Search

Acid-catalyzed condensation of pyrrole, 4-trifluoromethylbenzaldehyde, and azulene, followed by DDQ oxidation, has resulted in the isolation of the novel macrocycle azulicorrole, arguably the first example of a carbacorrole aside from N-confused corrole. Despite poor yields (

The solvothermal reaction of FeCl 2  ⋅ 4H 2 O and H 4 TBC[4] in a basic dmf/EtOH solution affords an [Fe III 18 ] Keplerate conforming to a stellated cuboctahedron. Magnetic and heat capacity measurements reveal spin frustration effects arising from the high symmetry. A crossover between inverse and direct magnetocaloric effects is observed at ~10 K for applied-field changes lower than 3 T., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

We compared serum anti-Mullerian hormone (AMH) levels in women with sickle cell disease (SCD) (n = 152) to those of Black comparison women (n = 128) between the ages of 20 and 45 years and evaluated the impact of hydroxyurea (HU) and iron overload on ovarian reserve in those with SCD. SCD treatment was abstracted from medical records. Linear regression models were fit to examine the relationship between log(AMH) and SCD, adjusting for age. The analysis was repeated to account for HU use (current, previous, never) and iron overload (ferritin ≥1000 ng/mL vs. <1000 ng/mL). AMH estimates among women with SCD were lower than those among comparison women (2.23, 95% confidence interval [CI] 1.80-2.76 vs. 4.12, 95% CI 3.11-5.45, respectively). Women with SCD who were currently using HU had 63% lower (95% CI 43-76) AMH values than comparison women; those with SCD with prior or no HU use also had lower AMH estimates than comparison women, but the difference was less pronounced. There were no differences in predicted AMH values among women with SCD for those with and without iron overload. Women with SCD and low AMH may have a shorter reproductive window and may benefit from referral to a reproductive specialist., (© 2024 British Society for Haematology and John Wiley & Sons Ltd.)

Coordination complexes of lanthanide metals with tris-1-naphthylphosphine oxide (Nap 3 PO, L) have not been previously reported in the literature. We describe here the formation of lanthanide(III) nitrate complexes Ln(NO 3 ) 3 L 4 (Ln = Eu to Lu) and the structures of [Ln(NO 3 ) 3 L 2 ]·2L (Ln = Eu, Dy, Ho, Er) and L. The core structure of the complexes is an eight-coordinate [Ln(NO 3 ) 3 L 2 ] with the third and fourth ligands H-bonded via their oxygen atoms to one of the naphthyl rings. The structures are compared with those of the analogous complexes of triphenylphosphine oxide and show that the Ln-O(P) bond in the Nap 3 PO complexes is slightly longer than expected on the basis of differences in coordination numbers. The reaction solutions, investigated by 31 P and 13 C NMR spectroscopy in CD 3 CN, show that coordination of L occurs across the lanthanide series, even though complexes can only be isolated from Eu onwards. Analysis of the 31 P NMR paramagnetic shifts shows that there is a break in the solution structures with a difference between the lighter lanthanides (La-Eu) and heavier metals (Tb-Lu) which implies a minor difference in structures. The isolated complexes are very poorly soluble, but in CDCl 3 , NMR measurements show dissociation into [Ln(NO 3 ) 3 L 2 ] and 2L occurs., Competing Interests: The authors declare no conflicts of interest.

