Novel supramolecular structures are inspired by many functional biological systems present in nature. The design of supramolecular components is concerned with the conceptualization of an organized state of matter that possess the steric and functional information necessary to translate complex mixture into ordered structures. The organization of matter brought about through non-covalent forces, and the structures generated are almost impossible to put together from a covalent perspective. Hydrogen bonding as a non-covalent interaction mostly used as a design tool, and the structures expressed have helices, 3D structures, sheets structures or cyclic rosettes. One of the first structures in supramolecular chemistry area is the cyclic hexameric aggregate based on the melamine-cyanuric acid cocrystal. Bisrosette structure shown that combine 6 compounds with 36 hydrogen bonding could not obtained because of steric hindrances, high energy eclipsed conformations of cyanuric acid and melamine units. The other important hydrogen bonding aggregate type molecules includes the use of GΛC heterocycles which forms well-ordered hexameric rosettes. Design of the DNA-base hybrid molecule was done in a way that each molecule function exclusively as the corner piece of a hexagon. The combination of the A-A-D sequence of cytosine and complementary D-D-A sequence of guanine at an angle of 120° to each other in pyrido [4,3-d]pyrimidine, leads to the assembly of independent hexagonal aggregates in the solid states. This is purely the result of the communication of programmed, 18 hydrogen-bonding information. Even though a variety of derivatives with different properties have been designed and synthesized, there is only one example of a bisrosette structure using GΛC heterocycles. Here we describe the synthesis of a compound that combines two GΛC units with a rigid bridging group that contains alkyl chains for solubility purposes. The synthesis of the compound was successfully achieved through a 12 step linear approach. The resulting materials was shown to form rosette nanotubes. Computational studies showed that rosette nanotubes were formed by first assembly of the synthesized unit to give a bisrosette structure which then stacked on top of each other. Interestingly, when the self-assembly process was performed in DMF, formation of an unusual tubular structure was observed. Detailed NMR and SEM analyses are ongoing to explain the formation of the tubular structures.

Synthesis of self-assembled bisrosette supramolecules

253rd National Meeting (2017)

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