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The radical reactions of dimethylsulfoxide (DMSO) and tetrahydrothiophene-1-oxide (THTO) with reactive oxygen species (ROS) in the presence of a nitroxide radical scavenger have been evaluated both synthetically and in analytical practice. Fenton-mediated generation of oxygen-centred radicals produced several unusual products that reflect the fragmentation and ring-opening radical mechanisms of DMSO and THTO respectively. Addition of pollution-derived ROS to DMSO/THTO nitroxide solutions produced LC-MS detectable amounts of the same products isolated from the larger-scaled Fenton reactions. For air pollution analysis, these results highlight the complexity surrounding DMSO reactivity and fragmentation, and indicate that THTO produces simpler outcomes that should facilitate analysis of the processes involved.

A range of morphologically distinct metallosupramolecular Cu(II) and Pd(II) complexes has been constructed, based on the tritopic ligand 1,1',1″-(benzene-1,3,5-triyl)tris(4,4-dimethylpentane-1,3-dione) (H). By control of the reaction conditions, it is possible to generate distinct coordination assemblies possessing either macrocyclic or polymeric structures and more importantly distinct activity in catalysis of the Suzuki-Miyaura cross-coupling.

The synthesis and crystal structures of a series of Ln(III) (Ln = Gd, Nd, Yb as well as Y) complexes of a bis-β-diketone ligand incorporating a 1,3-substituted phenyl ring between its two β-diketone domains (1,1′-(1,3-phenylene)bis(4,4-dimethylpentane-1,3-dione), H2L1) is reported. The crystal structures show the complexes are seven coordinate in the solid state with the general formula [Ln2L13(solvent)2]. The photophysical properties of the complexes were explored in both solution and the solid state, which show an increase in coordination number in solution.

Nature builds simple molecules into highly complex assemblies, which are involved in all fundamental processes of life. Some of the most intriguing biological assemblies are those that can be precisely reconfigured to achieve different functions using the same building blocks. Understanding the reconfiguration of synthetic self-assembled systems will allow us to better understand the complexity of proteins and design useful artificial chemical systems. Here we have prepared a relatively simple system in which two distinct self-assembled structures, a [Fe2L3]4+ helicate and a [Fe4L6]8+ cage that are formed from the same precursors, coexist at equilibrium. We have measured the rates of interconversion of these two species and propose a mechanism for the transformation.

Organic luminogens have been widely used in optoelectronic devices, bioimaging, and sensing. Conventionally, the synthesis of organic luminogens requires sophisticated, multistep design, reaction, and isolation procedures. Herein, the products of the melt-phase condensation of benzoguanamine (BG; 2,4-diamino-6-phenyl-1,3,5-triazine) at 370-410 °C display interesting reaction-condition-dependent luminescence properties, including photoluminescence (PL) at a variety of wavelengths in the visible spectrum and quantum efficiencies (PLQE) of up to 58% in the powder form. With a simple and straightforward solvent washing procedure, the prominent blue luminescent component BG dimer was obtained in gram scale with >93% purity (96.5% purity after fractional sublimation). The BG dimer exhibited distinct aggregation-induced emission (AIE) properties. PL measurements indicate that the electronically excited state of the BG dimer undergoes efficient intramolecular nonradiative deactivation in room-temperature solution, leading to a significantly reduced PLQE (

Selective oxidation of alcohols is an essential reaction for fine chemical production. Here, the photocatalytic oxidation of benzyl alcohol by zinc oxide (ZnO) nanocrystals was investigated to clarify the mechanism of selective oxidation with this process. Reactivity when in contact with three distinct ZnO nanocrystal shapes: nanocones, nanorods and nanoplates, was studied in order to compare crystal facet-specific effects in the reaction system. The same non-hydrothermal and non-hydrolytic aminolysis method was used to synthesise all three nanocrystal shapes. The ZnO catalysts were characterized using by a range of techniques to establish the key properties of the prominent ZnO crystal facets exposed to the reaction medium. The ZnO nanocrystals photocatalysed the benzyl alcohol oxidation reaction when irradiated by a 370 – 375 nm LED output and each ZnO crystal morphology exhibited different reaction kinetics for the oxidation reaction. ZnO nanocones displayed the highest benzyl alcohol conversion rate while nanorods gave the lowest. This established a facet-dependent kinetic activity for the benzyl alcohol reaction of (10 1 ¯ 1) > (0001) > (10 1 ¯ 0). Experimental and density functional theory computation results confirm that the {10 1 ¯ 1} facet is a surface that exposes undercoordinated O atoms to the reaction medium, which explains why the reactant benzyl alcohol adsorption on this facet is the highest. Light irradiation can excite valence band electrons to the conduction band, which are then captured by O2 molecules to yield superoxide (O2•–). In a non-aqueous solvent, the photogenerated holes oxidise benzyl alcohol to form a radical species, which reacts with O2•– to yield benzaldehyde. This results in 100% product selectivity for benzaldehyde, rather than the carboxylic acid derivative.

