Leveraging Intramolecular π-Stacking to Access an Exceptionally Long-Lived MC Excited State in an Fe(II) Carbene Complex.

The ability to manipulate excited-state decay cascades using molecular structure is essential to the application of abundant-metal photosensitizers and chromophores. Ligand design has yielded some spectacular results elongating charge-transfer excited state lifetimes of Fe(II) coordination complexes, but triplet metal-centered (MC) excited states─recently demonstrated to be critical to the photoactivity of isoelectronic Co(III) polypyridyls─have to date remained elusive, with temporally isolable examples limited to the picosecond regime. With this report, we show how strong-field donors and intramolecular π-stacking can conspire to stabilize a long-lived MC excited state for a remarkable 4.

Site-Selective Ligand Functionalization Reverses Hypsochromic Luminescence Shifts in Platinum(II) Complexes of Benzannulated NCN-Coordinating Ligands.

Ligands containing phenanthridine (benzo[c]quinoline) have presented notable exceptions to the conventional logic that increasing ligand benzannulation leads to bathochromic (red) shifts in the absorption and emission of their coordination complexes. The counterintuitive blue shifts have been attributed to the peculiar structure of phenanthridines, whose ground states are dominated by imine-bridged biphenyl resonance contributors. These serve to isolate the C=N unit electronically from the rest of the ligand framework and allow the C=N moiety to act as a 'shock-absorber', buffering against larger molecular distortions in a molecule's excited state, and reducing the observed pseudo-Stokes' shift.

Time-Resolved X-ray Emission Spectroscopy and Synthetic High-Spin Model Complexes Resolve Ambiguities in Excited-State Assignments of Transition-Metal Chromophores: A Case Study of Fe-Amido Complexes.

To fully harness the potential of abundant metal coordination complex photosensitizers, a detailed understanding of the molecular properties that dictate and control the electronic excited-state population dynamics initiated by light absorption is critical. In the absence of detectable luminescence, optical transient absorption (TA) spectroscopy is the most widely employed method for interpreting electron redistribution in such excited states, particularly for those with a charge-transfer character. The assignment of excited-state TA spectral features often relies on spectroelectrochemical measurements, where the transient absorption spectrum generated by a metal-to-ligand charge-transfer (MLCT) electronic excited state, for instance, can be approximated using steady-state spectra generated by electrochemical ligand reduction and metal oxidation and accounting for the loss of absorptions by the electronic ground state.

Switching on emission in Zn(II) coordination complexes by tempering N character.

A series of four-coordinate zinc(II) complexes is presented in which the amido . imino character of a ligated nitrogen donor correlates to the luminescence intensity. DFT analysis points to a distinct mechanism for this trend wherein emission can be switched on by restricting non-radiative decay pathways through the resonance-induced delocalization of amido ligand lone-pairs.

Donor-Acceptor Boron-Ketoiminate Complexes with Pendent -Heterocyclic Arms: Switched-on Luminescence through -Heterocycle Methylation.

A series of intramolecular, donor-stabilized BF complexes supported by phenanthridinyl-decorated, β-ketoiminate chelating ligand scaffolds is described, along with their characterization by spectroscopy and X-ray diffraction. In solution, the relative orientation of the pendent phenanthridinyl arm is fixed despite not coordinating to the boron center, and a well-resolved through-space interaction between a phenanthridinyl C-H and a single fluorine atom can be observed by F-H NOE NMR spectroscopy. The neutral compounds are nonetheless only weakly luminescent in fluid solution, ascribed to nonradiative decay pathways enabled by rotation of the -heterocyclic unit.

Brightly Luminescent Platinum Complexes of Ligands Forming Six-Membered Chelate Rings: Offsetting Deleterious Ring Size Effects Using Site-Selective Benzannulation.

