Self‐Assembly of an Unlikely Occurring Quadrangular Tube by Modulating Intramolecular Forces

• Published in: Angewandte Chemie International Edition Vol. 63; no. 45; pp. e202411401 - n/a
• Main Authors: Ge, Chenqi, Cao, Ze, Feng, Tinglong, Wu, Yating, Xiao, Mingrui, Tang, Hua, Wang, Kun, Wang, Linjun, Li, Hao
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 04.11.2024
• Edition: International ed. in English
• Subjects: Chemical synthesis; covalent cage compounds; Dibenzothiophene; multiple topological structures; Precursors; reversible transformation; Schiff bases; Self-assembly; Tubes; self-assembly multiple topological structures reversible transformation covalent cage compounds Schiff bases
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202411401

One of the central focuses in self‐assembly is precisely controlling the self‐assembly pathway so that the target molecules can be produced exclusively. Trans‐1,2‐cyclohexanediamine contains two amino units that form a 60° angle when projected on a plane. This angle naturally favors the formation of triangular products in most cases when trans‐1,2‐cyclohexanediamine is used as a bisamino building block in the synthesis of macrocycles and tubes. Here, we synthesized a slightly bent tetraformyl precursor bearing a central dibenzothiophene moiety, whose 3,7‐positions are functionalized with two m‐phthalaldehyde units. We observed that combining this tetraformyl building block with trans‐1,2‐cyclohexanediamine yielded a quadrangular tube when the concentrations of the precursors were relatively high. Both experimental measurements and theoretical calculations indicate that the formation of this unlikely occurring quadrangular product was driven by the intramolecular C−H⋅⋅⋅π interactions between the dibenzothiophene building blocks within the tube framework. This driving force, however, was disturbed in the triangular tube, a smaller counterpart whose formation was considered previously much more thermodynamically favored. These results improved our fundamental understanding on how to create those products whose syntheses are considered difficult or impossible, by modulating the intramolecular driving forces. We synthesized a slightly bent tetraformyl precursor with a central dibenzothiophene moiety, functionalized at the 3,7‐positions with m‐phthalaldehyde units. Combining this with trans‐1,2‐cyclohexanediamine at high concentrations produced a quadrangular tube, driven by intramolecular C−H⋅⋅⋅π interactions within the framework. This research highlights how modulating these forces can yield products previously deemed difficult or impossible to synthesize.