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. 2026 Oct 6. Online ahead of print. doi: 10.1039/d6ob01088a

A tetrachloroanthracene-walled glycoluril trimer: solvent-dependent conformational switching and host–guest binding

Niyati Arora a, Alok Shaurya a, Jessica Arcudia b, Gabriel Merino b, Lyle Isaacs a,✉
PMCID: PMC13657140  PMID: 42862195

Abstract

We report the synthesis of a tetrachloroanthracene-walled glycoluril trimer based host (H1) that adopts a time-averaged C2v-symmetric structure in DMSO but a self-satisfied “flipped-out” time-averaged Cs-symmetric structure in water. Dicationic guests like Me6PXDA form the cavity inclusion complexes Cs-H1·Me6PXDA and C2v-H1·Me6PXDA in water and DMSO, respectively.

An acyclic CB[n] host (H1) adopts a Cs-symmetric self-folded conformation in water but a C2v-symmetric structure in DMSO, where it binds to a variety of hydrophobic ammonium ions.graphic file with name d6ob01088a-ga.webp

Introduction

Modern supramolecular chemistry uses the fundamentals of non-covalent interactions to build functional systems spanning polymeric materials, chemical sensors, molecular machines, separation materials, and even pharmaceuticals.1,2 Macrocyclic hosts including crown ethers, cryptands, and carcerands played an essential role in the founding and development of supramolecular chemistry.3–5 Due to their inherent preorganization, macrocycles typically engage in high affinity and highly selective complexation events, which makes them well suited for various applications.3,6 Over the past four decades, a variety of macrocyclic hosts including cyclodextrins, calixarenes, cyclophanes, metal–organic cages, and pillararenes have been studied intensively from both a basic science viewpoint and a real-world applications viewpoint.7–13 For example, hydroxypropyl-β-cyclodextrin is the active ingredient in the household product Febreze™, sulfobutylether-β-cyclodextrin is used to formulate a variety of active pharmaceutical ingredients administered to humans, and the γ-cyclodextrin derivative sugammadex is used clinically to reverse the effects of the neuromuscular blocking agents rocuronium and vecuronium.14–16 A powerful alternative class of macrocycles are cucurbit[n]urils (CB[n], Fig. 1), which are derived from glycoluril building blocks.17–19 Although CB[6] was structurally elucidated by Mock in 1981,20 it was not until the arrival of CB[n] (n = 5, 6, 7, 8, 10) around the turn of the millennium that the field really took off.21,22 The distinguishing feature of CB[n] hosts is their ultrahigh binding affinity toward hydrophobic ammonium ions in water.23–26 These outstanding recognition properties were exploited by numerous research groups to create functional supramolecular systems including chemical sensors,27,28 separation materials,29,30 and materials for biomedical applications.31–34

Fig. 1. Structures of previously studied (acyclic) CB[n]-type receptors.

Fig. 1

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A variety of glycoluril derived acyclic hosts have also been prepared and studied, including Nolte's molecular clips35 and Rebek's tennis ball and jelly doughnut shaped systems.36 Our research group has prepared acyclic CB[n]-type receptors based on methylene-bridged glycoluril oligomers (dimer–pentamer) capped with aromatic sidewalls and shown that they retain the essential recognition properties of macrocyclic CB[n].37 As the length of the glycoluril oligomer unit increases, the binding strength of the acyclic CB[n] host also increases due to enhanced hydrophobic (larger cavity) and electrostatic ion–dipole driving forces.38 The prototypical acyclic CB[n] host (TetW1) has been used as an in vivo reversal agent for neuromuscular blockers, drugs of abuse, and anesthetics.39–43 We have also shown that increasing the length of the aromatic sidewalls from benzene to naphthalene to anthracene (e.g.TetW1–TetW3, Fig. 1) increases the binding strength of the host.40,44 Recently, we showed that an anthracene-walled glycoluril dimer bound the industrially important dye methylene blue with Ka = 1.24 × 108 M−1 in phosphate buffered saline.45 Most recently, we prepared a glycoluril dimer based host with tetrachloroanthracene sidewalls (e.g.DimW4). We found that DimW4 (Fig. 1) undergoes strong dimerization in water by π–π stacking.46(DimW4)2 often binds guests on its external π-faces to form (DimW4)2·(guest)2 complexes, but special guests (e.g. berberine) are capable of disrupting (DimW4)2 to give 1 : 1 DimW4·guest complexes. In this paper, we report the synthesis, solvent-dependent conformational changes, and molecular recognition properties of a tetrachloroanthracene-walled glycoluril trimer (H1, Scheme 1).

