Search

Seed coatings improve germination and offer higher crop yields through a blend of active ingredients (such as insecticides and fungicides), polymers, waxes, fillers, and pigments. To reach their full potential, fundamental formulation challenges bridging structure and function need to be addressed. In some instances, during industrial-volume packing and transportation, coated seeds do not flow well through elevators, conveyers, and applicators, which may reduce yield and add cost. In this work, we illustrate a combinatorial chemical imaging approach to study seed coatings at the microscale to link chemical and physical properties responsible for low seed flowability. The local chemical composition was examined using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and at comparable length scales, the local adhesive properties were examined using atomic force microscopy (AFM) force volume mapping. The link between the chemical and the adhesive properties was established by non-negative matrix factorization (NMF). The correlative multimodal imaging approach developed here utilizing AFM force volume mapping, ToF-SIMS chemical mapping, and data analytics offers a path for linking function with localized chemistry when investigating multicomponent soft material systems.

Although the use of ball milling to induce reactions between solids (mechanochemical synthesis) can provide lower-waste routes to chemical products by avoiding solvent during the reaction, there are further potential advantages in using one-pot multistep syntheses to avoid the use of bulk solvents for the purification of intermediates. We report here two-step syntheses involving formation of salen-type ligands from diamines and hydroxyaldehydes followed directly by reactions with metal salts to provide the corresponding metal complexes. Five salen-type ligands 2,2′-[1,2-ethanediylbis[(E)-nitrilomethylidyne]]bis-phenol, ‘salenH2’, 1; 2,2′-[(±)-1,2-cyclohexanediylbis-[(E)-nitrilomethylidyne]]bis-phenol, 2; 2,2′-[1,2-phenylenebis(nitrilomethylidyne)]-bis-phenol, ‘salphenH2’ 3; 2-[[(2-aminophenyl)imino]methyl]-phenol, 4; 2,2′-[(±)-1,2-cyclohexanediylbis[(E)-nitrilomethylidyne]]-bis[4,6-bis(1,1-dimethylethyl)]-phenol, ‘Jacobsen ligand’, 5) were found to form readily in a shaker-type ball mill at 0.5 to 3 g scale from their corresponding diamine and aldehyde precursors. Although in some cases both starting materials were liquids, ball milling was still necessary to drive those reactions to completion because precipitation of the product and or intermediates rapidly gave in thick pastes which could not be stirred conventionally. The only ligand which required the addition of solvent was the Jacobsen ligand 5 which required 1.75 mol equivalents of methanol to go to completion. Ligands 1–5 were thus obtained directly in 30–60 minutes in their hydrated forms, due to the presence of water by-product, as free-flowing yellow powders which could be dried by heating to give analytically pure products. The one-armed salphen ligand 4 could also be obtained selectively by changing the reaction stoichiometry to 1 : 1. SalenH21 was explored for the one-pot two-step synthesis of metal complexes. In particular, after in situ formation of the ligand by ball milling, metal salts (ZnO, Ni(OAc)2·4H2O or Cu(OAc)2·H2O) were added directly to the jar and milling continued for a further 30 minutes. Small amounts of methanol (0.4–1.1 mol equivalents) were needed for these reactions to run to completion. The corresponding metal complexes [M(salen)] (M = Zn, 6; Ni, 7; or Cu, 8) were thus obtained quantitatively after 30 minutes in hydrated form, and could be heated briefly to give analytically pure dehydrated products. The all-at-once ‘tandem’ synthesis of [Zn(salen)] 6 was also explored by milling ZnO, ethylene diamine and salicylaldehyde together in the appropriate mole ratio for 60 minutes. This approach also gave the target complex selectively with no solvent needing to be added. Overall, these syntheses were found to be highly efficient in terms of time and the in avoidance of bulk solvent both during the reaction and for the isolation of intermediates. The work demonstrates the applicability of mechanochemical synthesis to one-pot multi-step strategies.

The aim of this article is to put forward the novel concept of porous liquids, or, more precisely, liquids with permanent microporosity. In contrast to the small, transient cavities that exist between the molecules of any liquid (here called "extrinsic" porosity), we suggest that a truly microporous liquid could exist if it had empty pores within the molecules of the liquid ("intrinsic" porosity). By using rigid host molecules with restricted access windows, any unwanted occupation of the pores could be prevented (i.e., the pores could be kept empty and available so that the liquid would be genuinely microporous). The liquid could have permanent, well-defined, empty pores capable of molecular recognition when exposed to other species (e.g., gases etc.). We stress that these phases are not the same as simple solutions of host species, in which any pores would normally be occupied by solvent molecules. In microporous liquids, any solvent molecules, if present, would be deliberately sterically excluded from the host cavities, to leave them readily accessible. Microporous liquids would be of considerable fundamental interest. They could combine properties of microporous solids, such as size- and shape-selective sorption and so forth, with the rapid mass transfer, fluidity and fast kinetics of liquids. Some synthetic approaches to these materials are discussed in this article. Also, whilst the overall concept of microporous liquids is new, literature is described which suggests that some examples have arguably already been reported, even if they have not previously been recognised and characterised in such terms.