Carbon, although the central element in organic chemistry, has been traditionally neglected as a target for directional supramolecular interactions. The design of supramolecular structures involving carbon-rich molecules, such as arene hydrocarbons, has been limited almost exclusively to non-directional π-stacking, or derivatisation with heteroatoms to introduce molecular assembly recognition sites. As a result, the predictable assembly of non-derivatised, carbon-only π-systems using directional non-covalent interactions remains an unsolved fundamental challenge of solid-state supramolecular chemistry. Here, we propose and validate a different paradigm for the reliable assembly of carbon-only aromatic systems into predictable supramolecular architectures: not through non-directional π-stacking, but via specific and directional halogen bonding. We present a systematic experimental, theoretical and database study of halogen bonds to carbon-only π-systems (C-I⋯π C bonds), focusing on the synthesis and structural analysis of cocrystals with diversely-sized and -shaped non-derivatised arenes, from one-ring (benzene) to 15-ring (dicoronylene) polycyclic atomatic hydrocarbons (PAHs), and fullerene C 60 , along with theoretical calculations and a systematic analysis of the Cambridge Structural Database. This study establishes C-I⋯π C bonds as directional interactions to arrange planar and curved carbon-only aromatic systems into predictable supramolecular motifs. In >90% of herein presented structures, the C-I⋯π C bonds to PAHs lead to a general ladder motif, in which the arenes act as the rungs and halogen bond donors as the rails, establishing a unique example of a supramolecular synthon based on carbon-only molecules. Besides fundamental importance in the solid-state and supramolecular chemistry of arenes, this synthon enables access to materials with exciting properties based on simple, non-derivatised aromatic systems, as seen from large red and blue shifts in solid-state luminescence and room-temperature phosphorescence upon cocrystallisation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The influence of fluorinated substituents on the luminescent properties of rhenium-oxo, osmium-nitrido, and gold triarylcorroles was studied via a comparison of four ligands: triphenylcorrole (TPC), tris( p -trifluoromethylphenyl)corrole (T p CF 3 PC), tris{3,5-bis(trifluoromethyl)phenyl}corrole (T3,5-CF 3 PC), and tris(pentafluorophenyl)corrole (TPFPC). For each metal series examined, fluorinated substituents were found to enhance the luminescent properties, with the phosphorescence quantum yields and triplet decay times increasing in the order TPC < T p CF 3 PC < T3,5-CF 3 PC < TPFPC. Among the 11 complexes examined, the highest phosphorescence quantum yield, 2.2%, was recorded for Re[TPFPC](O)., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Ring-opening of furans at the equatorial methylene bridge positions of a calix[4]arene gives access to a range of new molecules (in good yield) that have widespread potential impact in supramolecular chemistry amongst other areas.

Industrial purification of propylene and ethylene requires cryogenic distillation and selective hydrogenation over palladium catalysts to remove propane, ethane and/or trace amounts of acetylene. Here, we report the excellent separation of equimolar mixtures of propylene/propane and ethylene/ethane, and of a 1/100 mixture of acetylene/ethylene by a highly robust microporous material, MFM-520, under dynamic conditions. In situ synchrotron single crystal X-ray diffraction, inelastic neutron scattering and analysis of adsorption thermodynamic parameters reveal that a series of synergistic host-guest interactions involving hydrogen bonding and π⋅⋅⋅π stacking interactions underpin the cooperative binding of alkenes within the pore. Notably, the optimal pore geometry of the material enables selective accommodation of acetylene. The practical potential of this porous material has been demonstrated by fabricating mixed-matrix membranes comprising MFM-520, Matrimid and PIM-1, and these exhibit not only a high permeability for propylene (≈1984 Barrer), but also a separation factor of 7.8 for an equimolar mixture of propylene/propane at 298 K., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The interaction of free-base triarylcorroles with Re 2 (CO) 10 in 1,2-dichlorobenzene in the presence of 2,6-lutidine at 180 °C under strict anerobic conditions afforded approximately 10% yields of rhenium corrole dimers. The compounds exhibited diamagnetic 1 H NMR spectra consistent with a metal-metal quadruple bond with a σ 2 π 4 δ 2 orbital occupancy. One of the compounds proved amenable to single-crystal X-ray structure determination, yielding a metal-metal distance of ∼2.24 Å, essentially identical to that in triple-bonded osmium corrole dimers. On the other hand, the electrochemical properties of Re and Os corrole dimers proved to be radically different. Thus, the reduction potentials of the Re corrole dimers are some 800 mV upshifted relative to those of their Os counterparts. Stated differently, the Re corrole dimers are dramatically easier to reduce, reflecting electron addition to δ* versus π* molecular orbitals for Re and Os corrole dimers, respectively. The data also imply electrochemical HOMO-LUMO gaps of only 1.0-1.1 V for rhenium corrole dimers, compared with values of 1.85-1.90 V for their Os counterparts. These HOMO-LUMO gaps rank among the first such values reported for quadruple-bonded transition-metal dimers for any type of supporting ligand, porphyrin-type or not.

