Arylethynylchromium(III) complexes of the form trans-[Cr(cyclam)(CCC(6)H(4)R)(2)]OTf (where cyclam = 1,4,8,11-tetraazacyclotetradecane, R = H, CH(3), or CF(3) in the para position, and OTf = trifluoromethanesulfonate) have been prepared and characterized by IR spectroscopy and X-ray diffraction. The complexes are emissive with excited-state lifetimes in a deoxygenated fluid solution between 200 and 300 micros.
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http://dx.doi.org/10.1021/ic801376p | DOI Listing |
Inorg Chem
December 2024
Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
The interest in chromium(III) complexes has been renewed over the past decade for the design of efficient earth-abundant phosphorescent red-to-near-infrared spin-flip emitters and photocatalysts with long excited state lifetimes. In this context, we report the energy tuning of spin-flip excited states based on heteroleptic bis(tridentate) polypyridine chromium(III) complexes , namely, , and with the tridentate ligands L and L [X/Y = NMe, ,'-dimethyl-,'-dipyridin-2-ylpyridine-2,6-diamine; X/Y = CH, 2,6-bis(2-pyridylmethyl)pyridine and X/Y = S, 2,6-bis(pyridine-2-ylthio)pyridine]. The heteroleptic complexes are obtained via a novel synthetic approach toward the required intermediate labile triflato complexes Cr(L)(OTf) () from the respective chlorido precursors CrCl(L) () using trimethylsilyl trifluoromethanesulfonate.
View Article and Find Full Text PDFChem Sci
December 2024
Department of Chemistry, Johannes Gutenberg University Mainz Duesbergweg 10-14 55128 Mainz Germany
Six-coordinate chromium(iii) complexes with high spin-flip (SF) photoluminescence quantum yields and lifetimes (molecular rubies) have attracted huge interest in the past years due to their applicability in sensing, photocatalysis or circularly polarised emission. However, clearcut design rules for high quantum yields and lifetimes are still lacking due to the multidimensional problem of the non-radiative decay of the SF states. Based on an isostructural series of complexes differing in the ligand backbone, we disentangle decisive structural and electronic features for SF excited state energies and non-radiative decays promoted by spin-orbit coupling, Jahn-Teller distortions and (thermally activated) multiphonon relaxation.
View Article and Find Full Text PDFLuminescence
December 2023
Centeral Research Laboratory, Esfarayen University of Technology, Esfarayen, Iran.
Aluminum, classified as one of the toxic heavy metals, has a recommended daily consumption limit of 3-10 mg, as specified by the World Health Organization (WHO). Herein, the selective and sensitive aluminum(III) fluorescence sensor based on TMU-16 metal-organic frameworks (MOFs) in aqueous medium, is reported. A sensing pathway was found via the cation exchange between aluminum(III) and zinc(II) ions, and caused selectivity and sensitivity detection of aluminum(III) with a 5-100 ppm linear range and 1.
View Article and Find Full Text PDFInorg Chem
October 2023
Department of Chemistry, Faculty of Science, Ain Shams University, Abbassia, Cairo 11566, Egypt.
In this study, we report the synthesis and characterization of some heteroleptic Cr(III) complexes of the form [Cr(Phen)L](OTf), where Phen = 1,10-phenanthroline and L is either 2,2'-bipyridine (bpy) or its derivatives, such as 4,4'-dimethyl-2,2'-bipyridine (4,4'-DMB), 4,4'-dimethoxy-2,2'-bipyridine (4,4'-DMOB), 4,4'-di-butyl-2,2'-bipyridine (4,4'-dbpy), 5,5'-dimethyl-2,2'-bipyridine (5,5'-DMB), 4,4'-dimethoxycarbonyl-2,2'-bipyridine (4,4'-dmcbpy) or 1,10-phenanthroline derivatives, such as 5-methyl-1,10-phenanthroline (5-Me-Phen) and 4,7-dimethyl-1,10-phenanthroline (4,7-DMP). Heteroleptic complexes were prepared in two stages the intermediate [Cr(Phen)(CFSO)](CFSO) and five examples have been crystallographically characterized. Steady-state absorption and luminescence emission characteristics of these complexes were measured in 1 M HCl solutions.
View Article and Find Full Text PDFInorg Chem
October 2023
Department of Chemistry, Johannes Gutenberg University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
Photoactive chromium(III) complexes saw a conceptual breakthrough with the discovery of the prototypical molecular ruby -[Cr(ddpd)] (ddpd = ,'-dimethyl-,'-dipyridin-2-ylpyridine-2,6-diamine), which shows intense long-lived near-infrared (NIR) phosphorescence from metal-centered spin-flip states. In contrast to the numerous studies on chromium(III) photophysics, only 10 luminescent molybdenum(III) complexes have been reported so far. Here, we present the synthesis and characterization of -MoX(ddpd) (, X = Cl; , X = Br) and -[Mo(ddpd)] (-), an isomeric heavy homologue of the prototypical molecular ruby.
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