Porous solids such as zeolites and metal-organic frameworks are useful in molecular separation and in catalysis, but their solid nature can impose limitations. For example, liquid solvents, rather than porous solids, are the most mature technology for post-combustion capture of carbon dioxide because liquid circulation systems are more easily retrofitted to existing plants. Solid porous adsorbents offer major benefits, such as lower energy penalties in adsorption-desorption cycles, but they are difficult to implement in conventional flow processes. Materials that combine the properties of fluidity and permanent porosity could therefore offer technological advantages, but permanent porosity is not associated with conventional liquids. Here we report free-flowing liquids whose bulk properties are determined by their permanent porosity. To achieve this, we designed cage molecules that provide a well-defined pore space and that are highly soluble in solvents whose molecules are too large to enter the pores. The concentration of unoccupied cages can thus be around 500 times greater than in other molecular solutions that contain cavities, resulting in a marked change in bulk properties, such as an eightfold increase in the solubility of methane gas. Our results provide the basis for development of a new class of functional porous materials for chemical processes, and we present a one-step, multigram scale-up route for highly soluble 'scrambled' porous cages prepared from a mixture of commercially available reagents. The unifying design principle for these materials is the avoidance of functional groups that can penetrate into the molecular cage cavities. Fil: Giri, Nicola. The Queens University of Belfast; Irlanda Fil: del Popolo, Mario Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. The Queens University of Belfast; Irlanda. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Melaugh, Gavin. The Queens University of Belfast; Irlanda Fil: Greenaway, Rebecca L.. University of Liverpool; Reino Unido Fil: Rätzke, Klaus. Technische Fakultät der Universität Kiel; Alemania Fil: Koschine, Tönjes. Technische Fakultät der Universität Kiel; Alemania Fil: Pison, Laure. Universite Blaise Pascal; Francia. Centre National de la Recherche Scientifique; Francia Fil: Gomes, Margarida F. Costa. Universite Blaise Pascal; Francia. Centre National de la Recherche Scientifique; Francia Fil: Cooper, Andrew I.. University of Liverpool; Reino Unido Fil: James, Stuart L.. The Queens University of Belfast; Irlanda

Grinding solid reagents under solvent-free or low-solvent conditions (mechanochemistry) is emerging as a general synthetic technique which is an alternative to conventional solvent-intensive methods. However, it is essential to find ways to scale-up this type of synthesis if its promise of cleaner manufacturing is to be realised. Here, we demonstrate the use of twin screw and single screw extruders for the continuous synthesis of various metal complexes, including Ni(salen), Ni(NCS)(2)(PPh3)(2) as well as the commercially important metal organic frameworks (MOFs) Cu-3(BTC)(2) (HKUST-1), Zn(2-methylimidazolate)(2) (ZIF-8, MAF-4) and Al(fumarate)(OH). Notably, Al(fumarate)(OH) has not previously been synthesised mechanochemically. Quantitative conversions occur to give products at kg h(-1) rates which, after activation, exhibit surface areas and pore volumes equivalent to those of materials produced by conventional solvent-based methods. Some reactions can be performed either under completely solvent-free conditions whereas others require the addition of small amounts of solvent (typically 3-4 mol equivalents). Continuous neat melt phase synthesis is also successfully demonstrated by both twin screw and single screw extrusion for ZIF-8. The latter technique provided ZIF-8 at 4 kg h(-1). The space time yields (STYs) for these methods of up to 144 x 10(3) kg per m(3) per day are orders of magnitude greater than STYs for other methods of making MOFs. Extrusion methods clearly enable scaling of mechanochemical and melt phase synthesis under solvent-free or low-solvent conditions, and may also be applied in synthesis more generally.

Disguising a metal complex as a micelle by using amphiphilic phosphine ligands enables it to switch between a coordination polymer and a discrete cage in response to solvent polarity or pH; this medium-dependent behaviour of the complex is rational because it parallels that of true micelles.

Instead of highly symmetrical T-symmetry cages common in self-assembly, the p-NMe(2)-substituted triphosphine CH(3)C{CH(2)P(4-C(6)H(4)NMe(2))(3) gives open, polar C(3) symmetry cages [Ag(6)(triphos)(4)X(3)](3+) which lack one of the expected face-capping anions; despite its subtlety this difference occurs selectively in solution and two examples have been crystallographically characterised.

A metal complex with a micelle-like, core–shell structure adopts higher nuclearity in water than in organic solvents, thereby imitating also the growth of a micelle, but through covalent rather than non-covalent aggregation.

Persilylation of nucleoside hydroxyls was effected in quantitative yields under solvent-free conditions using a ball mill. In addition, one-pot persilylation and acylation of cytidine was performed as an exemplar reaction demonstrating the utility of solvent-free approaches to nucleoside chemistry.

Metal enolates and functionalized allylzinc reagents react with optically active alpha-amidoalkylphenyl sulfones to give N-carbamoylamino derivatives with variable levels of anti diastereoselectivity. Zinc enolates provide comparable results with respect to lithium enolates in terms of diastereoselectivity but afford beta-amino ester derivatives in lower yield. The synthetic utility of the obtained chiral N-carbamoylamino esters is demonstrated by the first enantioselective synthesis of (-)-1-aminopyrrolizidine a central intermediate for the preparation of various biologically active substances.

Rigid organic iminospherand cages are rendered meltable by multiple alkylation; below their melting points they can take the form of permanently porous crystals, crystals unstable to desolvation or non-porous glassy solids depending on chain length and branching; melting points as low as 50 °C are observed and a fully Newtonian liquid phase is obtained above 80 °C. Thin glassy fibres can be drawn out from a molten phase.

Persilylation of nucleoside hydroxyls was effected in quantitative yields under solvent-free conditions using a ball mill. In addition, one-pot persilylation and acylation of cytidine was performed as an exemplar reaction demonstrating the utility of solvent-free approaches to nucleoside chemistry.