RESUMEN
B-cell chronic lymphocytic leukaemia (CLL) is associated with immunosuppression and patients are at increased clinical risk following SARS-CoV-2 infection. Covid-19 vaccines offer the potential for protection against severe infection but relatively little is known regarding the profile of the antibody response following first or second vaccination. We studied spike-specific antibody responses following first and/or second Covid-19 vaccination in 299 patients with CLL compared with healthy donors. 286 patients underwent extended interval (10-12 week) vaccination. 154 patients received the BNT162b2 mRNA vaccine and 145 patients received ChAdOx1. Blood samples were taken either by venepuncture or as dried blood spots on filter paper. Spike-specific antibody responses were detectable in 34% of patients with CLL after one vaccine (n = 267) compared to 94% in healthy donors with antibody titres 104-fold lower in the patient group. Antibody responses increased to 75% after second vaccine (n = 55), compared to 100% in healthy donors, although titres remained lower. Multivariate analysis showed that current treatment with BTK inhibitors or IgA deficiency were independently associated with failure to generate an antibody response after the second vaccine. This work supports the need for optimisation of vaccination strategy in patients with CLL including the potential utility of booster vaccines.
Asunto(s)
Anticuerpos Antivirales , Formación de Anticuerpos/efectos de los fármacos , Vacunas contra la COVID-19 , COVID-19 , Inmunización Secundaria , Leucemia Linfocítica Crónica de Células B , Adulto , Anciano , Anciano de 80 o más Años , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Vacuna BNT162 , COVID-19/sangre , COVID-19/inmunología , COVID-19/prevención & control , Vacunas contra la COVID-19/administración & dosificación , Vacunas contra la COVID-19/inmunología , Femenino , Humanos , Leucemia Linfocítica Crónica de Células B/sangre , Leucemia Linfocítica Crónica de Células B/inmunología , Masculino , Persona de Mediana EdadRESUMEN
Rational design of materials for energy storage systems relies on our ability to probe these materials at various length scales. Solid-state NMR spectroscopy is a powerful approach for gaining chemical and structural insights at the atomic/molecular level, but its low detection sensitivity often limits applicability. This limitation can be overcome by transferring the high polarization of electron spins to the sample of interest in a process called dynamic nuclear polarization (DNP). Here, we employ for the first time metal ion-based DNP to probe pristine and cycled composite battery electrodes. A new and efficient DNP agent, Fe(III), is introduced, yielding lithium signal enhancement up to 180 when substituted in the anode material Li4Ti5O12. In addition for being DNP active, Fe(III) improves the anode performance. Reduction of Fe(III) to Fe(II) upon cycling can be monitored in the loss of DNP activity. We show that the dopant can be reactivated (return to Fe(III)) for DNP by increasing the cycling potential window. Furthermore, we demonstrate that the deleterious effect of carbon additives on the DNP process can be eliminated by using carbon free electrodes, doped with Fe(III) and Mn(II), which provide good electrochemical performance as well as sensitivity in DNP-NMR. We expect that the approach presented here will expand the applicability of DNP for studying materials for frontier challenges in materials chemistry associated with energy and sustainability.