Scheme 1. Synthesis of the glycoluril trimer based host H1. Conditions: (a) TFA/Ac2O (1 : 1), 95 °C, 18 h, 23%.

Scheme 1

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Results and discussion

This results and discussion section is organized as follows. First, we present the design, synthesis, and characterization of H1 in DMSO. Next, we show that H1 assumes a Cs-symmetric conformation in water by flipping-out one of its sidewalls, as established by 1H and 13C NMR, DOSY, COSY, HSQC, and selective 1D NOESY spectroscopy and supported by DFT calculations. Thereafter, we present qualitative investigations of the binding properties of H1 in DMSO and water using 1H NMR spectroscopy. Finally, we use UV/Vis spectroscopy to study the binding of H1 toward six diammonium ion guests in DMSO.

Design, synthesis, and characterization of H1

As described above, the tetrachloroanthracene-walled glycoluril dimer DimW4 formed the tightly dimerized species DimW4·DimW4 due to its roughly co-planar aromatic walls. In order to avoid dimerization, we elected to create an analogous host based on a methylene-bridged glycoluril trimer (H1, Scheme 1) whose aromatic walls were expected to be noncoplanar, thereby reducing the tendency toward dimerization. For the synthesis of H1, we followed our building block approach involving the reaction of a glycoluril oligomer bis(cyclic ether) building block and an aromatic wall building block.37 Synthetically, we performed the double electrophilic aromatic substitution reaction between a C-shaped glycoluril trimer (Trimer)38 and W4 46 in a mixture of TFA and Ac2O at 95 °C. Host H1 was obtained in 23% yield after final purification by reprecipitation from a minimum amount of water upon the addition of MeOH. The solubility of H1 in DMSO is at least 26 mM, whereas it is only slightly soluble (1.55 mM) in D2O. Fig. 2a shows the 1H NMR spectrum recorded for H1 in DMSO-d6. As expected, based on the C2v-symmetry depicted in Scheme 1, we observed one resonance for the aromatic proton Ha, four doublets for the methylene bridges (He, Hf, Hg, Hh), one singlet for the glycoluril methine (Hk), two methyl resonances (C(H3)i and C(H3)j), and resonances for the propylene arms (Hb, Hc, Hd). The 13C NMR spectrum recorded in DMSO-d6 shows the expected 19 resonances based on time-averaged C2v-symmetry, including two C Created by potrace 1.16, written by Peter Selinger 2001-2019 O resonances, seven aromatic C-resonances, three glycoluril C-resonances, two CH3 resonances, and three resonances for the propylene arms (SI, Fig. S1). The low-resolution electrospray mass spectrum of H1 shows a major ion at m/z 879.94, which can be assigned to the [H1 − 4Na + 2H]2− species (calc. for C64H60N12O22S4(35Cl)6(37Cl)2, 880.01). Surprisingly, the 1H NMR spectrum of H1 recorded in D2O (Fig. 2b) shows a doubling of the number of resonances. For example, we observe two resonances for Ha, two doublets for Hk, and four resonances for (CH3)i and (CH3)j, including one that is shifted upfield to 1.09 ppm. These results establish that H1 assumes a form that is no longer C2v-symmetric. The 13C NMR spectrum in D2O (SI, Fig. S2) also shows a doubling of the resonances.

Fig. 2. 1H NMR spectra recorded (600 MHz, RT) for H1 in: (a) DMSO-d6 and (b) D2O.

Fig. 2

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Given the known propensity of DimW4 and other glycoluril dimer derived hosts to undergo tight dimerization in water,46,47 our initial thought was that H1 formed a discrete dimeric entity H1·H1. To investigate this possibility, we performed diffusion ordered spectroscopy (DOSY, SI, Fig. S5) for H1 (MW = 1684.9) and for similarly sized TetW2 (MW = 1641.5) and observed comparable diffusion coefficients (D = 4.47 × 10−10 m2 s−1 for H1; D = 4.26 × 10−10 m2 s−1 for TetW2). Dilution experiments (1.55 mM–25 μM) monitored by 1H NMR spectroscopy (SI, Fig. S3) did not produce the changes in the number of resonances expected for a monomer–dimer equilibrium. However, we did observe some sharpening and downfield shifting of Ha and Ha′ as [H1] is reduced, which suggests that the dissymmetric conformation of H1 is capable of self-association at higher concentrations in water. Similar changes in the 1H NMR spectrum were seen in variable temperature (VT) NMR experiments conducted from 293–343 K (SI, Fig. S4). Overall, the DOSY, dilution, and VT NMR experiments show that H1 remains monomeric in water over a broad range of concentrations and temperatures and establishes a Cs-symmetric conformation for H1 in water.

