Magic-angle spinning NMR spectroscopy provides insight into the impact of small molecule uptake by G-quartet hydrogels

Reddy, G. N. Manjunatha; Peters, Gretchen Marie; Tatman, Ben P.; Rajan, Teena S.; Kock, Si Min; Zhang, Jing; Frenguelli, Bruno G.; Davis, Jeffery T.; Marsh, Andrew; Brown, Steven P.

doi:10.1039/d0ma00475h

Cited by 8 publications

(5 citation statements)

References 72 publications

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“…This scenario is especially likely for aggregates, where interactions of very different natures are involved. In order to test this hypothesis, we carried out high-resolution MAS (HR-MAS) NMR titration experiments 55 with variable spinning frequencies using two different good solvents ( Figure 6 ). Our aim was to monitor the evolution of different noncovalent interactions in solid PBI-1 aggregates at an early stage of solvent-induced disassembly.…”

Section: Resultsmentioning

confidence: 99%

Cooperative Self-Assembly Driven by Multiple Noncovalent Interactions: Investigating Molecular Origin and Reassessing Characterization

Samanta

Raval²,

Reddy³

et al. 2021

ACS Cent. Sci.

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Cooperative interactions play a pivotal role in programmable supramolecular assembly. Emerging from a complex interplay of multiple noncovalent interactions, achieving cooperativity has largely relied on empirical knowledge. Its development as a rational design tool in molecular self-assembly requires a detailed characterization of the underlying interactions, which has hitherto been a challenge for assemblies that lack long-range order. We employ extensive one- and two-dimensional magic-angle-spinning (MAS) solid-state NMR spectroscopy to elucidate key structure-directing interactions in cooperatively bound aggregates of a perylene bisimide (PBI) chromophore. Analysis of 1 H– 13 C cross-polarization heteronuclear correlation (CP-HETCOR) and 1 H– 1 H double-quantum single-quantum (DQ-SQ) correlation spectra allow the identification of through-space 1 H··· 13 C and 1 H··· 1 H proximities in the assembled state and reveals the nature of molecular organization in the solid aggregates. Emergence of cooperativity from the synergistic interaction between a stronger π-stacking and a weaker interstack hydrogen-bonding is elucidated. Finally, using a combination of optical absorption, circular dichroism, and high-resolution MAS NMR spectroscopy based titration experiments, we investigate the anomalous solvent-induced disassembly of aggregates. Our results highlight the disparity between two well-established approaches of characterizing cooperativity, using thermal and good solvent-induced disassembly. The anomaly is explained by elucidating the difference between two disassembly pathways.

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Section: Resultsmentioning

confidence: 99%

Cooperative Self-Assembly Driven by Multiple Noncovalent Interactions: Investigating Molecular Origin and Reassessing Characterization

Samanta

Raval²,

Reddy³

et al. 2021

ACS Cent. Sci.

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“…The above results demonstrate that the DPC crosslinking approach incorporating both phototriggered S -nitrosylation and Schiff base reactions occurs at both the small molecule and macromolecular levels. To gain insight about the polymer structure, the 1 H magic-angle spinning (MAS) NMR spectra of the raw materials and the obtained gel were conducted according to the reported method 27 and the results confirmed the changes of polymer local environments caused by gelation (Fig. S15b, ESI†).…”

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confidence: 80%

Reinforced hydrogel network building by a rapid dual-photo-coupling reaction for 3D printing

et al. 2023

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“…Interestingly, density functional theory (DFT) calculations were also performed to complement the experimental 11 B NMR data by optimizing the structure of the guanosine-borate monoester and diesters and calculating 11 B NMR shieldings to correlate with the experimentally measured 11 B shifts. These showed that the cis diester form was the preferred one for gelation [26]. This expanded on prior work by Peters et al, who used solid-state 11 B MAS NMR to characterize the guanosine-borate hydrogels.…”

Section: Nmr Spectroscopymentioning

confidence: 80%

Advanced Methods for the Characterization of Supramolecular Hydrogels

Denzer

Kulchar

Huang

et al. 2021

Gels

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With the increased research on supramolecular hydrogels, many spectroscopic, diffraction, microscopic, and rheological techniques have been employed to better understand and characterize the material properties of these hydrogels. Specifically, spectroscopic methods are used to characterize the structure of supramolecular hydrogels on the atomic and molecular scales. Diffraction techniques rely on measurements of crystallinity and help in analyzing the structure of supramolecular hydrogels, whereas microscopy allows researchers to inspect these hydrogels at high resolution and acquire a deeper understanding of the morphology and structure of the materials. Furthermore, mechanical characterization is also important for the application of supramolecular hydrogels in different fields. This can be achieved through atomic force microscopy measurements where a probe interacts with the surface of the material. Additionally, rheological characterization can investigate the stiffness as well as the shear-thinning and self-healing properties of the hydrogels. Further, mechanical and surface characterization can be performed by micro-rheology, dynamic light scattering, and tribology methods, among others. In this review, we highlight state-of-the-art techniques for these different characterization methods, focusing on examples where they have been applied to supramolecular hydrogels, and we also provide future directions for research on the various strategies used to analyze this promising type of material.

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Magic-angle spinning NMR spectroscopy provides insight into the impact of small molecule uptake by G-quartet hydrogels

Abstract: Small molecule guests influence the functional properties of supramolecular hydrogels. Molecular-level understanding of such sol-gel compositions and structures is challenging due to the lack of long-range order and inherently heterogeneous...

Cited by 8 publications

References 72 publications

Cooperative Self-Assembly Driven by Multiple Noncovalent Interactions: Investigating Molecular Origin and Reassessing Characterization

Cooperative Self-Assembly Driven by Multiple Noncovalent Interactions: Investigating Molecular Origin and Reassessing Characterization

Reinforced hydrogel network building by a rapid dual-photo-coupling reaction for 3D printing

Advanced Methods for the Characterization of Supramolecular Hydrogels

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