Design and Sensing Properties of a Self-Assembled Supramolecular Oligomer

Steffen Bähring; Luis Martín-Gomis; Gunnar Olsen; Kent A Nielsen; Dong Sub Kim; Troels Duedal; Ángela Sastre-Santos; Jan O Jeppesen; Jonathan L Sessler

doi:10.1002/chem.201503701

Design and Sensing Properties of a Self-Assembled Supramolecular Oligomer

Chemistry. 2016 Feb;22(6):1958-1967. doi: 10.1002/chem.201503701. Epub 2015 Dec 2.

Authors

Steffen Bähring¹, Luis Martín-Gomis², Gunnar Olsen¹, Kent A Nielsen¹, Dong Sub Kim³, Troels Duedal¹, Ángela Sastre-Santos⁴, Jan O Jeppesen⁵, Jonathan L Sessler⁶

Affiliations

¹ Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
² Área de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, 03202, Alicante, Spain), Fax.
³ Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, Texas, 78712-1224, USA), Fax.
⁴ Área de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche, 03202, Alicante, Spain), Fax. asastre@umh.es.
⁵ Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark. joj@sdu.dk.
⁶ Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, Texas, 78712-1224, USA), Fax. Sessler@cm.utexas.edu.

PMID: 26626137
DOI: 10.1002/chem.201503701

Abstract

Supramolecular polymers are a class of macromolecules stabilized by weak non-covalent interactions. These self-assembled aggregates typically undergo stimuli-induced reversible assembly and disassembly. They thus hold great promise as so-called functional materials. In this work, we present the design, synthesis, and responsive behavior of a short supramolecular oligomeric system based on two hetero-complementary subunits. These "monomers" consist of a tetrathiafulvalene-functionalized calix[4]pyrrole (TTF-C[4]P) and a glycol diester-linked bis-2,5,7-trinitrodicyanomethylenefluorene-4-carboxylate (TNDCF), respectively. We show that when mixed in organic solvents, such as CHCl₃ , CH₂ ClCH₂ Cl, and methylcyclohexane, supramolecular aggregation takes place to produce short oligomers stabilized by hydrogen bonding and donor-acceptor charge-transfer (CT) interactions. The self-associated materials were characterized by ¹ H NMR and UV/Vis/NIR absorption spectroscopy, as well as by concentration- and temperature-dependent absorption spectroscopy and dynamic light scattering (DLS) analyses of both the monomeric and oligomerized species. The self-associated system produced from TTF-C[4]P and TNDCF exhibits a concentration-dependent aggregation behavior typical of supramolecular polymers. Further support for the proposed self-assembly came from theoretical calculations. The fluorescence emitting properties of TNDCF are quenched under conditions that promote the formation of supramolecular aggregates containing TTF-C[4]P and TNDCF. This quenching effect has been utilized as a probe for the detection of substrates in the form of anions (i.e., chloride) and nitroaromatic explosives (i.e., 1,3,5-trinitrobenzene). Specifically, the addition of these substrates to mixtures of TTF-C[4]P and TNDCF produced a fluorescence "turn-on" response.

Keywords: calix[4]pyrrole; fluorescence; sensors; supramolecular ensembles; tetrathiafulvalene.