Search

Renewable energy allows electricity generation with lower environmental and resource impact than generation from fossil fuels. However, the manufacture, use and ultimate disposal of the equipment used to capture this energy has an environmental impact, which should be minimised. Tidal turbine blades are currently primarily manufactured from glass-fibre reinforced polymers. Such blades cannot be recycled at the end of their life, and are disposed of in landfill or by incineration. As the tidal energy industry grows, the volume of non-recyclable waste is a potential problem. Here we consider the environmental impact of ten combinations of material and disposal method for tidal stream turbine blades, including recyclable options. Our findings suggest that glass fibre blades have greenhouse gas emissions of around 15,500 kgCO2e for the scope considered, and a significant environmental impact in all impact categories, which would be increased by changing to carbon fibre (99% mean increase from glass fibre across impact categories) or steel (134% mean increase from glass fibre across impact categories) blades, but that composite materials using flax fibre and recyclable resin may have lower impact (26% mean decrease from glass fibre across impact categories), provided they are treated correctly after use. These materials may also offer the potential for lower cost blades in future.

We present an analysis of major-axis surface-brightness profiles of bars in a volume-limited sample of 182 barred spiral galaxies, using Spitzer 3.6 micron images. Unlike most previous studies, we use the entire bar profile, and we classify profiles into four categories. These are "Peak+Shoulders" (P+Sh) -- updating the classic "flat bar" profile -- and three subtypes of the classic "exponential" profile: (true) Exponential, "Two-Slope" (shallow inner slope + steeper outer slope), and "Flat-Top" (constant inner region, steep outer slope). P+Sh profiles are preferentially found in galaxies with high stellar masses, early Hubble types, red colours, and low gas fractions; the most significant factor is stellar mass, and previous correlations with Hubble type can be explained by the tendency of higher-mass galaxies to have earlier Hubble types. The most common type of non-P+Sh profile is Exponential, followed by Flat-Top profiles; all non-P+Sh profiles appear to have similar distributions of stellar mass, Hubble type, colour, and gas fraction. We also morphologically classify the bars of an inclined subsample into those with and without boxy/peanut-shaped (B/P) bulges; as previously reported, the presence of a B/P bulge is very strong function of stellar mass. Essentially all bars with B/P bulges have P+Sh profiles; we associate the profile shoulders with the outer, vertically thin part of the bar. We find a small number of P+Sh profiles in bars without clear B/P bulges, which may indicate that P+Sh formation precedes the formation of B/P bulges., pdflatex, 21 pages, 12 figures; accepted by MNRAS. Data, code, and Jupyter notebooks available at https://github.com/perwin/barprofiles_paper

From the TNG50 cosmological simulation we build a sample of 191 well-resolved barred galaxies with a stellar mass $\logMstar > 10$ at $z=0$. We search for box/peanut bulges (BPs) in this sample, finding them in 55\% of cases. We compute $\fbp$, the BP probability for barred galaxies as a function of $\Mstar$, and find that this rises to a plateau, as found in observations of nearby galaxies. The transition mass where $\fbp$ reaches half the plateau value is $\logMstar = 10.14$, consistent with the observational value within measurement errors. We show that this transition in $\fbp$ can be attributed to the youth of the bars at low $\Mstar$, which is a consequence of downsizing of galaxies. Young bars, being generally shorter and weaker, have not yet had time to form BPs. At high mass, while we find a plateau, the value is at $\sim 60\%$ whereas observations saturate at $100\%$. We attribute this difference to excessive heating in TNG50, due to merger activity and to numerical resolution effects. BPs in TNG50 tend to occur in galaxies with more quiescent merger histories. As a result, the main driver of whether a bar hosts a BP in TNG50 is not the galaxy mass, but how long and strong the bar is. Separating the BP sample into those that have visibly buckled and those that have not, we find that fully half of BP galaxies show clear signs of buckling, despite the excessive heating and limited vertical resolution of TNG50., 20 pages, 24 figures, 5 tables. Submitted to MNRAS

The short-lived buckling instability is responsible for the formation of at least some box/peanut (B/P) shaped bulges, which are observed in most massive, $z=0$, barred galaxies. Nevertheless, it has also been suggested that B/P bulges form via the slow trapping of stars onto vertically extended resonant orbits. The key difference between these two scenarios is that when the bar buckles, symmetry about the mid-plane is broken for a period of time. We use a suite of simulations (with and without gas) to show that when the buckling is sufficiently strong, a residual mid-plane asymmetry persists for several Gyrs after the end of the buckling phase, and is visible in simulation images. On the other hand, images of B/P bulges formed through resonant trapping and/or weak buckling remain symmetric about the mid-plane. We develop two related diagnostics to identify and quantify mid-plane asymmetry in simulation images of galaxies that are within 3{\deg} of edge-on orientation, allowing us to test whether the presence of a B/P-shaped bulge can be explained by a past buckling event. We apply our diagnostics to two nearly edge-on galaxies with B/P bulges from the ${\it Spitzer}$ Survey of Stellar Structure in Galaxies, finding no mid-plane asymmetry, implying these galaxies formed their bulges either by resonant trapping or by buckling more than $\sim 5$ Gyr ago. We conclude that the formation of B/P bulges through strong buckling may be a rare event in the past $\sim 5$ Gyr., Comment: Accepted for pubblication in MNRAS