Background and Objectives: Dialysis facilities in the United States play a key role in access to kidney transplantation. Previous studies reported that patients treated at for-profit facilities are less likely to be waitlisted and receive a transplant, but their effect on early steps in the transplant process is unknown. The study's objective was to determine the association between dialysis facility profit status and critical steps in the transplantation process in Georgia, North Carolina, and South Carolina., Design, Setting, Participants, & Measurements: In this retrospective cohort study, we linked referral and evaluation data from all nine transplant centers in the Southeast with United States Renal Data System surveillance data. The cohort study included 33,651 patients with kidney failure initiating dialysis from January 1, 2012 to August 31, 2016. Patients were censored for event (date of referral, evaluation, or waitlisting), death, or end of study (August 31, 2017 for referral and March 1, 2018 for evaluation and waitlisting). The primary exposure was dialysis facility profit status: for profit versus nonprofit. The primary outcome was referral for evaluation at a transplant center after dialysis initiation. Secondary outcomes were start of evaluation at a transplant center after referral and waitlisting., Results: Of the 33,651 patients with incident kidney failure, most received dialysis treatment at a for-profit facility (85%). For-profit (versus nonprofit) facilities had a lower cumulative incidence difference for referral within 1 year of dialysis (-4.5%; 95% confidence interval, -6.0% to -3.2%). In adjusted analyses, for-profit versus nonprofit facilities had lower referral (hazard ratio, 0.84; 95% confidence interval, 0.80 to 0.88). Start of evaluation within 6 months of referral (-1.0%; 95% confidence interval, -3.1% to 1.3%) and waitlisting within 6 months of evaluation (1.0%; 95% confidence interval, -1.2 to 3.3) did not meaningfully differ between groups., Conclusions: Findings suggest lower access to referral among patients dialyzing in for-profit facilities in the Southeast United States, but no difference in starting the evaluation and waitlisting by facility profit status., (Copyright © 2021 by the American Society of Nephrology.)

As part of our efforts to develop rhenium-oxo corroles as photosensitizers for oxygen sensing and photodynamic therapy, we investigated the potential β-perhalogenation of five ReO meso-tris(para-X-phenyl)corroles, Re[TpXPC](O) (X = CF 3 , H, F, CH 3 , and OCH 3 ), with elemental chlorine and bromine. With Cl 2 , β-octachlorinated products Re[Cl 8 TpXPC](O) were rapidly obtained for X = CF 3 , H, and CH 3 , but X = OCH 3 resulted in overchlorination on the meso-aryl groups. Full β-octabromination proved slower relative to Cu and Ir corroles, but the desired Re[Br 8 TpXPC](O) products were finally obtained for X = H and F after a week at room temperature. For X = CH 3 and OCH 3 , these conditions led to undecabrominated products Re[Br 11 TpXPC](O). Compared to the β-unsubstituted starting materials, the β-octahalogenated products were found to exhibit sharp 1 H NMR signals at room temperature, indicating that the aryl groups are locked in place by the β-halogens, and substantially redshifted Soret and Q bands. Single-crystal X-ray structures of Re[Cl 8 TpCF 3 PC](O), Re[Cl 8 TpCH 3 PC](O), and Re[Br 8 TpFPC](O) revealed mild saddling for one Cl 8 structure and the Br 8 structure. These structural variations, however, appear too insignificant to explain the slowness of the β-octabromination protocols, which seems best attributed to the deactivating influence of the high-valent Re center.

Structural transitions of host systems in response to guest binding dominate many chemical processes. We report an unprecedented type of structural flexibility within a meta-rigid material, MFM-520, which exhibits a reversible periodic-to-aperiodic structural transition resulting from a drastic distortion of a [ZnO 4 N] node controlled by the specific host-guest interactions. The aperiodic crystal structure of MFM-520 has no three-dimensional (3D) lattice periodicity but shows translational symmetry in higher-dimensional (3 + 2)D space. We have directly visualized the aperiodic state which is induced by incommensurate modulation of the periodic framework of MFM-520·H 2 O upon dehydration to give MFM-520. Filling MFM-520 with CO 2 and SO 2 reveals that, while CO 2 has a minimal structural influence, SO 2 can further modulate the structure incommensurately. MFM-520 shows exceptional selectivity for SO 2 under flue-gas desulfurization conditions, and the facile release of captured SO 2 from MFM-520 enabled the conversion to valuable sulfonamide products. MFM-520 can thus be used as a highly efficient capture and delivery system for SO 2 .

Six-coordinate iridium(III) triarylcorrole derivatives, Ir[TpXPC)]L 2 , where TpXPC = tris(para-X-phenyl)corrole (X = CF 3 , H, Me, and OCH 3 ) and L = pyridine (py), trimethylamine (tma), isoquinoline (isoq), 4-dimethylaminopyridine (dmap), and 4-picolinic acid (4pa), have been examined, with a view to identifying axial ligands most conducive to near-infrared phosphorescence. Disappointingly, the phosphorescence quantum yield invariably turned out to be very low, about 0.02 - 0.04% at ambient temperature, with about a two-fold increase at 77 K. Phosphorescence decay times were found to be around ~5 µs at 295 K and ~10 µs at 77 K. Fortunately, two of the Ir[TpCF 3 PC)]L 2 derivatives, which were tested for their ability to sensitize singlet oxygen formation, were found to do so efficiently with quantum yields Φ( 1 O 2 ) = 0.71 and 0.38 for L = py and 4pa, respectively. Iridium corroles thus may hold promise as photosensitizers in photodynamic therapy (PDT). The possibility of varying the axial ligand and of attaching biotargeting groups at the axial positions makes iridium corroles particularly exciting as PDT drug candidates.

