Homochiral self-sorted and emissive IrIII metallo-cryptophanes

We thank the EPSRC (DTG award 1238852, EP/K039202/1, EP/M02105X/1, EP/J001325/1), Leverhulme Trust (RPG-2014-148), University of St Andrews, and the MEXT/JSPS Grants in Aid for Scientific Research (JP25102005 and JP25102001) for funding; Simon Barrett for assistance with NMR; Martin Huscroft for assistance with HPLC, and Stephen Boyer for elemental analysis measurements.The racemic ligands (±)-tris(isonicotinoyl)-cyclotriguaiacylene (L1), or (±)-tris(4-pyridyl-methyl)-cyclotriguaiacylene (L2) assemblewith racemic (Λ, Δ)- [Ir(ppy)2(MeCN)2]+, in which ppy = 2-phenylpyridinato to form [{Ir(ppy)2}3(L)2]3+ metallo-cryptophane cages. The crystal structure of [{Ir(ppy)2}3(L1)2]∙3BF4 has MM-ΛΛΛ nd PP-ΔΔΔ isomers, and homochiral self-sorting occurs in solution, a processaccelerated by a chiral guest. Self-recognition between L1 and L2 within cagesdoes not occur, and cages show very slow ligand-exchange. Both cages are phosphorescent,with [{Ir(ppy)2}3(L2)2]3+ havingenhanced and blue-shifted emission when compared with [{Ir(ppy)2}3(L1)2]3+ .PostprintPeer reviewe

Borylation–Reduction–Borylation for the Formation of 1,4-Azaborines

This project has received funding from the Leverhulme Trust (grant Number RPG-2022-032) and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 769599). M.J.I. and E.Z.-C. also thank the EPSRC Programme Grant “Boron: Beyond the Reagent” (EP/W007517/1) for support.Given the current interest in materials containing 1,4-azaborine units, the development of new routes to these structures is important. Carbonyl directed electrophilic borylation using BBr3 is a facile method for the ortho-borylation of N,N-diaryl-amide derivatives. Subsequent addition of Et3SiH results in carbonyl reduction and then formation of 1,4-azaborines that can be protected in situ using a Grignard reagent. Overall, borylation–reduction–borylation is a one-pot methodology to access 1,4-azaborines from simple precursors.Publisher PDFPeer reviewe

Chiral iridium(III) complexes in light-emitting electrochemical cells : exploring the impact of stereochemistry on the photophysical properties and device performances

Despite hundreds of cationic bis-cyclometalated iridium(III) complexes having been explored as emitters for light-emitting electrochemical cells (LEECs), uniformly their composition has been in the form of a racemic mixture of Λ and Δ enantiomers. The investigation of LEECs using enantiopure iridium(III) emitters, however, remains unprecedented. Herein, we report the preparation, the crystal structures and the optoelectronic properties of two families of cyclometalated iridium(III) complexes of the form of [(C^N)2Ir(dtBubpy)]PF6 (where dtBubpy is 4,4'-di-tert-butyl-2,2'-bipyridine) in both their racemic and enantiopure configurations. LEEC devices using Λ and Δ enantiomers as well as the racemic mixture of both families have been prepared and the device performances were tested. Importantly, different solid-state photophysical properties exist between enantiopure and racemic emitters, which are also reflected in the device performances.Publisher PDFPeer reviewe

The synthesis of brominated-boron-doped PAHs by alkyne 1,1-bromoboration: mechanistic and functionalisation studies

The research leading to these results has received funding from the European Research Council under the Horizon 2020 Research and Innovation Program (Grant no. 769599), the Leverhulme Trust (RPG-2014-340) and the EPSRC (EP/P010482/1). C. Si thanks the China Scholarship Council (201806890001).The synthesis of a range of brominated-Bn-containing (n = 1, 2) polycyclic aromatic hydrocarbons (PAHs) is achieved simply by reacting BBr3 with appropriately substituted alkynes via a bromoboration/electrophilic C-H borylation sequence. The brominated-Bn-PAHs were isolated as either the borinic acid or B-mesityl-protected derivatives, with the latter having extremely deep LUMOs for the B2-doped PAHs (with one example having a reduction potential of E1/2 = -0.96 V versus Fc+/Fc, Fc = ferrocene). Mechanistic studies revealed the reaction sequence proceeds by initial alkyne 1,1-bromoboration. 1,1-bromoboration also was applied to access a number of unprecedented 1-bromo-2,2-diaryl substituted vinylboronate esters direct from internal alkynes. Bromoboration/C-H borylation installs useful C-Br units onto the Bn-PAHs, which were utilised in Negishi coupling reactions, including for the installation of two triarylamine donor (D) groups onto a B2-PAH. The resultant D-A-D molecule has a low optical gap with an absorption onset at 750 nm and emission centered at 810 nm in the solid state.Publisher PDFPeer reviewe

