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The authors acknowledge funding from the Royal Society (University Research Fellowship URF\R1\180017 (CPJ) and associated Enhancement Award RGF\EA\181022 (CPJ and RHH)), and the EaSI-CAT Centre for Doctoral Training (RHH and NM). We report a cobalt-catalyzed Wagner-Meerwein rearrangement of gem-disubstituted allylarenes that generates fluoroalkane products with isolated yields up to 84%. Modification of the counteranion of the N-fluoropyridinium oxidant suggests the substrates undergo nucleophilic fluorination during the reaction. Subjecting the substrates to other known metal-mediated hydrofluorination procedures did not lead to observable 1,2-aryl migration. Thus, indicating the unique ability of these cobalt-catalyzed conditions to generate a sufficiently reactive electrophilic intermediate capable of promoting this Wagner-Meerwein rearrangement. Publisher PDF

Funding: The authors acknowledge the Universiti Teknologi MARA for funding under the UMP-IIUM-UiTM Sustainable Research Collaboration Grant [600–RMC/SRC/5/3(043/2020)]. A new isoxazole-based iodo-noium salt, C13 H13 INO5+ ·C2 F3 O2- , has been synthesized and structurally characterized. In the crystal, ions are linked by short I⋯O contacts to form a neutral tetra-ion aggregate. These combine with C-H⋯F and C-H⋯O inter-actions to form double-layered two-dimensional sheets in the (001) plane. Publisher PDF

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreement No. 897098 (AIE-RTP-PLED). T.W. acknowledges support from the Marie Skłodowska-Curie Individual Fellowship. The auhors thank the EPSRC (EP/R035164/1) for financial support. The S1 state and high-lying triplet excited states (ΔES1Tn) offer insight into clarifying the mechanism of efficiency roll-off of organic light-emitting diodes (OLEDs). However, experimental detection of the ΔES1Tn is challenging due to Kasha's rule. Here, two emitters, PhCz-O-DiKTa and PhCz-DiKTa , showing multi-resonant thermally activated delayed fluorescence (MR-TADF) are reported. By modulating the conjugation between the MR-TADF DiKTa emissive center and donor substituent, emission directly from the T2 state is for the first time observed in MR-TADF emitters. Single crystal and reduced density gradient analyses reveal the origin of the reduced observed concentration-quenching results from weak CH···π and slipped π···π stacking interactions, which suppress nonradiative transitions. Theoretical and photophysical investigations reveal that the ΔES1T2 difference influences the reverse intersystem crossing rate. The OLEDs employing PhCz-O-DiKTa and PhCz-DiKTa as emitters show maximum external quantum efficiencies (EQEmax) of over 20%, but very different efficiency roll-off behavior (54.5% vs 13.6% at 100 cd m−2). Thus, this design provides a possible solution to mitigating device efficiency roll-off by designing MR-TADF emitters with degenerate S1 and T2 states. Publisher PDF

Funding: J. M. H.-M. thanks the EPSRC Centre for Doctoral Training EaSI-CAT for a PhD studentship. A. J. B. W. thanks the Leverhulme Trust for a Research Fellowship (RF-2022-014) and the EPSRC Programme Grant “Boron: Beyond the Reagent” (EP/W007517/1) for support. A Rh-catalyzed [2+2+2] cycloaddition approach for the synthesis of BMIDA-functionalized arenes is reported. The developed method overcomes the long-standing reactivity problems associated with internal alkynes and allows access to highly functionalized borylated benzene scaffolds. The method is broadly functional group tolerant and generally high yielding. The utility of the products is demonstrated through elaboration of the BMIDA motif, and in the synthesis of fused heterocycles via intramolecular Chan–Lam etherification and amination. The dominance of sterically controlled reactivity is described. Publisher PDF

This research was funded by the European Research Council AdG grant number ADOR- 336 787073 and by the Faraday Institution (grant number FIRG018). The rapid growth in the field of metal-organic frameworks (MOFs) over recent years has highlighted their high potential in a variety of applications. For biological and environmental applications MOFs with low toxicity are vitally important to avoid any harmful effects. For this reason, Ca-based MOFs are highly desirable owing to their low cost and high biocompatibility. Useful Ca MOFs are still rare owing to the ionic character and large size of the Ca2+ ion tending to produce dense phases. Presented here is a novel Ca-based MOF containing 2,3-dihyrdoxyterephthalate (2,3-dhtp) linkers Ca(2,3-dhtp)(H2O) (SIMOF-4). The material undergoes a phase transformation on heating, which can be followed by variable temperature powder X-ray diffraction. The structure of the high temperature form was obtained using single-crystal X-ray diffraction. The electrochemical properties of SIMOF-4 were also investigated for use in a Na ion battery. Publisher PDF

