Synthesis and Emergent Photophysical Properties of Diketopyrrolopyrrole-Based Supramolecular Self-Assembly.

Diketopyrrolopyrrole (DPP)-based molecular semiconductors exhibit intriguing optical and charge transport properties. Herein, we rationally design a series of electronically identical but structurally distinct Hamilton receptor (HR)-based supramolecular assembly of DPP. The HR endows supramolecular assemblies via hydrogen bonding with enhanced structural ordering and excitonic couplings. The mechanism of supramolecular self-assembly was probed by diffusion ordered spectroscopy (DOSY) nuclear magnetic resonance (NMR) and solid-state IR spectroscopy studies. We investigated the morphology of self-assembly, photophysical and electrochemical properties and compared them with the identical DPP molecular structures without HRs. The microstructure of self-assembly was probed with atomic force microscopy in thin films. Subsequently, the influence of solid-state packing was studied by single-crystal X-ray diffraction. The single-crystal structure of HR-TDPP-C20 reveals slipped stack arrangements between the two neighboring chromophores with π-π stacking distance and slip angle of 3.55 Å and 35.4°, respectively. Notably, the slight torsional angle of 1° between thiophene and lactam rings and small π-π stacking distance suggest a significant intermolecular coupling between thiophene (D) and lactam (A) rings. This intramolecular coupling between two π-π chromophore stacks manifests in their optical properties. In this manuscript, we report rational design and synthesis of supramolecular self-assembly of DPP with a collection of compelling structural and optical properties.

Introduction

The supramolecular self-assembly of π-conjugated molecules exhibits enhanced π–π interactions and electronic coupling by bringing discrete building blocks together.[1] As a result, these materials display significant improvement in structural order and show remarkable applications in the field of flexible optoelectronic devices, self-healing materials, and biomedical applications.[2−10] The emergent field of supramolecular chemistry was introduced by Jean–Marie Lehn in the 1990, invoking interactions of non-covalent chemical bonds.[11,12] The concept was inspired by the ubiquity of intermolecular processes in naturally occurring light-harvesting photosynthetic units, DNA and RNA genetic materials.[13−16] However, decrypting the mechanism of supramolecular polymerization was a topic of debate even after prolonged research.[17,18] Meijer et al. acquired incredible ensemble of results toward understanding the complex mechanism of supramolecular polymerization and proposed a rational definition for supramolecular polymers as “polymeric arrays of monomeric units that are brought together by reversible and highly directional secondary interactions, resulting in polymeric properties in dilute and concentrated solution as well as in bulk.”[18−21] Meijer and co-workers also demonstrated remarkable mechanical properties of supramolecular polymers as robust as covalently linked repeating units in conventional polymers, since then the field has evolved immensely.[22−28] Moreover, a wide range of ordered supramolecular polymers have been studied to explore the potential application in the field of unidirectionally charge transport over a long distance, including molecular systems of hexabenzocoronene (molecular graphene), oligo(p-phenylene vinylene), perylene bisimide, and naphthalene diimides.[29−40]

In the recent past, donor–acceptor (D-A-D) π-conjugated polymers have shown promising properties in optoelectronic devices.[41−45] In D-A-D polymers, the electronic coupling is modulated by the donor and acceptor interaction through a π-conjugated bridge. Delocalization of charge in the D-A-D system is governed by alternating electron-donating and electron-accepting units due to the push–pull mechanism. In addition, such chromophores exhibit a broad dual band absorption spectrum with intermolecular charge transfer and large dipole moments within the π-conjugated backbone.[46] Such materials have shown low energetic disorder, high charge-carrier mobility in organic field-effect transistors (OFETs), and record efficiency in organic photovoltaic devices (OPVs).[47,48] In addition, the D-A-D system has also shown promising applications in non-linear optics such as two/three-photon absorptions.[49−52]