RESUMEN
Temperature-dependent 57Fe Mössbauer effect (ME) spectroscopic studies were carried out on ferrocene (Fc), 1,1'-dimethylferrocene (1,1'(CH3)2Fc) and ferrocenium hexafluorophosphate (FcPF6) guest species in cucurbit[n]uril (n = 7, 8) inclusion complexes. The solid inclusion complexes were isolated by freeze-drying of dilute aqueous solutions and/or microwave-assisted precipitation from concentrated mixtures. The presence of genuine 1 : 1 (host : guest) inclusion complexes in the isolated solids was supported by liquid-state 1H and solid-state 13C{1H} MAS NMR, elemental and thermogravimetric analyses, powder X-ray diffraction, FTIR spectroscopy, and diffuse reflectance UV-Vis spectroscopy. The ME spectra of the complexes CB7·Fc and CB7·1,1'(CH3)2Fc consist of well-resolved doublets with hyperfine parameters (isomer shift and quadrupole splitting at 90 K) and temperature-dependent recoil-free fraction data that are very similar to those for the neat parent compounds, Fc and 1,1'(CH3)2Fc, suggesting that the organometallic guest molecules do not interact significantly with the host environment over the experimental temperature range. The ME spectra for CB7·FcPF6 and CB8·FcPF6 consist of a major broad line resonance attributed to a paramagnetic FeIII site. From the temperature-dependence of the recoil-free fraction it is evident that the charged guest species in these systems interact with the host environment significantly more strongly than was observed in the case of the neutral guest species, Fc and 1,1'(CH3)2Fc. Moreover, the ME data indicate that the vibrational amplitude of the ferrocenium guest molecule is significantly larger in the CB8 host molecule than in the CB7 homologue, as expected on the basis of the different cavity sizes.
RESUMEN
High-oxidation-state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin-state preferences of threefold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(ImR)3}FeN], R = tBu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(ImR)3}Fe(NR')]+, R = Mes, R' = 1-adamantyl (3), tBu (4), were investigated by electronic absorption and Mössbauer effect spectroscopies. For comparison, two other Fe(IV) nitrido complexes, [(TIMENAr)FeN]+ (TIMENAr = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), were investigated by 57Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (for 3 and 4) and frequency-domain Fourier-transform (FD-FT) terahertz electron paramagnetic resonance (for 3), which reveal their zero-field splitting parameters. Experimentally correlated theoretical studies comprising ligand-field theory and quantum chemical theory, the latter including both density functional theory and ab initio methods, reveal the key role played by the Fe 3dz2 (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin-state preference of the complex. The ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.
RESUMEN
Cp(BIG)2Sn (Cp(BIG) = (4-n-Bu-C6H4)5cyclopentadienyl), prepared by reaction of 2 equiv of Cp(BIG)Na with SnCl2, crystallized isomorphous to other known metallocenes with this ligand (Ca, Sr, Ba, Sm, Eu, Yb). Similarly, it shows perfect linearity, C-H···C(π) bonding between the Cp(BIG) rings and out-of-plane bending of the aryl substituents toward the metal. Whereas all other Cp(BIG)2M complexes show large disorder in the metal position, the Sn atom in Cp(BIG)2Sn is perfectly ordered. In contrast, (119)Sn and (151)Eu Mößbauer investigations on the corresponding Cp(BIG)2M metallocenes show that Sn(II) is more dynamic and loosely bound than Eu(II). The large displacement factors in the group 2 and especially in the lanthanide(II) metallocenes Cp(BIG)2M can be explained by static metal disorder in a plane parallel to the Cp(BIG) rings. Despite parallel Cp(BIG) rings, these metallocenes have a nonlinear Cpcenter-M-Cpcenter geometry. This is explained by an ionic model in which metal atoms are polarized by the negatively charged Cp rings. The extent of nonlinearity is in line with trends found in M(2+) ion polarizabilities. The range of known calculated dipole polarizabilities at the Douglas-Kroll CCSD(T) level was extended with values (atomic units) for Sn(2+) 15.35, Sm(2+)(4f(6) (7)F) 9.82, Eu(2+)(4f(7) (8)S) 8.99, and Yb(2+)(4f(14) (1)S) 6.55. This polarizability model cannot be applied to predominantly covalently bound Cp(BIG)2Sn, which shows a perfectly ordered structure. The bent geometry of Cp*2Sn should therefore not be explained by metal polarizability but is due to van der Waals Cp*···Cp* attraction and (to some extent) to a small p-character component in the Sn lone pair.