Three new amine functionalised tetracarboxylate linkers with a variety of arm lengths were synthesised, namely N,N,N′N′-tetrakis(R1, R2 or R3)-trans-1,4-diaminocyclohexane, R1 = (4-carboxyphenyl)-1-methyl; R2 = (4-cinnamic)-1-methyl; R3 = 1′-carboxy-[4,4′-biphenyl]-1-methyl. The diagonal length of the linkers, from single crystal structural analysis and obtained by measuring between the furthest oxygen atoms, is 19.4, 24.6 and 27.5 A for L1, L2 and L3, respectively. The sp3 hybridization of the amino groups of the cyclohexyldiamine core and the carbon atoms of methylene spacers permits the rotation of the attached groups to occur around these atomic sites, giving the ligands a flexibility that manifests itself in two main dominant conformations: convergent, where carboxyl arm groups connected to the same nitrogen atom are π⋯π stacking, and divergent, where two carboxyl arms occupy equatorial positions and two occupy the axial positions relative to the ligand's cyclohexyl core. Analysis of the overall ligand conformations obtained from crystal structures of sixteen new coordination polymers showed that the overwhelmingly most common conformation (93%) was the divergent one. The formulae and topologies of the coordination polymers obtained were: poly-[Cd2(H2L1)(Cl)2(OH2)2]·5H2O (1) 2D (4,4), poly-[M2L2(OH2)2]·DMA M = Cd (2Cd) or Mn (2Mn) 3D (4·62·7·8)(42·66·75·82), poly-[Cd2(L3)(OH2)4(DMF)2] (3) 1D ladder, poly-[Cd2(L3)]·4DMA·16H2O (4) 3D fsc, poly-{((CH3)2NH2)4[Zn4Na4(L1)4(OH2)4(DMF)2]} (5) 3D pts, poly-[M5(HL1)2(O)2(OH2)2(DMF)2]·solv M/solv = Zn/2DMF·18H2O (6Zn) or Co/9DMF·10H2O (6Co) 3D cyc, poly-[Zn3(L1)(OH)2]·2DMF (7) 3D fsc, poly-{((CH3)2NH2)[Zn2(HL2)(O)]·DMF} (8) 3D pts, poly-[Zn8(L3)3(O)2]·16DMF (9) 3D fsy, poly-[Cu2(L1)(DMF)2] (10) 2D (4,4), poly-[Cu2(L2)(OH2)2] (11) 3D lvt, poly-[Na4Zr2(L1)3(DMF)4] (12) 3D (44·52)2(44·5·6)(46·513·68·7)2, poly-[Zr6(HL1)2(O)8(CH3COO)2(OH2)6] (13) 3D scu, and poly-[Co2K4(L1)2(DMF)3] (14) 3D (42·64)(42·610·83). Although we applied similar reaction conditions, none of the coordination polymers obtained with L1, L2 & L3 were isoreticular upon ligand change. The overall trend is of void space increase by using longer ligands but with no notable increase in the level of interpenetration. The predictability and control of the obtained frameworks was hindered by the formation of non-default topologies due to the high flexibility of the tetracarboxylate linkers used and the variety of metal nodes observed.

The major-axis density profiles of bars are known to be either exponential or 'flat'. We develop an automated non-parametric algorithm to detect flat profiles and apply it to a suite of simulations (with and without gas). We demonstrate that flat profiles are a manifestation of a bar's secular growth, producing a 'shoulder' region (an overdensity above an exponential) in its outskirts. Shoulders are not present when bars form, but develop as the bar grows. If the bar does not grow, shoulders do not form. Shoulders are often accompanied by box/peanut bulges, but develop separately from them and are independent tracers of a bar's growth. They can be observed at a wide range of viewing orientations with only their slope varying significantly with inclination. We present evidence that shoulders are produced by looped x1 orbits. Since the growth rate of the bar moderately correlates with the growth rate of the shoulder strength, these orbits are probably recently trapped. Shoulders therefore are evidence of bar growth. The properties of the shoulders do not, however, establish the age of a bar, because secondary buckling or strong spirals may destroy shoulders, and also because shoulders do not form if the bar does not grow much. In particular, our results show that an exponential profile is not necessarily an indication of a young bar., Comment: 20 pages, 23 figures, 2 tables. Published in MNRAS

Mixed donor phenanthroline-carboxylate linkers were combined with MnII or ZnII to form photoactive MOFs with large pore apertures. The MOFs display high CO2 adsorption capacities, which consequently causes structural framework flexibility, and align with favorable metrics for selective CO2 capture. The photophysical properties of the MOFs were investigated, with the MnII MOF giving rise to short triplet LMCT lifetimes.

We use an $N$-body+smoothed particle hydrodynamics simulation of an isolated barred galaxy to study the age dependence of bulge longitudinal proper motion ($��_l$) rotation curves. We show that close to the minor axis ($|l| \sim 0^\circ$) the relatively young stars rotate more rapidly than the old stars, as found by Hubble Space Telescope in the Milky Way's (MW's) bulge. This behaviour would be expected also if the MW were unbarred. At larger $|l|$ a different behaviour emerges. Because younger stars trace a strong bar, their galactocentric radial motions dominate their $��_l$ at $|l| \sim 6^\circ$, leading to a reversal in the sign of $\left< ��_l \right>$. This results in a rotation curve with forbidden velocities (negative $\left< ��_l \right>$ at positive longitudes, and positive $\left< ��_l \right>$ at negative longitudes). The old stars, instead, trace a much weaker bar and thus their kinematics are more axisymmetric, resulting in no forbidden velocities. We develop metrics of the difference in the $\left< ��_l \right>$ rotation curves of young and old stars, and forbidden velocities. We use these to predict the locations where rotation curve reversals can be observed by HST and the Vera Rubin Telescope. Such measurements would represent support for the amplitude of the bar being a continuous function of age, as predicted by kinematic fractionation, in which the bar strength variations are produced purely by differences in the random motions of stellar populations at bar formation., 20 pages, 18 figures, 2 tables, published in MNRAS

Introduction: There has been a surge in robotic surgery research publications over the past 20 years. However, to date, there has been no characterization of urology's contribution to the ...

One prominent aspect of metal organic frameworks (MOFs) is the ability to tune the size, shape, and chemical characteristics of their pores. MOF-5, with its open cubic connectivity of Zn 4 O clusters joined by two-dimensional, terephthalate linkers, is the archetypal example: Both functionalized and elongated linkers produce isoreticular frameworks that define pores with new shapes and chemical environments. The recent scalable synthesis of cubane-1,4-dicarboxylic acid (1,4-H 2 cdc) allows the first opportunity to explore its application in leading reticular architectures. Herein we describe the use of 1,4-H 2 cdc to construct [Zn 4 O(1,4-cdc) 3 ], referred to as CUB-5. Isoreticular with MOF-5, CUB-5 adopts a cubic architecture but features aliphatic, rather than aromatic, pore surfaces. Methine units point directly into the pores, delivering new and unconventional adsorption locations. Our results show that CUB-5 is capable of selectively adsorbing high amounts of benzene at low partial pressures, promising for future investigations into the industrial separation of benzene from gasoline using aliphatic MOF materials. These results present an effective design strategy for the generation of new MOF materials with aliphatic pore environments and properties previously unattainable in conventional frameworks.