Protection of Domestic bank Ownership in France and Germany: The Functional Equivalency of Institutional Diversity in Takeovers

We investigate the character of the market for corporate control (i.e. takeovers) in French and German banking. The key feature of this character is the marked ability of French and German banks to resist unsolicited takeover bids, especially – although not exclusively– those from foreign competitors. We present an institutional perspective to account for the restrained character of takeovers in French and German banking. Our perspective is composed of two elements. First, institutional arrangements are important since they structure power relations among firm stakeholders by providing opportunities, as well as imposing constraints, to influence the decision-making process in which takeover transactions take place. Second, institutional arrangements provide firm stakeholders with several potential opportunities, not just one, to block unsolicited bids since takeover contests are composed of sequences of decisions for which approval is needed at each stage. French and German banks have used different mixes of institutional arrangements, themselves located at different stages of takeover transactions, to secure restrained markets for corporate control. Our institutional analysis, in turn, also illustrates an important shortcoming of banking sector protectionism, namely the contribution of protection from unsolicited takeover bids to the building of banks carrying systemic risks

Green phosphorescence and electroluminescence of sulfur pentafluoride-functionalized cationic iridium(III) complexes

EZ-C acknowledges the University of St Andrews for financial support.We report four cationic iridium(III) complexes [Ir(C^N)2(dtBubpy)](PF6) that have sulfurpentafluoride-modified 1-phenylpyrazole and 2-phenylpyridine cyclometalating (C^N) ligands (dtBubpy = 4,4'-di-tert-butyl-2,2'-bipyridyl). Three of the complexes were characterized by single-crystal X-ray structure analysis. In cyclic voltammetry, the complexes undergo reversible oxidation of iridium(III) and irreversible reduction of the SF5 group. They emit bright green phosphorescence in acetonitrile solution and in thin films at room temperature, with emission maxima between 482–519 nm and photoluminescence quantum yields of up to 79%. The electron-withdrawing sulfur pentafluoride group on the cyclometalating ligands increases the oxidation potential and the redox gap and blue-shifts the phosphorescence of the iridium complexes more than do the commonly-employed fluoro and trifluoromethyl groups. The irreversible reduction of the SF5 group may be a problem in organic electronics; for example, the complexes do not exhibit electroluminescence in light-emitting electrochemical cells (LEECs). Nevertheless, the complexes exhibit green to yellow-green electroluminescence in doped multilayer organic light-emitting diodes (OLEDs) with emission maxima ranging from 501–520 nm and with an external quantum efficiency (EQE) of up to 1.7% in solution-processed devices.PostprintPeer reviewe

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

M. K. would like to thank 2214-A International Research Fellowship Programme for Ph.D. students (1059B141900585). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreement No 838885 (NarrowbandSSL). S.M.S. acknowledges support from the Marie Skłodowska-Curie Individual Fellowship (grant agreement No 838885 NarrowbandSSL). A. K. G. is grateful to the Royal Society for Newton International Fellowship NF171163. L.M acknowledges that the project who gave rise to these results received support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme Grant agreement No. 834431, the Spanish Ministry of Science, Innovation and Universities (MICIU, RTI2018-095362-A-I00, and EQC2018-004888-P) and the Comunitat Valenciana (IDIFEDER/2020/063 and PROMETEU/2020/077). D.T. acknowledges support from the Comunitat Valenciana (CIGE/2021/0).We designed and synthesized two new ionic thermally activated delayed fluorescent (TADF) emitters that are charged analogues of a known multiresonant TADF (MR-TADF) compound, DiKTa. The emission of the charged derivatives is red-shifted compared to the parent compound. For instance, DiKTa-OBuIm emits in the green (λPL = 499 nm, 1 wt % in mCP) while DiKTa-DPA-OBuIm emits in the red (λPL = 577 nm, 1 wt % in mCP). In 1 wt % mCP films, both emitters showed good photoluminescence quantum yields of 71% and 61%, and delayed lifetimes of 316.6 μs and 241.7 μs, respectively, for DiKTa-OBuIm and DiKTa-DPA-OBuIm, leading to reverse intersystem crossing rates of 2.85 × 103 s−1 and 3.04 × 103 s−1. Light-emitting electrochemical cells were prepared using both DiKTa-OBuIm and DiKTa-DPA-OBuIm as active emitters showing green (λmax = 534 nm) and red (λmax = 656 nm) emission, respectively.Publisher PDFPeer reviewe