To further elucidate the structure of Cs-H1, we performed COSY, DEPT, HSQC, and selective 1D NOESY spectroscopy (SI, Fig. S6–S9). Fig. 3 shows an expanded region (6.0–2.0 ppm) of the COSY spectrum. The COSY spectrum allowed the ready identification of three pairs of geminally coupled disatereotopic methylene protons (e and f; g and h; g′ and h′; highlighted with a blue box). Here, the primed (′) resonances arise due to the reduction in symmetry from C2v-H1 to Cs-H1. It was more challenging to identify the coupling partner for the remaining diastereotopic methylene e′ (at 3.97). Eventually, we realized that f′ resonates at ≈2.4 ppm and is buried under the resonances for c and c′ of the solubilizing sidearms. Further evidence of this assignment comes from the HSQC spectrum that shows correlations between the 13C resonance for this methylene group at 39.3 ppm and the 1H NMR resonances at 3.97 and 2.4 ppm. Based on the significant upfield shifts observed for e′ (Δδ ≈ −1.5 ppm), f′ (Δδ ≈ −1.9 ppm), and (CH3)i′ (Δδ ≈ −0.8 ppm) resonances relative to the unprimed resonances, and the upfield shifts observed for Ha and Ha′ (Δδ ≈ −0.4 to −0.8 ppm) relative to H1 in DMSO, we surmise that these protons become closer to the opposing tetrachloroanthracene sidewall in the Cs-H1 conformation. In accordance with the chemical shift evidence discussed above, Fig. 4 shows a three-dimensional representation of the proposed geometry of Cs-H1 with a flipped-out conformation of one of the aromatic walls. This flipped-out conformation has been previously observed experimentally for glycoluril monomer derived molecular clips,48,49 and has been suggested computationally for a glycoluril trimer derived host.50,51 We also performed selective 1D NOESY experiments to gain further insight into the proximity of various protons in the Cs-H1 form (SI, Fig. S9). Key NOESY spatial correlations were seen from (CH3)i′ to (CH3)j′, e′, h′, and the b′ diastereotopic methylene of the sidearm that allow assignment of this region of Cs-H1. Similarly, (CH3)j′ shows NOESY correlations with (CH3)i′, g′, h′, and k′. Finally, the upfield shifted aromatic wall resonance Ha′ shows correlations with the Hb′ diastereotopic methylenes of the sidearm, which definitively shows that Ha′, He′, Hf′, and (CH3)i′ are as assigned in Fig. 4. The aromatic wall proton Ha shows analogous NOESY correlations with the Hb diastereotopic methylene protons.

Fig. 3. Region of the 1H–1H COSY spectrum recorded (600 MHz, D2O, RT) for H1. The green box highlights the correlation between e′ and f′, whereas the blue box highlights the correlations between e and f, g and h, and g′ and h′.

Fig. 3

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Fig. 4. (a) Idealized depictions of the C2v- and Cs-symmetric forms of H1. Protons labelled in red are those that display upfield shifts in the Cs-symmetric form. (b, c) NCI plots of the DFT optimized (ωB97X-D4/def2-SVP) conformations in water (b) and DMSO (c). Relative E + ZPE values are given in kcal/mol. Color code: C, gray; H, white; N, blue; O, red; Cl, green, S, yellow.

Fig. 4

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DFT calculations for H1 in water and in DMSO

To gain computational insight into the proposed time-averaged Cs- and C2v-symmetric forms of H1, we optimized structures starting from idealized Cs and C2v geometries in water and DMSO. Fig. 4b and c show the resulting structures, their relative E+ZPE values and the corresponding NCI isosurfaces. Within the two conformers examined, the Cs-derived flipped-out conformer lies 3.9 kcal mol−1 below the C2v-derived conformer in water but do not reproduce the time-averaged C2v-symmetry inferred experimentally in DMSO. This ordering is consistent with the structure assigned from the NMR data. The NCI isosurfaces reveal more extensive contacts between the tetrachloroanthracene sidewalls in the Cs-derived structure, whereas the C2v-derived structure displays more localized contacts, primarily near the ends of the aromatic sidewalls. Both conformers contain inter-ring separations of approximately 3.2 Å. These qualitative NCI features are consistent with close intramolecular contacts but do not constitute an energetic decomposition.