The use of flexible ligands in coordination polymers provides both opportunities and unpredictability. A new series of flexible ligands derived from p-xylylenediamine, which vary in the positioning of carboxylic acid functional groups, have been found to form a series of coordination polymers and a discrete coordination complex. Use of the tetra-substituted meta-carboxylic acid ligand N,N,N′,N′-tetra(3-carboxybenzyl)-p-xylylenediamine, isolated as its dihydrochloride salt (H6M4pxy)Cl2, resulted in the simultaneous formation of two products from the same synthetic conditions. One of these products was a discrete cage-type coordination complex of the form [Cu4(M4pxy)2(DMF)2(OH2)] (1), while the other product was the two-dimensional coordination polymer poly-[Cu2(M4pxy)(OH2)2] (2). Synthesis utilising the tetra-substituted para-carboxylic acid ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-p-xylylenediamine dihydrochloride (H6P4pxy)Cl2, resulted in the formation of multiple two-dimensional coordination polymers, poly-[Cu2(P4pxy)(DMF)(OH2)]·2DMF·3H2O (3·2DMF·3H2O), poly-[Mn2(P4pxy)(DMA)2] (4), poly-[Co4(P4pxy)2(DMF)2(μ-OH2)2(OH2)2]·6DMF·4H2O (5·6DMF·4H2O) and poly-[Cd2(P4pxy)(OH2)2]·DMA·3H2O (6·DMA·3H2O). The last of these materials, a three-dimensional coordination polymer, was found to adsorb approximately 32 cm3 g−1 STP of CO2 at atmospheric pressure at 273 K.

A national undergraduate curriculum for General Practice might address current concerns regarding intellectual challenge and recruitment through articulating disciplinary knowledge and providing teaching guidance. However, there is ambivalence regarding this idea and the reasons appear incompletely understood.

The resurgence of interest in the hydrogen economy could hinge on the distribution of hydrogen in a safe and efficient manner. Whilst great progress has been made with cryogenic hydrogen storage or liquefied ammonia, liquid organic hydrogen carriers (LOHCs) remain attractive due to their lack of need for cryogenic temperatures or high pressures, most commonly a cycle between methylcyclohexane and toluene. Oxidation of methylcyclohexane to release hydrogen will be more efficient if the equilibrium limitations can be removed by separating the mixture. This report describes a family of six ternary and quaternary multicomponent metal-organic frameworks (MOFs) that contain the three-dimensional cubane-1,4-dicarboxylate (cdc) ligand. Of these MOFs, the most promising is a quaternary MOF (CUB-30), comprising cdc, 4,4'-biphenyldicarboxylate (bpdc) and tritopic truxene linkers. Contrary to conventional wisdom that adsorptive interactions with larger, hydrocarbon guests are dominated by π-π interactions, here we report that contoured aliphatic pore environments can exhibit high selectivity and capacity for LOHC separations at low pressures. This is the first time, to the best of our knowledge, where selective adsorption for cyclohexane over benzene is witnessed, underlining the unique adsorptive behavior afforded by the unconventional cubane moiety.

Porous coordination polymers, or metal–organic frameworks (MOFs), provide a unique materials platform due to their regular structure that allows for almost unlimited tunability in terms of pore size, shape, dimensionality and chemical functionalisation. The ability of this class of material to act as agents for the selective capture or separation of small molecules has driven much of the research in the field over the past two decades. One of the major driving forces in recent years has been the ability of porous coordination polymers to act as selective hosts for carbon dioxide, with obvious potential environmental implications for successful materials. Efforts to enhance the selectivity for CO2 over other gases (particularly those present in exhaust flues) have explored chemical functionalisation of the interior pore space using amines, to give materials that to some extent mimic the standard solution-based processing methods of flue gas that are currently employed. This review examines the three major synthetic routes that are used in order to affect this chemical modification of porous frameworks; (i) post-synthetic grafting of amines to coordinatively unsaturated metal sites, (ii) incorporation of ligands that contain terminal amine groups, and (iii) incorporation of ligands that contain amine embedded within the core of the ligand. The relative merits and shortcomings of these different synthetic approaches are discussed alongside examples of the materials generated using each method.

An understanding of the atomic-scale interactions between gas sorbent materials and their molecular guests is essential for the identification of the origins of desirable function and the rational optimization of performance. However, characterizations performed on equilibrated sorbent-guest systems may not accurately represent their behavior under dynamic operating conditions. The emergence of fast (minute-scale) neutron powder diffraction coupled with direct, real-time quantification of gas uptake opens up new possibilities for obtaining knowledge about concentration-dependent effects of guest loading upon function-critical features of sorbent materials, including atomic structure, diffusion pathways, and thermal expansion of the sorbent framework. This article presents a detailed investigation of the ultramicroporous metal-organic framework [Cu3 (cdm)4 ] as a case study to demonstrate the variety of insights into sorbent performance that can be obtained from real-time characterizations using neutron diffraction.

This communication briefly reviews why network topology is an important tool (for understanding, comparing, communicating, designing, and solving crystal structures from powder diffraction data) and then discusses the terms of an IUPAC project dealing with various aspects of network topology. One is the ambiguity in node assignment, and this question is addressed in more detail. First, we define the most important approaches: the “all node” deconstruction considering all branch points of the linkers, the “single node” deconstruction considering only components mixed, and the ToposPro “standard representation” also considering linkers as one node but, if present, takes each metal atom as a separate node. These methods are applied to a number of metal–organic framework structures (MOFs, although this is just one example of materials this method is applicable on), and it is concluded that the “all node” method potentially yields more information on the structure in question but cannot be recommended as the o...

Reactions of ortho-, para- and substituted meta-xylenyl bridged bis(tacn) ligands with two or three molar equivalents of Zn(NO3)2·6H2O at pH 5.0 in the presence of NaClO4 or NH4PF6 resulted in the formation of a range of crystalline zinc complexes. In the presence of perchlorate counter ions the Lpx and Lphx ligands gave rise to dinuclear Zn2+ coordination complexes [Zn2Cl2(Lpx)(H2O)2](ClO4)2(H2O) and [Zn2Cl2(Lphx)(H2O)2](ClO4)2(H2O)2 respectively, which formed infinite 1D polymeric chains. In contrast, in the presence of the hexafluorophosphate counter ion, the Lnix ligand formed a unique tetranuclear Zn2+ complex, [Zn2Cl2(Lnix)(H2O)3](Cl)(PF6)2(H2O)4, the Lcax ligand formed an octanuclear complex [Zn8Cl4(Lcax)4(H2O)10](PF6)6.7(NO3)1.3(H2O)3.3, whilst the Lox ligand formed a mononuclear sandwich structure, [Zn(Lox)](PF6)2(H2O). The protonated metal-free Lpx ligand crystallised as [H4(Lpx)](NO3)2(PF6)(H2O)2 with the stacked ligand cations forming a hydrogen-bonded network. These structural attributes provide an explanation for the significant differences in binding behaviour of recombinant N-terminally tagged proteins with the corresponding Zn2+-azamacrocyclic complexes, compared to the analogous Cu2+- or Ni2+-azamacrocyclic complexes, when immobilised onto support materials and used as immobilised metal affinity chromatographic (IMAC) adsorbents.