RESUMEN
The superbulky deca-aryleuropocene [Eu(Cp(BIG))2], Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT = 2-Me2N-α-Me3Si-benzyl, with two equivalents of Cp(BIG)H. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45% quantum yield). The crystal structure is isomorphic to those of [M(Cp(BIG))2] (M = Sm, Yb, Ca, Ba) and shows the typical distortions that arise from Cp(BIG)â â â Cp(BIG) attraction as well as excessively large displacement parameter for the heavy Eu atom (U(eq) = 0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(Cp(BIG))2] (M = Sm, Eu, Yb), several physical analyses have been applied. Temperature-dependent magnetic susceptibility data of [Yb(Cp(BIG))2] show diamagnetism, indicating stable divalent ytterbium. Temperature-dependent (151)Eu Mössbauer effect spectroscopic examination of [Eu(Cp(BIG))2] was examined over the temperature range 93-215â K and the hyperfine and dynamical properties of the Eu(II) species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal X-ray data at 203â K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low-frequency torsional and librational modes in [Eu(Cp(BIG))2]. X-ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(Cp(BIG))2] (Ln = Sm, Eu, Yb) compounds are divalent. The XANES white-line spectra are at 8.3, 7.3, and 7.8â eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100â K. XANES also showed that the [Ln(Cp(BIG))2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(Cp(BIG))2] shows already at room temperature strong orange photoluminescence (quantum yield: 45 %): excitation at 412â nm (24,270â cm(-1)) gives a symmetrical single band in the emission spectrum at 606â nm (νmax =16495â cm(-1), FWHM: 2090â cm(-1), Stokes-shift: 2140â cm(-1)), which is assigned to a 4f(6)5d(1) â 4f(7) transition of Eu(II). These remarkable values compare well to those for Eu(II)-doped ionic host lattices and are likely caused by the rigidity of the [Eu(Cp(BIG))2] complex. Sharp emission signals, typical for Eu(III), are not visible.
RESUMEN
The synthesis and spectroscopic and structural characterization of an extensive series of acyclic, monomeric tetrylene dichalcogenolates of formula M(ChAr)2 (M = Si, Ge, Sn, Pb; Ch = O, S, or Se; Ar = bulky m-terphenyl ligand, including two new acyclic silylenes) are described. They were found to possess several unusual features-the most notable of which is their strong tendency to display acute interligand, Ch-M-Ch, bond angles that are often well below 90°. Furthermore, and contrary to normal steric expectations, the interligand angles were found to become narrower as the size of the ligand was increased. Experimental and structural data in conjunction with high-level DFT calculations, including corrections for dispersion effects, led to the conclusion that dispersion forces play an important role in stabilizing their acute interligand angles.
Asunto(s)
Calcógenos/química , Metano/análogos & derivados , Compuestos Organometálicos/química , Metano/química , Estructura Molecular , Compuestos Organometálicos/síntesis química , Teoría CuánticaRESUMEN
(119)Sn Mössbauer spectroscopy was performed on a series of formal Sn(II) dichloride and dihydride adducts bound by either carbon- or phosphorus-based electron pair donors. Upon binding electron-withdrawing metal pentacarbonyl units to the tin centers in LB·SnCl2·M(CO)5 (LB = Lewis base; M = Cr or W), a significant decrease in isomer shift (IS) was noted relative to the unbound Sn(II) complexes, LB·SnCl2, consistent with removal of nonbonding s-electron density from tin upon forming Sn-M linkages (M = Cr and W). Interestingly, when the nature of the Lewis base in the series LB·SnCl2·W(CO)5 was altered, very little change in the IS values was noted, implying that the LB-Sn bonds were constructed with tin-based orbitals of large p-character (as supported by prior theoretical studies). In addition, variable temperature Mössbauer measurements were used to determine the mean displacement of the tin atoms in the solid state, a parameter that can be correlated with the degree of covalent bonding involving tin in these species.
