Synthesis, Reactivity, and Complexation with Fe(0) of a Tight-bite Bis(N-heterocyclic silylene).

The synthesis, reactivity, and complexation with Fe(0) precursor of a tight-bite bis(N-heterocyclic silylene) (bis(NHSi)) ligand 1 are reported. The reaction of 1 with p-toluidine led to the activation of both N-H bonds across Si(II) atoms to afford a four-membered heterocyclic cyclodisilazane 2, with hydride substituents attached to five-coordinate Si atoms. A 1 : 2 reaction of 1 with Fe(CO)5 led to an intriguing dinuclear complex 3 featuring a five-membered (N-Si-Fe-Fe-Si) ring with a Fe-Fe bond distance of 2.6892(13) Å. All compounds (1-3) were thoroughly characterized by various spectroscopic methods and X-ray diffraction studies conclusively established their molecular structures. DFT calculations were carried out to shed light on bonding and energetic aspects in 1-3.

Stabilization of NH- Group Adjacent to Naked Silicon(II) Atom in Base Stabilized Aminosilylenes.

Aminosilylene, comprising reactive NH- and Si(II) sites next to each other, is an intriguing class of compounds due to its ability to show diverse reactivity. However, stabilizing the reactive NH- group next to the free Si(II) atom is challenging and has not yet been achieved. Herein, we report the first examples of base stabilized free aminosilylenes Ar*NHSi(PhC(Nt Bu)2 ) (1 a) and Mes*NHSi(PhC(Nt Bu)2 ) (1 b) (Ar*=2,6-dibenzhydryl-4-methylphenyl and Mes*=2,4,6-tri-tert-butylphenyl), tolerating a NH- group next to the naked Si(II) atom. Remarkably, 1 a and 1 b exhibited interesting differences in their reactivity upon heating. With 1 a, an intramolecular C(sp3 )-H activation of one of the benzhydryl methine hydrogen atoms to the Si(II) atom produced the five-membered cyclic silazane 2. However, with 1 b, a rare 1,2-hydrogen shift to the Si(II) atom afforded a silanimine 3, with a hydride ligand attached to an unsaturated silicon atom. Further, the coordination capabilities of 1 a were also tested with Ru(II) and Fe(0) precursors. Treatments of 1 a with [Ru(η6 -p-cymene)Cl2 ]2 led to the isolation of a η6 -arene tethered complex [RuCl2 {Ar*NHSi(PhC(t BuN)2 )-κ1 -Si-η6 -arene}] (4), whereas with the Fe(CO)5 precursor a Fe(0) complex [Fe(CO)4 {Ar*NHSi(PhC(t BuN)2 )-κ1 -Si}] (5) was obtained. Density functional theory (DFT) calculations were conducted to shed light on the structural, bonding, and energetic aspects in 1-5.

Efficient Recycling of Gold and Copper from Electronic Waste by Selective Precipitation.

The recycling of metals from electronic waste (e-waste) using efficient, selective, and sustainable processes is integral to circular economy and net-zero aspirations. Herein, we report a new method for the selective precipitation of metals such as gold and copper that offsets the use of organic solvents that are traditionally employed in solvent extraction processes. We show that gold can be selectively precipitated from a mixture of metals in hydrochloric acid solution using triphenylphosphine oxide (TPPO), as the complex [(TPPO)4 (H5 O2 )][AuCl4 ]. By tuning the acid concentration, controlled precipitation of gold, zinc and iron can be achieved. We also show that copper can be selectively precipitated using 2,3-pyrazinedicarboxylic acid (2,3-PDCA), as the complex [Cu(2,3-PDCA-H)2 ]n ⋅ 2n(H2 O). The combination of these two precipitation methods resulted in the recovery of 99.5 % of the Au and 98.5 % of the Cu present in the connector pins of an end-of-life computer processing unit. The selectivity of these precipitation processes, combined with their straightforward operation and the ability to recycle and reuse the precipitants, suggests potential industrial uses in the purification of gold and copper from e-waste.

A prospective, observational study for optimization of antibody screening in pretransfusion compatibility testing.