The encapsulation of metal complexes within halogen-bonded networks may lead to modulation of their properties in the solid state without the need to chemically incorporate donor or acceptor moieties on the metal complex itself. Here, we investigate the effect of anionic halogen-bonded structure formation on the organization of arene-rich bis(4′-phenyl-2,2′:6′,2″-terpyridine)nickel(II) cations, varying both the topicity and the geometry of the halogen bond donor in a heteromeric three-component system. The X-ray structures of four cocrystals (1-4), [Ni(terpy-ph)][(1,2-DITFB)(I)] (1), [Ni(terpy-ph)][(1,3-DITFB)(I)] (2), [Ni(terpy-ph)][(1,4 DITFB)(I)](I)·9HO (3), and [Ni(terpy-ph)][(1,3,5-TITFB)(HO)(I)]·2HO (4), as well as the iodide salt of the parent complex [Ni(terpy-ph)]I·4HO are reported along with characterization to assess bulk sample and phase purity. Within assemblies of complex cations, we observe the ubiquitous aryl embrace motif often seen in the crystal packing of such terpyridine complexes; however, these assemblies are separated from one another by a variety of halogen-bonded structures, including discrete supramolecular complexes, 1D chains, pseudo-2D sheets, and unusual racemic double helices. The results herein demonstrate how typical crystal packing motifs of metal terpy-ph complexes can be altered and disrupted through their incorporation into halogen-bonded heteromeric three-component systems.

This study has evaluated the use of the P450 metalloenzymes CYP176A1, CYP101A1 and CYP102A1, together with engineered protein variants of CYP101A1 and CYP102A1, to alter the regioselectivity of 1,8- and 1,4-cineole hydroxylation. CYP176A1 was less selective for 1,4-cineole oxidation when compared to its preferred substrate, 1,8-cineole. The CYP102A1 variants significantly improved the activity over the WT enzyme for oxidation of 1,4- and 1,8-cineole. The CYP102A1 R47L/Y51F/A74G/F87V/L188Q mutant generated predominantly (1S)-6α-hydroxy-1,8-cineole (78% e.e.) from 1,8-cineole. Oxidation of 1,4-cineole by the CYP102A1 R47L/Y51F/F87A/I401P variant generated the 3α product in >90% yield. WT CYP101A1 formed a mixture metabolites with 1,8-cineole and very little product was generated with 1,4-cineole. In contrast the F87W/Y96F/L244A/V247L and F87W/Y96F/L244A variants of CYP101A1 favoured formation of 5α-hydroxy-1,8-cineole (>88%, 1S 86% e.e.) while the F87V/Y96F/L244A variant generated (1S)-6α-hydroxy-1,8-cineole in excess (90% regioselective, >99% e.e.). The CYP101A1 F87W/Y96F/L244A/V247L and F87W/Y96F/L244A mutants improved the oxidation of 1,4-cineole generating an excess of the 3α metabolite (1S > 99% e.e. with the latter). The CYP101A1 F87L/Y96F variant also improved the oxidation of this substrate but shifted the site of oxidation to the isopropyl group, (8-hydroxy-1,4-cineole). When this 8-hydroxy metabolite was generated in significant quantities desaturation of C8C9 to the corresponding alkene was also detected.

A bis-β-diketone ligand incorporating a 3,5-substituted pyridine ring between its two β-diketone domains (1,1′-(pyridine-3,5-diyl)bis(4,4-dimethylpentane-1,3-dione), H2L1) and its interaction with three divalent cations (Cu2+, Zn2+ and Pd2+) is reported. Charge neutral dinuclear metallocycles of type [M2L12] were obtained in each case and their X-ray structures determined. [Pd2L12] incorporates two square-planar O4-coordinated metal centres. The zinc(II) and copper(II) complexes contain five-coordinate O4N1-metal centres in which the pyridyl nitrogen from adjacent [M2L12] metallocycles coordinates apically forming two-dimensional coordination polymers of type {[Zn2L12]n(dmf)n} and {[Cu2L12]n(dmf)n}. Desolvation of the coordination polymers led to loss of crystallinity.