The interdependent effects of temperature and guest uptake on the structure of the ultramicroporous metal-organic framework [Cu3 (cdm)4 ] (cdm=C(CN)2 (CONH2 )- ) were explored in detail by using in situ neutron scattering and density functional theory calculations. The tetragonal lattice displays an anisotropic thermal response related to a hinged "lattice-fence" mechanism, unusual for this topology, which is facilitated by pivoting of the rigid cdm anion about the Cu nodes. Calculated pore-size metrics clearly illustrate the potential for temperature-mediated adsorption in ultramicroporous frameworks due to thermal fluctuations of the pore diameter near the value of the target guest kinetic diameter, though in [Cu3 (cdm)4 ] this is counteracted by a competing contraction of the pore with increasing temperature as a result of the anisotropic lattice response.

Fourteen three-dimensional (3D) lanthanide coordination polymers (CPs) with dicarboxylate mixed ligands, [Ln(fum)1.5(H2O)2]·0.5(H2bdc)·H2O (Ln = Sm (1), Tb (2)), [Ln2(fum)2(bdc)(H2O)4]·2H2O (Ln = Sm (3), Eu (4), Tb (5), Er (6)), [Ln(fum)0.5(bdc)] (Ln = Sm (7), Eu (8), Tb (9), Er (10)), and [Ln2(bdc)2(ox)(H2O)4]·0.7H2O (Ln = Sm (11), Gd (12), Tb (13), Dy (14)), have been synthesized hydrothermally from the self-assembly of lanthanide(III) ions (Ln3+), fumaric acid (H2fum), and terephthalic acid (H2bdc) in the presence of potassium hydroxide at different temperatures. The compounds fall into four classes. Compounds 1 and 2 were isolated from hydrothermal reactions performed at a relatively low temperature of 100 °C and found to crystallize in the triclinic space group P. The 3D framework is assembled from 2D layers of [Ln(fum)(H2O)2] units pillared by the chelating fum ligands and has 1D rhombic channels templated by H2bdc and lattice H2O molecules. The framework presents a binodal (4,5)-connected tcs topology with the point symbol (44·62)(44·66). Raising the reaction temperature to 140 °C resulted in the formation of compounds 3–6. These materials crystallize in the monoclinic system with the polar space group P21 and feature a 3D network constructed from dinuclear {Ln2(OCO)6(H2O)4} units interlinked by fum and bdc ligands, showing a uninodal 6-connected two-fold interpenetrated pcu topology. The small channels of the framework are occupied by lattice H2O molecules. Further increase of the reaction temperature to 160 °C gave rise to the formation of compounds 7–10, crystallizing in the orthorhombic space group Pbca. The 3D framework is generated from 2D corrugated sheets of [Ln(fum)]2+ bound by bdc ligands and contains no intercalated H2O molecules in the lattice. The framework possesses a trinodal (4,6,7)-connected net with the point symbol (42·64)2(46·68·8)(412·69)2. Finally, compounds 11–14 contained an in situ generated oxalate (ox) ligand formed under hydrothermal conditions conducted at a high reaction temperature of 180 °C. These compounds crystallize in the monoclinic space group P21/c and possess a 3D open framework consisting of a dinuclear [Ln2(ox)(H2O)4]2+ unit linked by bridging bdc ligands and has small void channels occupied by lattice H2O molecules. The frameworks were topologically simplified as a binodal (4,5)-connected tcj/hc net with a total point symbol of (42·52·72)(42·53·75). In the solid state at room temperature, the Tb (2, 5, 9, and 13) and Eu (4 and 8) compounds emit green and red light, respectively.

A new Cd(II) based metal–organic framework (MOF), having formula {(CH3)2NH2)6[Cd5(L)4]·H2O·3DMF}n (1), has been synthesized based on a rigid tetracarboxylate ligand of terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4L). 1 shows a complicated 3D tetranodal 3,3,4,8-c network with uncoordinated –COO− groups. The highly selective luminescent sensing of 2,4-dinitrophenol (2,4-DNP), 2,4,6-trinitrophenol (TNP) and ferric ions was studied for 1 through the alleviation in its fluorescence intensity. The detection limit of 2,4-DNP was found to be 0.84 ppm, which is 20 times higher than that of 1,3,5-trimethylbenzene, demonstrating greater and selective quenching ability. The possible mechanism associated with the decrease in fluorescence intensity of 1 in the presence of nitroaromatics (NACs) has been addressed by theoretical calculations. Furthermore, 1 displays excellent capacity to adsorb methylene blue (MB) with high selectivity, and it maintains an almost identical adsorption performance after being recycled five times.

A new metal–organic framework, formulated as {[Zn2(L)(DMF)3]·2DMF·2H2O} (1), has been synthesized using a symmetrical rigid carboxylate ligand terphenyl-3,3′′,5,5′′-tetracarboxylic acid (H4L). Single-crystal X-ray diffraction analysis shows that 1 possesses a 3D uninodal 4-c lonsdaleite (lon) topology based on binuclear Zn clusters. 1 behaves as a fluorescent chemosensor for highly selective and sensitive detection of Fe3+/Fe2+ ions, 2,4-dinitrophenol (2,4-DNP), p-nitrophenol (PNP) and 2,4,6-trinitrophenol (TNP). Furthermore, the photocatalytic properties of 1 for degradation of methyl violet (MV) and Rhodamine B (RhB) have been explored. The possible emission quenching of 1 in the presence of aromatic compounds has been addressed by theoretical calculations and the photocatalytic activity of 1 against organic dyes has been addressed using density of states (DOS) calculations.