RESUMEN
The lithiation of ferrocenylphosphane Fc-PH(2) (Fc = -C(5)H(4)FeC(5)H(5)) has been reinvestigated and both Fc-PHLi and Fc-PLi(2) have been identified by NMR-spectroscopy. The lithiated phosphanides have been converted to the corresponding mono and bis(silylated) species the latter of which gave synthetic access to an oligomer in which three ferrocene units are symmetrically connected by phosphaalkene units. The charge distribution within this oligomer and its isomers has been analyzed using DFT calculations which indicates that the iron atom of the central metallocene unit is slightly more positive than the terminal ones. These findings are supported experimentally by Mößbauer spectroscopy and cyclic voltammetry.
RESUMEN
A series of cationic cryptand complexes of tin(II), [Cryptand[2.2.2]SnX][SnX(3)] (10, X = Cl; 11, X = Br; 12, X = I) and [Cryptand[2.2.2]Sn][OTf](2) (13), were synthesized by the addition of cryptand[2.2.2] to a solution of either tin(II) chloride, iodide, or trifluoromethanesulfonate. The complexes could also be synthesized by the addition of the appropriate trimethylsilyl halide (or pseudohalide) reagent to a solution of tin(II) chloride and cryptand[2.2.2]. The complexes were characterized using a variety of techniques including NMR, Raman, and temperature-dependent Mössbauer spectroscopy, mass spectrometry, and X-ray diffraction.
RESUMEN
Reaction of [(PPh(2)âNSiMe(3))(PPh(2)âS)CSn:](2) (1) with elemental sulfur in toluene afforded [{(µ-S)Sn(IV)C(PPh(2)âNSiMe(3))(PPh(2)âS)}(3)Sn(II)(µ(3)-S)] (2) and [CH(2)(PPh(2)âNSiMe(3))(PPh(2)âS)] (3). Compound 2 comprises a Sn(II)S moiety coordinated with the Sn(IV) and S atoms of a trimeric 2-stannathiomethendiide {(PPh(2)âNSiMe(3))(PPh(2)âS)CSn(µ-S)}(3). Compound 2 has been characterized by NMR spectroscopy, (119)Sn Mössbauer studies, X-ray crystallography, and theoretical studies. (119)Sn NMR spectroscopy and Mössbauer studies show the presence of Sn(IV) and Sn(II) atoms in 2. X-ray crystallography suggests that the Sn(II)S moiety does not have multiple bond character. Theoretical studies illustrate that the C(methanediide)-Sn bonds comprise a lone pair orbital on each C(methanediide) atom and an C-Sn occupied σ orbital.
RESUMEN
A series of tin(II) triflate and chloride salts in which the cations are complexed by either cyclic or acyclic polyether ligands and which have well-characterized single-crystal X-ray structures are investigated using a variety of experimental and computational techniques. Mössbauer spectroscopy illustrates that the triflate salts tend to have valence electrons with higher s-character, and solid-state NMR spectroscopy reveals marked differences between superficially similar triflate and chloride salts. Cyclic voltammetry investigations of the triflate salts corroborate the results of the Mössbauer and NMR spectroscopy and reveal substantial steric and electronic effects for the different polyether ligands. MP2 and DFT calculations provide insight into the effects of ligands and substituents on the stability and reactivity of the low-valent metal atom. Overall, the investigations reveal the existence of more substantial binding between tin and chlorine in comparison to the triflate substituent and provide a rationale for the considerably increased reactivity of the chloride salts.
RESUMEN
Four (57)Fe-labeled tetrachloroferrates(III) of organic cations (1-butyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1-methyl-1-propylpyrrolidinium, tetraphenylphosphonium) were examined by temperature-dependent Mössbauer spectroscopy. The hyperfine and dynamic parameters of the iron(III) site were determined. Single crystal X-ray diffraction data of [Ph(4)P][FeCl(4)] were collected at four temperatures (295, 223, 173, and 123 K), and the dynamics of the iron atom inferred from the Mössbauer data and the single crystal U(i,j) parameters have been compared.
