Dipankar Ghosh

Electron-rich and electron-deficient naphthalene-capped dipeptides co-assemble into a light-responsive network that shows nanoscale reorganisation and a reversible yellow–to–red response.

Fluorenylmethoxycarbonyl-diphenylalanine (FmocFF) is a widely studied low molecular weight gelator known for its ability to self-assemble into supramolecular gels with diverse applications. Despite extensive literature, the reported circular dichroism (CD) spectra of FmocFF are remarkably inconsistent, even under seemingly identical experimental conditions. In this study, we systematically investigate the factors contributing to this variability and propose a protocol for reproducible CD measurements of FmocFF in solution and gel states. We compare gelation triggers including HCl, glucono-δ-lactone (GdL), CaCl₂ and dimethyl sulfoxide (DMSO)/water solvent switch, and assess the impact of sample handling, loading techniques and cuvette geometry on spectral features. Our findings demonstrate that sample homogeneity, cuvette path length and high-tension signal monitoring are critical for reliable CD analysis of short peptide-based gels. This work highlights the importance of rigorous experimental practices in interpreting the supramolecular chirality of dynamic, heterogeneous systems, such as FmocFF gels.

LMWGs containing the tripeptide FFD motif show selective Li ⁺ responsiveness, forming entangled networks in the presence of Li ⁺ . This offers a simple supramolecular route to selective Li ⁺ uptake over competing monovalent cations.

Tissue engineering and regenerative medicine applications require the integration of multifunctional materials, offering tissue‐specific mechanical cues and geometric guidance to support cell differentiation. In this context, supramolecular gel noodles formed by ionic cross‐linking of pre‐assembled micellar networks offer unique opportunities for creating anisotropic soft materials. However, controlling fibrillar alignment over extended lengths remains a challenge. Herein, a shear‐induced method to fabricate 1D gel noodles with enhanced macroscopic alignment using dipeptide‐based gelators is reported. By implementing a two‐stage extrusion protocol, we generate a thin tail segment with a distinct flow history that exhibits higher retained alignment than the pump‐driven segment. Polarized optical microscopy and small‐angle neutron scattering confirm superior fibrillar orientation in the thin segment, and mechanical testing reveals up to ∼400‐fold increase in nominal stress at failure. The method is effective across multiple gelators, demonstrating its broad applicability for tuning macroscopic alignment in gel noodles. Preliminary C2C12 culture on the thin segment demonstrates improved cell adhesion, elongation, and increased MyoD expression compared to the thick segment. These findings provide a scalable route to introduce anisotropy in supramolecular gel noodles through processing history, and we present cell culture data as proof of compatibility and contact guidance relevant to aligned tissue‐mimetic scaffolds.

Twist-and-lock assembly of supramolecular gel noodles creates hierarchical filaments that combine strength and function. We studied twisting mechanics, crossover spacing, tensile strength, and stimuli-responsiveness to enable targeted applications.

Benzophenone-based materials remain widely used as photoinitiators for ultraviolet light-induced free radical polymerizations. Traditionally, polymerization is spatially controlled using top-down techniques such as photomasks, which produce well-defined polymeric films. In contrast, we present an alternative method for controlling polymerization by employing supramolecular materials to localize the photoinitiator. This approach uses benzophenone-functionalized dipeptides that are specifically tuned to enable supramolecular gel noodle formation, which act as structural templates. We show that polymerization of acrylate monomers around the gel noodles can increase the Young's modulus by up to 2 orders of magnitude and produce mechanically robust structures that can be handled. The self-assembly of the supramolecular photoinitiators is also explored using viscosity and SAXS measurements, providing an understanding of why only 4BPAcFF successfully forms gel noodles. Our method offers a simple yet effective technique for localizing polymerization, enabling fine-tuning of mechanical properties and the fabrication of intricate designs such as hollow-core structures.

Different co-assembly modes depending on the nature of the solvents observed in multi-component systems with structurally similar components.

Supramolecular assembly can be used to fabricate complex functional materials by organizing simple building blocks. However, it is difficult to control the hierarchical assembly across multiple length scales. The correlation of a supramolecular gel network and a pre‐gelling aggregate will help to understand how a molecular‐level assembly is translated into a higher order. Here, a functional dipeptide 2NapFF is used that can assemble in different micellar structures at high pH by varying the counterion. Replacing the counterions with a divalent calcium salt results in a cross‐linked gel network, or an interesting analog “gel noodles.” The physical properties of the gel noodles can be varied by choosing specific micellar assemblies as the pre‐gel. The mechanical rigidity of the gel networks is compared by nanoindentation and tensile testing, and the pattern to the structures of the micelles observed by small‐angle X‐ray scattering is correlated. The supramolecular assembly can be fine‐tuned by using different micelles as the pre‐gel without affecting the inherent gel‐state properties.

The nature of functional groups and their relative position and orientation play an important role in tuning the gelation properties of stimuli-responsive supramolecular gels. In this work, we synthesized and characterized mono-/bis-pyridyl-N-oxide compounds of N-(4-pyridyl)nicotinamide (L₁–L₃). The gelation properties of these N-oxide compounds were compared with the reported isomeric counterpart mono-/bis-pyridyl-N-oxide compounds of N-(4-pyridyl)isonicotinamide. Hydrogels obtained with L₁ and L₃ were thermally and mechanically more stable than the corresponding isomeric counterparts. The surface morphology of the xerogels of di-N-oxides (L₃ and diNO) obtained from the water was studied using scanning electron microscopy (SEM), which revealed that the relative position of N-oxide moieties did not have a prominent effect on the gel morphology. The solid-state structural analysis was performed using single-crystal X-ray diffraction to understand the key mechanism in gel formation. The versatile nature of N-oxide moieties makes these gels highly responsive toward an external stimulus, and the stimuli-responsive behavior of the gels in water and aqueous mixtures was studied in the presence of various salts. We studied the effect of various salts on the gelation behavior of the hydrogels, and the results indicated that the salts could induce gelation in L₁ and L₃ below the minimum gelator concentration of the gelators. The mechanical properties were evaluated by rheological experiments, indicating that the modified compounds displayed enhanced gel strength in most cases. Interestingly, cadmium chloride formed supergelator at a very low concentration (0.7 wt% of L₃), and robust hydrogels were obtained at higher concentrations of L₃. These results show that the relative position of N-oxide moieties is crucial for the effective interaction of the gelator with salts/ions resulting in LMWGs with tunable properties.

The synthesis of catalytically active metal–organic frameworks (MOFs) with copper(II) paddle-wheel clusters and urea–carboxylate linkers was achieved at room temperature in the presence of sulphate anions. The role of various anions in determining the MOF structure was analysed using X-ray diffraction. Structural analysis of the MOFs indicated that a two-fold interpenetrated rhombus grid (HI-101) was formed in the presence of sulphate anions, but a three-fold interpenetrated square grid network (HI-102) was obtained with nitrate and perchlorate anions. The experiment performed with various anions in the presence of sulphate anions also resulted in the formation of HI-101, indicating the selectivity of sulphate anions in the formation of the HI-101 framework. HI-101 proved to be an efficient catalyst for the cycloaddition of CO₂ at room temperature, the oxidation of primary alcohols to aldehydes and the methanolysis of epoxides, but the other MOFs were not catalytically active. Thus, the size, charge and affinity of sulphate anions play an important role in generating a two-fold interpenetrated rhombus grid, which is crucial for catalytic reactions. This study shows that anion-templated synthesis could generate a versatile urea-based MOF catalyst for CO₂ fixation and other reactions.