Among the family of D-A-D π-conjugated polymers, the diketopyrrolopyrrole (DPP) unit served as an excellent electron acceptor and attracted a great deal of attention not only for their outstanding photophysical and optoelectronic properties but also for their self-assembly properties.[53−65] The molecular structure of DPP contains a planar conjugated backbone and a cyclic amide functional group, which can be substituted with a variety of alkyl chains.[66] In addition, the substituted DPP with the appropriate donor group shows high thermal stability, fluorescent quantum yield, and exhibit enhanced charge-carrier mobility. In recent years, DPP derivatives have shown a potential application in the field of molecular-based optoelectronic devices such as organic electrochemical transistors (OECTs),[73] organic thermoelectric materials (OTEs),[72] OFETs,[69−71] and OPVs.[67,68] In search of ambipolar organic semiconductors, our group has developed a novel series of DPP-based alternating copolymers.[74−78] Surprisingly, simple molecular engineering has led to a remarkable improvement in electron mobility (∼3 cm2V−1s−1) in OFETs and acts more like conventional inorganic semiconductors with a band-like transport.[79,80] Till date, Ajayaghosh and co-workers demonstrated 2D nanosheets of the self-assembly layer under organic and aqueous conditions by substituting hydrophilic and hydrophobic groups with DPP,[81] showing a anisotropic charge-carrier mobility of 0.33 cm2 V–1 s–1.

Inspired by DPP’s unique optical and charge transport properties, in this work, we rationally combined the DPP molecular backbone with a terminal functional group of the Hamilton receptor (HR). The complementary intermolecular hydrogen bonding of the HR was earlier reported by Lehn and co-workers.[82−86] In our rational approach, we have introduced planar thiophene moiety of DPP, substituted with two different alkyl chains, n-hexyl (HR-TDPP-HEX) and 2- octyldodecyl (HR-TDPP-C20). In addition, we introduced twist in the backbone with the phenyl group (HR-PhDPP-HEX) attached with C3 and C6 positions of the DPP core.[87] The genericity of such a design strategy is to (i) combine multiple hydrogen bonds of the HR to increase the strength of non-covalent interactions via supramolecular polymerization, (ii) manipulate excitonic coupling by twisting the backbone of DPP, and (iii) gain structural order via supramolecular self-assembly. We observed intriguing optical and structural properties such as reversible supramolecular self-assembly, ordered microstructures, and enhancement in intermolecular excitonic coupling. We established the role of intermolecular hydrogen bonding by the concentration-dependent 1H NMR study, whereas the variable temperature 1H NMR study reveals the reversible nature of polymerization. A notable difference observed in the relative diffusion coefficient in the two-dimensional diffusion-ordered spectroscopy (2D-DOSY) nuclear magnetic resonance (NMR) experiment suggests the formation of supramolecular polymers. Based on these experimental studies, we report synthesis of a new family of DPP-based supramolecular self-assembly with a detailed mechanistic study on the origin of supramolecular polymerization, reversible self-assembly, and persuasive photophysical properties.

Results and Discussion

Design and Synthesis

The basic molecular structure contains a DPP core with two different π-bridges, planar thiophene and the twisted phenyl moiety. The DPP core is covalently linked with the HR, which undergoes polymerization via self-complementary H-bonding, as shown in Figure a. To investigate further the role of the alkyl chain in supramolecular packing, we have substituted −NH– of the lactam ring with “two different alkyl chains, that is, hydrophobic n-hexyl (HEX) and bulky soluble hydrophobic 2-octyl dodecyl (C20) groups. The synthetic scheme for the DPP derivatives, HR-TDPP-HEX (1), HR-TDPP-C20 (2), and HR-PhDPP-HEX (3), is shown in Figure a,b. They were synthesized via Sonogashira C–C, cross-coupling reactions involving appropriate monomers having acetylene functionality HR (2.2 equiv) and respective di-iodo derivatives of N-alkylated DPP (1 equiv) in the presence of the palladium catalyst Pd(PPh3)4 with an activating catalyst CuI in tetrahydrofuran and di-isopropylamine mixture (3:1; v/v) medium (Figure c). The HR was synthesized according to the reported procedure with necessary modifications. The detailed synthetic procedures and structural characterization of the final products were carried out using 1H and 13C NMR spectroscopies and MALDI-MS (extended data in Supporting Information). The newly synthesized supramolecules are named as HR-TDPP-HEX, HR-TDPP-C20, and HR-PhDPP-HEX by the molecular components involved in the backbone.

Figure 2

(a) Schematic illustration of the supramolecular polymerization of DPPs via self-complementary hydrogen bonding (−NH...C=O−) through the HR. Concentration-dependent 1H NMR spectra of (b) HR-TDPP-C20 and (c) HR-PhDPP-HEX molecules in CDCl3 solvent at room temperature. A concentration-dependent systematic shift of amide protons (star mark) of the HR. (d) FT-IR spectra of HR-TDPP-HEX and TDPP-HEX. (e–g) 2D-DOSY spectra at different concentrations of HR-TDPP-C20 molecule at room temperature. Diffusion coefficients of supramolecular polymers are given in Supporting Information (Table S3) relative to the diffusion coefficient (D/Dr) of the internal reference CDCl3.

