Luminescent complexes of heavy metals such as iridium, platinum, and ruthenium play an important role in photocatalysis and energy conversion applications as well as organic light-emitting diodes (OLEDs). Achieving comparable performance from more–earth-abundant copper requires overcoming the weak spin-orbit coupling of the light metal as well as limiting the high reorganization energies typical in copper(I) [Cu(I)] complexes. Here we report that two-coordinate Cu(I) complexes with redox active ligands in coplanar conformation manifest suppressed nonradiative decay, reduced structural reorganization, and sufficient orbital overlap for efficient charge transfer. We achieve photoluminescence efficiencies >99% and microsecond lifetimes, which lead to an efficient blue-emitting OLED. Photophysical analysis and simulations reveal a temperature-dependent interplay between emissive singlet and triplet charge-transfer states and amide-localized triplet states.

A systematic study is presented on the physical and photophysical properties of isoelectronic and isostructural Cu, Ag, and Au complexes with a common amide (N-carbazolyl) and two different carbene ligands (i.e., CAAC = (5R,6S)-2-(2,6-diisopropylphenyl)-6-isopropyl-3,3,9-trimethyl-2-azaspiro­[4.5]­decan-2-ylidene, MAC = 1,3-bis­(2,6-diisopropylphenyl)-5,5-dimethyl-4-keto-tetrahydropyridylidene). The crystal structures of the (carbene)­M(I)(N-carbazolyl) (MCAAC) and (MAC)­M(I)(N-carbazolyl) (MMAC) complexes show coplanar carbene and carbzole ligands and C–M–N bond angles of ∼180°. The electrochemical properties and energies for charge transfer (CT) absorption and emission compounds are not significantly affected by the choice of metal ion. All six of the (carbene)­M­(Cz) complexes examined here display high photoluminescence quantum yields of 0.8–1.0. The compounds have short emission lifetimes (τ = 0.33–2.8 μs) that fall in the order Ag < Au < Cu, with the lifetimes of (carbene)­Ag­(Cz) roughly a factor of 10 shorter than for (carbene)­Cu­(Cz) complexes. Detailed temperature-dependent photophysical measurements (5–325 K) were carried out to determine the singlet and triplet emission lifetimes (τfl and τph, respectively) and the energy difference between the singlet and triplet excited state, ΔE S1–T1. The τfl values range between 20 and 85 ns, and the τph values are in the 50–200 μs regime. The emission at room temperature is due exclusively to E-type delayed fluorescence or TADF (i.e., ). The emission rate at room temperature is fully governed by ΔE S1–T1, with the silver complexes giving ΔE S1–T1 values of 150–180 cm–1 (18–23 meV), whereas the gold and copper complexes give values of 570–590 cm–1 (70–73 meV).

A series of six luminescent two-coordinate Cu(I) complexes were investigated bearing nonconventional N-heterocyclic carbene ligands, monoamido-aminocarbene (MAC*) and diamidocarbene (DAC*), along with carbazolyl (Cz) as well as mono-and dicyano-substituted Cz derivatives. The emission color can be systematically varied over 270 nm, from violet to red, through proper choice of the acceptor (carbene) and donor (carbazolyl) groups. The compounds exhibit photoluminescent quantum efficiencies up to 100% in fluid solution and polystyrene films with short decay lifetimes (τ ≈ 1 μs). The radiative rate constants for the Cu(I) complexes (k r = 10 5 −10 6 s −1 ) are comparable to state of the art phosphorescent emitters with noble metals such as Ir and Pt. All complexes show strong solvatochromism due to the large dipole moment of the ground states and the transition dipole moment that is in the opposite direction. Temperature-dependent studies of (MAC*)Cu(Cz) reveal a small energy separation between the lowest singlet and triplet states (ΔE S 1 −T 1 = 500 cm −1 ) and an exceptionally large zero-field splitting (ZFS = 85 cm −1 ). Organic light-emitting diodes (OLEDs) fabricated with (MAC*)Cu(Cz) as a green emissive dopant have high external quantum efficiencies (EQE = 19.4%) and brightness of 54 000 cd/m 2 with modest roll-off at high currents. The complex can also serve as a neat emissive layer to make highly efficient OLEDs (EQE = 16.3%).

Measuring extracellular dopamine in the brain of living animals by means of microdialysis and/or voltammetry is a route towards understanding both normal brain function and pathology. Previous reports, however, suggest that the tissue response to implantation of devices may affect the outcome of the measurements. To address the source of the tissue response and its impact on striatal dopamine systems microdialysis probes were placed in the striatum of anesthetized rats. Images obtained by dual-label fluorescence microscopy show signs of ischemia and opening of the blood-brain barrier near the probe tracks. Opening of the blood-brain barrier was further examined by determining dialysate concentrations of carbi-DOPA, a drug that normally does not penetrate the brain. Although carbi-DOPA was recovered in brain dialysate, it did not alter dialysate dopamine levels or evoked dopamine release as measured by voltammetry near the probes. Microdialysis probes also significantly diminished the effect of intrastriatal infusion of kynurenate on extracellular dopamine levels as measured by voltammetry near the probes.

Pepsin was immobilized on ethyl-bridged hybrid (BEH) particles and digestion performance was evaluated in a completely online format, with the specific intent of using the particles for hydrogen deuterium exchange mass spectrometry (HDX MS) experiments. Because the BEH particles are mechanically strong, they could withstand prolonged, continuous high-pressure at 10,000 psi. Online digestion was performed under isobaric conditions with continuous solvent flow, in contrast to other approaches where the pressure or flow is cycled. As expected, digestion efficiency at 10,000 psi was increased and reproducibly produced more peptic peptides versus digestion at 1,000 psi. Prototype columns made with the BEH pepsin particles exhibited robust performance and deuterium back-exchange was similar to that of other immobilized pepsin particles. These particles can be easily incorporated in existing HDX MS workflows to provide more peptide coverage in experiments where fast, efficient, and reproducible online pepsin digestion is desired.