In DMSO (Fig. 4c), the same protocol also places the Cs-derived conformer below the C2v-derived conformer, by 9.9 kcal mol−1 after ZPE correction. Thus, the present continuum-solvent calculations do not reproduce the time-averaged C2v symmetry inferred experimentally in DMSO. This discrepancy indicates that contributions not captured by the present model (including specific host–solvent and counterion interactions, conformational entropy, and conformers outside the two structures examined) may influence the solution-phase ordering. Resolving this discrepancy would require broader conformational sampling and, ideally, explicit treatment of the most relevant solvent and counterion interactions.

Qualitative 1H NMR investigation of the binding properties of H1 in D2O and in DMSO

We first decided to look at the H1·guest binding in water using 1H NMR spectroscopy. Fig. 5 shows the 1H NMR spectra recorded for 1 : 0.5, 1 : 1, and 1 : 2 mixtures of H1 and Me6PXDA (Fig. 6). At a 1 : 1 ratio (Fig. 5c), we observe a downfield shifted pair of resonances for Ha and Ha′ in the 8–9 ppm region, along with resonances for uncomplexed H1. At a 1 : 2 ratio (Fig. 5d), resonances for uncomplexed Me6PXDA and the new species are observed and the host resonances remain doubled, indicating that the Cs-H1·Me6PXDA complex maintains Cs-symmetry. The Hx resonance for the guest Me6PXDA shifts upfield to 6.2 ppm upon complexation, suggesting binding within the cavity of Cs-H1. Other notable spectral changes upon the formation of Cs-H1·Me6PXDA include the shifting of (CH3)i′ and (CH3)j′ back to ≈1.85 ppm, He′ back to ≈5.5 ppm, and Hf′ back to ≈4.4 ppm. These spectral shifts indicate changes in the relative orientation of the aromatic sidewalls with respect to themselves and with respect relative to each other and to (CH3)i′ and (CH3)j′. We suggest that Me6PXDA binding disrupts the π-stacked geometry of Cs-H1 while maintaining a flipped-out tetrachloroanthracene wall. The DFT optimized (ωB97X-D4/def2-SVP, SMD continuum solvation model for water) geometry of the H1·PXDA complex with a flipped-out sidewall (SI, Fig. S21) shows how the cavity of H1 expands to accommodate the PXDA guest.

Fig. 5. 1H NMR spectra recorded (600 MHz, D2O, RT) for: (a) H1, (b) a 1 : 0.5 mixture of H1 and Me6PXDA, (c) a 1 : 1 mixture of H1 and Me6PXDA, (d) a 1 : 2 mixture of H1 and Me6PXDA, and (e) Me6PXDA. The resonances marked with green labels refer to the H1·Me6PXDA complex, whereas uncomplexed H1 and Me6PXDA are marked with black labels.

Fig. 5

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Fig. 6. Chemical structures of guests used in this study.

Fig. 6

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Fig. 7 shows the 1H NMR spectra recorded for 1 : 0.5, 1 : 1, and 1 : 2 mixtures of H1 and PXDA in DMSO-d6. At a 1 : 1 stoichiometry, we observe a small downfield shifting of Ha of the host, likely due to the separation of the walls of H1 to accommodate the guest. In contrast, the Hx and Hy resonances of PXDA undergo larger upfield shifts upon the formation of the C2v-H1·PXDA complex due to the well-known shielding effect of the glycoluril cavity and the anisotropic shielding effect of the tetrachloroanthracene sidewalls. The Hz resonance of PXDA also shifts upfield upon complexation due to the release of its solvating DMSO molecules and formation of H-bonds with the portals of H1. At a 1 : 2 H1·PXDA ratio (Fig. 7d), we observe separate resonances for uncomplexed PXDA and C2v-H1·PXDA, which indicate slow kinetics of exchange on the 1H NMR chemical shift timescale. The DFT minimized (ωB97X-D4/def2-SVP, SMD continuum solvation model for DMSO) geometry of H1·PXDA (SI, Fig. S22) shows typical host–guest cavity binding. Related 1H NMR stack plots were constructed for guests HDA, CHDA, Bipip, and Diam (SI, Fig. S11–S14). For these guests, we observe large upfield shifts for the guest resonances along with intermediate to fast kinetics of exchange, which is in accordance with the moderate Ka values reported below.

