Garbe, Simon, Krause, Maren, Klimpel, Annika, Neundorf, Ines ORCID: 0000-0001-6450-3991, Lippmann, Petra, Ott, Ingo
ORCID: 0000-0002-8087-4618, Brunink, Dana, Strassert, Cristian A., Doltsinis, Nikos L. and Klein, Axel
ORCID: 0000-0003-0093-9619
(2020).
Cyclometalated Pt Complexes of CNC Pincer Ligands: Luminescence and Cytotoxic Evaluation.
Organometallics, 39 (5).
S. 746 - 757.
WASHINGTON:
AMER CHEMICAL SOC.
ISSN 1520-6041
Abstract
In the framework of our attempts to develop cyclometalated Pt(II) complexes toward bifunctional targeting inhibitors or agents for photodynamic therapy, diagnostics, and bioimaging, a series of bis-cyclometalated Pt(II) complexes [Pt(CNC)(L)] (L = DMSO, MeCN) containing various (CNC)(2-) ligands based on 2,6-diphenylpyridine were synthesized and characterized analytically and spectroscopically, focusing on their electrochemical, luminescence, and antiproliferative properties. Electrochemical experiments and UV-vis absorption spectroscopy suggest ligand-centered LUMOs and metal-centered HOMOs in line with DFT calculations. Extension of the ancillary phenyl to naphthyl cores and a central 4-phenylpyridine group instead of pyridine results in bathochromic shifts of the long-wavelength absorption bands ranging from 420 to 440 nm, with the latter shift being more pronounced. The complexes of the fused CNC heterocyclic systems dba (H(2)dba = dibenzo[c,h] acridine), db(ph)a (H(2)db(ph)a = 7-phenyldibenzo[c,h]acridine), and bzqph (HbzqphH = 2-phenylbenzo[h]quinoline) absorb far more red-shifted in the range 500-530 nm. All complexes show reversible first electrochemical reductions and irreversible oxidations with an electrochemical gap of about 3 V, roughly in line with the absorption energies. While the 2,6-diphenylpyridine complexes [Pt(CNC)(DMSO)] show no luminescence at ambient temperature in solution, the fused dba, db(ph)a, and bzqph derivatives are efficient triplet emitters at ambient temperature with emission wavelengths in the region 575-600 nm and quantum yields ranging from 7 to 23%. Vibrationally resolved emission spectra calculated in the framework of DFT faithfully reproduce the experimental data. TD-DFT calculations at the excited-state T-1 geometry reveal intraligand, pi-pi*/MLCT character of the emission for all three investigated complexes. Antiproliferative tests on selected complexes gave very different toxicities, ranging from lower than 1 mu M to virtually nontoxic. The data allowed drawing some structure-activity relationships (SAR), even though variations in solubility could also significantly account for the different toxicities.
Item Type: | Journal Article | ||||||||||||||||||||||||||||||||||||||||||||
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URN: | urn:nbn:de:hbz:38-341324 | ||||||||||||||||||||||||||||||||||||||||||||
DOI: | 10.1021/acs.organomet.0c00015 | ||||||||||||||||||||||||||||||||||||||||||||
Journal or Publication Title: | Organometallics | ||||||||||||||||||||||||||||||||||||||||||||
Volume: | 39 | ||||||||||||||||||||||||||||||||||||||||||||
Number: | 5 | ||||||||||||||||||||||||||||||||||||||||||||
Page Range: | S. 746 - 757 | ||||||||||||||||||||||||||||||||||||||||||||
Date: | 2020 | ||||||||||||||||||||||||||||||||||||||||||||
Publisher: | AMER CHEMICAL SOC | ||||||||||||||||||||||||||||||||||||||||||||
Place of Publication: | WASHINGTON | ||||||||||||||||||||||||||||||||||||||||||||
ISSN: | 1520-6041 | ||||||||||||||||||||||||||||||||||||||||||||
Language: | English | ||||||||||||||||||||||||||||||||||||||||||||
Faculty: | Faculty of Mathematics and Natural Sciences | ||||||||||||||||||||||||||||||||||||||||||||
Divisions: | Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Inorganic Chemistry | ||||||||||||||||||||||||||||||||||||||||||||
Subjects: | no entry | ||||||||||||||||||||||||||||||||||||||||||||
Uncontrolled Keywords: |
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Refereed: | Yes | ||||||||||||||||||||||||||||||||||||||||||||
URI: | http://kups.ub.uni-koeln.de/id/eprint/34132 |
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