8 research outputs found
Bi- and trinuclear coinage metal complexes of a PNNP ligand featuring metallophilic interactions and an unusual charge separation
A selective synthesis of bi- and trinuclear complexes featuring a tetradentate monoanionic PNNP ligand is presented. The binuclear coinage metal complexes show a typical fourfold coordination for Cu and Ag, which changes to a bifold coordination for Au. The latter is accompanied by an unusual charge separation. Optical properties are investigated using photoluminescence spectroscopy and complemented by time-dependent density-functional-theory calculations. All compounds demonstrate clearly distinguished features dependent on the metals chosen and differences in the complex scaffold
Hetero-bimetallic Lanthanide-Coinage Metal Compounds Featuring Possible Metal-Metal Interactions in the Excited State
Heterometallic complexes, combining metals of the outer rims of the d-block, for example lanthanides(III) (Ln) and coinage metals(I) (M) are scarcely reported, synthetically challenging and highly interesting in terms of their interactions. In this context, we synthesized hetero-bimetallic LnâM compounds ligated by the phosphine functionalized amidinate system (N,Nâ-bis[(2-diphenylphosphino)phenyl]formamidinate, âdpfamâ). The resulting compounds [dpfam3LnM][OTf] (Ln = La, Nd and M = Ag, Au) feature a close proximity of the two metal centres and were investigated experimentally by photoluminescence spectroscopy and quantum chemical calculations. The latter showed rare LaâAu interactions for the first excited state
Nonanuclear zincâgold [ZnAu] heterobimetallic complexes
Nonanuclear zincâgold heterobimetallic complexes were synthesized in a two-step process. Commercially available carboxy-functionalized phosphine ligands were used for selective binding to Zn and Au centers. In the first step, bipyridine coordinated Zn-metalloligands with free phosphine moieties were prepared. Reaction of Zn-metalloligands with [AuCl(tht)] (tht = tetrahydrothiophene) resulted in the formation of nonanuclear ZnâAu heterobimetallic complexes. The flexibility of the carboxy-functionalized phosphine ligands was shown to be crucial for the formation of aurophilic interactions. Further, the photoluminescence of the Zn-metalloligands and one ZnâAu complex was investigated at room temperature as well as 77 K. The emission spectra showed clear difference between the Zn-metalloligands and the ZnâAu complex
Tetra- And hexanuclear string complexes of the coinage metals
Reaction of the PNNP ligand system N,NâČ-bis[(2-diphenylphosphino)phenyl]formamidinate (dpfam) featuring different coordination compartments with [AuCl(tht)], [CuMes], [AgMes], or [AuCF(tht)] (tht = tetrahydrothiophene) resulted in tetranuclear homo- and heterometallic coinage metal complexes, as well as a hexanuclear gold complex. All of them feature a metal string conformation. Photophysical investigation revealed a significant dependence of the photoluminescence properties on the metal composition. Below 100 K, the PL efficiency of three compounds approaches nearly 100%
Investigation of the Coordination Chemistry of a Bisamidinate Ferrocene Ligand with Cu, Ag, and Au
The coordination chemistry of a ferrocene ligand with one bulky amidinate function attached to each ring toward two different coinage metal precursors was investigated. In dependence of the metal and the co-ligands, âansaâ type structures and non-bridged structures were obtained. Six different compounds are reported. In the âansaâ type structures, short FeâM (M = Cu, Ag) distances were observed in the molecular structures in the solid state. However, theoretical calculations (DFT) did not reveal a stabilizing metalâmetal interaction. Instead, dispersion interactions within the ligand and between the ligand and metal seem to represent the main stabilization forces
Bright Luminescence in Three PhasesâA Combined Synthetic, Spectroscopic and Theoretical Approach
