Aggregation-Induced Emission by Molecular Design: A Route to High-Performance Light-Emitting Electrochemical Cells

The emission efficiency of organic semiconductors (OSCs) often suffers from aggregation caused quenching (ACQ). An elegant solution is aggregation-induced emission (AIE), which constitutes the design of the OSC so that its morphology inhibits quenching π–π interactions and non-radiative motional deactivation. The light-emitting electrochemical cell (LEC) can be sustainably fabricated, but its function depends on motion of bulky ions in proximity of the OSC. It is therefore questionable whether the AIE morphology can be retained during LEC operation. Here, we synthesize two structurally similar OSCs, which are distinguished by that 1 features ACQ while 2 delivers AIE. Interestingly, we find that the AIE-LEC significantly outperforms the ACQ-LEC. We rationalize our finding by showing that the AIE morphology remains intact during LEC operation, and that it can feature appropriately sized free-volume voids for facile ion transport and suppressed non-radiative excitonic deactivation.     

Frontispiece: Cationic Tetrylene-Iron(0) Complexes: Access Points for Cooperative,Reversible Bond Activation and Open-Shell Iron(−I) Ferrato-Tetrylenes

The open-shell cationic stannylene-iron(0) complex 4 ( 4 =[^PhiPDippSn⋅Fe⋅IPr]⁺; ^PhiPDipp={[Ph₂PCH₂Si(ⁱPr)₂](Dipp)N}; Dipp=2,6-ⁱPr₂C₆H₃; IPr=[(Dipp)NC(H)]₂C:) cooperatively and reversibly cleaves dihydrogen at the Sn−Fe interface under mild conditions (1.5 bar, 298 K), in forming bridging hydrido-complex 6 . The One-electron oreduction of the related Ge^II−Fe⁰ complex 3 leads to oxidative addition of one C−P linkage of the ^PhiPDipp ligand in an intermediary Fe^−I complex, leading to Fe^I phosphide species 7 . One-electron reduction reaction of 4 gives access to the iron(−I) ferrato-stannylene, 8 , giving evidence for the transient formation of such a species in the reduction of 3 . The covalently bound tin(II)-iron(−I) compound 8 has been characterised through EPR spectroscopy, SQUID magnetometry, and supporting computational analysis, which strongly indicate a high localization of electron spin density at Fe^−I in this unique d⁹-iron complex.     

Substrates and Cyclic Peptide Inhibitors of the Oligonucleotide-Activated Sirtuin 7**

The sirtuins are NAD⁺-dependent lysine deacylases, comprising seven isoforms (SIRT1–7) in humans, which are involved in the regulation of a plethora of biological processes, including gene expression and metabolism. The sirtuins share a common hydrolytic mechanism but display preferences for different ϵ-N-acyllysine substrates. SIRT7 deacetylates targets in nuclei and nucleoli but remains one of the lesser studied of the seven isoforms, in part due to a lack of chemical tools to specifically probe SIRT7 activity. Here we expressed SIRT7 and, using small-angle X-ray scattering, reveal SIRT7 to be a monomeric enzyme with a low degree of globular flexibility in solution. We developed a fluorogenic assay for investigation of the substrate preferences of SIRT7 and to evaluate compounds that modulate its activity. We report several mechanism-based SIRT7 inhibitors as well as de novo cyclic peptide inhibitors selected from mRNA-display library screening that exhibit selectivity for SIRT7 over other sirtuin isoforms, stabilize SIRT7 in cells, and cause an increase in the acetylation of H3 K18.     

A Series of Low-Coordinate Iron Selenido Complexes: Reactivity of a Linear Iron(I) Silylamide towards Selenium

A variety of different low-coordinate iron selenide complexes is reported. These are obtained by reaction of the linear iron(I) silylamide K{18c6}[Fe(N(Dipp)SiMe₃)₂] (Dipp=2,6-diisopropylphenyl) with red selenium. Careful adjustment of the reaction conditions results in the formation of unique low-coordinate selenido iron complexes, namely a monoselenide bridged [2Fe−1Se]²⁺ complex, as well as mononuclear iron per- and triselenides. Further, C−H bond activation of one of the silylamide ligands by a putative terminal iron monoselenide is observed.     

Interpolation of multidimensional diabatic potential energy matrices

A method for constructing diabatic potential energy matrices by interpolation of ab initio quantum chemistry data is described and tested. This approach is applicable to any number of interacting electronic states, and relies on a formalism and a computational procedure that are more general than those presented previously for the case of two electronic states. The method is tested against an analytic model for three interacting electronic states of NH(3) (+).     

