Choo YSL, Giamberini M, Antonio J, Waddell PG, Benniston AC. Functionalized fluorescent terephthalate monomers and their attempted polyester formation.
Org Biomol Chem 2020;
18:8735-8745. [PMID:
33094783 DOI:
10.1039/d0ob01533d]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of diethyl 2,5-bis(tert-butyl)phenoxy-3,6-dihydroxyterephthalate (1) with tetraethylene glycol di(p-toluenesulfonate) under high-dilution conditions afforded several isolated products. Two products were identified as macrocycles with one being the 1 + 1 crown ether derivative 3 (10% yield), and the second being the 2 + 2 crown ether compound D3 (19% yield). The X-ray structure for 3 was determined with the asymmetric unit observed to comprise half of the molecule. The small crown ether ring of 3 interacts with K+ or H+ ions in MeOH, but binding is weak and the macrocyclic cavity is too small to fully encapsulate the K+ ion. Transesterification of compounds 1, its methylated version 2 and 3 with diols such as ethylene glycol or 1,4-butandiol produced monomers (M1-M3) which were reacted with terephthaloyl chloride. Short oligomers were produced (PolyM1-PolyM3) rather than extensive polymeric materials and all displayed solid state fluorescence. The absorption and fluorescence properties of M1-M2 and their polymers can be related to subtle structural changes. The Stokes shift for M2 of 15 627 cm-1 in DCM is one of the largest observed for a simple organic chromophore in fluid solution.
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