A traditionally good chelating motif has been incorporated into a ligand for the synthesis of coordination polymers with vacant amine sites. A novel tetracarboxylic acid diamine ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-1,3-diaminopropane dihydrochloride trihydrate (H6L1)Cl2·3H2O, has been prepared, structurally characterised, and subsequently used in the formation of three new coordination polymers. Poly-[Cu2(L1)(OH2)2]·6DMF·3H2O 1 consists of (4,4) sheets formed by each L1 ligand coordinating to four copper(II) ‘paddlewheel’ dinuclear clusters. The amines of the ligand are non-coordinating. After solvent exchange and evacuation, 1 was found to adsorb approximately 23 cm3(STP) g−1 of CO2 at atmospheric pressure at 273 K. The isostructural compounds poly-[Zn(H2L1)(OH2)]·DMF·4H2O and poly-[Cd(H2L1)(OH2)]·DMF·3H2O 2Zn/2Cd are self-penetrating (10,3) coordination polymers containing square-shaped one-dimensional solvent channels. After solvent exchange it was found that 2Zn and 2Cd lost crystallinity, which accounts for the low N2 and CO2 uptakes observed.

An unexploited pentacarboxylate ligand, 2,5-bis(3′,5′-dicarboxylphenyl)-benzoic acid (H5L), was designed and used for the preparation of metal organic material using Zn2+ as a node. The new compound, {(Me2NH2)[Zn2(L)(H2O)]·0.5DMF}n (1) (DMF = dimethylformamide), has been synthesized and structurally characterized. The topology of the 5-connected anionic framework may be described as (44)(66) (Schlafli symbol) based on {M2(CO2)5} molecular building blocks (MBBs) and L ligands in 1. It has been demonstrated that 1 can act as a fluorescent sensor for highly sensitive detection of nitroaromatics and Fe3+, with a detection limit of 0.54 ppm for 2,4,6-trinitrophenol (TNP) and 0.81 ppm for Fe3+. The possible emission quenching mechanism in the presence of nitroaromatics has been addressed by theoretical calculations.

Mentorship carries benefits for surgically inclined students: attraction to and retention in surgical training, improved understanding of surgical career pathways, increased research participation and output, and development of surgical skills. With assistance of surgeons and faculty, a surgical mentorship program for medical students was developed and established by the Sydney University Surgical Society, a student organisation of the University of Sydney, Australia. The program was audited at the end of the calendar year with a non-validated survey of participants, informed further by qualitative participant reports and personal observations of convenors. High program satisfaction rates were found for mentee participants, with flexible and informal mentorship interactions characterising the program. Comparatively lower mentor satisfaction rates and qualitative reports suggest that an initial formalised meeting may improve mentor satisfaction and mentee engagement levels. This article describes the evolution and reflects on key features of a novel student-led surgical mentorship program for medical students. It suggests that with faculty support, student-led mentoring initiatives can be established to achieve the desired outcomes of mentoring and provides guidance to assist establishment of similar programs in the future.

Holstein calves fed pasteurized waste milk were blocked by sex and randomly assigned to 1 of 3 treatment groups, control with no vitamin supplementation (CON, n = 18) and 2 levels of an oral vitamins A, D, and E supplement: 0.25 mL/d of supplement (0.25ADE, n = 12) or 0.5 mL/d of supplement (0.5ADE, n = 10). The supplemented calves also received a 5 mL subcutaneous injection of vitamins A, D, and E at birth. The oral and injectable supplements contained 50,000 international units (IU) of vitamin A as retinyl-palmitate, 50,000 IU of vitamin D3, and 500 IU of vitamin E as RRR-α-tocopherol per milliliter of product. Concentrations of 25-hydroxyvitamin D and a-tocopherol, but not retinol, in serum of 0.25ADE and 0.5ADE calves were greater than CON calves. We observed that supplemented calves gained less weight compared with CON calves in the first 28 d; however, height and starter grain intakes did not differ among treatments. Incidence of respiratory infection or diarrhea did not differ among groups. In conclusion, injection plus supplementation of pasteurized waste milk with vitamins A, D, and E increased concentrations of 25(OH)D and a-tocopherol in serum but decreased body weight gain, due possibly to over-supplementation of the vitamins., The Bovine Practitioner, Vol. 53, No. 2 (2019 Summer)

Two unusual isostructural nanocage-based 3D Ln-MOFs, 1-Ln (Ln = Tb and Eu), were constructed using a new diisophthalate ligand with active Lewis basic triazole sites. 1-Eu exhibits highly efficient luminescent sensing for Fe3+ cations and Cr2O72- anions, and selective CO2 capture over CH4.

A new metal–organic framework having formula {[Cd3(H2O)(L)2][Cd(im)3(H2O)2]·3 H2O} (H4L = 5-bis(4-carbonylbenzyl)aminoisophthalic acid and im = imidazole) (1) has been synthesized. X-ray investigation reveals that 1 is rare 4,4,8-connected (46)(45 · 6)(411 · 615 · 82) topology. The present work indicates that 1 could be a prospective candidate for developing novel luminescence sensors for the selective sensing of nitrobenzene which can be used as a precursor for explosives. Furthermore, the luminescent property of 1 in different solvents analytes as well as nitrobenzene have been investigated and the observed quenching in fluorescence have been corroborated by theoretical calculations.

A new ZnII metal-organic framework, [Zn6 (L)3 (DMA)4 ]⋅5 DMA (H4 L=[1,1':3',1''-terphenyl]-3,3'',5,5''-tetracarboxylic acid, DMA=dimethylacetamide), has been synthesized and characterized. The structure contains a three-dimensional 3,4,4,6-connected net with (4.62 )2 (66 )(66 )(42 .610 .83 ) topology and displays selective detection of nitrobenzene, CrO42- and Fe3+ ions. The present work thus indicates that this metal-organic framework could be a prospective candidate for developing novel luminescence sensors for the selective sensing of nitrobenzene, which can be used as a precursor for explosives. Furthermore, the photoluminescent properties of this material in different solvents and with various analytes were investigated and corroborated by theoretical calculations. The results were in good agreement with the experimental solvent-dependent luminescence behavior.

