Synthesis and Host-Guest Properties of Acyclic Pillar[ n]naphthalenes

Yuanyin Jia; Ming Dong; Bin Wang; Chunju Li

doi:10.3389/fchem.2019.00828

Synthesis and Host-Guest Properties of Acyclic Pillar[ n]naphthalenes

Front Chem. 2019 Dec 3:7:828. doi: 10.3389/fchem.2019.00828. eCollection 2019.

Authors

Yuanyin Jia¹, Ming Dong², Bin Wang², Chunju Li^{1

2

3}

Affiliations

¹ School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai, China.
² Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, College of Chemistry, Tianjin Normal University, Tianjin, China.
³ Department of Chemistry, Center for Supramolecular Chemistry and Catalysis, Shanghai University, Shanghai, China.

Abstract

Here we report a new class of synthetic receptors, acyclic pillar[n]naphthalene (n = 2-4, Dimer, Trimer, and Tetramer) oligomers, which are made up of 2,3-diethoxynaphthalene units linked by methylene bridges at the 1- and 4-positions. They can be synthesized through a one-step condensation of 2,3-diethoxynaphthalene monomer and paraformaldehyde in the presence of BF₃•(Et)₂O catalyst. The crystal structure of Tetramer has an interesting pseudo-cycle shaped structure in the solid state. Their complexation behaviors toward several organic ammonium cations (1 ⁺-15 ⁺) and electron-deficient neutral guests (16-17), were examined by means of ¹H NMR spectroscopy. Tetramer shows good host-guest properties toward the ammonium guests, giving association constants (K _a) in the magnitude of 10²-10⁴ M^-1, which are comparable with those for some macrocyclic hosts.

Keywords: acyclic hosts; calixarenes; host-guest chemistry; molecular recognition; pillararenes.