Silver ion dynamics in the Ag5Te2Cl-polymorphs revealed by solid state NMR lineshape and two- and three-time correlation spectroscopies

The relation between structure and ion dynamics in the three polymorphs of Ag(5)Te(2)Cl has been investigated using (109)Ag, (125)Te, and (35)Cl NMR spectroscopies. Specifically, the influence of the structural phase transitions observed near 240 K (P2(1)/c<-->P2(1)/n) and near 332 K (P2(1)/n<-->I4/mcm) upon silver ion mobilities has been studied by temperature dependent (109)Ag NMR lineshapes and spin-lattice relaxation times. While the superionic high temperature phase alpha-Ag(5)Te(2)Cl is characterized by a molten cationic sublattice, fast ion dynamics in the medium-temperature phase beta-Ag(5)Te(2)Cl occurs in spatially restricted regions comprising all the crystallographically distinct silver sites. Temperature dependent magic-angle-spinning linewidths yield an activation energy of 0.38 eV, consistent with 0.44 eV measured from dc electric conductivities. For the low-temperature gamma-modification, results of two- and three-time (109)Ag correlation spectroscopies provide a detailed insight into the nature of the silver ionic hopping motion. Temperature dependent jump rates measured by two-time correlation functions yield an activation energy E(a)= 0.48 eV. (109)Ag NMR three-time correlation functions indicate that the non-exponential relaxation behavior of the silver ions can be attributed to a broad distribution of jump rates rather than correlated forward-backward jumps. Nevertheless, all the silver ions are mobile down to temperatures of about 185 K.     

Artificial Intelligence Computation to Establish Relationships Between APS Process Parameters and Alumina–Titania Coating Properties

Modeling the behavior of air plasma spray (APS) process, one of the challenges nowadays is to identify the parameter interdependencies, correlations and individual effects on coating properties, characteristics and influences on the in-service properties. APS modeling requires a global approach which considers the relationships between coating characteristics/ in-service properties and process parameters. Such an approach permits to reduce the development costs. This is why a robust methodology is needed to study these interrelated effects. Artificial intelligence based on fuzzy logic and artificial neural network concepts offers the possibility to develop a global approach to predict the coating characteristics so as to reach the required operating parameters. The model considered coating properties (porosity) and established the relationships with power process parameters (arc current intensity, total plasma gas flow rate, hydrogen content) on the basis of artificial intelligence rules. Consequently, the role and the effects of each power process parameter were discriminated. The specific case of the deposition of alumina–titania (Al₂O₃–TiO₂, 13% by weight) by APS was considered.     

Pd（OAc）2／[mmim]I催化体系催化胺氧化羰化合成氨基甲酸酯、脲和2-噁唑啉酮

采用Pd(OAc)2/[mmim]I催化体系,在不同反应条件下可以将烷基胺、芳香胺及氨基醇(酚)一步转化为氨基甲酸酯、脲和2-噁唑啉酮.N-苯基氨基甲酸甲酯、二苯基脲及苯并-2-噁唑酮的催化转化频率分别为12417,17638和4114h-1.     

Gold(I)-dithioether supramolecular polymers: synthesis, characterization, and luminescence

A series of discrete compounds and supramolecular polymers were synthesized by self-assembly of dithioether building blocks and HAuCl4.3H2O. In complexes 1 {[AuL(1-Me)Cl], where L(1-Me) is bis(methylthio)methane} and 2 {[Au2L(2-Ph)Cl2], where L(2-Ph) is 1,2-bis(phenylthio)ethane}, adjacent units are connected via aurophilic interactions. Complex 1, a one-dimensional (1D) supramolecular polymer, and complex 2, a two-dimensional supramolecular network, both feature nearly linear [Au-Au-](infinity) chains. Complexes 4a, 4b, and 4c, all of which contain 1,3-bis(phenylthio)propane (L(3-Ph)), are polymorphs having the composition [Au2L(3-Ph)Cl2]. Complex 3 {[Au2L(1-Ph)Cl2], where L(1-Ph) is bis(phenylthio)methane}and complexes 4a and 4b consist of nearly identical 1D supramolecular polymers formed through Au-Au interactions. The third polymorph, 4c, is a molecular complex, as it does not have metal-metal interactions. Complex 5 {[Au2L(4-Ph)Cl2], where L(4-Ph) is 1,4-bis(phenylthio)butane} is also molecular. UV-vis spectra showed that the absorption bands of these complexes are allowed ligand-centered transitions between 230 and 260 nm. Complexes 1, 2, and 6 {[AuL(3-Me)Cl], where L(3-Me) is 1,3-bis(methylthio)propane} exhibited solid-state luminescence at 5 K with vibronic progressions and band maxima at approximately 570 nm. It is suggested that complex 6 contains [Au-Au-](infinity) chains.