CONCLUSIONS: Despite known use of antibody screening (AS), it has not been adopted uniformly across blood centers in India. Many centers in India are currently using a type and hold policy with subsequent antihuman globulin (AHG) crossmatch when blood units are requested. The main aim of this study was to assess the benefits of a type and screen (TS) policy in which blood grouping and AS are performed simultaneously during the first hospital visit. If the AS is negative, subsequent requests for blood units would require an immediate spin test (IST) crossmatch with release of blood units, followed by an AHG crossmatch. This prospective, observational study was conducted at a tertiary health care center between July 2014 and December 2018 and included only Indian patients. Blood grouping and AS were performed during the first hospital visit on a total of 22,888 patients; the majority of patients were from hemato-oncology and blood marrow transplant, hepatology and liver transplant, cardiothoracic vascular surgery, and medical intensive care units. Demographic parameters were evaluated for risk of alloimmunization, and a record of the same was maintained. Depending on the AS results, a further course of action was chosen. Clinically significant alloantibodies were detected in 145 patients, and autoantibodies were detected in 53 patients. Alloantibodies were mainly against Rh and Kell blood group antigens. A significantly higher proportion of patients in the AS+ group required blood transfusion when compared with the AS- group. In cases wherein the IST crossmatch was compatible but AHG crossmatch was not, follow-up did not demonstrate any clinical or laboratory evidence of hemolysis. AS is a safe, efficient, and beneficial tool for pretransfusion compatibility testing in both AS+ and AS- patients. With a TS policy, AHG crossmatch can be omitted in AS- patients without compromising safety.

Blood component administration to multiple myeloma patients treated with daratumumab: suggesting a novel approach with use of 0.1 M dithiothreitol.

CONCLUSIONS: Storage of dithiothreitol (DTT)-treated red blood cells (RBCs) leads to hemolysis. The aim of this study was to compare 0.1 M DTT with 0.2 M DTT treatment of RBCs and to share our experience of providing components to seven patients on daratumumab (DARA). This prospective, observational study included patients who required RBC transfusion within 6 months of DARA administration. All patients underwent a baseline serologic evaluation followed by a repeat evaluation after DARA administration. In addition, use of 0.1 M DTT was compared with 0.2 M DTT in terms of concordance of results, hemolysis with storage of treated RBCs, and ease of use. A total of 22 RBC requisitions were received for seven patients. Antibody screen was positive for one patient (anti-C) at baseline; it was panreactive for all patients after DARA. Concordance of results between the two concentrations was 98.5 percent. Laboratory personnel found results obtained with use of 0.1 M DTT-treated RBCs easy to interpret. Supernatant hemoglobin was found to be significantly greater for 0.2 M DTT-treated RBCs at the sixth day of storage. In conclusion, component administration to patients on DARA can be done without delay if adequate policies and procedures are in place. Use of 0.1 M DTT-pretreated RBCs can be used to avoid delay in transfusion and reduce the burden on the laboratory of weekly preparation of 0.2 M DTT-treated RBCs.

Odd and Even Numbered Ferric Wheels.

The structurally related odd and even numbered wheels [FeIII 11 ZnII 4 (tea)10 (teaH)1 (OMe)Cl8 ] (1) and [FeIII 12 ZnII 4 (tea)12 Cl8 ] (2) can be synthesized under ambient conditions by reacting FeIII and ZnII salts with triethanolamine (teaH3 ), the change in nuclearity being dictated by the solvents employed. An antiferromagnetic exchange between nearest neighbors, J = -10.0 cm-1 for 1 and J = -12.0 cm-1 for 2, leads to a frustrated S = 1/2 ground state in the former and an S = 0 ground state in the latter.

Interferon-gamma release assay has poor diagnostic accuracy in differentiating intestinal tuberculosis from Crohn's disease in tuberculosis endemic areas.

BACKGROUND/AIMS: Intestinal tuberculosis (ITB) and Crohn's disease (CD) frequently present with a diagnostic dilemma because of similar presentation. Interferon-gamma release assay (IGRA) has been used in differentiating ITB from CD, but with sparse reports on its diagnostic accuracy in tuberculosis endemic regions and this study evaluated the same. METHODS: Patients with definitive diagnosis of ITB (n=59) or CD (n=49) who underwent IGRA testing (n=307) were retrospectively included at All India Institute of Medical Sciences, New Delhi (July 2014 to September 2021). CD or ITB was diagnosed as per standard criteria. IGRA was considered positive at >0.35 IU/mL. Relevant data was collected and IGRA results were compared between ITB and CD to determine its accuracy. RESULTS: Among 59 ITB patients (mean age, 32.6±13.1 years; median disease duration, 1 year; male, 59.3%), 24 were positive and 35 tested negative for IGRA. Among 49 CD patients (mean age, 37.8±14.0; median disease duration, 4 years; male, 61.2%), 12 were positive and 37 tested negative for IGRA. Hence, for diagnosing ITB, IGRA showed a sensitivity, specificity, positive and negative predictive values of 40.68%, 75.51%, 66.67%, and 51.39%, respectively. The area under the curve of IGRA for ITB diagnosis was 0.66 (95% confidence interval, 0.55-0.75). In a subset (n=64), tuberculin skin test (TST) showed sensitivity, specificity, positive and negative predictive values of 64.7%, 73.3%, 73.3%, and 64.71%, respectively. IGRA and TST were concordant in 38 (59.4%) patients with κ=0.17. CONCLUSIONS: In a tuberculosis endemic region, IGRA had poor diagnostic accuracy for differentiating ITB from CD, suggesting a limited value of IGRA in this setting.