Metal-catalyzed C–N cross-coupling generally forms C−N bonds by reductive elimination from metal complexes bearing covalent C- and N-ligands. We have identified a Cu-mediated C–N cross-coupling that uses a dative N-ligand in the bond-forming event, which, in contrast to conventional methods, generates reactive cationic products. Mechanistic studies suggest the process operates via transmetalation of an aryl organoboron to a CuII complex bearing neutral N-ligands, such as nitriles or N-heterocycles. Subsequent generation of a putative CuIII complex enables the oxidative C–N coupling to take place, delivering nitrilium intermediates and pyridinium products. The reaction is general for a range of N(sp) and N(sp2) precursors and can be applied to drug synthesis and late-stage N-arylation, and the limitations in the methodology are mechanistically evidenced.

We would like to thank the University of St Andrews, and the EPSRC Centre for Doctoral Training in Critical Resource Catalysis (CRITICAT) for financial support [Ph.D. studentship to SG; Grant code: EP/L016419/1], and the EPSRC for funding of JAF (EP/M003868/1). The use of Rh catalysts derived from a phospholane-phosphite ligand were found to be more productive than the classic rhodium/BINAP system in enantioselective conjugate additions. These catalysts enable the use of lower amounts of aryl boronic acid in an asymmetric arylation reaction that required an impractical excess of nucleophile. This catalyst was also found to enable the coupling of a poorly reactive Michael acceptor, N-CBz-2-3-dehydro-4-piperidone, or the coupling of poorly reactive 2-furyl boronic acids at ambient or near temperatures. Publisher PDF

The syntheses and structures of five mol­ecular salts of protonated 4,4,7,7-tetra­methyl-3a,5,6,7a-tetra­hydro­benzo­thia­zol-2-yl­amine (C11H19N2S+) with different deprotonated carb­oxy­lic acids (4-methyl­benzoic acid, 4-bromo­benzoic acid, 3,5-di­nitro­benzoic acid, fumaric acid and succinic acid) are reported·In every case, the cation protonation occurs at the N atom of the thia­zole ring and the six-membered ring adopts a half-chair conformation (in some cases, the deviating methyl­ene groups are disordered over two sets of sites). The C—N bond lengths of the nominal –NH+=C—NH2 fragment of the cation are indistinguishable, indicating a significant contribution of the –NH—C=N+H2 resonance form to the structure., The syntheses and structures of five mol­ecular salts of protonated 4,4,7,7-tetra­methyl-3a,5,6,7a-tetra­hydro­benzo­thia­zol-2-yl­amine (C11H19N2S+) with different deprotonated carb­oxy­lic acids (4-methyl­benzoic acid, 4-bromo­benzoic acid, 3,5-di­nitro­benzoic acid, fumaric acid and succinic acid) are reported, namely 2-amino-4,4,7,7-tetra­methyl-4,5,6,7-tetra­hydro-1,3-benzo­thia­zol-3-ium 4-methyl­benzoate, C11H19N2S+·C8H7O2 −, (I), 2-amino-4,4,7,7-tetra­methyl-4,5,6,7-tetra­hydro-1,3-benzo­thia­zol-3-ium 4-bromo­benzoate, C11H19N2S+·C7H4BrO2 −, (II), 2-amino-4,4,7,7-tetra­methyl-4,5,6,7-tetra­hydro-1,3-benzo­thia­zol-3-ium 3,5-di­nitro­benzoate, C11H19N2S+·C7H3N2O6 −, (III), bis­(2-amino-4,4,7,7-tetra­methyl-4,5,6,7-tetra­hydro-1,3-benzo­thia­zol-3-ium) fumarate, 2C11H19N2S+·C4H2O4 2−,(IV), and the 1:1 co-crystal of bis­(2-amino-4,4,7,7-tetra­methyl-4,5,6,7-tetra­hydro-1,3-benzo­thia­zol-3-ium) succinate and 2-amino-4,4,7,7-tetra­methyl-4,5,6,7-tetra­hydro-1,3-benzo­thia­zol-3-ium hydrogen succin­ate 4,4,7,7-tetra­methyl-3a,5,6,7a-tetra­hydro­benzo­thia­zol-2-yl­amine, 1.5C11H19N2S+·0.5C4H4O4 2−·0.5C4H5O4 −. 0.5C11H18N2S, (V). In every case, the cation protonation occurs at the N atom of the thia­zole ring and the six-membered ring adopts a half-chair conformation (in some cases, the deviating methyl­ene groups are disordered over two sets of sites). The C—N bond lengths of the nominal –NH+=C—NH2 fragment of the cation are indistinguishable, indicating a significant contribution of the –NH—C=N+H2 resonance form to the structure. The packing for (I)–(V) features a robust local R 2 2(8) loop motif in which the cation forms two near-linear N—H⋯O hydrogen bonds from the N+—H group and syn H atom of the amine group to the carboxyl­ate group of an adjacent anion [(V) shows disorder of one of these bonds over N—H⋯O and N⋯H—O contributors but the same R 2 2(8) loop results for both disorder components]. The anti H atom of the –NH2 group also forms an N—H⋯O hydrogen bond, which results in [001] chains in (I) and (II), isolated centrosymmetric tetra­mers in (III) and [100] chains in (IV) and (V). Hirshfeld fingerprint plots and contact percentages for the different types of contacts of the cations are discussed.

