The Conductance and Thermopower Behavior of Pendent -Coordinated Palladium(II) Complexes in Single-Molecule Junctions.

The present work provides insight into the effect of connectivity within isomeric 1,2-bis(2-pyridylethynyl)benzene (bpb) palladium complexes on their electron transmission properties within gold|single-molecule|gold junctions. The ligands 2,2'-((4,5-bis(hexyloxy)-1,2-phenylene)bis(ethyne-2,1-diyl))bis(4-(methylthio)pyridine) ( ) and 6,6'-((4,5-bis(hexyloxy)-1,2-phenylene)bis(ethyne-2,1-diyl))bis(3-(methylthio)pyridine) ( ) were synthesized and coordinated with PdCl to give the -Pd( )Cl complexes. X-ray photoelectron spectroscopy (XPS) measurements shed light on the contacting modes of the molecules in the junctions.

Transparent Colloids of Detonation Nanodiamond: Physical, Chemical and Biological Properties.

Aqueous suspensions (colloids) containing detonation nano-diamond (DND) feature in most applications of DND and are an indispensable stage of its production; therefore, the interaction of DND with water is actively studied. However, insufficient attention has been paid to the unique physico-chemical and biological properties of transparent colloids with DND content (≤0.1%), which are the subject of this review.

Oxidation State Tuning of Room Temperature Phosphorescence and Delayed Fluorescence in Phenothiazine and Phenothiazine-5,5-dioxide Dimers.

Heterocyclic dimers consisting of combinations of butterfly-shaped phenothiazine (PTZ) and its chemically oxidized form phenothiazine-5,5-dioxide (PTZ(SO )) have been synthesized. A twist is imposed across the dimers by ortho-substituents including methyl ethers, sulfides and sulfones. X-ray crystallography, cyclic voltammetry and optical spectroscopy, underpinned by computational studies, have been employed to study the interplay between the oxidation state, conformational restriction, and emission mechanisms including thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP).

Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt?

Intramolecular hydrogen bonding between donor and acceptor segments in thermally activated delayed fluorescence (TADF) materials is now frequently employed to─purportedly─rigidify the structure and improve the emission performance of these materials. However, direct evidence for these intramolecular interactions is often lacking or ambiguous, leading to assertions that are largely speculative. Here we investigate a series of TADF-active materials incorporating pyridine, which bestows the potential ability to form intramolecular H-bonding interactions.

Versatile Para-Substituted Pyridine Lanthanide Coordination Complexes Allow Late Stage Tailoring of Complex Function.

A series of cationic and neutral p-Br and p-NO pyridine substituted Eu(III) and Gd(III) coordination complexes serve as versatile synthetic intermediates. Nucleophilic aromatic substitution occurs readily at the para position under mild conditions, allowing C-N and C-C bond forming reactions to take place, permitting the introduction of azide, amino and alkynyl substituents. For Eu(III) complexes, this approach allows late stage tuning of absorption and emission spectral properties, exemplified by the lowering of the energy of an LMCT transition accompanied by a reduction in the Eu-N bond length.

Discovery of a photochemical cascade process by flow-based interception of isomerising alkenes.

Herein we report the discovery of a new photochemical cascade process through a flow-based strategy for intercepting diradicals generated from simple alkenes. This continuous process delivers a series of unprecedented polycyclic reaction products. Exploring the scope of this novel process revealed that this approach is general and affords a variety of structurally complex reaction products in high yields (up to 81%), short reaction times (7 min) and high throughputs (up to 5.

Vibrational Damping Reveals Vibronic Coupling in Thermally Activated Delayed Fluorescence Materials.

We investigate a series of D-A molecules consisting of spiro[acridan-9,9'-fluorene] as the donor and 2-phenylenepyrimidine as the acceptor. In two of the materials, a spiro center effectively electronically isolates the D unit from (consequently) optically innocent yet structurally influential adamantyl side groups. In a third material, adamantyl groups attached directly to the acceptor strongly influence the electronic properties.

Correction: Electronic conductance and thermopower of single-molecule junctions of oligo(phenyleneethynylene) derivatives.

Correction for 'Electronic conductance and thermopower of single-molecule junctions of oligo(phenyleneethynylene) derivatives' by Hervé Dekkiche et al., Nanoscale, 2020, 12, 18908-18917, DOI: 10.1039/D0NR04413J.

Conformational Dependence of Triplet Energies in Rotationally Hindered N- and S-Heterocyclic Dimers: New Design and Measurement Rules for High Triplet Energy OLED Host Materials.

A series of four heterocyclic dimers has been synthesized, with twisted geometries imposed across the central linking bond by ortho-alkoxy chains. These include two isomeric bicarbazoles, a bis(dibenzothiophene-S,S-dioxide) and a bis(thioxanthene-S,S-dioxide). Spectroscopic and electrochemical methods, supported by density functional theory, have given detailed insights into how para- vs.