In the dedicated pursuit of dedicated capital: restoring an indigenous investment ethic to British capitalism

Tony Blair’s landslide electoral victory on May 1 (New Labour Day?) presents the party in power with a rare, perhaps even unprecedented, opportunity to revitalise and modernise Britain’s ailing and antiquated manufacturing economy.* If it is to do so, it must remain true to its long-standing (indeed, historic) commitment to restore an indigenous investment ethic to British capitalism. In this paper we argue that this in turn requires that the party reject the very neo-liberal orthodoxies which it offered to the electorate as evidence of its competence, moderation and ‘modernisation’, which is has internalised, and which it apparently now views as circumscribing the parameters of the politically and economically possible

Exploring the self-assembly and energy transfer of dynamic supramolecular iridium-porphyrin systems

EZ-C acknowledges the University of St Andrews for financial support. IDWS acknowledges support from EPSRC (EP/J009016) and the European Research Council (grant 321305). IDWS also acknowledges support from a Royal Society Wolfson research merit award. DJ acknowledges the European Research Council (grant: 278845) and the RFI Lumomat for financial support.We present the first examples of dynamic supramolecular systems composed of cyclometalated Ir(III) complexes of the form of [Ir(C^N)2(N^N)]PF6 (where C^N is mesppy = 2-phenyl-4-mesitylpyridinato and dFmesppy = 2-(4,6-difluorophenyl)-4-mesitylpyridinato and N^N is 4,4':2',2'':4'',4'''-quaterpyridine, qpy) and zinc tetraphenylporphyrin (ZnTPP), assembled through non-covalent interactions between the distal pyridine moieties of the qpy ligand located on the iridium complex and the zinc of the ZnTPP. The assemblies have been comprehensively characterized by a series of analytical techniques (1H NMR titration experiments, 2D COSY and HETCOR NMR spectra and low temperature 1H NMR spectroscopy) and the crystal structures have been elucidated by X-ray diffraction. The optoelectronic properties of the assemblies and the electronic interaction between the iridium and porphyrin chromophoric units have been explored with detailed photophysical measurements, supported by time-dependent density functional theory (TD-DFT) calculations.PostprintPeer reviewe

Ligand electronic fine-tuning and its repercussion on the photocatalytic activity and mechanistic pathways of the copper-photocatalysed aza-Henry Reaction

C.Li thanks the Prof. & Mrs Purdie Bequests Scholarship and AstraZeneca PhD Studentship.A family of six structurally related heteroleptic copper(I) complexes of the form of [Cu(N^N)(P^P)]+ bearing a 2,9-dimethyl-1,10-phenanthroline diimine (N^N) ligand and a series of electronically tunable xantphos (P^P) ligands have been synthesized and their optoelectronic properties characterized. The reactivity of these complexes in the copper-photocatalyzed Aza-Henry reaction of N-Phenyltetrahydroisoquinoline was evaluated, while the related excited state kinetics were comprehensively studied. By subtlety changing the electron-donating properties of the P^P ligands with neglegible structural differences, we could tailor the photoredox properties and relate it to their reactivity. Moreover, depending on the exited-state redox potential of the catalysts, the preferred mechanism can shift between reductive quenching, energy transfer and oxidative quenching pathways. A combined study of structural modulation of copper(I) photocatalysts, optoelectronic properties and photocatalytic reactivity resulted in a clearer understanding of both the rational design of the photocatalyst and the complexity of competing photoinduced electron and energy transfer mechanisms.Publisher PDFPeer reviewe