Synthetic self‐assembly is a powerful technique for the bottom‐up construction of discrete and well‐defined polyhedral nanostructures resembling the spherical shape of large biological systems. In recent years, numerous Archimedean‐shaped coordination cages have been reported based on the assembly of bent monodentate organic ligands containing two or more distal pyridyl rings and square‐planar PdII ions. The formation of photoactive PdII metallamacrocycles and cages, however, remain rare. Here we report the first examples of emissive and homochiral supramolecular cages of the form [Ir8Pd4]16+. These cages provide a suitably sized cavity to host large guest molecules. Importantly, encapsulation and energy transfer have been observed between the blue‐emitting NBu4[Ir(dFppy)2(CN)2] guest and the red‐emitting Δ8‐[Ir8Pd4]16+ cage.

A family of six orange/red-emitting cationic iridium complexes were synthesized and their optoelectronic properties comprehensively characterized., A series of six novel [Ir(C^N) (N^N)](PF ) complexes (C^N is one of two cyclometalating ligands: 2-phenyl-4-(2,4,6-trimethylphenyl)pyridine, MesppyH, or 2-(napthalen-1-yl)-4-(2,4,6-trimethylphenyl)pyridine, MesnpyH; N^N denotes one of four neutral diamine ligands: 4,4′-di- -butyl-2,2′-bipyridine, dtbubpy, 1 ,1′ -2,2′-bibenzimiazole, H bibenz, 1,1′-(α,α′- -xylylene)-2,2′-bibenzimidazole, -xylbibenz or 2,2′-biquinoline, biq) were synthesised and their structural, electrochemical and photophysical properties comprehensively characterised. The more conjugated MesnpyH ligands confer a red-shift in the emission compared to MesppyH but maintain high photoluminescence quantum yields due to the steric bulk of the mesityl groups. The H bibenz and -xylbibenz ligands are shown to be electronically indistinct to dtbubpy but give complexes with higher quantum yields than analogous complexes bearing dtbubpy. In particular, the rigidity of the -xylbibenz ligand, combined with the steric bulk of the MesnpyH C^N ligands, gives a red-emitting complex ( = 586, 623 nm) with a very high photoluminescence quantum yield ( = 44%) for an emitter in that region of the visible spectrum. These results suggest that employing these ligands is a viable strategy for designing more efficient orange-red emitters for use in a variety of photophysical applications.

The catalytic enantioselective 6-exo-trig Michael addition-lactonization of enone-acid substrates to form cis-chromenones with high diastereo- and enantiocontrol was developed using the commercially available isothiourea tetramisole., The catalytic enantioselective 6-exo-trig Michael addition-lactonization of enone-acid substrates to form cis-chromenones with high diastereo- and enantiocontrol was developed using the commercially available isothiourea tetramisole. An acidic workup proved necessary to minimize product epimerization and maximize product er, providing cis-chromenones in excellent yield, and with excellent diastereo- and enantioselectivity.