Two new isomeric bis(tacn) ligands, 3,5-bis(1,4,7-triazacyclonon-1-ylmethyl)-1-(hydroxymethyl)-benzene (HLhyx) and 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)anisole (Lanx) have been synthesised. In addition, 2,6-bis(1,4,7-triazacyclonon-1-ylmethyl)-4-methylphenol (HLohx) was also synthesised in a considerably higher yield than the previously reported method. The ligands were reacted with two equivalents of Cu(NO3)2·3H2O at pH 5 resulting in the formation of three binuclear complexes. The ligands Lanx and HLhyx form complexes [Cu2Cl3(L)(H2O)](PF6) containing two unique Cu2+ centres coordinated to the ligand. In contrast, the phenolic HLohx ligand forms a bridged complex [Cu2(μ-Cl)(Lohx)](PF6)2, with the two Cu centres further linked by (μ-Cl) and (μ-O) bridges.

A highly connected metal–organic framework (MOF), namely, [Co5(μ3-OH)2(iapt)4(4,4′-bipy)0.5(H2O)·CH3CN·3H2O] (1) (H2iapt = 5-aminoisophthalic acid and 4,4′-bipy = 4,4′-bipyridine), is reported. 1 shows a complicated pentanodal 4,4,4,4,13-c 3D net with (43)(43)(43)(43)(420·514·623·78·813) topology based on an uncommon Co5 cluster. The magnetic analysis reveals antiferromagnetic interactions in 1, and both the local spin–orbit coupling of octahedral Co(II) ions and the antiferromagnetic interactions are the primary factors in the magnetic behaviour.

The effect of a common surfactant, cocamidopropyl betaine (CAPB), on the growth and meso- to micro-structural morphology of a prototypical metal–organic framework, HKUST-1 (Hong Kong University of Science and Technology-1, copper 1,3,5-benzenetricarboxylate) has been investigated. Surfactant molecules direct growth of HKUST-1 into wheat sheaf-shaped structures, comprising flat, ribbon-like individual ‘stems’ of HKUST-1. Comparison of wheat sheaf-like structures to bulk HKUST-1, as well as their respective decomposition products, was made. Upon pyrolysis, both bulk and wheat sheaf structures thermally decomposed to amorphous carbon decorated with metallic copper nanoparticles, that in each case retained the base morphology of the starting MOF.

The synthesis, characterizations and crystal structures for [Cu(ipnm)(hmpH)] (1), mixed-valent tetranuclear [MnII2MnIII2(dcnm)2(hmp)6Cl2] (2) and the homo-valent hexanuclear [FeIII6(dcnm)6(hmp)8O2] (3), (where ipnm = imido[cyano (picolinoyl)methyl]nitrosomethanide, hmpH = 2-hydroxymethylpyridine; dcnm = dicyanonitrosomethanide) are reported. The formation of new dianionic ligand, ipnm which is also an imide derivative, represents the scarce example of metal-mediated in-situ dehydrogenative cross-coupling between amide derivatives with primary alcohol. Structure of 2 is known as ‘butterfly’ type structure while hexanuclear cluster 3 exists in chair-like conformation which in both structures, the dcnm acting as a terminal ligand.

A new divergent ligand, N,N′-bis(4-carboxyphenylmethylene)ethane-1,2-diamine (H4L1), has been prepared in high yield and used to generate two copper(II) coordination polymer materials, poly-[Cu(H2L1)(OH2)]·H2O (1) and poly-[Cu(H2L1)(OH2)]·H2O·DMF (2). Both networks possess (4,4) sheet topologies and have almost identical compositions and coordination modes. The only major difference between the compounds lies with the conformation of the chelating ethylenediamine cores; compound 1 adopts a trans-(R,R/S,S) conformation, while compound 2 exhibits a cis-(R,S) conformation. This seemingly small difference arising from variation in synthetic conditions influences the extended structures of each network through hydrogen bonding interactions, resulting in the formation of a close packed 2-fold 2D → 2D parallel interpenetrated network for 1, while the extended, non-interpenetrated structure of 2 contains aligned one-dimensional solvent channels. After solvent exchange and evacuation, compound 2 was found to adsor...

A new piperazine-derived ligand has been prepared and used to synthesise a porous coordination polymer which displays selective carbon dioxide uptake after solvent exchange and thermal activation. The ligand N,N′-bis(4-carboxyphenylmethylene)piperazine H2L1 was prepared from piperazine in three steps and good yield. A structure containing the deprotonated form K2L1·2H2O was determined and consists of a three-dimensional coordination polymer containing inorganic K2(COO)2(OH2) layers separated by the long organic bridging linker. The free compound H2L1 displays a one-dimensional hydrogen-bonded polymeric structure in the solid state with hydrogen bonding interactions between carboxylic acids and piperazine groups tightly linking molecules together. The two-dimensional polymeric complex [Zn3(L1)2(OH)2]·2DMF·0.5H2O 1 was prepared and analysed in the solid state to reveal tubular one-dimensional channels which, when activated by solvent exchange and evacuation, displayed selective affinity for CO2 over N2 and H2.

A new metal–organic framework having formula {[NH2(CH3)][Cu6(L)3(OAc)(H2O)4]·xsolvent} (H4L = 3,5-bis(isophthalic acid)-1H-1,2,4-triazole) (1) was synthesized, in which two types of polyhedral cages and one-dimensional channels coexist. The incorporation of the drug 5-fluorouracil (5-FU) into the desolvated 1 was around 24.9 wt% per gram of dehydrated 1. 5-FU is released in a controlled and progressive fashion with 98% of the drug released after 120 h at PBS. The result from this work provides a new avenue for MOF to be used as potential drug delivery.

A precursor solution to the metal-organic framework (MOF), Cd(1,4,7,10-tetrakis(4-carboxybenzyl)-1,4,7,10-tetraazacyclododecane), was aged in a surface-functionalised 250μm-diameter capillary, to generate a film containing the constituents of the bulk phase crystalline material. EDX analysis revealed a higher ratio of ligand elements (C, N and O) to Cd in the capillary coated phase compared to that achieved from bulk synthesis in a vial. Separation performance of the coated capillary for gas chromatography (GC) was compared to the performance of the original MOF crystals packed in tips for liquid elution chromatography (LEC) towards the separation of polycyclic aromatic hydrocarbons (PAHs) and small probe analytes with different properties. This study showed that different retention mechanisms were observed for the same set of analytes in gas and liquid phases. Independently of the trend of vapour pressure difference, the GC result showed less specific size selective retention, but with stronger retention towards larger PAHs. A linear solvation energy relationship correlation further revealed enhanced retention contributions (positive stationary phase descriptor values) by cavity formation/dispersion interactions and H-bonding with acid functionality of the probe analytes in both GC and LEC (though stronger in LEC), whilst H-bonding with basic functional groups slightly increased retention in GC; retention was strengthened by dipole-dipole/dipole-induced dipole interactions only in LEC.