Figure 1

Chemical structure of DPP-based supramolecules (a) HR-TDPPs 1–2 and (b) HR-PhDPP 3. (c) Synthetic scheme of HR-DPP molecules.

Spectroscopic Investigation of Supramolecular Polymerization

Spectroscopic studies focused on the mechanism of supramolecular polymerization. To understand the mechanism of polymerization, a series of NMR experiments were carried out, viz. Concentration dependent, variable temperature, and 2D-DOSY in solution. The nature of H-bonding in the HR-TDPP-C20 molecule was investigated in detail by concentration-dependent 1H NMR. When the concentration of HR-TDPP-C20 increased from 50 μM to 36.5 mM, the well-resolved amide peaks in the aromatic region shifted downfield gradually and converged into a broad spectrum, suggesting the presence of intermolecular hydrogen bonding (Figure b). The peak assignment of the aromatic region is shown in Figure S3. These results also reveal that the supramolecular polymers via the self-complementary intermolecular hydrogen bonding network could be constructed at high concentrations. Upon dilution, amide proton shifted upfield (Figure b), and a similar trend was also observed in HR-PhDPP-HEX molecules (as shown in Figure c). At a very high concentration in HR-TDPP-C20 (36.5 mM), the two broad peaks at 8.87 and 8.54 ppm and the peaks resonating at 137.9 and 145.3 ppm (15N–1H HSQC, heteronuclear single quantum coherence spectra) refer to the unsymmetrical two-amide protons (total four in each HR) involved in intermolecular hydrogen bonding, as shown in Figures b and S5d. To further understand the mechanism of polymerization, we have also conducted the two-dimensional nuclear Overhauser effect spectroscopy (NOESY) NMR experiment. The correlation peak at 8.4 ppm in HR-TDPP-C20 (10.6mM) refers to the spatial proximity between the terminal amide and HR −CH2 protons as they are approaching through intermolecular hydrogen bonding (Figures a and S5e,f). While the core amide protons at 8.73 ppm show a significant correlation with water molecules, which is also concluded from the single-crystal X-ray diffraction structure (as discussed later). These results suggest that the supramolecular polymers are formed via intermolecular hydrogen bonding of the HR involving amide and neighboring carbonyl groups.

To further substantiate the formation of supramolecular polymers, 2D-DOSY[88,89] experiments were performed at different concentrations in CDCl3 solution, as shown in Figure e–g. A significant difference in diffusion values at different concentrations in CDCl3 solution was observed. The high concentration (36.5 mM) of HR-TDPP-C20 exhibits a low value of the relative diffusion coefficient[90] (0.034), which suggests the formation of an aggregate with large hydrodynamic diameter and results into sluggish motion in solution. The notable difference in the diffusion coefficient D = 2.66 × 10–10m2s–1 at high (36.5 mM) and D = 1.55 × 10–9m2s–1 and low concentrations (50 μM) clearly ascertains that the supramolecular polymerization occurred through intermolecular hydrogen bonding via the HR (Table S3).

To further establish the role of hydrogen bonding in supramolecular polymerization of DPP, we conducted Fourier-transform infrared (FT-IR) spectroscopy studies. As shown in Figure d, the FT-IR spectra in the high-frequency region is dominated by a broad peak at 3165 to 3600 cm–1, associated with −N–H groups forming hydrogen bonds with C=O groups of HR-DPP. However, non-hydrogen-bonded inner amide N–H shows signature peak at wavenumber (∼3500 cm–1), overlapped with the hydrogen bonded region. To identify these peaks, a deconvolution of the region to different peaks are shown in Figure S6c-e. Such broad peaks in the high-frequency region are not observed for the DPP sample without HR (Figures d and S6). Combined studies of NMR and FT-IR clearly established the role of the HR for supramolecular polymerization.