α,β‐Unsaturated acyl ammoniums generated from the reaction of α,β‐unsaturated 2,4,6‐trichlorophenol (TCP) esters bearing a pendent enone with an isothiourea organocatalyst are versatile intermediates in a range of enantioselective nucleophile‐dependent domino processes to form complex products of diverse topology with excellent stereoselectivity. Use of either 1,3‐dicarbonyls, acyl benzothiazoles, or acyl benzimidazoles as nucleophiles allows three distinct, diastereodivergent domino reaction pathways to be accessed to form various fused polycyclic cores containing multiple contiguous stereocentres.

Halogen bonding between an oxygen acceptor and an iodotriazole donor can be switched on an off by cycling the solution pH., Phenols and their corresponding phenoxide anions can form halogen bonds with neutral iodotriazoles. The strength of these interactions depends critically on the protonation state of the oxygen atom – the interaction of the phenoxide anion is more than an order of magnitude stronger than the corresponding phenol. The assembly of a molecule bearing both an iodotriazole and a phenoxide anion into a self-complementary dimer, stabilised by two halogen bonds between the phenoxide anions and the neutral iodotriazoles has been demonstrated. The corresponding phenol shows no halogen bond mediated assembly either in the solid or in the solution state. This assembly process can be actuated simply by a change in protonation state – treatment of the phenol with one equivalent of base results in deprotonation and assembly of the dimer. The structure of the homodimer formed by the phenoxide-bearing iodotriazole has been determined in the solid state and 19F NMR spectroscopy demonstrates that the assembled dimer persists in solution and that it has significant stability. 19F NMR spectroscopy has also been used to demonstrate that the assembly process is completely reversible.

Phthalocyanines and their main group and metal complexes are important classes of organic semiconductor materials but are usually highly insoluble and so frequently need to be processed by vacuum deposition in devices. We report two highly soluble silicon phthalocyanine (SiPc) diester compounds and demonstrate their potential as organic semiconductor materials. Near-infrared (λ(EL) = 698-709 nm) solution-processed organic light-emitting diodes (OLEDs) were fabricated and exhibited external quantum efficiencies (EQEs) of up to 1.4%. Binary bulk heterojunction solar cells employing P3HT or PTB7 as the donor and the SiPc as the acceptor provided power conversion efficiencies (PCE) of up to 2.7% under simulated solar illumination. Our results show that soluble SiPcs are promising materials for organic electronics.

Combining a sterically bulky, electron-deficient cyclometalating C∧N ligands with an electron rich, highly rigidified N∧N ligand gives an iridium complex, that achieves extraordinarily bright blue emission (Φ PL = 90%; λ max = 459 nm in MeCN) for a cationic iridium complex., Combining a sterically bulky, electron-deficient 2-(2,4-difluorophenyl)-4-(2,4,6-trimethylphenyl)pyridine (dFMesppy) cyclometalating C∧N ligand with an electron rich, highly rigidified 1,1′-(α,α′-o-xylylene)-2,2′-biimidazole (o-xylbiim) N∧N ligand gives an iridium complex, [Ir(dFMesppy)2(o-xylbiim)](PF6), that achieves extraordinarily bright blue emission (Φ PL = 90%; λ max = 459 nm in MeCN) for a cationic iridium complex. This complex is compared with two reference complexes bearing 4,4′-di-tert-butyl-2,2′-bipyridine, and solution-processed organic light emitting diodes (OLEDs) have been fabricated from these materials.

The scope of dihydropyranone and dihydropyridinone products accessible by isothiourea‐catalyzed processes has been expanded and explored through the use of 2‐N‐tosyliminoacrylates and 2‐aroylacrylates in a Michael addition‐lactonization/lactamization cascade reaction. Notably, to ensure reproducibility it is essential to use homoanhydrides as ammonium enolate precursors with 2‐aroyl acrylates, while carboxylic acids can be used with 2‐N‐tosyliminoacrylates, delivering a range of 3,5,6‐substituted dihydropyranones and dihydropyridinones with high enantioselectivity (typically >90 % ee). The derivatization of the heterocyclic core of a 3,5,6‐substituted dihydropyranone through hydrogenation is also reported.

