing and new properties that arise from placing these redox active dye molecules together, allowing interactions, whilst allowing the molecules to separate as required. In particular we observe excimer emission from a perylene diimide dimer handcuff and the formation of an unusual radical anion π-dimer upon double reduction of the same molecule. The latter exhibits a unique visible absorption profile for a PDI-based molecule. We demonstrate the flexibility of our approach by making an unprecedented mixed perylene diimide/naphthalene diimide dimer which also reveals interactions between the two components. Our synthetic strategy facilitates the creation of unusual dimeric structures and allows the investigation of intermolecular interactions and the effects they have on electronic and magnetic properties.

Progress in the synthesis of perylene bisimide dyes

Rapid progress in the synthesis of perylene bisimide dyes gave an old scaffold new life.

Direct (Hetero)Arylation for the Synthesis of Molecular Materials: Coupling Thieno[3,4-c]pyrrole-4,6-dione with Perylene Diimide to Yield Novel Non-Fullerene Acceptors for Organic Solar Cells

Herein we report on the synthesis of an N-annulated perylene diimide (PDI) disubstituted thieno[3,4-c]pyrrole-4,6-dione (TPD) molecular acceptor (PDI–TPD–PDI) by direct heteroarylation (DHA) methods. Three sets of DHA conditions that explore the effects of solvent, temperature, and catalyst were employed to find the optimal conditions for the synthesis of two PDI–TPD–PDI derivatives. We then selected one PDI–TPD–PDI for use as a non-fullerene acceptor in organic solar cell devices with the donor polymer PBDB-T. Active layer bulk-heterojunction blends were modified using several post-deposition treatments, including thermal annealing, solvent vapour annealing, and high boiling solvent additives. It was found that active layers cast from o-dichlorobenzene with a 3% v/v diphenylether additive yielded films with adequate phase separation, and subsequently gave the best organic solar cell performance, with power conversion efficiencies greater than 3%.

Controllable Monobromination of Perylene Ring System: Synthesis of Bay-Functionalized Perylene Dyes

Practical synthesis of bay-monofunctionalized perylene dyes has been developed based on controllable NBS bromination of tetrabenzyl perylene-3,4,9,10-tetracarboxylate. The ability to perform the convenient and high-yielding synthesis highlights the potential utility of our multifunctional approach to access a diverse range of new perylene systems.

Ultrafast Long-Range Charge Separation in Nonfullerene Organic Solar Cells

Rapid, long-range charge separation in polymer-fullerene organic solar cells (OSCs) enables electrons and holes to move beyond their Coulomb capture radius and overcome geminate recombination. Understanding the nature of charge generation and recombination mechanisms in efficient, nonfullerene-acceptor-based OSCs are critical to further improve device performance. Here we report charge dynamics in an OSC using a perylene diimide (PDI) dimer acceptor. We use transient absorption spectroscopy to track the time evolution of electroabsorption caused by the dipolar electric field generated between electron-hole pairs as they separate after ionization at the donor-acceptor interface. We show that charges separate rapidly (<1 ps) and that free charge carriers are generated very efficiently (∼90% quantum yield). However, in the PDI-based OSC, external charge extraction is impaired by faster nongeminate decay to the ground state and to lower-lying triplet states.

Comparison of the Optical and Electrochemical Properties of Bi(perylene diimide)s Linked through Ortho and Bay Positions

The Ullmann homocoupling of 2-bromo-perylene diimides (PDIs) gave [2,2'-biperylene]-3,4:9,10:3',4':9',10'-tetrakis(dicarboximide)s, 2,2'-bi(PDI)s, and the Suzuki coupling of a PDI-2-boronic ester and a 1-bromo-PDI gave a [1,2'-biperylene]-3,4:9,10:3',4':9',10'-tetrakis(dicarboximide), 1,2'-bi(PDI). These were compared with [1,1'-biperylene]-3,4:9,10:3',4':9',10'-tetrakis(dicarboximide)s, 1,1'-bi(PDI)s. Solution absorption spectra suggest that the PDIs in 2,2'-bi(PDI)s are more planar and less strongly coupled than those in 1,1'-bi(PDI)s, which is consistent with density functional theory calculations. 2,2'-Bi(PDI)s are less easily reduced than 1,1'- and 1,2'-bi(PDI)s by ca. 70-90 mV. Bulk heterojunction organic solar cells incorporating a 2,2'-bi(PDI) acceptor behaved similarly to those employing its 1,1'-bi(PDI) analogue.