The reversible nature of the supramolecular polymer was investigated by the variable temperature studies. A concentrated solution (10.6 mM) of HR-TDPP-C20 in CDCl3 was taken for the temperature variation study to observe the reversible nature of polymerization. The NMR spectra of HR-TDPP-C20 exhibit broad and multiple peaks at various heating and cooling temperature cycles (see Figure S2). A broad peak in the aromatic region primarily arises due to the formation of aggregates upon decreasing the temperature. It is particularly noteworthy that the peaks in the forward and reverse heating cycles are superimposable. These results suggest that the formation of supramolecular polymers formed via hydrogen bonds is prevalent and reversible in nature in response to temperature.

Crystal Structure

The mode of non-covalent interactions responsible for supramolecular polymerization is further established by single-crystal XRD. Among the three derivatives, single crystal of HR-TDPP-C20 was obtained in chlorobenzene via a slow evaporation method. The crystallographic details are summarized in Table S1 (see Supporting Information). Analysis of the crystal structure reveals that the molecule crystallizes in the monoclinic lattice with a space group I2/a and Z = 4, an inversion symmetry concerning two thiophene groups. The two thiophene remains trans-oriented with a small torsion angle of 1° with the lactam ring core of the DPP (Figure a and S7). Notably, the initial part of the receptor, that is, acetylene bridge aryl, remains planar with the lactam core (Figure S7). The molecule crystalizes with residual four water molecules in hydrogen bonding. The free amide group (terminal two amide) in the HR part plays a crucial role in extended intermolecular H-bonding (Figure b,c). The HR-TDPP-C20 exhibits slip-stack or head-to-tail 2D layer structures due to intermolecular H-bonding between the amide functional group in HR, locking the orientation. Interestingly, only the terminal amide participates in self-complementary hydrogen bonding with the neighboring chromophore HR group via N–H...O=C interaction, and the intermolecular hydrogen bonding distance is 1.98 Å (Figure b). Therefore, each chromophore can hold a side-by-side four chromophore and forms an extended 2D supramolecular polymer network in a solid state. Therefore, each layer slipped away from each other by the angle of 32°, and the shortest π–π stacking distance is 3.55 Å. Also, the diagonal distance between the two-mass center (R) is 8.3 Å. The crystal structure truly represents the role of the HR for initiate the polymerization and providing non-covalent interaction functional groups to obtain a unique 2D solid-state structure.

Figure 3

X-ray structure of HR-TDPP-C20 in capped stick representation. (a) Front view with the alkyl chain. (b) Intermolecular hydrogen bonding through N–H...O=C (green) interactions in the HR. (c) Supramolecular polymerization growth via intermolecular hydrogen bonding. (b,c) Alkyl chains and hydrogen atoms are omitted for clarity.

Microscopic Structure (AFM)

The thin-film morphology of supramolecular polymers was examined with tapping mode atomic force microscopy (AFM). The thin films were prepared on a silicon wafer by drop-casting a dilute solution (0.25 mg/ml) of molecules in the chloroform solvent. As shown in Figure , the height image clearly shows a drastic change in the morphology of the self-assembled microstructure by varying the side chain or twist in the DPP lactam ring. Notably, HR-TDPP-HEX exhibits microfibers with a densely interconnected network. Similarly, HR-TDPP-C20 and HR-PhDPP-HEX do not form such well-ordered structures; however, they show a self-assembled layer structures with 10–20 nm, consisting of periodic distribution of pinholes. The presence of a short alkyl chain and extended network of intermolecular hydrogen bonding makes HR-TDPP-HEX molecule a perfect candidate for order supramolecular microstructure. From the microscopic observation, it is distinctly evident that a change in the side chain or incorporating twist in the bridge provides a drastic change in molecular packing, leading to the morphological variation in supramolecular self-assembly of these derivatives.

Figure 4

AFM height images of 15 × 15 μm for (a) HR-TDPP-HEX, (b) HR-TDPP-C20, and (c) HR-PhDPP-HEX. (d–f) Corresponding 5 × 5 μm height images.

To establish the role of hydrogen bonding on regulating the morphology, we have probed morphology of DPP derivative without the HR. We have adopted similar experimental conditions of HR-TDPP and preparation method to compare the morphology of thin films. Interestingly, TDPP-HEX, TDPP-C20, and PhDPP-HEX reveal small plate-like crystallites microstructures (Figure S8). We observed a pronounced difference in the morphology of thin films. All three DPP derivatives exhibit lack of periodic microstructures as compared to HR-DPP molecules. This study clearly highlights the importance of non-covalent interactions provided by hydrogen bonding, gaining precise nanostructured morphology in thin films of DPP-based supramolecular self-assembly.