A bis-calix[4]arene-supported [CuII16] cage.

Reaction of 2,2'-bis-p-tBu-calix[4]arene (H8L) with Cu(NO3)2·3H2O and N-methyldiethanolamine (Me-deaH2) in a basic dmf/MeOH mixture affords [CuII16(L)2(Me-dea)4(µ4-NO3)2(µ-OH)4(dmf)3.5(MeOH)0.5(H2O)2](H6L)·16dmf·4H2O (4), following slow evaporation of the mother liquor. The central core of the metallic skeleton describes a tetracapped square prism, [Cu12], in which the four capping metal ions are the CuII ions housed in the calix[4]arene polyphenolic pockets. The [CuII8] square prism is held together "internally" by a combination of hydroxide and nitrate anions, with the N-methyldiethanolamine co-ligands forming dimeric [CuII2] units which edge-cap above and below the upper and lower square faces of the prism. Charge balance is maintained through the presence of one doubly deprotonated H6L2- ligand per [Cu16] cluster. Magnetic susceptibility measurements reveal the predominance of strong antiferromagnetic exchange interactions and an S = 1 ground state, while EPR is consistent with a large zero-field splitting.

Serum albumin is the strongest predictor of anti-tumor necrosis factor nonresponse in inflammatory bowel disease in resource-constrained regions lacking therapeutic drug monitoring.

BACKGROUND/AIMS: Evidence on predictors of primary nonresponse (PNR), and secondary loss of response (SLR) to anti-tumor necrosis factor (anti-TNF) agents in inflammatory bowel disease is scarce from Asia. We evaluated clinical/biochemical/molecular markers of PNR/SLR in ulcerative colitis (UC) and Crohn's disease (CD). METHODS: Inflammatory bowel disease patients treated with anti-TNF agents (January 2005-October 2020) were ambispectively included. Data concerning clinical and biochemical predictors was retrieved from a prospectively maintained database. Immunohistochemistry for expression of oncostatin M (OSM), OSM receptor (OSM-R), and interleukin-7 receptor (IL-7R) were done on pre anti-TNF initiation mucosal biopsies. RESULTS: One-hundred eighty-six patients (118 CD, 68 UC: mean age, 34.1±13.7 years; median disease duration at anti-TNF initiation, 60 months; interquartile range, 28-100.5 months) were included. PNR was seen in 17% and 26.5% and SLR in 47% and 28% CD and UC patients, respectively. In CD, predictors of PNR were low albumin (P<0.001), postoperative recurrence (P=0.001) and high IL-7R expression (P<0.027) on univariate; and low albumin alone (hazard ratio [HR], 0.09; 95% confidence interval [CI], 0.03-0.28; P<0.001) on multivariate analysis respectively. Low albumin (HR, 0.31; 95% CI, 0.15-0.62; P=0.001) also predicted SLR. In UC, predictors of PNR were low albumin (P<0.001), and high C-reactive protein (P<0.001), OSM (P<0.04) and OSM-R (P=0.07) stromal expression on univariate; and low albumin alone (HR, 0.11; 95% CI, 0.03-0.39; P=0.001) on multivariate analysis respectively. CONCLUSIONS: Low serum albumin at baseline significantly predicted PNR in UC and PNR/SLR in CD patients. Mucosal markers of PNR were high stromal OSM/OSM-R in UC and high IL-7R in CD patients.

A graceful break-up: serendipitous self-assembly of a ferromagnetically coupled [NiII14] wheel.

