Rational Design, Green Synthesis, and Initial Evaluation of a Series of Full-Color Tunable Fluorescent Dyes Enabled by the Copper-Catalyzed N-Arylation of 6-Phenyl Pyridazinones and Their Application in Cell Imaging

Construction of a Near-Infrared Fluorescent Probe for Dynamic Monitoring and Early Diagnosis of Heart Failure

Cardiac hypertrophy characterized by abnormal cardiomyocyte viscosity is a typical sign of heart failure (HF) with vital importance for early diagnosis. However, current biochemical and imaging diagnostic methods are unable to detect this subclinical manifestation. In this work, we developed a series of NIR-I fluorescence probes for detecting myocardial viscosity based on the pyridazinone scaffold. The probes showed weak fluorescence due to free intramolecular rotation under low-viscosity conditions, while they displayed strong fluorescence with limited intramolecular rotation in response to a high-viscosity environment. Among them, CarVis2 exhibited higher stability and photobleaching resistance than commercial dyes. Its specific response to viscosity was not influenced by the pH and biological species. Furthermore, CarVis2 showed rapid and accurate responses to the viscosity of isoproterenol (ISO)-treated H9C2 cardiomyocytes with good biocompatibility. More importantly, CarVis2 demonstrated excellent sensitivity in monitoring myocardial viscosity variation in HF mice in vivo, potentially enabling earlier noninvasive identification of myocardial abnormalities compared to traditional clinical imaging and biomarkers. These findings revealed that CarVis2 can serve as a powerful tool to monitor myocardial viscosity, providing the potential to advance insights into a pathophysiological mechanism and offering a new reference strategy for early visual diagnosis of HF.

Photoinduced electron transfer (PeT) based fluorescent probes for cellular imaging and disease therapy

Typical PeT-based fluorescent probes are multi-component systems where a fluorophore is connected to a recognition/activating group by an unconjugated linker. PeT-based fluorescent probes are powerful tools for cell imaging and disease diagnosis due to their low fluorescence background and significant fluorescence enhancement towards the target. This review provides research progress towards PeT-based fluorescent probes that target cell polarity, pH and biological species (reactive oxygen species, biothiols, biomacromolecules, etc.) over the last five years. In particular, we emphasise the molecular design strategies, mechanisms, and application of these probes. As such, this review aims to provide guidance and to enable researchers to develop new and improved PeT-based fluorescent probes, as well as promoting the use of PeT-based systems for sensing, imaging, and disease therapy.

ANALYSIS OF THE SPECTRAL-LUMINESCENT PROPERTIES OF IMIDAZO[1,2-b]PYRIDO[4,3-e][1,2,4]TRIAZIN-6(7Н)-ONES

The article presents a method for the construction of a new tricyclic system of imidazo[1,2-b]pyrido[4,3-e][1,2,4]triazin-6(7Н)-ones based on subsequent reactions of the obtained 1,2-diamino-4-phenylimidazole ethyl ether of 3-methyl-6-phenylimidazo[1,2-b][1,2,4]triazin-2-carboxylic acid with dimethylformamide dimethylacetal and primary amines. The structures of the obtained compounds were confirmed using the data obtained by ¹ Н and ¹³ С NMR, HRMS, and XRD. We analysed the dependence of the absorption and photoluminescence spectra on the structure of the compounds obtained using methods of quantum chemistry. The theoretical results were compared to the data of a real experiment. The article suggests a range of practical applications for imidazo[1,2-b]pyrido[4,3-e][1,2,4]triazin-6(7Н)-ones.