Optical and Electrochemical Properties

We probed optical properties of the HR-DPP derivatives using UV–visible and photoluminescence (PL) spectroscopy in dilute solution of chloroform. The UV–visible absorption spectra of HR-TDPP-HEX and HR-TDPP-C20 are very similar (see Figure a,b). This clearly indicates that the side chain does not play any role in electronic coupling of HR-TDPP chromophores. HR-PhDPP-HEX shows a significant blue shift in the peak maxima of 104 nm compared to the HR-TDPP derivative, revealing a substantial difference in intramolecular electronic coupling between the DPP core and phenyl donor. Twist around the aromatic phenyl ring to the lactam plane of 31° (as shown in energy-optimized structure, S10) and the higher aromatic resonance energy of phenyl, compared to the thiophene analogue, lead to the less quinoidal character between the donor–acceptor. This causes a reduction in the effective conjugation length, increased optical band gap, and dwindling in the extinction coefficient of the molecule. The extinction coefficient values for all three molecules are shown in Figure S9 and Table S5. The HR-TDPP derivatives exhibit pronounced vibronic excitation states with dual-band absorption, typical characteristic features of the D-A-D system. However, HR-PhDPP-HEX shows a broad peak, which is consistent with the twist observed in dihedral angle along the π-conjugated backbone. The twist impedes the delocalization of π-electrons, solid-state packing, and electronic coupling. Notably, we observed a bathochromic shift of 71 and 100 nm absorption spectra compared to their corresponding building block TDPP and PhDPP without HR. This clearly reveals that the effective conjugation length of the HR-TDPP chromophores increased due to coupling between the receptor’s moiety, that is, acetylene and phenyl (Figure S7d).

Figure 5

Absorption and emission spectra of HR-DPP molecules in solutions and thin films; absorption/emission spectra were recorded in chloroform (10 × 10–6 M) solution. Spectra in solid blue and black (light yellow shaded) line stand for corresponding solution and thin-film absorption; blue and red dot lines represent for solution and thin film emission of (a) HR-TDPP-HEX, (b) HR-TDPP-C20, and (c) HR-PhDPP-HEX, respectively. Emission lifetime decay profiles in solution (blue), thin film (red), and fits (black) for the four molecules obtained from the TCSPC measurements. (d) HR-TDPP-HEX, emission collected at 642 and 775 nm for solution and thin films. (e) HR-TDPP-C20, emission collected at 642 and 750 nm for solution and thin films. (f) HR-PhDPP-HEX, emission collected at 586 and 660 nm for solution and thin films.

Compared to solution spectra, a bathochromic shift and peak broadening are observed in thin-film absorption spectra, indicating strong intermolecular coupling between the chromophores. As shown in Figure a,b, the thin-film absorption spectra of HR-TDPP-HEX and HR-TDPP-C20 display a bathochromic shift of 33 and 19 nm, respectively. Such a major shift in the absorption spectra was not observed for HR-PhDPP-HEX thin films. These results suggest that both effects, twist in the backbone and side chains, play an important role in determining the nature of exciton band and photophysical response.

The electrochemical properties of the three DPP supramolecules were evaluated using cyclic voltammetry (CV). The CV of three derivatives of HR-DPP are shown in Figure S12. The thiophene derivatives of HR-DPP show a one-electron reversible redox cycle, whereas phenyl derivative HR-PhDPP-HR shows two electrons reversible in the reduction cycle. The lowest unoccupied molecular orbital energy level (LUMO) values were estimated from the onset of the first reduced peak, using the ferrocene/ferrocenium (Fc/Fc+) redox couple as a reference standard (details are shown in the Supporting Information). The highest occupied molecular orbital energy levels were estimated by combining optical band gaps (estimated in thin films) with electrochemically estimated LUMO values, as summarized in Table S2. The electrochemical experiments suggest that these materials are promising candidates for developing n-channel and/or ambipolar field-effect transistors.

