Temperature-Dependent Spin-Driven Dimerization Determines the Ultrafast Dynamics of a Copper(II)-Bound Tripyrrindione Radical.

Radicals and other open-shell molecules play a central role in chemical transformations and redox chemistry. While radicals are often highly reactive, stable radical systems are desirable for a range of potential applications, ranging from materials chemistry and catalysis to spintronics and quantum information. Here we investigate the ultrafast properties of a stable radical system with temperature-dependent spin-tunable properties.

Time-resolved dynamics of stable open- and closed-shell neutral radical and oxidized tripyrrindione complexes.

Stable open- and closed-shell Pd(II) and Cu(II) complexes of hexaethyl tripyrrin-1,14-dione (TD1) produce triplet, doublet or singlet states depending on the metal center and the redox state of the ligand. Pd(II) and Cu(II) form neutral TD1 complexes featuring ligand-based radicals, thus resulting in doublet and triplet states, respectively. The reversible one-electron oxidation of the complexes removes an unpaired electron from the ligand, generating singlet and doublet states.

Perception of Primary School Teachers Towards Voice Problems and Vocal Health-Seeking Behaviors: A qualitative study.

Objective: Teachers are the most common occupational group reporting to the voice clinics with dysphonia across the globe. However, less is known about teachers' perceptions about their voice and voice problems. Hence the present study aimed to explore teachers' perception about their teaching voice, voice problems and vocal health-seeking behaviors.

Manual Anesthesia Record Keeping at a Tertiary Care Center: A Descriptive Cross-sectional Study.

Introduction: Intraoperative record form is one of the cardinal parts of anesthesia practices. Ideally, it should contain complete information about patients under anesthesia and intraoperative events. It serves as valuable information for subsequent patient management, research, or during medicolegal conditions.

Using X-ray Diffraction Techniques for Biomimetic Drug Development, Formulation, and Polymorphic Characterization.

Drug development is a decades-long, multibillion dollar investment that often limits itself. To decrease the time to drug approval, efforts are focused on drug targets and drug formulation for optimal biocompatibility and efficacy. X-ray structural characterization approaches have catalyzed the drug discovery and design process.

Ultrafast Dynamics of Tripyrrindiones in Solution Mediated by Hydrogen-Bonding Interactions.

The optical properties and ultrafast dynamics of hexaethyl tripyrrin-1,14-dione (HTD1) are tuned by hydrogen-bonding interactions between the solute and the solvent. In solvents with low hydrogen-bonding affinity, HTD1 preferentially forms hydrogen-bonded dimers, whereas in solvents that can either donate or accept hydrogen bonds HTD1 is present as a monomer. The distinction between dimer and monomer determines the dynamics of the system, with faster internal conversion observed in the dimer form.

Ghrelin Receptor Influence on Cocaine Reward is Not Directly Dependent on Peripheral Acyl-Ghrelin.

The peptide hormone acyl-ghrelin and its receptor, GHSR, represent intriguing therapeutic targets due to their actions in metabolic homeostasis and reward activity. However, this pleotropic activity makes it difficult to intervene in this system without inducing unwanted effects. Thus, it is desirable to identify passive and active regulatory mechanisms that allow differentiation between functional domains.

Paramagnetism and Fluorescence of Zinc(II) Tripyrrindione: A Luminescent Radical Based on a Redox-Active Biopyrrin.

The ability of bilins and other biopyrrins to form fluorescent zinc complexes has been known for more than a century; however, the exact identity of the emissive species remains uncertain in many cases. Herein, we characterize the hitherto elusive zinc complex of tripyrrin-1,14-dione, an analogue of several orange urinary pigments. As previously observed for its Pd(II), Cu(II), and Ni(II) complexes, tripyrrindione binds Zn(II) as a dianionic radical and forms a paramagnetic complex carrying an unpaired electron on the ligand π-system.

Synthetic molecules for disruption of the MYC protein-protein interface.

MYC is a key transcriptional regulator involved in cellular proliferation and has established roles in transcriptional elongation and initiation, microRNA regulation, apoptosis, and pluripotency. Despite this prevalence, functional chemical probes of MYC function at the protein level have been limited. Previously, we discovered 5a, that binds to MYC with potency and specificity, downregulates the transcriptional activities of MYC and shows efficacy in vivo.

Peptide-Based Fluorescent Probes for Deacetylase and Decrotonylase Activity: Toward a General Platform for Real-Time Detection of Lysine Deacylation.

Histone deacetylases regulate the acetylation levels of numerous proteins and play key roles in physiological processes and disease states. In addition to acetyl groups, deacetylases can remove other acyl modifications on lysines, the roles and regulation of which are far less understood. A peptide-based fluorescent probe for single-reagent, real-time detection of deacetylase activity that can be readily adapted for probing broader lysine deacylation, including decrotonylation, is reported.

Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers.

The ability of tetrapyrrolic macrocycles to stabilize unpaired electrons and engage in π-π interactions is essential for many electron-transfer processes in biology and materials engineering. Herein, we demonstrate that the formation of π dimers is recapitulated in complexes of a linear tripyrrolic analogue of naturally occurring pigments derived from heme decomposition. Hexaethyltripyrrindione (HTD1) coordinates divalent transition metals (i.

Metal-binding effects of sirtuin inhibitor sirtinol.

Sirtinol, a Schiff base derived from 2-hydroxy-1-naphthaldehyde, is an inhibitor of sirtuin proteins, a family of deacetylases active in gene regulation and relevant to the study of cancer growth. The formation of copper(II) and zinc(II) complexes of sirtinol is investigated by spectroscopic and structural methods. The molecular structure of this protein inhibitor allows for coordination of first-row transition metals in both tridentate and bidentate fashion.

Tripyrrindione as a Redox-Active Ligand: Palladium(II) Coordination in Three Redox States.

The tripyrrin-1,14-dione scaffold of urinary pigment uroerythrin coordinates divalent palladium as a planar tridentate ligand. Spectroscopic, structural and computational investigations reveal that the tripyrrindione ligand binds as a dianionic radical, and the resulting complex is stable at room temperature. One-electron oxidation and reduction reactions do not alter the planar coordination sphere of palladium(II) and lead to the isolation of two additional complexes presenting different redox states of the ligand framework.