Influencing the Self-Sorting Behavior of [2.2]Paracyclophane-Based Ligands by Introducing Isostructural Binding Motifs

Lucia Volbach; Niklas Struch; Fabian Bohle; Filip Topić; Gregor Schnakenburg; Andreas Schneider; Kari Rissanen; Stefan Grimme; Arne Lützen

doi:10.1002/chem.201905070

Influencing the Self-Sorting Behavior of [2.2]Paracyclophane-Based Ligands by Introducing Isostructural Binding Motifs

Chemistry. 2020 Mar 12;26(15):3335-3347. doi: 10.1002/chem.201905070. Epub 2020 Feb 19.

Authors

Lucia Volbach¹, Niklas Struch^{1

2}, Fabian Bohle³, Filip Topić^{4

5}, Gregor Schnakenburg⁶, Andreas Schneider¹, Kari Rissanen⁴, Stefan Grimme³, Arne Lützen¹

Affiliations

¹ Kekulé-Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk Strasse 1, 53121, Bonn, Germany.
² current address: Arlanxeo Netherlands B.V., Urmonderbaan 24, 6167 RD, Geleen, The Netherlands.
³ Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstrasse 4, 53115, Bonn, Germany.
⁴ Department of Chemistry, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland.
⁵ current address: Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, Qc, H3A 0B8, Canada.
⁶ Institute of Inorganic Chemistry, University of Bonn, Gerhard-Domagk Strasse 1, 53121, Bonn, Germany.

Abstract

Two isostructural ligands with either nitrile (L^nit ) or isonitrile (L^iso ) moieties directly connected to a [2.2]paracyclophane backbone with pseudo-meta substitution pattern have been synthesized. The ligand itself (L^nit ) or its precursors (L^iso ) were resolved by HPLC on a chiral stationary phase and the absolute configuration of the isolated enantiomers was assigned by XRD analysis and/or by comparison of quantum-chemical simulated and experimental electronic circular dichroism (ECD) spectra. Surprisingly, the resulting metallosupramolecular aggregates formed in solution upon coordination of [(dppp)Pd(OTf)₂ ] differ in their composition: whereas L^nit forms dinuclear complexes, L^iso exclusively forms trinuclear ones. Furthermore, they also differ in their chiral self-sorting behavior as (rac)-L^iso undergoes exclusive social self-sorting leading to a heterochiral assembly, whereas (rac)-L^iso shows a twofold preference for the formation of homochiral complexes in a narcissistic self-sorting manner as proven by ESI mass spectrometry and NMR spectroscopy. Interestingly, upon crystallization, these discrete aggregates undergo structural transformation to coordination polymers, as evidenced by single-crystal X-ray diffraction.

Keywords: isonitrile ligands; nitrile ligands; self-assembly; self-sorting; supramolecular chemistry.

Abstract

Grants and funding