Water-Assisted Self-Aggregation of Benzimidazole and Triazole Adducts

Abstract

The manuscript revolves around an interesting observation of solidification of a solution of N -((1-((1-ethyl-1 H -benzo[ d ]imidazol-2-yl)methyl)-1 H -1,2,3-triazole-4-yl)methyl)aniline ( A6) in the NMR tube after around 12 h. Real-time images showed fibrillar and spherulitic growth with tip branching and side branching, which is thermoreversible. The compound under investigation is unique because it is synthesized to understand the anticancer activity with two pharmacophores, benzimidazole and triazole. Click chemistry is employed for in situ generation of triazole moiety on benzimidazole. Previously, benzimidazole-based compounds have shown self-aggregation-induced gel-like behavior because of hydrogen bonding and/or π–π stacking interactions. In the present case, NMR titrations with D 2 O addition showed two distinct changes in the chemical shift for methylene bridges (connecting benzimidazole and triazole ring) and ortho protons of the phenyl ring (attached to triazole ring). Interestingly, a single-crystal X-ray structure shows the absence of hydrogen bonds and π–π stacking while in the presence of only two distinct close contacts, completely correlating NMR data discussed in detail. A similar “molecular origin” for self-aggregation is observed in seven other flexible but regioisomeric compounds, which were designed and synthesized for inducing hydrogen bonding through the removal of N -ethyl group and insertion of aniline and/or fluoro group.

Highly Optically Responsive Divalent Benzimidazolium-Based Axles with Pseudorotaxane Potential

“…To try to narrow down the contributing causes we attempted to disrupt the aggregates by changing the solvent, believing that the trace water in the DMSO could be affecting molecular solvation, as reported for similar systems. [24] Employing DMSO (d6), pre-dried over previously washed 4 Å molecular sieves, induced no change in the fluorescent behaviour, but did induce a red-shift compared to the slightly wet sample (Figure S4; Table S3). Considering that water could be expected to break-up aggregates, and that aggregates are likely responsible for the extreme shift in the λabs, max, one would anticipate that a solution in wet DMSO would behave like a lower concentration sample in DMSO in terms of aggregation( Figure S4; Table S3).…”

Divalent benzimidazolium-based axles for self-reporting pseudorotaxanes

“…[28] The shift likely arises from a combination of the emergence of a new species that replaces the computationally calculated energy minimum (Figure S1 solvation, as reported for similar systems. [29] Employing DMSO-d6, pre-dried over previously washed 4 Å molecular sieves, induced no change in the fluorescent behaviour, but did induce a red-shift compared to the slightly wet sample (Figure S4; Table S3). Considering that water could be expected to break-up aggregates, and that aggregates are likely responsible for the extreme shift in the λabs, max, one would anticipate that a solution in wet DMSO would behave like a lower concentration sample in DMSO in terms of aggregation (Figure S4; Table S3).…”

Controllable Fabrication of Novel Multi‐Responsive Nano‐Aggregates and Metallacycle Based on Bis‐Acylhydrazone Functionalized Pillar[5]arene

“…Among them, hydrogen bonding is one of the most proeminent weak intermolecular forces found in nature due to its high stability, directionality and play a pivotal role in the construction and stabilization of supramolecular self‐assembly systems . The stability of hydrogen‐bond networks is affected by external conditions such as temperature and pH values which lead to a change in the morphology of the corresponding supramolecular aggregates …”

“…[9] The stability of hydrogen-bond networks is affected by external conditions such as temperature and pH values which lead to a change in the morphology of the corresponding supramolecular aggregates. [10] Hydrazones have two typical properties. Firstly, the carbonnitrogen double bond (-C=N-) can isomerize through physical stimuli such as light and heat.…”