Modulating Paratropicity Strength in Diareno-Fused Antiaromatics

Understanding and controlling the electronic structure of molecules is crucial when designing and optimizing new organic semiconductor materials. We report the regioselective synthesis of eight π-expanded diarenoindacene analogues based on the indeno[1,2-b]fluorene framework along with the computational investigation of an array of diareno-fused antiaromatic compounds possessing s-indacene, pentalene, or cyclobutadiene cores. Analysis of the experimental and computationally derived optoelectronic properties uncovered a linear correlation between the bond order of the fused arene bond and the paratropicity strength of the antiaromatic unit. The E_red¹ for the pentalene and indacene core molecules correlates well with their calculated NICS_πZZ values. The findings of this study can be used to predict the properties of, and thus rationally design, new diareno-fused antiaromatic molecules for use as organic semiconductors.

Optical and photophysical properties of anisole- and cyanobenzene-substituted perylene diimides

Substituent and solvent effects on the one- and two-photon absorption and the photophysical properties of eight bay-substituted perylene-diimides are reported and analyzed.

Charge versus Energy Transfer Effects in High-Performance Perylene Diimide Photovoltaic Blend Films

Perylene diimide (PDI)-based organic photovoltaic devices can potentially deliver high power conversion efficiency values provided the photon energy absorbed is utilized efficiently in charge transfer (CT) reactions instead of being consumed in nonradiative energy transfer (ET) steps. Hitherto, it remains unclear whether ET or CT primarily drives the photoluminescence (PL) quenching of the PDI excimer state in PDI-based blend films. Here, we affirm the key role of the thermally assisted PDI excimer diffusion and subsequent CT reaction in the process of PDI excimer PL deactivation. For our study we perform PL quenching experiments in the model PDI-based composite made of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2-6-diyl] (PBDTTT-CT) polymeric donor mixed with the N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) acceptor. Despite the strong spectral overlap between the PDI excimer PL emission and UV-vis absorption of PBDTTT-CT, two main observations indicate that no significant ET component operates in the overall PL quenching: the PL intensity of the PDI excimer (i) increases with decreasing temperature and (ii) remains unaffected even in the presence of 10 wt % content of the PBDTTT-CT quencher. Temperature-dependent wide-angle X-ray scattering experiments further indicate that nonradiative resonance ET is highly improbable due to the large size of PDI domains. The dominance of the CT over the ET process is verified by the high performance of devices with an optimum composition of 30:70 PBDTTT-CT:PDI. By adding 0.4 vol % of 1,8-diiodooctane we verify the plasticization of the polymer side chains that balances the charge transport properties of the PBDTTT-CT:PDI composite and results in additional improvement in the device efficiency. The temperature-dependent spectral width of the PDI excimer PL band suggests the presence of energetic disorder in the PDI excimer excited state manifold.

A bridge-like polymer synthesized by tandem metathesis cyclopolymerization and acyclic diene metathesis polymerization

A novel bridge-like polymer with excellent thermal stability, an ordered ladder-like structure, and a fence-like ribbon morphology was synthesized by tandem metathesis cyclopolymerization and acyclic diene metathesis polymerization.

Precisely designed perylene bisimide-substituted polyethylene with a high glass transition temperature and an ordered architecture

A polyethylene with a precise repeat of perylene bisimide branches was synthesized by acyclic diene metathesis polymerization and hydrogenation of the as-synthesized polymer, and displayed good thermal stability and an ordered architecture.

Laterally expanded rylene diimides with uniform branched side chains for solution-processed air stable n-channel thin film transistors

Molecular packing motifs in solid states is the dominant factor affecting the n-channel organic field-effect transistors (OFETs). However, few systematic researches were performed in the different extensions of π-conjugated molecules with the uniform substitution effecting the molecular packing motifs. In this manuscript, OFET devices based on three latterally expanded rylene diimides end-functionalized with uniform 3-hexylundecyl substitution on the imide positions were systematically studied on the relationship of molecular stacking, film microstructure, and charge transport. As the π-conjugated systems expanded from doubly linked perylene diimide dimer (d-4CldiPDI, 1), triply linked perylene diimide dimer (t-4CldiPDI, 2), to hybrid array (NDI-PDI-NDI, 3), their corresponding molecular packing motifs exhibited a divide: the optimized molecular configuration became more planar and d (001) spacing distances became larger, which resulted in a larger π-π overlapping. Thus, an enhanced electron mobility was obtained. A typical n-channel field-effect characteristic was observed in thin film devices based on these molecules under ambient conditions. Especially, the hybrid system (3) with more planar and π-expanded aromatic backbone exhibited superior electron mobility approaching 0.44 cm(2) V(-1) s(-1) and on/off ratio of 10(6) after optimal annealing in this study.