The relationship between the NMR chemical shifts of phosphinidene and selenourea compounds and the π-accepting ability of the related carbene ligands has been investigated., The electronic nature of the interaction of NHCs with metal centres is of interest when exploring their properties, how these properties influence those of metal complexes, and how these properties might depend on ligand structure. Selenourea and phosphinidene complexes have been proposed to allow the measurement of the π-accepting ability of NHCs, independent of their σ-donating ability, via the collection of 77Se or 31P NMR spectra, respectively. Herein, the synthesis and characterisation of selenoureas derived from a range of imidazol-2-ylidenes, 4,5-dihydroimidazol-2-ylidenes and triazol-2-ylidenes are documented. Computational studies are used to explore the link between the shielding of the selenium centre and the electronic properties of the NHCs. Results show that δ Se is correlated to the energy gap between a filled lone pair orbital on Se and the empty π* orbital corresponding to the Se–NHC bond. Bond energy decomposition analysis indicated no correlation between the orbital σ-contribution to bonding and the chemical shielding, while a good correlation was found between the π-contribution to bonding and the chemical shielding, confirming that this technique is indeed able to quantify the ability of NHCs to accept π-electron density. Calculations conducted on phosphinidene adducts yielded similar results. With the link between δ Se and δ P and π-back bonding ability clearly established, these compounds represent useful ways in which to fully understand and quantify this aspect of the electronic properties of NHCs.

A new family consisting of three luminescent neutral Ir(III) complexes with the unprecedented [Ir(C^N^C)(N^N)Cl] architecture, where C^N^C is a bis(six-membered) chelating tridentate tripod ligand derived from 2-benzhydrylpyridine (bnpy) and N^N is 4,4′-di-tert-butyl-2,2′-bipyridine (dtBubpy), is reported. X-ray crystallography reveals an unexpected and unusual double C–H bond activation of the two distal nonconjugated phenyl rings of the bnpy coupled with a very short Ir–Cl bond trans to the pyridine of the bnpy ligand. Depending on the substitution on the bnpy ligand, phosphorescence, ranging from yellow to red, is observed in dichloromethane solution. A combined study using density functional theory (DFT) and time-dependent DFT (TD-DFT) corroborates the mixed charge-transfer nature of the related excited states., An unprecedented tridentate tripod C^N^C ligand resulting from an unusual double C−H bond activation of 2-benzhydrylpyridine (bnpyH2) opens access to a new class of bis-cyclometalated Ir(III) luminophores. X-ray crystal structures reveal an unstrained geometry thanks to the formation of two six-membered chelate rings. The complexes display a yellow to red emission attributed to mixed charge-transfer excited states.

We report the synthesis of nine new N-heterocyclic carbene gold bifluoride complexes starting from the corresponding N-heterocyclic carbene gold hydroxides. A new methodology to access N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) fluoride starting from N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) hydroxide and readily available potassium bifluoride is also reported. These gold bifluorides were shown to be efficient catalysts in the hydrofluorination of symmetrical and unsymmetrical alkynes, thus affording fluorinated stilbene analogues and fluorovinyl thioethers in good to excellent yields with high stereo- and regioselectivity. The method is exploited further to access a fluorinated combretastatin analogue selectively in two steps starting from commercially available reagents.

Synthetic self-assembly is a powerful technique for the bottom-up construction of discrete and well-defined polyhedral nanostructures resembling the spherical shape of large biological systems. In recent years, numerous Archimedean-shaped coordination cages have been reported based on the assembly of bent monodentate organic ligands containing two or more distal pyridyl rings and square-planar PdII ions. The formation of photoactive Pd-II metallamacrocycles and cages, however, remain rare. Here we report the first examples of emissive and homochiral supramolecular cages of the form [(IrPd4)-Pd-8](16+). These cages provide a suitably sized cavity to host large guest molecules. Importantly, encapsulation and energy transfer have been observed between the blue-emitting NBu4[Ir(dFppy)(2)(CN)(2)] guest and the red-emitting Delta(8)-[Ir8Pd4](16+) cage.

This work was partly funded by the British Heart Foundation (NH/11/8/29253) and the EPSRC (EP/K005499/1). CCDC 1416048 and 1416049 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif Two salts of the chlorhexidine di-cation (H2CHx2+) – (H2CHx)(SO4)·3H2O and (H2CHx)(CO3)·4H2O – have been synthesised and characterised crystallographically. Publisher PDF