Externally Regulated Specific Molecular Recognition Driven Pathway Selectivity in Supramolecular Polymerization

• Published in: Chemistry : a European journal 2021-08, Vol.27 (44), p.11458-11467
• Main Authors: Chakraborty, Anwesha, Manna, Rabindra Nath, Paul, Ankan, Ghosh, Suhrit
• Format: Article
• Language: English
• Subjects: Carboxylic acids; Chemistry; Complexity; Computer applications; Cooling; Diimide; Externally regulated nucleation-elongation; Hydrogen-bonding; Kinetic and thermodynamic control; Morphology; Naphthalene; Nucleation; Pathway complexity; Polymerization; Selectivity; Supramolecular polymerization; Temperature
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202101492

This article reveals 4‐dimethylaminopyridine (DMAP) regulated pathway selectivity in the supramolecular polymerization of a naphthalene‐diimide derivative (NDI‐1), appended with a carboxylic acid group. In decane, NDI‐1 produces ill‐defined aggregate (Agg‐1) due to different H‐bonding motifs of the −COOH group. With one mole equivalent DMAP, the NDI‐1/DMAP complex introduces new nucleation condition and exhibits a cooperative supramolecular polymerization producing J‐aggregated fibrillar nanostructure (Agg‐2). With 10 % DMAP and fast cooling (10 K/min), similar nucleation and open chain H‐bonding with the free monomer in an anti‐parallel arrangement produces identical J‐aggregate (Agg‐2a). With 2.5 % DMAP and slow cooling (1 K/min), a distinct nucleation and supramolecular polymerization pathway emerge leading to the thermodynamically controlled Agg‐3 with face‐to‐face stacking and 2D‐morphology. Slow cooling with 5–10 % DMAP produces a mixture of Agg‐2a and Agg‐3. Computational modelling studies provide valuable insights into the internal order and the pathway complexity. Externally added 4‐dimethylaminopyridine (DMAP) introduces new nucleation conditions and influences the thermodynamic landscape in the supramolecular polymerization of a carboxylic‐acid appended NDI‐monomer. With 100 % DMAP, well‐defined J‐aggregation results in the formation of fibrillar morphology, irrespective of the cooling rate. With 10 % DMAP, depending on the cooling rate, either J‐aggregate or H‐aggregate (or mixture) is noticed with 1D and 2D morphology, respectively. With 2.5 % DMAP and slow cooling, extended 2D sheet can be obtained from the thermodynamically controlled H‐aggregation.