Steady-State Emission and Lifetime Characterization

Excited-state dynamics of the molecule were probed by using time-correlated single-photon counting (TCSPC) measurements. Figure a–c shows the steady-state PL spectra obtained in solution and thin films. A far more dramatic effect is observed in the excited-state dynamics. The thiophene derivatives (HR-TDPP-HEX and HR-TDPP-C20) exhibit PL spectra with a minimal Stoke shift of 527 cm–1 (Table S5). However, the HR-PhDPP-HEX shows a broad structureless emission band with a significant Stoke shift of 2144 cm–1. The HR-PhDPP-HEX exhibits a high photoluminescence quantum yield (PLQY) of 77%, while HR-TDPP-C20 and HR-TDPP-HEX show 64 and 36%, respectively. Although the thiophene derivatives have identical backbones, HR-TDPP-HEX shows high aggregation tendency in chloroform and exhibits less quantum yield than HR-TDPP-C20.

The PL spectra in thin films show a broad emission, significant Stoke shift, and absence of vibronic peak progression in HR-TDPP-HEX, HR-TDPP-C20, and HR-PhDPP-HEX (see Figure a–c). In thiophene derivatives, the emission quenched drastically compared to solution. The trend in optical properties is similar to those observed earlier by our group for TDPP-HEX, TDPP-C20, and PhDPP-HEX (see Figure S10).

The excited-state lifetime was measured using TCSPC (Figure d–f). The thiophene derivatives in solution (HR-TDPP-HEX and HR-TDPP-C20) exhibit monoexponential decay in both vibronic peaks of the emission, with a lifetime of 2.87 to 3 ns (Table ). While HR-PhDPP-HEX displays a monoexponential decay with 4 ns at the 586 nm emission peak maximum. This mono exponential component attributes to the singlet exciton emission lifetime of the monomer, as similarly reported for DPP molecules. The decay profiles of all DPP derivatives without HR in thin films are triexponential in nature with an average lifetime of 2 to 5 ns.[75,76] Remarkably, in the thin film, the HR-TDPP-HEX and HR-TDPP-C20 shows a considerably small emission lifetime (Figure d,e), reflecting the faster radiative rates; however, the decreased PL quantum yield for thin films suggests an increasing non-radiative pathway for decay (knr). The same quenching was also observed in other emission vibronic peaks (750, 775, and 800 nm). The fluorescence lifetime in thin films is considerably smaller than solution, indicating the presence of a strong competing non-radiative decay pathway such as triplet or CT state formation in thin films. However in HR-PhDPP-HEX, the emission lifetime does not change significantly (3.45 ns). It reveals that the improvement in molecular packing and electron couplings is negligible compared to all thiophene derivatives via supramolecular self-assembly. In summary, such well-ordered supramolecular self-assembly leads to enhanced electronic coupling between molecules in the solid state, which can induce interesting, excited-state phenomena and an efficient pathway for charge transport.

Table 1

Photophysical Data of HR-DPP Derivativesa

	ΔEg(optical gap) (eV)		Φfl (%)		τfl (ns)		kr (ns–1)
	solution	thin film	solution	thin film	solution	thin film	solution	thin-film
HR-TDPP-HEX	1.88	1.72	36.14	0.18	2.87	∼0.28	0.12	∼6.4 × 10–3
HR-TDPP-C20	1.89	1.76	64.65	0.28	2.95	∼0.62	0.21	∼4.5 × 10–3
HR-PhDPP-HEX	2.10	2.07	77.68	5.70	4.0	3.49	0.19	16.3 × 10–3

ϕfl, fluorescence quantum yield; τfl, fluorescence lifetime; and kr = ϕfl/τfl (ns–1). The optical gap of the molecules is calculated from the absorption spectra red edge(λabs). ΔE = 1240/λabs eV)

Conclusions

In conclusion, the non-covalent interactions of the HR units tend to add up cooperatively. The π-conjugated backbone and nature of the alkyl chain are key factors, which affect the macroscopic structures. The combination of these factors leads to emergent photophysical properties and hierarchy of structures over range of different length scales. The presence of a slipped stack arrangement between two DPP units and self-complementary intermolecular hydrogen bonding through the amide moiety of the HR was clearly elucidated from the single-crystal XRD structure of HR-TDPP-C20. Notably, each molecule can accommodate four neighboring chromophores by the side via hydrogen bonding through the HR group and forms a two-dimension interconnected network, which can be utilized as an efficient pathway for charge transport. We envisage from the preliminary optical study that such supramolecular self-assemblies could lead to interesting, excited-state dynamics distinct from its monomeric behavior. The rational synthetic strategy demonstrated in this work provides an efficient way to control structural disorder and realize emergent photophysical properties in DPP-based molecular systems.