Early Diagnosis of Cerebral Ischemia Reperfusion Injury and Revelation of Its Regional Development by a H3R Receptor-Directed Probe

In vivo imaging of cerebral hydrogen peroxide (H2O2) may facilitate early diagnosis of cerebral ischemia reperfusion injury (CIRI) and a revelation of its pathological progression. In this study, we report our rational design of a brain-targeting fluorescent probe using the basis of a pyridazinone scaffold. A structure-activity relationship study reveals that PCAB is the best candidate (K_i = 15.8 nM) for a histamine H3 receptor (H3R), which is highly expressed in neurons of the central nervous system. As a two-photon fluorescent probe, PCAB exhibits a fast, selective reaction toward both extra- and intracellular H2O2 in SH-SY5Y cells under oxygen glucose deprivation and resupply. In vivo fluorescent imaging of a middle cerebral artery occlusion mouse confirms that PCAB is an ultrasensitive probe with potent blood-brain barrier penetration, precise brain targeting, and fast detection of CIRI.

Phthalazinone Scaffold: Emerging Tool in the Development of Target Based Novel Anticancer Agents

Phthalazinones are important nitrogen-rich heterocyclic compounds which have been a topic of considerable medicinal interest because of their diversified pharmacological activities. This versatile scaffold forms a common structural feature for many bioactive compounds, which leads to the design and development of novel anticancer drugs with fruitful results. The current review article discusses the progressive development of novel phthalazinone analogues that are targets for various receptors such as PARP, EGFR, VEGFR-2, Aurora kinase, Proteasome, Hedgehog pathway, DNA topoisomerase and P-glycoprotein. It describes mechanistic insights into the anticancer properties of phthalazinone derivatives and also highlights various simple and economical techniques for the synthesis of phthalazinones.

Development of novel proteasome inhibitors based on phthalazinone scaffold

In this study we designed a series of proteasome inhibitors using pyridazinone as initial scaffold, and extended the structure with rational design by computer aided drug design (CADD). Two different synthetic routes were explored and the biological evaluation of the phthalazinone derivatives was investigated. Most importantly, electron positive triphenylphosphine group was first introduced in the structure of proteasome inhibitors and potent inhibition was achieved. As 6c was the most potent inhibitor of proteasome, we examined the structure-activity relationship (SAR) of 6c analogs.

Competition and cooperativity of σ-hole and π-hole intermolecular interactions between carbon monoxide and bromopentafluorobenzene

The electronic complementary relationship between C₆F₅Br and CO enables them to interact with each other via σ-hole and π-hole intermolecular interactions.

Lanthanide coordination polymers constructed from 5-(1H-tetrazol-5-yl)isophthalic acid ligand: white light emission and color tuning

A series of lanthanide coordination polymers (LnCPs), namely [Ln(TZI) (H₂O)₅]_n(1–5) [Ln = Nd (1), Eu (2), Gd (3), Tb (4) and Sm (5)], were synthesized through the self-assembly of 5-(1H-tetrazol-5-yl)isophthalic acid (H₃TZI) ligand and lanthanide ions.

Synthesis of substituted quinolines via allylic amination and intramolecular Heck-coupling

A new catalytic approach for the synthesis of substituted quinolines via C-N and C-C bond formation using 2-haloaryl hydroxylamines and allylic C-H substrates is described. Fe-catalyzed allylic C-H amination followed by Pd-catalyzed intramolecular Heck-coupling and aerobic dehydrogenation deliver the valuable quinoline and naphthyridine heterocycles in good to excellent overall yields. In this process, Pd(OAc)2 plays a dual role in catalyzing Heck coupling as well as aerobic dehydrogenation of dihydroquinolines.

A new mild synthetic route to N-arylated pyridazinones from aryldiazonium salts

A mild method to synthesise N-arylated pyridazinones is described and its mechanism unravelled by DFT calculations and experimental techniques.

Towards full-color-tunable emission of two component Eu(iii)-doped Gd(iii) coordination frameworks by the variation of excitation light

Eu(iii)-doped Gd(iii) pyrazine-2,3,5,6-tetracarboxylate alkali–lanthanide metal–organic frameworks (LnMOF) with a unique (4¹¹·6⁸·8²)(4³·6²·8)(4³) topology present full color-tunable luminescence and white emission by the variation of excitation wavelengths.