Background and Objectives: Access to kidney transplantation requires a referral to a transplant center for medical evaluation. Prior research suggests that the distance that a person must travel to reach a center might be a barrier to referral. We examined whether a shorter distance from patients' residence to a transplant center increased the likelihood of referral and initiating the transplant evaluation once referred., Design, Setting, Participants, & Measurements: Adults who began treatment for ESKD at any Georgia, North Carolina, or South Carolina dialysis facility from 1/1/2012 to 12/31/2015 were identified from the US Renal Data System. Referral (within 1 year of dialysis initiation) and evaluation initiation (within 6 months of referral) data were collected from all nine transplant centers located in that region. Distance was categorized as <15, 15-30, 31-60, 61-90, and >90 miles from the center of a patient's residential zip code to the nearest center. We used multilevel, multivariable-adjusted logistic regression to quantify the association between distance with referral and evaluation initiation., Results: Among 27,250 adult patients on incident dialysis, 9582 (35%) were referred. Among those referred, 58% initiated evaluation. Although patients who lived farther from a center were less likely to be referred, distance was not statistically significantly related to transplant referral: adjusted odds ratios of 1.08 (95% confidence interval, 0.96 to 1.22), 1.07 (95% confidence interval, 0.95 to 1.22), 0.96 (95% confidence interval, 0.84 to 1.10), and 0.87 (95% confidence interval, 0.74 to 1.03) for 15-30, 31-60, 61-90, and >90 miles, respectively, compared with <15 miles ( P trend =0.05). There was no statistically significant association of distance and evaluation initiation among referred patients: adjusted odds ratios of 1.14 (95% confidence interval, 0.97 to 1.33), 1.12 (95% confidence interval, 0.94 to 1.35), 1.04 (95% confidence interval, 0.87 to 1.25), and 0.89 (95% confidence interval, 0.72 to 1.11) for 15-30, 31-60, 61-90, and >90 miles, respectively, compared with <15 miles ( P trend =0.70)., Conclusions: Distance from residence to transplant center among patients undergoing long-term dialysis in the southeastern United States was not associated with increased likelihood of referral and initiating transplant center evaluation., (Copyright © 2020 by the American Society of Nephrology.)

Although research shows that minorities exhibit higher levels of medical mistrust, perceived racism, and discrimination in healthcare settings, the degree to which these underlying sociocultural factors preclude end-stage renal disease (ESRD) patients from initiating kidney transplant evaluation is unknown. We telephone surveyed 528 adult ESRD patients of black or white race referred for evaluation to a Georgia transplant center (N = 3) in 2014-2016. We used multivariable logistic regression to examine associations between sociocultural factors and evaluation initiation, adjusting for demographic, clinical, and socioeconomic characteristics. Despite blacks (n = 407) reporting higher levels of medical mistrust (40.0% vs 26.4%, P < .01), perceived racism (55.5% vs 18.2%, P < .01), and experienced discrimination (29.0% vs 15.7%, P < .01) than whites (n = 121), blacks were only slightly less likely than whites to initiate evaluation (49.6% vs 57.9%, P = .11). However, after adjustment, medical mistrust (odds ratio [OR]: 0.59; 95% confidence interval [CI]: 0.39, 0.91), experienced discrimination (OR: 0.62, 95% CI: 0.41, 0.95), and perceived racism (OR: 0.61; 95% CI: 0.40, 0.92) were associated with lower evaluation initiation. Results suggest that sociocultural disparities exist in early kidney transplant access and occur despite the absence of a significant racial disparity in evaluation initiation. Interventions to reduce disparities in transplantation access should target underlying sociocultural factors, not just race., (© 2019 The American Society of Transplantation and the American Society of Transplant Surgeons.)