Asunto(s)
Líquidos Iónicos/química , Hierro/química , Magnetismo , Cristalografía por Rayos X , Isótopos de Hierro/química , Marcaje Isotópico , Conformación Molecular , Espectroscopía de MossbauerRESUMEN
The title compound 2 was prepared and its crystal structure was determined at 100 K. The neat solid was examined by temperature dependent (57)Fe Mössbauer effect (ME) spectroscopy over the interval 92 < T < 318 K, and evidences two diamagnetic Fe(II) sites and one paramagnetic Fe(III) site. The latter shows spin-lattice relaxation, but there is no evidence of electron delocalization among the three iron sites in the above temperature interval. The mean-square-amplitude-of-vibration of the diamagnetic iron site has been determined from the recoil-free fraction ME resonance, and compared to the neutral Fc(3)COH homologue (1). The ME dynamical data are in good agreement with the U(i,j) value at 100 K extracted from the crystallographic results. The ME parameters at 5 K have also been determined with the sample compound embedded in a paraffin wax matrix as well as pelletized with BN.
RESUMEN
The N-heterocyclic stannylenes (NHSns), [(Dipp) N(CH(2))(n)N(Dipp)S n] (Dipp = 2,6- (i)Pr(2)C(6)H(3); n = 2, 1; n = 3, 5) and [((t)Bu) N(CHMe)(2)N((t)Bu)S n] (10) are competent ligands toward a variety of transition metal centers, as seen in the complexes [W(CO)(5)·1] (2), [(OC)(4)Fe(µ-1)(2)Fe(CO)(4)] (3), [(OC)(4)Fe(µ-1)Fe(CO)(4)] (4), [Fe(CO)(4)·5](n) (6, n = 1 or 2), [(OC)(4)Fe(µ-5)Fe(CO)(4)] (7), [Ph(3)PPt(µ-1)(2)PtPPh(3)] (8), [Fe(CO)(4)·10] (11), and [(η(5)-C(5)H(5))(OC)(2)Mn·10] (12). X-ray crystallographic studies show that the NHSns are structurally largely unperturbed binding to the metal, but in contrast to the parent NHCs, NHSns often adopt a bridging position across dinuclear metal units. The balance between terminal and bridging positions for the stannylene is evidently closely balanced as shown by the observation of both monomers and dimers for 6 in the solid state and in solution. (119)Sn and (57)Fe Mössbauer spectroscopy of the complexes shows the tin atoms in such complexes to be consistent with electron deficient Sn(II) centers.
Asunto(s)
Compuestos Heterocíclicos/química , Compuestos Heterocíclicos/síntesis química , Compuestos Orgánicos de Estaño/química , Compuestos Orgánicos de Estaño/síntesis química , Cristalografía por Rayos X , Modelos Moleculares , Estructura Molecular , Espectroscopía de Mossbauer , EstereoisomerismoRESUMEN
Redox properties of H(2)TFcP [TFcP(2-) = 5,10,15,20-tetraferrocenylporphyrin(2-)] were investigated using cyclic voltammetry, differential pulse voltammetry, and square-wave voltammetry methods in a large variety of solvents and electrolytes. When DMF, THF, and MeCN were used with TBAP as the supporting electrolyte, the first oxidation wave was assigned to a single four-electron oxidation process reflecting simultaneous oxidation of all iron(II) centers into iron(III) centers in H(2)TFcP. When an o-DCB (1,2-dichlorobenzene)/TBAP combination was used in electrochemical experiments, four ferrocene substituents underwent two very diffuse, "two-electron" stepwise oxidations. The use of a weakly coordinating TFAB ([NBu(4)][B(C(6)F(5))(4)]) electrolyte in o-DCB or DCM results in four single-electron oxidation processes for ferrocene substituents in which the first and second single-electron waves have a relatively large separation, while the second, third, and fourth oxidation processes are more closely spaced; similar results were observed when a DCM/TBAP system and