Tailor-made rylene arrays for high performance n-channel semiconductors

Rylene dyes, made up of naphthalene units linked in peri-positions, are emerging as promising key building blocks to create π-functional materials. Chemists have found uses for these ribbonlike structures in a wide range of applications of optoelectronic devices. Because their structure combines two sets of six-membered electron-withdrawing dicarboxylic imide rings, rylene diimides exhibit enhanced solubility, excellent chemical and thermal stabilities, high electron affinities, and remarkable electron-transporting properties. Among them, perylene diimide (PDI) and naphthalene diimide (NDI) derivatives are important representatives improving the performance of electron-transporting technologies, relative to their p-channel counterparts. Pioneering works by Müllen and Langhals have inspired chemists to extend the π-conjugation along the peri-positions of rylene diimides, which generally results in impressive bathochromic shifts and a nearly linear increase in the extinction coefficient. In addition, in the past years, researchers have focused on π-expansion of NDI or PDI systems through bay-functionalization with carbocyclic and heterocyclic rings annulated onto the skeleton. However, chemists have rarely investigated lateral expansion via both bay- and nonbay-functionalization to construct homologous series of rylene arrays with different electronic delocalization and fine-tuned flexible linkage. This is probably due to the lack of effective procedures for the (multi) carbon-carbon formation and annulation of electron-deficient rylene imide units. In this Account, we discuss our recent progress in the design and synthesis of laterally expanded rylene dyes based on homocoupling and cross-coupling reactions of core-functionalized PDIs and NDIs to achieve novel high performance n-channel organic semiconducting materials. These new achievements offer us opportunities to learn fundamental issues about how chemical and physical properties alter with incremental changes in structure. We highlight synthetic methodology of transition-metal mediated coupling reactions (and/or C-H transformation) for singly linked, doubly linked, and fully conjugated triply linked oligoPDIs, and further for the construction of hybrid rylene arrays via bay- and/or nonbay-functionalization. In addition, we summarize the informative correlations between the molecular structures and their optoelectronic properties, especially the modulation of progressively red-shifted absorption maxima and positive shifts in the redox potentials. This decreases the energy gaps and increases the electron-accepting abilities through expansion of π-system, which has direct impacts on the compounds' potential applications in optoelectronic devices. Finally, we introduce the promising applications of these laterally expanded rylene dyes as exceptional high performance n-channel semiconductors in organic field-effect transistors (OFETs) and competitive candidates for non-fullerene acceptors in high efficient organic photovoltaic devices (OPVs).

What makes fullerene acceptors special as electron acceptors in organic solar cells and how to replace them

Low lying excited states of the fullerene anion promote a faster charge separation in organic solar cells containing fullerene derivatives as electron acceptors. Alternative electron acceptors, not based on fullerenes but that share the same property, can be easily designed. On the other hand, it is unlikely for a generic electron acceptor to replicate this fullerene characteristic by chance.

Redox-switchable intramolecular π-π-stacking of perylene bisimide dyes in a cyclophane

Molecular actuation by stepwise electrochemical reduction is demonstrated for a cyclophane that exhibits a pronounced conformational transition from a closed cavity with cofacially stacked PBIs in the neutral state to an expanded open cavity in the three- and fourfold reduced state.

Photophysical properties and conformational effects on the circular dichroism of an azobenzene-cyclodextrin [1]rotaxane and its molecular components

The photophysical properties of a multicomponent [1]rotaxane bearing a β-cyclodextrin ring covalently connected to an axle comprising an azobenzene photoisomerisable moiety and a naphthalimide-type fluorescent stopper are investigated by a combined experimental and computational study. The absorption and fluorescence spectra, and particularly the induced circular dichroism (ICD) signal, are determined. The latter shows a sign relation that cannot be rationalised in terms of the simple general rules commonly employed to analyse the ICD spectra of achiral guests encircled by chiral hosts. To assist the interpretation of experimental results, DFT and time-dependent (TD) DFT calculations are performed to explore the availability of low-energy conformations and to model their spectroscopic response. Molecular dynamics simulations performed in water show the interconversion of a number of conformers, the contribution of which to the ICD signal is in agreement with the observation.