Complementarity and preorganisation in the assembly of heterometallic-organic cages via the metalloligand approach : recent advances

The design of new metallocage polyhedra towards pre-determined structures can offer both practical as well as intellectual challenges. In this mini-review we discuss a selection of recent examples in which the use of the metalloligand approach has been employed to overcome such challenges. An attractive feature of this approach is its stepwise nature that lends itself to the design and rational synthesis of heterometallic metal–organic cages, with the latter often associated with enhanced functionality

Investigating the conformations of a family of [M2L3]4+ helicates using single crystal X-ray diffraction

We present five new dinuclear triple helicate compounds of types [Mn2L3](ClO4)4, [Co2L3](BF4)4, [Ni2L3](BF4)4, [Cu2L3](BF4)4, and [Zn2L3](BF4)4, where L is a previously reported semi-rigid ligand incorporating two α-diimine primary donor groups and two secondary 4-pyridyl donor groups. All complexes have been characterized in both solution and the solid state. Single crystal X-ray diffraction studies were used to probe the variation in the respective helical structures as the coordinated metal ion was altered, including the effect on the orientations of the secondary binding domains. The influence of the metal ion size, the spin state in the case of Fe(II), and the presence of Jahn-Teller distortions on the overall helical structure has been investigated. These results form a basis for the design and construction of new large metallosupramolecular architectures which manifest properties associated with the constituent helical metalloligand units

Myrtinols A-F : new anti-inflammatory peltogynoid flavonoid derivatives from the leaves of Australian Indigenous plant Backhousia myrtifolia

Our in-house ethnopharmacological knowledge directed our anti-inflammatory investigation into the leaves of Backhousia mytifolia. Bioassay guided isolation of the Australian indigenous plant Backhousia myrtifolia led to the isolation of six new rare peltogynoid derivatives named myrtinols A–F (1–6) along with three known compounds 4-O-methylcedrusin (7), 7-O-methylcedrusin (8) and 8-demethylsideroxylin (9). The chemical structures of all the compounds were elucidated by detailed spectroscopic data analysis, and absolute configuration was established using X-ray crystallography analysis. All compounds were evaluated for their anti-inflammatory activity by assessing the inhibition of nitric oxide (NO) production and tumor necrosis factor- α (TNF-α) in lipopolysaccharide (LPS) and interferon (IFN)-γ activated RAW 264.7 macrophages. A structure activity relationship was also established between compounds (1–6), noting promising anti-inflammatory potential by compounds 5 and 9 with an IC50 value of 8.51 ± 0.47 and 8.30 ± 0.96 µg/mL for NO inhibition and 17.21 ± 0.22 and 46.79 ± 5.87 µg/mL for TNF-α inhibition, respectively

Tristaenone A : a new anti-inflammatory compound isolated from the Australian Indigenous plant Tristaniopsis laurina

Inspired by ethnopharmacological knowledge, we conducted a bioassay-guided fractionation of the leaves of Tristaniopsis laurina which led to the discovery of a new anti-inflammatory compound, tristaenone A (1). The structure was elucidated by detailed spectroscopic data analysis, and the absolute configuration was established using X-ray crystallography analysis. Tristaenone A (1) suppressed LPS and IFN-γ-induced NO, TNF-α and IL-6 production in RAW 264.7 cells with IC50 values of 37.58 ± 2.45 μM, 80.6 ± 5.82 μM and 125.65 ± 0.34 μM, respectively. It also inhibited NF-κB nuclear translocation by 52.93 ± 14.14% at a concentration of 31.85 μM

Self-assembly of a rare high spin FeII/PdII tetradecanuclear cubic cage constructed via the metalloligand approach

Polynuclear heterobimetallic coordination cages in which different metal cations are con-nected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanu-clear heterobimetallic [Fe8 Pd6 L8 ](BF4 ]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3 OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of the eight corners of the discrete cubic structure

Preface

The 6th International Symposium on Nano & Supramolecular Chemistry (ISNSC) was held in Bali, Indonesia, 10–14 August 2014, with 130 scientists from all over the world presenting their recent research

Metalloligand strategies for assembling heteronuclear nanocages : recent developments

The use of metalloligands as building blocks for the assembly of metallo-organic cages has received increasing attention over the past two decades or so. In part, the popularity of this approach reflects its stepwise nature that lends itself to the predesigned construction of metallocages and especially heteronuclear metallocages. The focus of the present discussion is on the use of metalloligands for the construction of discrete polyhedral cages, very often incorporating heterometal ions as structural elements. The metalloligand approach uses metal-bound multifunctional ligand building blocks that display predesigned structural properties for coordination to a second metal ion such that the rational design and construction of both homo-and heteronuclear metal-organic cages are facilitated. The present review covers published literature in the area from early 2015 to early 2019

Oligo-β-diketones as versatile ligands for use in metallo-supramolecular chemistry : recent progress and perspectives

Classical β-diketones have long been demonstrated to be excellent chelating ligands for a wide range of metal ions from across the Periodic Table. More recently, bis- and tris-bidentate derivatives of this ligand class, in which two or three β-diketone domains are linked by a spacer unit, have increasingly been employed in wide-ranging studies that have often resulted in diverse metallosupramolecular architectures that include dinuclear platforms, trinuclear triangles, triple and quadruple helices, tetrahedral cages, polyrotaxanes along with other coordination polymer types. These systems have often been shown to display a range of interesting properties that, for example, include diverse photophysical, magnetic, chiral and/or light switching behaviour. Here we review the major developments in the above area covering the literature from late 2016 through to August 2021

Structural diversity in coordination polymers constructed from a naphthalene-spaced dipyridyl ligand and iron(II) thiocyanate

Employing N,N'-bis-(4-pyridinylmethylene)-1,5-naphthalenediamine (nbpy4) and iron(II) thiocyanate as building blocks, three coordination polymers, [Fe(NCS)2(nbpy4)(MeOH)2]n, 1, [Fe(NCS)2(nbpy4)2]n_2nCHCl3_nH2O•2nEtOH, 2, and [Fe(NCS)2(nbpy4)(bpy)]n_2.5nDCM_0.75nH2O, 3, have been prepared. The three metal-organic materials were prepared by varying the solvent systems used and the inclusion of a second pyridine containing ligand (4,4′-bipyridine, bpy). Single crystal X-ray diffraction revealed 1 to be a one-dimensional structure with hydrogen bonding between adjacent chains and 2-3 to be two-dimension network solids with (4,4)-topologies

HMM-based H∞ filtering for Markov jump systems with partial information and sensor nonlinearities

This work examines the H∞ filtering issue for Markov jump systems in the circumstances of partial information on Markov chain and randomly occurring sensor nonlinearities. The partial information considered in this work includes partial information on the Markov state, on transition probabilities and on detection probabilities. A hidden Markov model with partially known transition probabilities and detection probabilities is introduced to describe the above partial information phenomenon. The randomly occurring sensor nonlinearities considered in this work depend on the system operating mode. Based on the Lyapunov methodology and the introduced hidden Markov model, some effective H∞ performance analysis criteria are derived for the filtering error system under the circumstances of partial information and sensor nonlinearities. In addition, the design procedure of the desired hidden Markov model-based filter is established, and finally two examples are used to verify the theoretical results