The complex [NiII14(HL2)12(HCOO)14Cl14(MeOH)(H2O)] describes an aesthetically pleasing wheel displaying ferromagnetic nearest neighbour exchange.

An [FeIII8] molecular oxyhydroxide.

An [FeIII8] hexagonal bipyramid displays antiferromagnetic exchange between the two capping tetrahedral ions and the six ring octahedral ions resulting in a spin ground state of S = 10.

Guest-induced magnetic exchange in paramagnetic [M2L4]4+ coordination cages.

Paramagnetic complexes that possess magnetically switchable properties show promise in a number of applications. A significantly underdeveloped approach is the use of metallocages, whose magnetic properties can be modulated through host-guest chemistry. Here we show such an example that utilises a simple [CuII2L4]4+ lantern complex. Magnetic susceptibility and magnetisation data shows an absence of exchange in the presence of the diamagnetic guest triflate. However, replacement of the bound triflate by ReBr62- switches on antiferomagnetic exchange between the Cu and Re ions, leading to an S = 1/2 ground state for the non-covalent complex [ReBr62-⊂CuII2L4]2+. Comparison of this complex to a "control" palladium-cage host-guest complex, [ReBr62-⊂PdII2L4]2+, shows that the encapsulated ReBr62- anions retain the same magnetic anisotropy as in the free salt. Theoretically calculated spin-Hamiltonian parameters are in close agreement with experiment. Spin density analysis shows the mode of interaction between the CuII and ReIV centres is through the Re-Br⋯Cu pathway, primarily mediated through the Cu(dx2-y2)|Brsp|Re(dyz) interaction. This is further supported by overlap integral calculations between singly occupied molecular orbitals (SOMOs) of the paramagnetic ions and natural bonding orbitals analysis where considerable donor-to-acceptor interactions are observed between hybrid 4s4p orbitals of the Br ions and the empty 4s and 4p orbitals of the Cu ions.

A ferromagnetically coupled pseudo-calixarene [Co16] wheel that self-assembles as a tubular network of capsules.

Reaction of Co(OAc)2·4H2O and Hsal in a basic MeCN solution affords the hexadecanuclear wheel [Co16(sal)16(OAc)16]·16MeCN (1·16MeCN) that displays ferromagnetic nearest neighbour exchange and has pseudo-calixarene character. Symmetry equivalent wheels self-assemble to form remarkable tubular networks of capsules in the extended structure.

[Fe15]: a frustrated, centred tetrakis hexahedron.

The combination of two different FeIII salts in a solvothermal reaction with triethanolamine results in the formation of a high symmetry [FeIII15] cluster whose structure conforms to a centred, tetrakis hexahedron.

The structural manipulation of a series of Ni4 defective dicubanes: Synthesis, X-ray Structures, Magnetic and Computational analyses.

We report the synthesis and characterization of four new tetranuclear Ni(ii) complexes, C1-C4, all of which exhibit defective dicubane cores. C1-C4 are derived from the same salicylaldoxime derived ligand, H2L1. Complexes C1 and C4 have isostructural cores, differing in structure only by solvate molecules. Magnetic and computational analyses have revealed that complexes C1, C2, and C4 exhibit competing ferro- and antiferromagnetic interactions, however the different solvated species in C1 and C4 leads to notably different magnitudes in their magnetic coupling constants. Theoretical magneto-structural studies show that the pairwise magnetic exchange interaction is highly dependent on the Ni-X-Ni angle, as revealed by orbital overlap calculations.

A [Mn18] wheel-of-wheels.

A [Mn18] wheel of wheels is obtained from the reaction of MnBr2·4H2O and LH3 in MeOH. The metallic skeleton reveals two asymmetric [MnIII6MnII2] square wheels connected into a larger wheel via two MnII ions. Magnetic susceptibility and magnetisation data reveal competing exchange interactions, supported by computational studies.

Synthesis and bioefficacy evaluation of new 3-substituted-3,4-dihydro-1,3-benzoxazines.