Cyclophane Molecules Exhibiting Thermally Activated Delayed Fluorescence: Linking Donor Units to Influence Molecular Conformation.

The synthetic methodology to covalently link donors to form cyclophane-based thermally activated delayed fluorescence (TADF) molecules is presented. These are the first reported examples of TADF cyclophanes with "electronically innocent" bridges between the donor units. Using a phenothiazine-dibenzothiophene-,-dioxide donor-acceptor-donor (D-A-D) system, the two phenothiazine (PTZ) donor units were linked by three different strategies: (i) ester condensation, (ii) ether synthesis, and (iii) ring closing metathesis.

Resonance-Enhanced Charge Delocalization in Carbazole-Oligoyne-Oxadiazole Conjugates.

There are notably few literature reports of electron donor-acceptor oligoynes, even though they offer unique opportunities for studying charge transport through "all-carbon" molecular bridges. In this context, the current study focuses on a series of carbazole-(C≡C)-2,5-diphenyl-1,3,4-oxadiazoles ( = 1-4) as conjugated π-systems in general and explores their photophysical properties in particular. Contrary to the behavior of typical electron donor-acceptor systems, for these oligoynes, the rates of charge recombination after photoexcitation increase with increasing electron donor-acceptor distance.

Carbazole isomers induce ultralong organic phosphorescence.

Commercial carbazole has been widely used to synthesize organic functional materials that have led to recent breakthroughs in ultralong organic phosphorescence, thermally activated delayed fluorescence, organic luminescent radicals and organic semiconductor lasers. However, the impact of low-concentration isomeric impurities present within commercial batches on the properties of the synthesized molecules requires further analysis. Here, we have synthesized highly pure carbazole and observed that its fluorescence is blueshifted by 54 nm with respect to commercial samples and its room-temperature ultralong phosphorescence almost disappears.

Electronic conductance and thermopower of single-molecule junctions of oligo(phenyleneethynylene) derivatives.

We report the synthesis and the single-molecule transport properties of three new oligo(phenyleneethynylene) (OPE3) derivatives possessing terminal dihydrobenzo[b]thiophene (DHBT) anchoring groups and various core substituents (phenylene, 2,5-dimethoxyphenylene and 9,10-anthracenyl). Their electronic conductance and their Seebeck coefficient have been determined using scanning tunneling microscopy-based break junction (STM-BJ) experiments between gold electrodes. The transport properties of the molecular junctions have been modelled using DFT-based computational methods which reveal a specific binding of the sulfur atom of the DHBT anchor to the electrodes.

Nitrogen Fixation and Biological Behavior of Nanodiamond Colloidal Solutions.

Detonation-produced nanodiamond, both as a powder (with adsorbed water) and especially when suspended in an aqueous colloid, can support the growth (both aerobic and anaerobic) of bacteria and fungi. These were isolated and identified by microbiological methods, optical and electron microscopy, as species of Penicillium, Purpureocillium, Beaveria, Trichoderma and Aspergillus genera. The C : N molar ratio of the developing fibers (comprising fungal mycelia with attached bacteria and entrapped nanodiamond) decreased from 25 to 11 between the 1 and 10 week of incubation (cf.

Phospho-rescent mono- and diiridium(III) complexes cyclo-metalated by fluorenyl- or phenyl-pyridino ligands with bulky substituents, as prospective OLED dopants.

The crystal structures of tris-[9,9-dihexyl-2-(5-meth-oxy-pyridin-2-yl-κ)-9-fluoren-3-yl-κ ]iridium pentane monosolvate, [Ir(CHNO)]·CH, (I), di-μ-chlorido-bis-{bis-[2-(5-fluoro-pyridin-2-yl)-9,9-dihexyl-9-fluoren-3-yl]iridium} pentane 0.3-solvate, [Ir(CHFN)Cl]·0.3CH, (II), di-μ-cyanato-bis-{bis-[9,9-dihexyl-2-(5-meth-oxy-pyridin-2-yl)-9-fluoren-1-yl]iridium} pentane monosolvate, [Ir(CHNO)(NCO)(NCO)]·CH, (III), and {μ-,'-bis-[3,5-bis-(tri-fluoro-meth-yl)phen-yl]oxamidato}bis(bis{2-[4-(2,4,6-trimethylphenyl)pyridin-2-yl]phenyl-κ ,'}iridium)-chloro-benzene-pentane (1/2.

Delayed Blue Fluorescence via Upper-Triplet State Crossing from C-C Bonded Donor-Acceptor Charge Transfer Molecules with Azatriangulene Cores.