The utility of the pyrazole-carboxylate mixed ligand system has been probed with the synthesis of five new coordination polymers, derived from bis-pyrazole ligand 4,4′-methylenebis(3,5-dimethyl-1H-pyrazole) H2L1, large semirigid dicarboxylate coligands, and the deliberately designed and synthesized ligand para-((3,5-dimethyl-1H-pyrazol-4-yl)methylene)benzoic acid H2L4. Complex poly-[Co(H2L1)(L2)(OH2)]·1/2H2O 1 features the coligand (S,S)-1,4,5,8-naphthalenetetracarboxylic diimide-N,N′-bis(2-propionate) L2, and comprises chiral two-dimensional sheets, associating via substantial π–π stacking interactions. Complexes 2 and 3 contain the coligand 1,4-bis((3-carboxyphenyl)methyl)piperazine L3. Complex poly-[Co(H2L1)2(L3)] 2 is a two-dimensional polymer containing octahedral Co(II) ions, whereas modifying the synthesis conditions gave complex poly-[Co2(HL1)2(L3)] 3, a three-dimensional α-Po structure containing pyrazolate-bridged dimers of tetrahedral Co(II) ions, displaying weak antiferromagnetic coupling. Mag...

A series of soluble metal ethylxanthate compounds was synthesised as precursors for metal sulfide thin films to be deposited using solution-based techniques. Initially, a range of air- and moisture-stable organic ethylxanthate (EtXn) salts were synthesised (cation=Me4N (1), Et4N (2), Pr4N (3), Ph4P (4), guanidinium (5), NMeH3 (6), NMe2H2 (7), NMe3H (8), NH4 (9)). Thermogravimetric analysis (TGA) was used to examine their decomposition profiles, which in turn informed the decision of which counter cation was best suited for inclusion in the metal xanthate compounds. Periodic NMR spectroscopy studies and single-crystal X-ray diffraction (SXRD) were used to determine the role protic ammonium counter cations play in the detrimental conversion of xanthates to dithiocarbamate anions. The organic salts 1 and 4 were used to form the metal ethylxanthate compounds (Me4N)[M(EtXn)x] (x=3 for M=Cd (10 Cd), Ni (10 Ni), Zn (10 Zn); x=4 for M=La (11 La)) and (Ph4P)[M(EtXn)3] (M=Cd (12 Cd), Ni (12 Ni), Zn (12 Zn)). Solubility studies on these compounds were performed using a range of solvents to demonstrate the viability of using these compounds for solution-based deposition methods for thin-film formation. TGA of the metal xanthate compounds was used to examine their thermal-decomposition profiles and the product resulting from thermolysis was found to be the respective metal sulfide. In addition, the coproducts of thermal decomposition were analysed by headspace gas-chromatography mass spectrometry (HS GC–MS) to probe the decomposition mechanism of the precursors. In situ variable-temperature synchrotron XRD studies on both bulk and thin-film samples of 10 Cd and 12 Cd were used to examine metal sulfide crystalline phase formation. Decomposition of both precursors was found to give CdS in a hexagonal phase, with the addition of CdCl2 found to aid in increasing the crystallite size during crystallisation.

An ultramicroporous metal–organic framework (MOF) is reported that contains 0.35 nm nanotube-like channels with an unprecedented concentration of vacant CuII coordination sites. The nonintersecting, narrow channels in [Cu3(cdm)4] (cdm = C(CN)2(CONH2)−) align in two perpendicular directions, structurally resembling copper-doped carbon nanotubes with CuII embedded in the walls of the channels. The combination of ultramicroporosity with the exposed CuII coordination sites gives size-based selectivity of CO2 over CH4, based on pore-size distribution and modeling. Neutron powder diffraction and molecular dynamics simulations show the close packing of single rows of guests within the tubular nanostructure and interaction of CO2 with the exposed metal sites.

Summary In 2009, QGC (a BG Group company) began developing coal-seam-gas (CSG) feedstock for its new liquefied-natural-gas (LNG) plant and required a subsurface model and field-development plan to underpin the investment case for the project. Fundamental to the modeling process was acquiring appropriate data to calibrate subsurface models and enhance confidence in their predictive quality. As part of an integrated reservoir-surveillance strategy, specific pressure- and temperature-monitoring wells were required. This paper describes the successful laboratory and field implementation of an innovative completion technique that converts suspended coreholes into reservoir- and aquifer-monitoring wells. The coreholes are re-entered, and vibrating wire piezometers attached to capillary coiled tubing are positioned and cemented in place alongside selected reservoir intervals. The well is then “plugged and abandoned,” and the lease is remediated to leave only a small surface footprint for the data logger and telemetry. The cement is effectively impermeable to fluid movement, but possesses sufficient permeability to transmit reservoir pore pressure to an adjacent piezometer. Recompletion of coreholes provides a cost-effective means of acquiring valuable downhole data while eliminating the need to drill a well specifically for monitoring in the same vicinity. Data gathered over the reservoir interval (the Walloon Coal Measures) can inform and help resolve reservoir properties on a regional scale, enhance understanding of the contribution to flow, and provide data points to pressure match a reservoir model. Data gathered over the aquifers within Springbok sandstone and Gubbermunda sandstone enable estimates of any CSG-production effects on groundwater.

Examination of the crystal structures of (Me4N)(dcnm) (1), (Me4N)(dcnom) (2), and (Me4N)(nbdm) (3) [dcnm = dicyanonitrosomethanide, dcnom = dicyanonitromethanide, nbdm = nitroso-N,N-bis(dicyanometh...

Two isostructural series of compounds NH4[Ln(cdm)4(H2O)4]·18c6·3H2O (1Ln) and [K(18c6)(H2O)2][Ln(cdm)4(H2O)4]·H2O (2Ln) have been synthesised and structurally characterised (Ln = Gd, Dy, Er, cdm = C(CN)2(CONH2)−). These two classes of compounds are shown to be essentially isostructural to each other despite the change in counter-cation (ammonium vs. potassium) and the ensuing changes in coordination and hydrogen-bonding of water molecules in the structure. Structural data for 1Dy and 2Dy have been obtained using single crystal Laue neutron diffraction, allowing the precise location of all hydrogen atoms to be determined using fully anisotropic models. Both 1 and 2 contain the anionic complex [Ln(cdm)4(H2O)4]− in which the 8-coordinate lanthanoid is coordinated by a ring of four O-bound cdm ligands supported by inter-ligand N–H⋯O hydrogen bonds. The structures pack with complicated hydrogen-bonding networks in which both coordinated and non-coordinated water molecules are hydrogen-bond donors and all of the nitrile groups of the cdm ligands are hydrogen-bond acceptors. The change in cation between ammonium and potassium affects two water molecule sites which are both coordinated in 2Ln but not in 1Ln; in 1Ln one of these water molecules forms a hydrogen bond with NH4+ whilst the other has neither a coordination interaction nor a hydrogen bond to its oxygen atom.