Fig. 7. 1H NMR spectra recorded (600 MHz, DMSO-d6, 40 °C) for: (a) H1, (b) a 1 : 0.5 mixture of H1 and PXDA, (c) a 1 : 1 mixture of H1 and PXDA, (d) a 1 : 2 mixture of H1 and PXDA, and (e) PXDA. The resonances marked with an asterisk (*) arise from uncomplexed PXDA.

Fig. 7

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Measurement of H1·guest binding affinities by UV/Vis spectroscopy in DMSO

Once we had a qualitative understanding that guests bind inside the cavity of H1 in DMSO in a manner similar to that seen for other acyclic CB[n], we set out to measure the binding affinity for H1·guest complexation. We selected UV/Vis spectroscopy as the analytical technique due to the very good anthracene chromophore of H1 and a desire to avoid the challenges of performing ITC using DMSO as the solvent. Fig. 8a shows the UV/Vis spectra recorded when a solution of H1 (2.8 μM) in DMSO was titrated with a solution of CHDA (0–6.5 μM). At λmax = 281 nm, the absorbance value significantly increases upon the formation of the H1·CHDA complex. Fig. 8b shows a plot of absorbance at 281 nm versus [CHDA]. The change in absorbance versus [CHDA] was fitted to a 1 : 1 binding model using BindFit52,53 to determine that Ka = 8.8 ± 0.28 × 105 M−1 for H1·CHDA (Table 1). Related UV/Vis titrations were performed for H1 with guests HDA, PXDA, Me6PXDA, Bipip, and Diam (SI, Fig. S15–S20) and the Ka values are reported in Table 1. Overall, we find that H1 binds a variety of diammonium ions in DMSO with good affinity but low levels of selectivity, which is consistent with a substantial electrostatic contribution to binding.

Fig. 8. (a) UV/Vis spectra recorded during the titration of H1 (2.8 μM) with CHDA (0–6.5 μM) in DMSO. (b) Plot of the absorbance at 281 nm versus [CHDA]; the solid line represents the best fit of the data to a 1 : 1 binding model using BindFit.

Fig. 8

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Table 1. Binding constants for H1·guest complexes determined by UV/Vis spectroscopy.

Guest K a (M−1)
CHDA (8.8 ± 0.28) × 105
HDA (4.0 ± 0.21) × 106
PXDA (2.8 ± 0.35) × 106
Bipip (6.6 ± 0.20) × 105
Diam (5.1 ± 0.72) × 105
Me6PXDA (3.4 ± 0.45) × 106
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Conclusions

In summary, we have reported the synthesis of a tetrachloroanthracene-walled glycoluril trimer based host (H1). The results of 1H and 13C NMR, DOSY, COSY, HSQC, and selective 1D NOESY spectroscopy establish that H1 assumes a self-satisfied Cs-symmetric conformation with a flipped-out aromatic sidewall in water. In DMSO, H1 assumes the expected C2v-symmetric conformation. In water, Me6PXDA disrupts the π-stacking of the tetrachloroanthracene walls during the formation of the Cs-H1·Me6PXDA complex. In DMSO, guests bind in the central cavity of H1 to form C2v-H1·guest complexes. The results of UV/Vis spectroscopic titrations show that H1 forms discrete 1 : 1 complexes with diammonium ion guests with Ka up to 4.0 × 106 M−1 in DMSO. DFT calculations support the preference for the flipped-out Cs-derived conformer in water but do not reproduce the time-averaged C2v-symmetry inferred experimentally in DMSO. In conclusion, we document that acyclic CB[n]-type receptors have the capacity to adopt a flipped-out conformation, which results in self-filling of its own cavity. This work establishes a new pitfall that must be avoided in the preparation of new acyclic CB[n]-type receptors for molecular recognition.

Experimental

General experimental

Chemicals were purchased from commercial suppliers and used without further purification. Trimer and W4 were prepared according to literature procedures.38,46 NMR spectra were measured on commercial spectrometers operating at 400, 600, or 800 MHz for 1H using D2O or DMSO-d6 as the solvent. Chemical shifts (δ) are referenced relative to the residual protonated resonances at 4.80 ppm and 2.49 ppm, respectively. UV/Vis spectroscopy was performed on a Cary Bio100 spectrometer with the temperature maintained at 25 °C using a Neslab RTE-111 recirculating bath.