We report the synthesis and structural and photophysical characterization of two series of molecules with functionalized azatriangulene electron donor cores and three pendant electron acceptor units. The presented donor and acceptor units are joined by C-C bonds, instead of the usual C-heteroatom bonds often found in thermally activated delayed fluorescence (TADF) emitters. The effects of the donor-acceptor strength and donor-acceptor dihedral angle on the emission properties are assessed.

Unusual dual-emissive heteroleptic iridium complexes incorporating TADF cyclometalating ligands.

Five new neutral heteroleptic iridium(iii) complexes IrL(pic) (2-6) based on the archetypical blue emitter FIrpic have been synthesised. The cyclometallating ligands L are derived from 2-(2,6-F-3-pyridyl)-4-mesitylpyridine (7), 2-(3-cyano-2,6-F-phenyl)-4-mesitylpyridine (8), 2-(2,6-F-phenyl)-4-[2,7-(HexO)-9H-carbazol-9-yl]pyridine (9), 2-(2,6-F-3-pyridyl)-4-[2,7-(HexO)-9H-carbazol-9-yl]pyridine (10) and 2-(3-cyano-2,6-F-phenyl)-4-[2,7-(HexO)-9H-carbazol-9-yl]pyridine (11) for complexes 2, 3, 4, 5 and 6, respectively. The carbazole-functionalised ligands 9-11 show weak thermally activated delayed fluorescence (TADF) in solution.

Correction to "Temperature-Induced Single-Crystal-to-Single-Crystal Transformations with Consequential Changes in the Magnetic Properties of Fe(III) Complexes".

[This corrects the article DOI: 10.1021/acsomega.8b03400.

Copper-Mediated Nitrosation: 2-Nitrosophenolato Complexes and Their Use in the Synthesis of Heterocycles.

A simple protocol yielding -substituted nitrosophenols from phenols is demonstrated, in the form of copper(II) (nitrosophenolato) complexes. The developed methodology was applied to a range of substrates, confirming the role of the copper in both the formation and protection of the challenging 1, 2-substitution pattern. Using polymer supported thiourea, the Cu could be stripped from the complexes and thus enabled the isolation or identification of the uncoordinated ligands and their decomposition products, in yields generally low in line with the intrinsic high reactivity of 2-nitrosophenols.

Carbazole-Based Tetrapodal Anchor Groups for Gold Surfaces: Synthesis and Conductance Properties.

As the field of molecular-scale electronics matures and the prospect of devices incorporating molecular wires becomes more feasible, it is necessary to progress from the simple anchor groups used in fundamental conductance studies to more elaborate anchors designed with device stability in mind. This study presents a series of oligo(phenylene-ethynylene) wires with one tetrapodal anchor and a phenyl or pyridyl head group. The new anchors are designed to bind strongly to gold surfaces without disrupting the conductance pathway of the wires.

Excitation modulation of Eu:BPEPC based complexes as low-energy reference standards for circularly polarised luminescence (CPL).

The enantiomers of [EuL]·3Cl, an analogue of Eu:BPEPC with a lowered energy excitation wavelength, serve as effective reference complexes for the calibration of circularly polarised luminescence (CPL) spectrometers.

Temperature-Induced Single-Crystal-to-Single-Crystal Transformations with Consequential Changes in the Magnetic Properties of Fe(III) Complexes.

The present article deals with an one-to-one structure-property correspondence of a dinuclear iron complex, [Dipic(HO)FeOH]·HO () (Dipic = pyridine-2,6-dicarboxylic acid). Variable-temperature X-ray single-crystal structural analysis confirms a phase transition of complex to complex ([Dipic(HO)FeOH]) at 120 °C. Further, single-crystal-to-single-crystal (SCSC) transformation was monitored by temperature-dependent single crystal X-ray diffraction, powder X-ray diffraction, time-dependent Fourier-transform infrared spectroscopy, and differential scanning calorimetry.

Molecular Design Strategies for Color Tuning of Blue TADF Emitters.

New thermally activated delayed fluorescence (TADF) blue emitter molecules based on the known donor-acceptor-donor (D-A-D)-type TADF molecule, 2,7-bis(9,9-dimethylacridin-10-yl)-9,9-dimethylthioxanthene-,-dioxide (DDMA-TXO2), are reported. The motivation for the present investigation is via the use of rational molecular design, based on DDMA-TXO2, to elevate the organic light emitting diode (OLED) performance and obtain deeper blue color coordinates. To achieve this goal, the strength of the donor (D) unit and acceptor (A) units have been tuned with methyl substituents.

Unravelling the Complexities of Pseudocontact Shift Analysis in Lanthanide Coordination Complexes of Differing Symmetry.

In two closely related series of eight-coordinate lanthanide complexes, a switch in the sign of the dominant ligand field parameter and striking variations in the sign, amplitude and orientation of the main component of the magnetic susceptibility tensor as the Ln ion is permuted conspire to mask modest changes in NMR paramagnetic shifts, but are evident in Yb EPR and Eu emission spectra.