Expedient synthesis of chiral poly-substituted morpholine and oxazepine derivatives for the preparation of cyclophilin A inhibitors

An efficient and expedient synthetic method was developed for the preparation of chiral poly-substituted morpholine and oxazepine derivatives. The method was designed in the objective of applying the synthesis to the preparation of Cyclophilin A inhibitors.The stereo- and regioselective method involves the reaction of enantiopure beta-amino alcohols with alpha,beta-unsaturated aldehydes. The synthesis proceeds through three steps; i) Reductive amination, ii) N-alkylation/ N-tosylation and iii) intramolecular-haloetherification. Stereoselectivity of this last step was controlled by N-alkyl/ N-tosyl groups and substitution across the double bond, and was enhanced by the addition of Bronsted acids. Substitution across the double bond of the starting material controlled the regioselectivity of the method. Morpholines were obtained through 6- exo cyclization and oxazepines were obtained through 7-endo cyclization.A small library of morpholine-based derivatives was designed in-silico. Affinity and binding modes to the Cyclophilin A were investigated through a docking-based virtual screening study

Thiosemicarbazone Modified Zeolitic Imidazolate Framework (TSC-ZIF) for Mercury(II) Removal From Water

Electronic supplementary information (ESI) available: For general methods, supplementary details on the preparation and characterization of Ald-ZIFs and TSC-ZIFs, sorption isotherms and kinetics, and regeneration of the adsorbent. See DOI: 10.1039/d1ra02025k[Abstract] Zeolitic imidazolate frameworks (ZIF-8), and their derivatives, have been drawing increasing attention due to their thermal and chemical stability. The remarkable stability of ZIF-8 in aqueous and high pH environments renders it an ideal candidate for the removal of heavy metals from wastewater. In this study, we present the preparation of novel aldehyde-based zeolitic imidazolate frameworks (Ald-ZIF) through the integration of mixed-linkers: 2-methylimidazole (MIM) and imidazole-4-carbaldehyde (AldIM). The prepared Ald-ZIFs were post-synthetically modified with bisthiosemicarbazide (Bisthio) and thiosemicarbazide (Thio) groups, incorporating thiosemicarbazone (TSC) functionalities to the core of the framework. This modification results in the formation of TSC-functionalized ZIF derivatives (TSCZIFs). Thiosemicarbazones are versatile metal chelators, hence, adsorption properties of TSC-ZIFs for the removal of mercury(II) from water were explored. Removal of mercury(II) from homoionic aqueous solutions, binary and tertiary systems in competition with lead(II) and cadmium(II) under ambient conditions and neutral pH are reported in this study. MIM3.5:Thio1:Zn improved the removal efficiency of mercury(II) from water, up to 97% in two hours, with an adsorption capacity of 1667 mg g 1. Desorption of mercury(II) from MIM3.5:Thio1:Zn was achieved under acidic conditions, regenerating MIM3.5:Thio1:Zn for five cycles of mercury(II) removal. TSC-ZIF derivatives, designed and developed here, represent a new class of dynamically functionalized adsorption material displaying the advantages of simplicity, efficiency, and reusability.https://www.rsc.org/suppdata/d1/ra/d1ra02025k/d1ra02025k1.pdf?_ga=2.90571418.1846997019.1635238700-352143482.163004971

Functionalised electrospun membranes (TETA-PVC) for the removal of lead(ii) from water

Publisher Copyright: © 2022 The Royal Society of Chemistry.Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, electrospun PVC membranes were functionalised with triethylenetetramine (TETA) and were used to remove lead(ii) ions selectively from water. The membranes were characterised and their adsorption behavior towards the removal of lead from water was investigated. The incorporation of TETA on the membrane's surface significantly improved the removal efficiency of lead(ii) up to 99.8% in 30 minutes and under ambient conditions, with the lowest concentration of 50 ppm. The adsorption mechanism was investigated and kinetic data showed a better correlation with the pseudo-second-order model. Similarly, the equilibrium data best fitted with the Langmuir adsorption isotherm model with a relatively high maximum adsorption capacity of 1250 mg g−1 for lead(ii) ions, larger than recently reported adsorption capacities for similar membranes. The functionalised membrane also showed high selectivity to lead(ii) in a mixed solution containing lead(ii), mercury(ii), cadmium(ii), arsenic(iii), copper(ii), and zinc(ii). The functionalised membrane was regenerated, where desorption of lead(ii) was achieved, under mildly acidic conditions. The removal efficiency of the regenerated membrane after six cycles of adsorption/desorption was maintained at a high level of 98%. The proposed design offers a simple yet effective, sustainable, and environmentally friendly solution for water treatment.Peer reviewe

Guest Binding Drives Host Redistribution in Libraries of CoII 4 L4 Cages.