A new series of 1, 3-Benzoxazines were synthesized, characterized ((1)H NMR and (13)C NMR) and evaluated for their pesticidal activity. Six new 3-alkyl-3, 4-dihydro-4-methyl-2H-1, 3-benzoxazines (1-6) were prepared by hydroxymethylation of secondary amines with formaldehyde in 65-68% yields. These compounds were screened for there IGR activity against Spodoptera litura and for antifungal fungal activity in vitro against Sclerotium rolfsii ITCC 6181 by poisoned food technique. Insect Growth Regulatory (IGR) activity against Spodoptera litura showed that compound 3-Nonyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines was most effective as IGR with larval GI(50) of 1.863 mu g/Insect. Compounds 3-Octyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines and 3-Decyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines were effective IGRs. Antifungal screening revealed that compound 3-Dodecyl-3, 4-dihydro-4-methyl-2H-1,3-benzoxazines, was highly effective against Sclerotium rolfsii with LC(50) value 31.7 mg L(-1) comparable with commercial fungicide Hexaconazole (LC(50) 1.27 mg L(-1)). Also compounds 3-Nonyl-3, 4-dihydro-4-methyl-2H-1,3-benzoxazines and 3-Decyl-3,4-dihydro-4-methyl-2H-1,3-benzoxazines displayed promising fungitoxicity. The results described in this paper are promising and provides new array of synthetic chemicals to be utilized as pesticides.

Development of controlled release formulations of azadirachtin-A employing poly(ethylene glycol) based amphiphilic copolymers.

Controlled release (CR) formulations of azadirachtin-A, a bioactive constituent derived from the seed of Azadirachta indica A. Juss (Meliaceae), have been prepared using commercially available polyvinyl chloride, polyethylene glycol (PEG) and laboratory synthesized poly ethylene glycol-based amphiphilic copolymers. Copolymers of polyethylene glycol and various dimethyl esters, which self assemble into nano micellar aggregates in aqueous media, have been synthesized. The kinetics of azadirachtin-A, release in water from the different formulations was studied. Release from the commercial polyethylene glycol (PEG) formulation was faster than the other CR formulations. The rate of release of encapsulated azadirachtin-A from nano micellar aggregates is reduced by increasing the molecular weight of PEG. The diffusion exponent (n value) of azadirachtin-A, in water ranged from 0.47 to 1.18 in the tested formulations. The release was diffusion controlled with a half release time (t(1/2)) of 3.05 to 42.80 days in water from different matrices. The results suggest that depending upon the polymer matrix used, the application rate of azadirachtin-A can be optimized to achieve insect control at the desired level and period.

Microwave synthesis and antifungal evaluations of some chalcones and their derived diaryl-cyclohexenones.

Microwave irradiation (MWI) of acetophenones and substituted benzaldehydes in water resulted in a "green-chemistry" procedure for the preparation of chalcones (1-14), through base catalyzed Claisen-Schmidt condensation reaction, in good yields. Further 3,5-diaryl-6-carbethoxy-2-cyclohexen-1-ones (1a-14a) were prepared through base catalyzed cyclocondensation of above chalcones with ethylacetoacetate using MWI as the energy source and silica as support. Out of fourteen cyclohexenones, ten (1a, 4a, 5a, 6a, 7a, 9a, 10a, 11a, 12a and 13a) are reported for the first time in literature. The synthesized compounds were characterized using various spectroscopic techniques, viz. ((1)H NMR and IR) and screened for their antifungal activity in vitro against Sclerotium rolfsii and Rhizoctonia solani by poisoned food technique. The compounds tested were found to be active against R. solani whereas against S. rolfsii, moderate activity was observed, as evident from LC(50) values. The most potent compounds against R. solani were 1-(4-Fluoro-phenyl)-3-phenyl-propenone (13) and 1,3-Diphenyl-propenone (14) having LC(50) values of 2.36 and 2.49 mg L(- 1) respectively (LC(50) of Hexaconazole = 1.12 mg L(- 1)) and against S. rolfsii 3-(4-Fluoro-phenyl)-5-(3-nitro-phenyl)-6-carbethoxy-2-cyclohexen-1-one (12a) was most active having LC(50) value of 285 mg L(- 1)compared to Hexaconazole (LC(50) = 1.27 mg L(- 1)).

Geometrical control of the magnetic anisotropy in six coordinate cobalt complexes.

The geometry of cobalt(ii) ions in the axially distorted octahedral cation in [Co(MeCN)6](BF4)2 (1) was compared to the trigonal prismatic cation in [CoTppy]PF6 (2) which revealed significant differences in magnetic anisotropy. Combined experimental and ab initio CASSCF/NEVPT2 calculations support the observed zero field SMM behaviour for 2, with easy axis anisotropy, attributed to the rigidity of the trigonal prismatic ligand. Strong transverse anisotropy for 1 leads to significant quantum tunnelling processes.