6277-72-1Relevant articles and documents
Cyclometalated pt complexes of cnc pincer ligands: Luminescence and cytotoxic evaluation
Garbe, Simon,Krause, Maren,Klimpel, Annika,Neundorf, Ines,Lippmann, Petra,Ott, Ingo,Brünink, Dana,Strassert, Cristian A.,Doltsinis, Nikos L.,Klein, Axel
, p. 746 - 756 (2020/03/30)
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 (H2dba = dibenzo[c,h]acridine), db(ph)a (H2db(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 T1 geometry reveal intraligand π-π*/MLCT character of the emission for all three investigated complexes. Antiproliferative tests on selected complexes gave very different toxicities, ranging from lower than 1 μM 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.
Optimization of Catalyst Structure for Asymmetric Propargylation of Aldehydes with Allenyltrichlorosilane
Vaganov, Vladimir Yu.,Fukazawa, Yasuaki,Kondratyev, Nikolay S.,Shipilovskikh, Sergei A.,Wheeler, Steven E.,Rubtsov, Aleksandr E.,Malkov, Andrei V.
, p. 5467 - 5474 (2020/10/19)
The design of catalysts for asymmetric propargylations remains a challenging task, with only a handful of methods providing access to enantioenriched homopropargylic alcohols. In this work, guided by previously reported computational predictions, a set of
Luminescent PtII Complexes of Tridentate Cyclometalating 2,5-Bis(aryl)-pyridine Ligands
Krause, Maren,Kourkoulos, Dimitrios,González-Abradelo, Darío,Meerholz, Klaus,Strassert, Cristian A.,Klein, Axel
supporting information, p. 5215 - 5223 (2017/10/18)
Bis-cyclometalated PtII complexes of dianionic 2,5-bis(aryl)-pyridine ligands (L1–6)2–, carrying various cyclometalating or pending aryl groups, are synthesised in two steps. The reactions of H2L protoligands with K2[PtCl4] in acetic acid give the mono-cyclometalated complexes [Pt(HL)Cl]2. Heating these complexes in hot DMSO (dimethyl sulfoxide) yields the double-cyclometalated DMSO complexes [Pt(L1–6)(DMSO)]. The reaction of [Pt(L4)(DMSO)] with N,N-dimethylimidazolium iodide in the presence of KOtBu as the base gives the carbene complex [Pt(L4)(Me2Imd)]. Detailed photophysical studies reveal the intense orange luminescence of these complexes in CH2Cl2 solution, with quantum yields up to 0.22, and increased quantum yields of up to 1.00 in glassy frozen CH2Cl2/MeOH (1:1) and up to 0.44 in PMMA matrices. Detailed electrochemistry (including spectroelectrochemistry) reveals reversible ligand-based first reductions at –2.1 to –2.3 V, irreversible Pt-centred oxidations at around 0.8 V and electrochemical band gaps of 2.8–3.0 eV. Further reduction waves at very negative potentials interfere with the solvent (THF with traces of water) discharge and can be traced, with UV/Vis spectroelectrochemistry, to Pt-centred reductions for the DMSO complexes and to a second ligand-centred reduction for the Me2Imd complex from. The photo/electrochemical properties can be roughly correlated with the ligand pattern and suggest their use in optoelectronic applications.