A range of morphologically distinct metallosupramolecular Cu(II) and Pd(II) complexes has been constructed, based on the tritopic ligand 1,1',1″-(benzene-1,3,5-triyl)tris(4,4-dimethylpentane-1,3-dione) (H

Herein, we pioneer a wavelength‐gated synthesis route to phenalene diimides. Consecutive Diels–Alder reactions of methylisophthalaldehydes and maleimides afford hexahydro‐phenalene‐1,6‐diol diimides via 5‐formyl‐hexahydro‐benzo[f]isoindoles as the intermediate. Both photoreactions are efficient (82–99 % yield) and exhibit excellent diastereoselectivity (62–98 % d.r.). The wavelength‐gated nature of the stepwise reaction enables the modular construction of phenalene diimide scaffolds by choice of substrate and wavelength. Importantly, this synthetic methodology opens a facile avenue to a new class of persistent phenalenyl diimide neutral radicals, constituting a versatile route to spin‐active molecules., Methylisophthalaldehydes form two highly reactive ortho‐quinodimethane dienophiles in a step‐wise and wavelength gated fashion. Trapping with maleimides proceeds with high stereoselectivity under the formation of phenalene diimide scaffolds. Subsequent elimination and oxidation affords a new class of persistent phenalenyl diimide neutral radicals.

A re-refinement of the published but chemically implausible, crystal structure of "Form III" of 4-bromophenyl 4-bromobenzoate shows that it is not a polymorph, but instead a co-crystal containing both 4-bromophenyl 4-bromobenzoate (≈25%) and likely 4-bromophenyl 4-nitrobenzoate (≈75%).

Classical β-diketone ligands have been well demonstrated to exhibit a rich metal coordination chemistry yielding metal complexes displaying a variety of properties. The investigation of polydentate ligand derivatives containing more than one β-diketone domain, and in many instances also incorporating additional donor sites, have been demonstrated to react with a range of metal ion types to yield a wide range of metallo-supramolecular topologies. These include metallocyclic platforms, triangles, squares, cubes, helicates, tetrahedrons as well as other intricate structures that include a universal 3-ravel. In this report we cover the published literature in the area from 2008 with emphasis on the synthetic strategies employed as well as on the diverse structures of the metallo-supramolecular products obtained.

Elastically flexible crystals form an emerging class of materials that exhibit a range of notable properties. The mechanism of thermal expansion in flexible crystals of bis(acetylacetonato)copper(II) is compared with the mechanism of molecular motion induced by bending and it is demonstrated that the two mechanisms are distinct. Upon bending, individual molecules within the crystal structure reversibly rotate, while thermal expansion results predominantly in an increase in intermolecular separations with only minor changes to molecular orientation through rotation.

A unique pressure-induced Cu-N bond breaking/bond forming reaction is reported. The variation of pressure on a single crystal of a one-dimensional copper(II)-containing coordination polymer (Cu2L2(1-methylpiperazine)2]n, where H2L is 1,1'-(1,3-phenylene)-bis(4,4-dimethylpentane-1,3-dione)), was monitored using single crystal X-ray diffraction with the aid of a diamond anvilcell. At a very low elevated pressure (~0.05 GPa) a remarkable reversible phase change was observed. The phase change results in the depolymerization of the material through the cleavage and formation of axial Cu-N bonds as well as “ring flips” of individual axially coordinated 1-methylpiperazine ligands. Overall, thepressure-induced phase change is associated with a surprising (and non-intuitive) shift in structure – from a 1-dimensional coordination polymer to a discrete dinuclear complex.

Two new tetradentate tripodal ligands (L1 and L2) have been synthesized via Schiff base condensation of tris(2-aminoethyl)amine (tren) with 4-(4-pyridinyl)benzaldehyde or 4-(3-pyridinyl)benzaldehyde in ethanol. Four Cu(I) complexes [CuL1]PF6, [CuL1]I, [CuL2]PF6 and [CuL2]I (1–4) have been prepared and characterised by NMR, HR-MS, SEM-EDS, FT-IR, Raman and UV–Vis measurements. X-ray structures for 1 and 4 are presented. In both structures, the four-coordinate copper(I) centres are bound within the cavity defined by the tren backbone. In such Cu(I) complexes, steric considerations dictate that the three uncoordinated pyridine nitrogen donors will have their coordination vectors oriented in a mutually divergent manner suitable for coordination to three different metal centres and thus are preorganized to act as new tripodal metalloligands.