an imidazolium cation-based ionic liquid ((bmim)Tf(2)N = N-butyl-N'-methylimidazolium bis(trifluoromethanesulfonyl)imide) were used. Spectroelectrochemical oxidation of H(2)TFcP in o-DCB or DCM with TFAB as the supporting electrolyte allowed for characterization of the mixed-valence [H(2)TFcP](+), [H(2)TFcP](2+), and [H(2)TFcP](3+) compounds by UV-vis spectroscopy in addition to the "all-Fe(III)" [H(2)TFcP](4+). The chemical oxidation of H(2)TFcP was tested using a variety of oxidants which resulted in formation of mixed-valence [H(2)TFcP](+) and [H(2)TFcP](2+) as well as [H(2)TFcP](4+), which were characterized by UV-vis-NIR, MCD, IR, Mossbauer, and XPS spectroscopy. The intervalence-charge-transfer bands observed in the near-IR region in [H(2)TFcP](+) and [H(2)TFcP](2+) complexes were analyzed using Hush formalism and found to be of class II (in Robin-Day classification) character with localized ferrous and ferric centers. Class II behavior of [H(2)TFcP](+) and [H(2)TFcP](2+) complexes was further confirmed by Mossbauer, IR, and XPS data.
RESUMEN
The metal atom dynamics of four triferrocenylmethane derivatives have been elucidated, using temperature-dependent 57Fe Mössbauer effect (ME) spectroscopy. The hyperfine parameters (IS and QS) at 90 K are compared to each other and those of related ferrocenoids. The metal atom vibrational amplitudes as a function of temperature have been extracted from the ME recoil-free fraction data, and are compared to the X-ray U(i,j) values for two of the compounds. The single crystal structural data for triferrocenylmethanol have been determined at 173 and 295 K. The vibrational anisotropy of the metal atom for all of the compounds is negligibly small over the accessible temperature range.
RESUMEN
The di- and trinuclear ferrocene species Li[Fc-BPh(2)-Fc] (Li[]) and Li(2)[Fc-BPh(2)-fc-BPh(2)-Fc] (Li(2)[]) have been investigated with regard to their electrochemical properties and the degree of intervalence charge-transfer after partial oxidation. Li[] shows two distinct one-electron redox waves for its chemically equivalent ferrocenyl substituents in the cyclic voltammogram (E(1/2) = -0.38 V, -0.64 V; vs. FcH/FcH(+)). The corresponding values of Li(2)[] are E(1/2) = -0.45 V (two-electron process) and -1.18 V. All these redox events are reversible at r. t. on the time scale of cyclic voltammetry. X-ray crystallography on the mixed-valent Fe(II)(2)Fe(III) complex Li(12-c-4)(2)[] reveals the centroid-centroid distance between the cyclopentadienyl rings of each of the terminal ferrocenyl substituents (3.329 A) to be significantly smaller than in the central 1,1'-ferrocenediyl fragment (3.420 A). This points towards a charge-localized structure (on the time scale of X-ray crystallography) with the central iron atom being in the Fe(III) state. Mössbauer spectroscopic measurements on Li(12-c-4)(2)[] lend further support to this interpretation. Spectroelectrochemical measurements on Li[] and Li(2)[] in the wavelength range between 300-2800 nm do not show bands interpretable as intervalence charge-transfer absorptions for the mixed-valent states. All data accumulated so far lead to the conclusion that electronic interaction between the individual Fe atoms in Li[] and Li(2)[] occurs via a through-space pathway and/or is electrostatic in nature.
RESUMEN
We have designed a new family of layered Sn(iv)phosphonate (SnPP) materials which are very efficient catalysts in the BV oxidation of aromatic aldehydes without any solvent and using aqueous H(2)O(2) (30%) as the oxidant.