Brightly emissive platinum(II) complexes (λ = 607-612 nm) of the type PtCl are reported, where is a cyclometalated -coordinating ligand derived from 1,3-di(2-trifluoromethyl-4-phenanthridinyl)benzene () or 1,3-di(2--butyl-4-phenanthridinyl)benzene (). Metathesis of the chlorido ligand can be achieved under mild conditions, enabling isolation of ionic compounds with the formula [PtL']PF where L' = pyridine or (4-dimethylamino)pyridine (DMAP), as well as the charge-neutral species Pt(C≡C─CH─Bu) (C≡C─CH─Bu = 4--butylphenylacetylido). Compared with -ligated Pt(II) complexes that form 5-membered chelates, these compounds all contain 6-membered rings.

(8-Amino)quinoline and (4-Amino)phenanthridine Complexes of Re(CO) Halides.

In this report, we present a study on the synthesis, structure, and electronics of a series of (8-amino)quinoline and (4-amino)phenanthridine complexes of Re(CO)X, where X = Cl and Br. In all cases, the (amino)heterocycles bind as bidentate ligands, with surprisingly symmetric modes of binding based on Re-N bond lengths. Between the complexes of (8-amino)quinolines and (4-amino)phenanthridines studied in this report, we do not observe much structural variation, and remarkably similar UV-visible absorption spectra.

A Systematic Review on the Effectiveness of Active Recovery Interventions on Athletic Performance of Professional-, Collegiate-, and Competitive-Level Adult Athletes.

Ortiz Jr, RO, Sinclair Elder, AJ, Elder, CL, and Dawes, JJ. A systematic review on the effectiveness of active recovery interventions on athletic performance of professional-, collegiate-, and competitive-level adult athletes. J Strength Cond Res 33(8): 2275-2287, 2019-Active recovery (AR) is a popular approach to enhancing athlete recovery from participation through physical action, and it has a perceived benefit in the recovery of athletes' enhancement of postexertional physiological status; however, it is unclear whether these recovery techniques enhance athletic performance.

Modeling the pharmacokinetic-pharmacodynamic relationship of the monoclonal anti-macaque-IL-15 antibody Hu714MuXHu in cynomolgus monkeys.

Hu714MuXHu is a recombinant chimeric murine-human monoclonal antibody directed against interleukin-15 (IL-15), a proinflammatory cytokine associated with memory CD8+ and natural killer (NK) T-cell activation and implicated in the pathogenesis of inflammatory diseases. A pharmacokinetic-pharmacodynamic (PK/PD) model was developed to describe the NK cell count reduction in cynomolgus monkeys after treatment with Hu714MuXHu. Cynomolgus monkeys were dosed with Hu714MuXHu in three studies: as a single dose at 0.

Simultaneous analysis of multiple monoclonal antibody biotherapeutics by LC-MS/MS method in rat plasma following cassette-dosing.

We have recently developed a general liquid chromatography-tandem mass spectrometric (LC-MS/MS) method using a stable isotope-labeled (SIL) monoclonal antibody (mAb) as an internal standard (IS) for single-analyte quantification of mAb (Li et al. Anal Chem 84(3):1267-1273, 2012). The method offers an advantage over ligand binding assay in reducing the time and resources needed for bioanalytical support in preclinical stages of drug development.

General LC-MS/MS method approach to quantify therapeutic monoclonal antibodies using a common whole antibody internal standard with application to preclinical studies.

Ligand binding assays (LBAs) are widely used for therapeutic monoclonal antibody (mAb) quantification in biological samples. Major limitations are long method development times, reagent procurement, and matrix effects. LC-MS/MS methods using signature peptides are emerging as an alternative approach, which typically use a stable isotope labeled signature peptide as the internal standard (IS).

Ligand-binding mass spectrometry to study biotransformation of fusion protein drugs and guide immunoassay development: strategic approach and application to peptibodies targeting the thrombopoietin receptor.

The knowledge of in vivo biotransformation (e.g., proteolysis) of protein therapeutic candidates reveals structural liabilities that impact stability.