In this work, we report on the synthesis of a free-standing, macroscopic robust supramolecular membrane by introducing silver-nitrogen coordinate bonding into preorganized, supramolecular hydrogen-bonded cyanuric acid-melamine (CAM) crystals. With the assistance of ammonia, silver ions competitively replace two of the three hydrogen atoms from cyanuric acid resulting in the transformation from short CAM nanorods to long CAM-Ag nanofibers (length over 1000 μm), accompanied by tautomerization of cyanuric acid. The single crystal structure of the CAM-Ag nanofibers is solved in the space group P1, with the asymmetric unit containing eight silver atoms, four melamine and four cyanuric acid molecules, which generate 1D coordination polymer chains consisting of alternating melamine and dianionic cyanurate ligands linked via silver-nitrogen bonds. The presence of interchain hydrogen bonds results in the expansion of the supramolecular network into undulating 2D sheets, which then stack into a 3D network via a series of intersheet hydrogen bonds and π-π interactions. Significantly, the CAM-Ag nanofibers spontaneously assemble into a free-standing membrane, with lateral size up to square centimeters and thickness of 30 μm. The membrane shows high flexibility and mechanical strength, owing to the improved flexibility of the CAM-Ag nanofibers with bonded chain structure, and can be reversibly and repeatedly bent over 90 degrees. Remarkably, the CAM-Ag membrane demonstrates distinct optical transmittance being shortwave IR transmissive but impenetrable to UV and visible light.

The rational, deliberate design of supramolecular architectures is of great importance for the discovery of complex materials. A three-dimensional cubic halogen-bonded network has been prepared by combination of an octahedral metal-containing halogen bond acceptor and a linear ditopic donor. This material displays α-Po pcu topology and is seven-fold interpenetrated. This is the first neutral, metal-containing three-dimensional halogen-bonded network to be reported.

Studying multi-purpose applications of a specific material is a challenging topic in the organic electronics community. In this work, through molecular engineering and smart device structure design strategy, high performance in transistors and thin film display devices is simultaneously achieved by applying a simple new dye molecule, naphthalene flanked diketopyrrolopyrrole (DPPN), as the active layer material. Short alkyl chains (hexyl or octyl side groups for H-DPPN and O-DPPN, respectively) are adapted to improve the hole mobility in organic thin film transistors (OTFTs) and single crystal transistors (SCTs). Specifically, H-DPPN shows a similar hole mobility in either OTFTs or SCTs, while O-DPPN exhibits a dramatically enhanced mobility, reaching 0.125 cm2 V−1 s−1 in SCTs. Additionally, a smart organic light emitting diode (OLED) device is designed by using DPPN molecule as the dopant with a host matrix. The promising external quantum efficiencies of 4.0% and 2.3% are achieved for H-DPPN and O-DPPN fabricated OLEDs. Overall, in this work, it is reported that DPP-based small molecules can simultaneously function well in both transistors and thin film displays with high device performance through molecular and smart device engineering.

Correction for ‘Straightening out halogen bonds’ by Caitlin J. Setter et al., CrystEngComm, 2020, 22, 1687–1690, DOI: 10.1039/D0CE00176G.

Biopolymers are researched extensively for their applications in biomaterials science and drug delivery including structures and complexes of more than one polymer. Chemical characterization of complexes formed between chitosan (CHI) and alginate dialdehyde (ADA) biopolymers established that while electrostatic interactions dominate (as determined from X-ray photoelectron spectroscopy (XPS)) covalent cross-linking between these biopolymers also contribute to their stability (evidenced from immersion in salt solution). It was furthermore found that imine bond formation could not be directly detected by any of the techniques XPS, FTIR, (1)H NMR, or fluorescence. The layer-by-layer assemblies of the biopolymers formed on silica colloids, glass slides, and alginate hydrogel beads were evaluated using XPS, as well as zeta potential measurements for the silica colloids and changes to hydration properties for the hydrogels. It was found that the degree of oxidation of ADA affected the LbL assemblies in terms of a greater degree of CHI penetration observed when using the more conformationally flexible biopolymer ADA (higher degree of oxidation).

