A Fluorescence-Detected Coordination-Induced Spin State Switch

Kurz H, Schoetz K, Papadopoulos I, Heinemann FW, Maid H, Guldi DM, Koehler A, Hoerner G, Weber B (2021)

Publication Type: Journal article

Publication year: 2021

Journal

Journal of the American Chemical Society American Chemical Society

Book Volume: 143

Pages Range: 3466-3480

Journal Issue: 9

DOI: 10.1021/jacs.0c12568

Abstract

The response of the spin state to in situ variation of the coordination number (CISSS) is a promising and viable approach to smart sensor materials, yet it suffers to date from insensitive detection. Herein, we present the synthetic access to a family of planar nickel(II) complexes, whose CISSS is sensitively followed by means of fluorescence detection. For this purpose, nickel(II) complexes with four phenazine-based Schiff base-like ligands were synthesized and characterized through solution-phase spectroscopy (NMR and UV-vis), solid-state structure analysis (single-crystal XRD), and extended theoretical modeling. All of them reveal CISSS in solution through axial ligating a range of N- and O-donors. CISSS correlates nicely with the basicity of the axial ligand and the substitution-dependent acidity of the nickel(II) coordination site. Remarkably, three out of the four nickel(II) complexes are fluorescent in noncoordinating solvents but are fluorescence-silent in the presence of axial ligands such as pyridine. As these complexes are rare examples of fluorescent nickel(II) complexes, the photophysical properties with a coordination number of 4 were studied in detail, including temperature-dependent lifetime and quantum yield determinations. Most importantly, fluorescence quenching upon adding axial ligands allows a "black or white", i.e. digital, sensoring of spin state alternation. Our studies of fluorescence-detected CISSS (FD-CISSS) revealed that absorption-based CISSS and FD-CISSS are super proportional with respect to the pyridine concentration: FD-CISSS features a higher sensitivity. Overall, our findings indicate a favored ligation of these nickel(II) complexes in the excited state in comparison to the ground state.

Authors with CRIS profile

Ilias Papadopoulos Lehrstuhl für Physikalische Chemie I Frank Wilhelm Heinemann Lehrstuhl für Anorganische und Allgemeine Chemie Harald Maid Lehrstuhl für Organische Chemie II Dirk Michael Guldi Lehrstuhl für Physikalische Chemie I

Involved external institutions

Universität Bayreuth DE Germany (DE)

How to cite

APA:

Kurz, H., Schoetz, K., Papadopoulos, I., Heinemann, F.W., Maid, H., Guldi, D.M.,... Weber, B. (2021). A Fluorescence-Detected Coordination-Induced Spin State Switch. Journal of the American Chemical Society, 143(9), 3466-3480. https://dx.doi.org/10.1021/jacs.0c12568

MLA:

Kurz, Hannah, et al. "A Fluorescence-Detected Coordination-Induced Spin State Switch." Journal of the American Chemical Society 143.9 (2021): 3466-3480.

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