Emissions of SO 2 from flue gas and marine transport have detrimental impacts on the environment and human health, but SO 2 is also an important industrial feedstock if it can be recovered, stored and transported efficiently. Here we report the exceptional adsorption and separation of SO 2 in a porous material, [Cu 2 (L)] (H 4 L = 4',4‴-(pyridine-3,5-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid)), MFM-170. MFM-170 exhibits fully reversible SO 2 uptake of 17.5 mmol g -1 at 298 K and 1.0 bar, and the SO 2 binding domains for trapped molecules within MFM-170 have been determined. We report the reversible coordination of SO 2 to open Cu(II) sites, which contributes to excellent adsorption thermodynamics and selectivities for SO 2 binding and facile regeneration of MFM-170 after desorption. MFM-170 is stable to water, acid and base and shows great promise for the dynamic separation of SO 2 from simulated flue gas mixtures, as confirmed by breakthrough experiments.

Air pollution by nitrogen oxides, NO x , is a major problem, and new capture and abatement technologies are urgently required. Here, we report a metal-organic framework (Manchester Framework Material 520 (MFM-520)) that can efficiently confine dimers of NO 2 , which results in a high adsorption capacity of 4.2 mmol g -1 (298 K, 0.01 bar) with full reversibility and no loss of capacity over 125 cycles. Treatment of NO 2 @MFM-520 with water in air leads to a quantitative conversion of the captured NO 2 into HNO 3 , an important feedstock for fertilizer production, and fully regenerates MFM-520. The confinement of N 2 O 4 inside nanopores was established at a molecular level, and the dynamic breakthrough experiments using both dry and humid NO 2 gas streams verify the excellent stability and selectivity of MFM-520 and confirm its potential for precious-metal-free deNO x technologies.

NMR spectroscopy of paramagnetic materials (pNMR) has the potential to provide great structural insight, but many challenges remain in interpreting the spectra in detail. This work presents a study of a series of structurally analogous metal-organic frameworks (MOFs) based on 5-substituted isophthalate linkers and Cu(II) paddlewheel dimers, of interest owing to their "crumple zone" structural rearrangement on dehydration/rehydration. 13 C MAS NMR spectra reveal a wide variation in the observed resonance position for chemically similar C species in the different MOFs but, despite this, resonances are overlapped in several cases. However, by considering a combination of the integration of quantitative spectra, the resonance position as a function of temperature and T 1 relaxation measurements, the spectra can be fully assigned. It is also demonstrated that the prototypical MOF in this series, STAM-1, displays a crumple zone rearrangement on dehydration, similar to the well-characterised 5-ethoxyisophthalate MOF (STAM-17-OEt) although, while the materials have similar local C environments, dehydrated STAM-1 exhibits less long-range order., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: The Reducing Disparities in Access to kidNey Transplantation Community Study (RaDIANT) was an End-Stage Renal Disease (ESRD) Network 6-developed, dialysis facility-level randomized trial testing the effectiveness of a 1-year multicomponent education and quality improvement intervention in increasing referral for kidney transplant evaluation among selected Georgia dialysis facilities., Methods: To assess implementation of the RaDIANT intervention, we conducted a process evaluation at the conclusion of the intervention period (January-December 2014). We administered a 20-item survey to the staff involved with transplant education in 67 dialysis facilities randomized to participate in intervention activities. Survey items assessed facility participation in the intervention (fidelity and reach), helpfulness and willingness to continue intervention activities (sustainability), suggestions for improving intervention components (sustainability), and factors that may have influenced participation and study outcomes (context). We defined high fidelity to the intervention as completing 11 or more activities, and high participation in an activity as having at least 75% participation across intervention facilities., Results: Staff from 65 of the 67 dialysis facilities completed the questionnaire, and more than half (50.8%) reported high adherence (fidelity) to RaDIANT intervention requirements. Nearly two-thirds (63.1%) of facilities reported that RaDIANT intervention activities were helpful or very helpful, with 90.8% of facilities willing to continue at least one intervention component beyond the study period. Intervention components with high participation emphasized staff and patient-level education, including in-service staff orientations, patient and family education programs, and patient educational materials. Suggested improvements for intervention activities emphasized addressing financial barriers to transplantation, with financial education materials perceived as most helpful among RaDIANT educational materials. Variation in facility-level fidelity of the RADIANT intervention did not significantly influence the mean difference in proportion of patients referred pre- (2013) and post-intervention (2014)., Conclusions: We found high fidelity to the RaDIANT multicomponent intervention at the majority of intervention facilities, with sustainability of select intervention components at intervention facilities and feasibility for dissemination across ESRD Networks. Future modification of the intervention should emphasize financial education regarding kidney transplantation and amend intervention components that facilities perceive as time-intensive or non-sustainable., Trial Registration: Clinicaltrials.gov number NCT02092727 . Registered 13 Mar 2014 (retrospectively registered).