In a study of multifunctional ('hybrid') molecular materials, with one function being spin-crossover and the second being reversible redox behaviour, we describe ferrocene-appended ligands and their d(6) and d(7) complexes trans-[Fe(II)(FTP)2(NCS)2] (1), [Co(II)(FTTP)2](ClO4)2·2(MeCN) (2) and [Fe(II)(FTTP)2](ClO4)2·Et2O (3) (where FTP = 4-(2-pyridyl)-1H-1,2,3-triazol-1-ylferrocene and FTTP = 4'-ferrocenyl-2,2':6',2''-terpyridine). The structures, magnetism and solution electrochemistry are described. Complex 1 remains high-spin, 2 displays gradual, incomplete spin crossover and 3 remains low-spin between 350-2 K. The electrochemical results show that one-electron oxidations at the ferrocene group, located external to the coordination site, occur at more positive potentials than the 'inner' M(II/III) couple in 1 and 2, but not in 3, and this has implications for retaining and influencing spin transitions at the M(II) centres, in future.

The initial pH in the preparation of STA-16(Co) was found to have a great impact on the assembly of the MOF and the resulting porosity. The formation of a non-porous Co(II)-phosphonate pillared layer-structure was observed after changing the initial pH from 6.2 to 7.2 with distinct differences in the coordination environment of the cobalt centres.

Two new bis-(cyanobenzyl)piperazine ligands have been prepared, and have been used to prepare five Ag(I) coordination polymers which have been structurally characterised. Ligand N,N′-bis((4-cyanophenyl)methyl)piperazine L1 gave two structurally related two-dimensional coordination polymers poly-[Ag2(L1)(CF3SO3)2] 1 and poly-[Ag2(L1)(CF3SO3)2(C3H6O)1.5] 2 when reacted with silver trifluoromethanesulfonate in tetrahydrofuran and acetone, respectively. Compounds 1 and 2 display similar ligand geometries but form different extended networks, as a result of the inclusion of coordinating solvent molecules and the resulting influence on the flexible metal geometry. Reaction of N,N′-bis((3-cyanophenyl)methyl)piperazine L2 with silver ions gave rise to three new structurally characterised species. Complex poly-[Ag2(L2)(C3H6O)2]2(PF6) 3 forms a one-dimensional chain structurally related to 1. Complex poly-[Ag2(L2)(C3H8O)2(CF3SO3)2] 4 formed under similar conditions to 3, except with the inclusion of a coordinating anion which links equivalent chains to those found in 3 into a two-dimensional sheet. Finally, complex poly-[AgL2]CF3SO35 was formed simply by altering the reaction stoichiometry, producing a three-dimensional PtS network containing linear, acentric anion channels. Analysis of the structures reveals that the ligand geometries are largely consistent, leading to the extended structures being more influenced by the nature of the anions and solvent molecules.

A novel porous metal–organic framework, {[Zn2(L)·H2O]·3H2O·3DMAc·NH2(CH3)2}n (Zn(II)–MOF), was synthesized under solvothermal conditions using a flexible multicarboxylic acid (H5L = 3,5-bis(1-methoxy-3,5-benzene dicarboxylic acid)benzoic acid). Zn(II)–MOF contains 1D nanotubular channels of 13.8 A × 16.4 A and exhibits a rare 5-connected vbk net with a Schlafli symbol of {45.65} topology. Notably, Zn(II)–MOF can adsorb toluidine blue fast and effectively, and trap lanthanide ions such as Eu3+ and Tb3+ to sensitize their emissions in the solid state through a Ln3+-exchanged approach. Furthermore, we successfully obtained white light emitting materials.

Two divergent ligands 1,4,7,10-tetrakis-(4-cyanobenzyl)-1,4,7,10-tetraazacyclododecane L1 and 1,4,7,10-tetrakis-(4-carboxybenzyl)-1,4,7,10-tetraazacyclododecane dihydrochloride dihydrate H6L2·2Cl·2H2O have been prepared and structurally characterised, and the solid-state structures of four new metal complexes have been elucidated. Ligand L1 was found to form a dimeric complex of the form [Ag2(L1)2]·2ClO4 when reacted with silver perchlorate, in which a macrocycle-bound Ag(I) ion is coordinated by the nitrile group of an adjacent ligand, forming a tightly-bound pair of Ag(I) ions supported by intramolecular π–π interactions. Compound H6L2·2Cl·2H2O was prepared by a solvothermal recrystallization following hydrolysis of the ester precursor, and forms a densely packed three-dimensional structure containing numerous hydrogen bonding interactions. Complexes [Ni(H4L2)Cl]2·[NiCl4]·2EtOH 2 and [Co(H4L2)Cl]2·[CoCl4]·2EtOH 3 were characterised as isostructural discrete macrocycle-bound Ni(II) and Co(II) species where the formation of rare hydrogen-bonded carboxylic acid tetramers gives rise to a series of 2-dimensional sheets, containing checkerboard-type cavities encapsulating alternating tetrachloridometallate anions and regions containing disordered solvent molecules. Complex poly-{[Cu2Cl(H2L1)(HOEt)]2·[CuCl4]·5H2O} 4 consists of a series of two-dimensional sheets formed from a macrocycle-bound CuCl species linked by copper paddlewheel clusters and hydrogen-bonded carboxylic acid dimers. Charge balance is again achieved by tetrachloridometallate anions, and the sheets undergo parallel 2D → 2D interpenetration. The influence of the flexible geometry and donor ability of the methylene-linked pendant arms is clearly visible when comparing discrete complex 1 with hydrogen-bonded networks 2 and 3 and polymeric species 4. The presence of tetrachloridometallate counterions resulting from the presence of excess chloride ions in the reaction mixtures also provides powerful structure-directing effects in complexes 2, 3 and 4.