Metallo-supramolecular capsules and cages epitomise the elegant manner in which self-assembled functional materials can be designed from first principles. Not only are these materials inherently beautiful, they are useful, performing myriad functions within the spaces that they enclose. Metallo-supramolecular capsules and cages can be prepared to be charged or neutral, large or small, open or closed and often display interesting properties including notable spectrochemical, electrochemical and magnetic effects in their own right. Through encapsulation, metallo-supramolecular capsules and cages have been demonstrated to be useful agents for host–guest chemistry, binding a wide variety of guests such as anions, cations or neutral molecules (including gases) and have been shown to catalyse a number of reactions producing unusual products more efficiently. In this chapter, after briefly discussing the design of these materials and the process of encapsulation, we survey the functions performed by metallo-supramolecular capsules and cages including selective guest binding, separations of molecular mixtures, sequestration of greenhouse gases and their use as modulators of chemical reactivity.

The known Schiff base, 3-(2-aminophenylamino)-1-phenylbut-2-en-1-one (1), formed by 1:1 condensation of o-phenylenediamine and benzoylacetylacetone reacts at its free amine site with salicylaldehyde and 5-tert-butylsalicylaldehyde in the presence of Ni(II) and Cu(II) acetates, or with 5-tert-butylsalicylaldehyde in the presence of Zn(II) acetate, to generate 1:1 (M:L) diimine complexes (2) of the corresponding doubly deprotonated, unsymmetric, O2N 2-tetradentate ligands. In contrast, reaction of Zn(II) acetate with 1 and salicylaldehyde led to Schiff base exchange (with loss of benzoylacetylacetone) to yield symmetric [ZnL3] [where L3 is N,N′-o-phenylenebis(salicyliminato)]. Similarly, when Fe(II) chloride was substituted for metal acetate in the reaction of 1 with 5-tert-butyl- salicylaldehyde and the initial product crystallised in the presence of dabco (as base), a related Schiff base exchange reaction occurred along with aerial oxidation of the Fe(II) to produce the neutral dinuclear [Fe III(L4)2(μ-O)] species [where L4 is N,N′-o-phenylenebis(5-tert-butylsalicyliminato)] in which Fe(III) centres are linked by an oxo group to produce two 5-coordinate Fe(III) centres; pairs of these (oxo-bridged) dinuclear complex units are further linked via elongated intermolecular Fe-Ophenolic contacts (Fe-O, 2.44 A) to form an unusual tetranuclear supramolecular cluster. This complex was also synthesised directly by the in situ reaction of 5-tert-butyl-salicylaldehyde, o-phenylenediamine and Fe(II) chloride (2:1:1 mol ratio) in air. In an extension of these studies, the in situ reaction of the 1,3-aryl linked bis-β-diketone, 1,1-(1,3-phenylene)-bis-butane-1,3-dione), o-phenylenediamine, salicylaldehyde and Ni(II) acetate in a 1:2:2:2 ratio yielded [Ni2L5], the dinuclear analogue of the unsymmetric mononuclear Ni(II) complex 2, in which each nickel centre has a square planar environment. Reaction of the above 1,3-phenylene linked bis-β-diketone precursor with o-phenylenediamine in a 1:2 M ratio yields 1,3-bis(4-methyl-3H- benzo[b][1,4]diazepin-2-yl)benzene as its monohydrate (3·H2O) incorporating two 7-membered diaza heterocyclic rings; thus contrasting with the 'open' Schiff base structure observed for 1. X-ray structures of 1, 3·H2O, [NiL1]·py, [NiL1] ·EtOH, [NiL2], [CuL1]·py, [CuL 1]·0.5CHCl3, [(FeL4)2(μ-O) ]2·1.5THF·0.4EtOH·0.6H2O and [NiL5]·0.25EtOH·0.125py are reported.

The introduction of this paper was amended by the authors following feedback from the community.

The co-crystallisation behaviour of three symmetrical dipyridylacetylacetone ligands (1,3-di(2-pyridyl)-1,3-propanedione (o-bppdH), 1,3-di(3-pyridyl)-1,3-propanedione (m-bppdH), and 1,3-di(4-pyridyl)-1,3-propanedione (p-bppdH)), with the linear halogen-bond donor 1,4-diiodotetrafluorobenzene (1,4-DITFB) has been investigated. The reaction of these components under ambient conditions in a 1 : 1 stoichiometry produced four halogen-bonded assemblies ([o-bppdH·1,4-DITFB, [m-bppdH·1,4-DITFB], [2(m-bppdH)·1,4-DITFB], and [p-bppdH·1,4-DITFB]). The combination of multiple supramolecular interactions including halogen bonding, hydrogen bonding, and π-stacking produces a range of supramolecular architectures, including one-, two-, and three-dimensional motifs. The crystal structure of m-bppdH is also reported.