Combining phase-dependent photoluminescence (PL) measurements and quantum chemical calculations is a powerful approach to help understand the influence of the molecular surroundings on the PL properties. Herein, a phosphine functionalized amidinate was used to synthesize a recently presented bimetallic gold complex, featuring an unusual charge separation. The latter was subsequently used as metalloligand to yield heterotetrametallic complexes with an Au-M-M-Au âmolecular wireâ arrangement (M=Cu, Ag, Au) featuring metallophilic interactions. All compounds show bright phosphorescence in the solid state, also at ambient temperature. The effect of the molecular environment on the PL was studied in detail for these tetrametallic complexes by comparative measurements in solution, in the solid state and in the gas phase and contrasted to time-dependent density functional theory computations
Cancer data quality and harmonization in Europe: the experience of the BENCHISTA Project â international benchmarking of childhood cancer survival by stage
IntroductionVariation in stage at diagnosis of childhood cancers (CC) may explain differences in survival rates observed across geographical regions. The BENCHISTA project aims to understand these differences and to encourage the application of the Toronto Staging Guidelines (TG) by Population-Based Cancer Registries (PBCRs) to the most common solid paediatric cancers.MethodsPBCRs within and outside Europe were invited to participate and identify all cases of Neuroblastoma, Wilms Tumour, Medulloblastoma, Ewing Sarcoma, Rhabdomyosarcoma and Osteosarcoma diagnosed in a consecutive three-year period (2014-2017) and apply TG at diagnosis. Other non-stage prognostic factors, treatment, progression/recurrence, and cause of death information were collected as optional variables. A minimum of three-year follow-up was required. To standardise TG application by PBCRs, on-line workshops led by six tumour-specific clinical experts were held. To understand the role of data availability and quality, a survey focused on data collection/sharing processes and a quality assurance exercise were generated. To support data harmonization and query resolution a dedicated email and a question-and-answers bank were created.Results67 PBCRs from 28 countries participated and provided a maximally de-personalized, patient-level dataset. For 26 PBCRs, data format and ethical approval obtained by the two sponsoring institutions (UCL and INT) was sufficient for data sharing. 41 participating PBCRs required a Data Transfer Agreement (DTA) to comply with data protection regulations. Due to heterogeneity found in legal aspects, 18 months were spent on finalizing the DTA. The data collection survey was answered by 68 respondents from 63 PBCRs; 44% of them confirmed the ability to re-consult a clinician in cases where stage ascertainment was difficult/uncertain. Of the total participating PBCRs, 75% completed the staging quality assurance exercise, with a median correct answer proportion of 92% [range: 70% (rhabdomyosarcoma) to 100% (Wilms tumour)].ConclusionDifferences in interpretation and processes required to harmonize general data protection regulations across countries were encountered causing delays in data transfer. Despite challenges, the BENCHISTA Project has established a large collaboration between PBCRs and clinicians to collect detailed and standardised TG at a population-level enhancing the understanding of the reasons for variation in overall survival rates for CC, stimulate research and improve national/regional child health plans
Molecular Lanthanide Switches for Magnetism and Photoluminescence
International audienceSolvation of [(η9-CNT)Ln(η8-COT)] (Ln = La, Ce, Nd, Tb, Er; CNT = cyclononatetraenyl, i.e., C9H9-; COT = cyclooctatetraendiid, i.e., C8H82-) complexes with tetrahydrofuran (THF) gives rise to neutral [(η4-CNT)Ln(thf)2(η8-COT)] (Ln = La, Ce) and ionic [Ln(thf)x(η8-COT)][CNT] (x = 4 (Ce, Nd, Tb), 3 (Er)) species in a solid-to-solid transformation. Due to the severe distortion of the ligand sphere upon solvation, these species act as switchable luminophores and single-molecule magnets. The desolvation of the coordinated solvents can be triggered by applying a dynamic vacuum, as well as a temperature gradient stimulus. Raman spectroscopic investigations revealed fast and fully reversible solvation and desolvation processes. Moreover, we also show that a Nd:YAG laser can induce the necessary temperature gradient for a self-sufficient switching process of the Ce analogue in a spatially resolved manner