Host H1

Trimer (100 mg, 0.16 mmol) and W4 (420 mg, 0.64 mmol) were charged in a round bottom flask equipped with a stir bar and a condenser. The setup was flushed with nitrogen from the top of the condenser. A solution of TFA/Ac2O (1 : 1, 8 mL) was added and the flask was lowered into a preheated oil bath (95 °C) and stirred for 18 hours. The reaction was poured into a flask containing rapidly stirred MeOH (300 mL). The resulting precipitate was collected by centrifugation, giving crude H1 (250 mg). Crude H1 was combined with water (16 mL) in a centrifuge tube and stirred overnight in the dark. The following day, the tube was centrifuged and the supernatant was collected and filtered through a syringe filter (Acrodisc 32 mm 0.45 μm Supor membrane) and then concentrated by rotary evaporation. The residue was dissolved in a minimum amount of water and treated with MeOH (4 times the volume of water) and the solution was left in the refrigerator overnight. A greenish precipitate was formed, which was separated by centrifugation and dried under high vacuum to give H1 (70 mg, 23%) as a pale green solid. M.p.: >300 °C. 1H NMR (DMSO-d6, 600 MHz): 8.80 (s, 4H), 5.54 (d, J = 15.2 Hz, 4H), 5.41 (s, 2H), 5.35 (d, J = 16.0 Hz, 4H), 4.42 (d, J = 16.0 Hz, 4H), 4.29 (m, 4H), 4.13 (d, J = 15.2 Hz, 4H), 3.97 (m, 4H), 2.91 (m, 8H), 2.17 (m, 8H), 1.78 (s, 6H), 1.73 (s, 6H), 13C NMR (DMSO-d6, 125 MHz, 26.2 mM): 156.0, 154.3, 147.9, 129.7, 129.1, 128.2, 127.4, 126.7, 120.1, 77.4, 76.3, 74.4, 70.6, 48.8, 48.8, 36.1, 26.4, 16.0, 15.7 (19 resonances expected, 19 found). IR (ATR, cm−1): 3425 (br.), 2929 (w), 1714 (s), 1462 (m), 1419 (w), 1310 (m), 1181 (m), 1035 (s), 788 (m), 667 (w). MS (ESI negative mode): m/z 879.94 [M − 4Na + 2H]2−. Calc. for [C64H60N12O22S4(35Cl)6(37Cl)2]2−, 880.01.

Computational details

All density functional theory (DFT) calculations were performed with ORCA 6.1.154 using the ωB97X-D455,56 density functional in combination with the def2-SVP57 basis set. Solvent effects were included using the SMD continuum-solvation model58 for water or DMSO, as appropriate. Geometry optimizations and vibrational frequency calculations were carried out for the tetraanionic host H14−, the dicationic guest PXDA2+, and the corresponding host–guest complexes, all in the singlet state. Zero-point energy (ZPE) corrections were obtained from the calculated harmonic vibrational frequencies. Non-covalent interactions were analyzed using the NCIPLOT program59 based on the electron density of the DFT-optimized geometries.

Conflicts of interest

L. I. is co-founder and holds equity in Reversal Therapeutics (College Park, Maryland) and holds equity in Clear Scientific (Cambridge, Massachusetts).

Supplementary Material

OB-OLF-D6OB01088A-s001

Acknowledgments

We thank the National Science Foundation (CHE-1807486) for past financial support. We thank the National Institute of General Medical Sciences of the National Institutes of Health (R35GM153362) for current financial support of this project. J. A. acknowledges SECIHTI for a postdoctoral fellowship. The authors thank the Ixchel HPC facility at CINVESTAV-Mérida for the allocation of computational resources.

Data availability

Data supporting this article have been included as part of the supplementary information (SI). Supplementary information: details of synthesis, NMR, IDA, and ITC experiments. See DOI: https://doi.org/10.1039/d6ob01088a.

Electronic versions of the supporting data for this article, including NMR spectra and UV/Vis spectra, and computational output files are available at the Digital Repository at the University of Maryland at https://doi.org/10.13016/cagf-ay54.

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Associated Data

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

Supplementary Materials

OB-OLF-D6OB01088A-s001
OB-OLF-D6OB01088A-s001.pdf (4.8MB, pdf)

Data Availability Statement

Data supporting this article have been included as part of the supplementary information (SI). Supplementary information: details of synthesis, NMR, IDA, and ITC experiments. See DOI: https://doi.org/10.1039/d6ob01088a.

Electronic versions of the supporting data for this article, including NMR spectra and UV/Vis spectra, and computational output files are available at the Digital Repository at the University of Maryland at https://doi.org/10.13016/cagf-ay54.

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