Two CoII 4 L4 tetrahedral cages prepared from similar building blocks showed contrasting host-guest properties. One cage did not bind guests, whereas the second encapsulated a series of anions, due to electronic and geometric effects. When the building blocks of both cages were present during self-assembly, a library of five CoII LA x LB 4-x cages was formed in a statistical ratio in the absence of guests. Upon incorporation of anions able to interact preferentially with some library members, the products obtained were redistributed in favor of the best anion binders. To quantify the magnitudes of these templation effects, ESI-MS was used to gauge the effect of each template upon library redistribution

Cation- and anion-exchanges induce multiple distinct rearrangements within metallosupramolecular architectures

Different anionic templates act to give rise to four distinct Cd II-based architectures: a Cd2L3 helicate, a Cd8L12 distorted cuboid, a Cd10L15 pentagonal prism, and a Cd12L18 hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of FeII prompted metal exchange and transformation to a Fe4L6 tetrahedron or a Fe10L15 pentagonal prism, depending on the anionic templates present. The equilibrium between the Cd12L18 prism and the Cd2L3 triple helicate displayed concentration dependence, with higher concentrations favoring the prism. The Cd12L18 structure serves as an intermediate en route to a hexafluoroarsenate-templated Cd10L15 complex, whereby the structural features of the hexagonal prism preorganize the system to form the structurally related pentagonal prism. In addition to the interconversion pathways investigated, we also report the single-crystal X-ray structure of bifluoride encapsulated within a Cd10L15 complex and report solution state data for J-coupling through a CH··· F- hydrogen bond indicating the strength of these interactions in solution

[C–H⋯anion] interactions mediate the templation and anion binding properties of topologically non-trivial metal–organic structures in aqueous solutions

[Abstract] Two synthetic approaches—temperature variation and anion templation—allowed for the selective formation of a [2]catenane ([2]C4+) or a trefoil knot (TK6+), or for the enhanced formation of a Solomon link (SL8+), all from a simple set of starting materials (Zn(II) acetate, diformylpyridine (DFP) and a diamino-2,2′-bipyridine (DAB)) in mixed aqueous solutions. The catenane formed exclusively at 90 °C in a 1 : 1 mixed solvent of D2O and MeOD. In the presence of bromide ion as template, TK6+ formed exclusively at 50 °C in the same solvent. In the solid state, TK6+ hosts two bromide ions in its central cavity by forming six Csp2–H hydrogen bonds. In D2O, TK6+, which was originally prepared as a trifluoroacetate (TFA) salt, was found to exchange two TFA counterions for two monovalent anions of different sizes and shapes, which lodged within the knot's central cavity. In contrast to bromide, the larger triflate anion (CF3SO3−) promoted the formation of SL8+, which was characterized by 1H NMR spectroscopy and mass spectrometry. Two dimensional heteronuclear 19F-1H-HOSEY NMR experiments detected CH⋯F interactions inside the cavity of SL8+. Thus, the product distribution of this dynamic link forming system is sensitive to temperature and the size and shape of the anion template, and one of the products, TK6+, is capable of binding a variety of monovalent anions in D2O with high affinity (with log β2 values of 4 to 6 being typical)

Cation- and Anion-Exchanges Induce Multiple Distinct Rearrangements within Metallosupramolecular Architectures

Different anionic templates act to give rise to four distinct Cd^II-based architectures: a Cd₂L₃ helicate, a Cd₈L₁₂ distorted cuboid, a Cd₁₀L₁₅ pentagonal prism, and a Cd₁₂L₁₈ hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of Fe^II prompted metal exchange and transformation to a Fe₄L₆ tetrahedron or a Fe₁₀L₁₅ pentagonal prism, depending on the anionic templates present. The equilibrium between the Cd₁₂L₁₈ prism and the Cd₂L₃ triple helicate displayed concentration dependence, with higher concentrations favoring the prism. The Cd₁₂L₁₈ structure serves as an intermediate en route to a hexafluoroarsenate-templated Cd₁₀L₁₅ complex, whereby the structural features of the hexagonal prism preorganize the system to form the structurally related pentagonal prism. In addition to the interconversion pathways investigated, we also report the single-crystal X-ray structure of bifluoride encapsulated within a Cd₁₀L₁₅ complex and report solution state data for <i>J</i>-coupling through a CH···F^– hydrogen bond indicating the strength of these interactions in solution