6,6'-Biindeno[1,2-]fluorene: an open-shell indenofluorene dimer.

Nakano reported that the antiaromatic indenofluorene (IF) isomers are diradicaloid molecules having varying degrees of open-shell character, with indeno[1,2-]fluorene displaying a weaker diradical character index ( = 0.072). Unlike 6,12-trimethylsilylethynyl disubstituted [1,2-]IF, the 6,12-aryl disubstituted [1,2-]IF derivatives did not show any experimental evidence of diradical properties.

Light-induced reversible switching of generation and extinction of an organic radical anion.

Radicals play a crucial role across various domains, ranging from serving as catalysts in chemical reactions to materials for spintronic applications. Currently, a major challenge for the chemists is the development of the next generation of organic radicals controllable by photons. To tackle this challenge, here we introduce a dyad system that combines a dimethyldihydropyrene (DHP) photochromic unit with a naphthalene diimide (NDI) moiety.

Cyano disubstituted tetrabenzoindeno[2,1-]fluorene: open-shell or closed-shell?

Organic diradicaloids have lately emerged as potential spintronic materials. We report the unprecedented synthesis of a near-IR absorbing indeno[2,1-]fluorene derivative that displays remarkably low LUMO (-4.15 eV) and a small HOMO-LUMO gap (0.

Stable Diradical on the Dimethyldihydropyrene Scaffold.

The diradical character in a molecular architecture can be customized primarily in two ways: first, by employing a quinoidal pro-aromatic system with net energy gained by aromatization that compensates for the energy required to generate the diradical species and, second, by employing an antiaromatic system having easily accessible triplet states that impart a diradical character. We have chosen a 14π aromatic framework, Boekelheide's dimethyldihydropyrene, and perturbed its aromaticity through the construction of its quinoidal form. The perturbed aromaticity was evident from the bond alteration in the X-ray diffraction structure, H nuclear magnetic resonance chemical shifts, and quantum chemical calculations.

Detection of Sialic Acid and Imaging of Cell-Surface Glycan Using a Fluorescence-SERS Dual Probe.

Sialic acid (SA) is an acidic monosaccharide present in the human brain and body fluids in the form of -acetylneuraminic acid. It is also a well-known cancer biomarker. For decades, it has remained a challenging task to design synthetic receptors for SA.

Highly Selective and Quantitative Point-of-Care Diagnostic Method for Adrenaline.

Adrenaline, also known as epinephrine, is a neurotransmitter/hormone that is an important target in diagnostics. Development of an effective method for detecting it in the presence of other neurotransmitters is a challenging task. The electrochemical and fluorescent techniques commonly used have low selectivity in distinguishing among catecholamines.

Mimicking the Energy Funnel of the Photosynthetic Unit Using a Dendrimer-Dye Supramolecular Assembly.

Photosynthesis involves light-harvesting complexes where an array of antenna pigment channels the absorbed solar energy to the reaction centre of a photosystem. This work reports a supramolecular dendrimer-dye assembly that mimics the natural light-harvesting mechanism. A dendrimeric molecule based on two-fluorophores has been constructed with three coumarin units at the end of three long arms and a 7-diethylaminocoumarin unit at the interior.

A naphthalimide-linked new pyridylazo phenol derivative for selective sensing of cyanide ions (CN) in sol-gel medium.

Napthalimide-linked pyridylazo derivatives 1 and 2 have been designed and synthesized. Compound 1 acts as a gelator in DMF-HO (1 : 1, v/v). The brown gel is photostable and shows good viscoelastic properties.

Live-cell imaging of lipid droplets using solvatochromic coumarin derivatives.

Lipid droplets (LDs), the lipid-rich intracellular organelles, serve to regulate many physiological processes and therefore attention has been attracted towards their selective detection. We report positively solvatochromic lipophilic dyes, based on the push-pull framework containing coumarin-pyridine heterocycles for selective live-cell imaging of lipid droplets (LDs) in Cos-7 and McA-RH7777 cells at ultralow concentrations (200 nM). The fluorescent probes show a remarkable increase in fluorescence intensity with time with the hydrophobic core of the lipid droplets contributing to the observed intensity enhancement.

Superior Resonant Nanocavities Engineering on the Photonic Crystal-Coupled Emission Platform for the Detection of Femtomolar Iodide and Zeptomolar Cortisol.

Although luminescence spectroscopy has been a promising sensing technology with widespread applications in point-of-care diagnostics and chem-bio detection, it fundamentally suffers from low signal collection efficiency, considerable background noise, poor photostability, and intrinsic omnidirectional emission properties. In this regard, surface plasmon-coupled emission, a versatile plasmon-enhanced detection platform with >50% signal collection efficiency, high directionality, and polarization has previously been explored to amplify the limit of detection of desired analytes. However, high Ohmic loss in metal-dependent plasmonic platforms has remained an inevitable challenge.

Aggregation-Induced Emission and Organogels with Chiral and Racemic Pyrene-Substituted Cyanostyrenes.

The synthesis, photophysical investigations, and organogel formation of pyrene-phenyl acrylonitriles (-) bearing mono-, di-, and trichiral and racemic substitutions were studied. The molecules self-assemble in water and show remarkable emission wavelength and intensity changes associated with distinct color changes. Cryo-scanning electron microscopy (Cryo-SEM) images show the formation of uniform nanoaggregates for the monosubstituted derivatives and network-like structures for di- and trisubstituted derivatives.

A "turn-off" red-emitting fluorophore for nanomolar detection of heparin.

A simple fluorophore bearing a diethylaminocoumarin donor and a pyridinium acceptor was synthesized and utilized for the ultra-sensitive detection of heparin. The synthesized dicationic push-pull coumarin derivative emits strongly in the red-region (665 nm) and detects nanomolar concentrations (14.8 nM to 148 nM) of heparin in HEPES buffer and FBS serum solutions.