Explore the vast range of titles available.

Inorganic metal halide perovskite system is considered as a promising candidate for applications from display to biomedical industry. Intrinsic inorganic lead halides possess small Stokes shift or self‐absorption, providing negative impact for both photo voltaic and biomedical applications. Therefore, the development of an inorganic halide perovskite system with large Stokes shift is a significant venture. This review aims to provide an updated survey of the Stokes shift phenomena in the inorganic lead halide perovskites. The first section focuses about the mechanism, the second section gives different approaches in preparing inorganic perovskites with distinct Stokes shift, while the third section highlights the potential applications in both photovoltaic and biomedical areas. This review provides deep insight about the importance and usefulness of such phenomena in inorganic lead halides, essential for various applications. Inorganic metal halide perovskites are considered as promising candidates for a number of applications in both display and medical industries. The mechanism of Stokes Shift plays a significant role in controlling the issue of reabsorption in many systems. So, the system of inorganic halide perovskites with the mechanism of Stokes shift is in highly demand in getting enhanced benefits.

Solvatofluorochromic molecules provide strikingly high fluorescent outputs to monitor a wide range of biological, environmental, or materials‐related sensing processes. Here, thiazolo[5,4‐d]thiazole (TTz) fluorophores equipped with simple alkylamino and nitrophenyl substituents for solid‐state, high‐performance chemo‐responsive sensing applications are reported. Nitroaromatic substituents are known to strongly quench dye fluorescence, however, the TTz core subtly modulates intramolecular charge transfer (ICT) enabling strong, locally excited‐state fluorescence in non‐polar conditions. In polar media, a planar ICT excited‐state shows near complete quenching, enabling a twisted excited‐state emission to be observed. These unique fluorescent properties (spectral shifts of 0.13 – 0.87 eV and large transition dipole moments Δµ = 20.4 – 21.3 D) are leveraged to develop highly sought‐after chemo‐responsive, organic vapor optical sensors. The sensors are developed by embedding the TTz fluorophores within a poly(styrene‐isoprene‐styrene) block copolymer to form fluorescent dye/polymer composites (ΦF = 70 – 97%). The composites respond reversibly to a comprehensive list of organic solvents and show low vapor concentration sensing (e.g., 0.04% solvent saturation vapor pressure of THF – 66 ppm). The composite films can distinguish between solvent vapors with near complete fluorescent quenching observed when exposed to their saturated solvent vapor pressures, making this an extremely promising material for optical chemo‐responsive sensing. Thiazolo[5,4‐5]thiazole push‐pull fluorophores with nitrophenyl substituents demonstrate unique dual fluorescence properties and strong solvatofluorochromism. The high‐performance dyes are embedded in a block copolymer and utilized in a solid‐state, solvent vapor optical sensing application. TTz/polymer sensors show reversible, low‐concentration vapor sensing, and the ability to distinguish between different organic vapors.

Solution-processed OLEDs offer a promising and affordable technology for solid-state lighting and superior self-luminous display panels. Herein, an imidazo[1,5-a]pyridine (ImPy)-based fluorophore decorated with an aromatic π-system anthracene is synthesized by a one-pot condensation approach. From the theoretical study, the energy difference between HOMO and LUMO is 3.1 eV. The molecule shows excellent thermal stability and electrochemical stability. It exhibits efficient intramolecular charge transfer and displays a positive solvatochromic photoluminescence emission band ranging from 528 nm in hexane to 586 nm in acetonitrile with large Stokes' shift of ∼11,000 cm −1 . The OLEDs made of this emitter displayed good device performance with luminous efficiency of 4.4 cd A -1 , power efficiency of 2.2 lm W -1 and external quantum efficiency of 3.2%. Additionally, this OLED emitted greenish-yellow light with CIE coordinate (0.34, 0.45) and possessed a low turn-on voltage of 7 V. The material also used in white LED fabrication and the fabricated white LED displayed an excellent color rendering index (CRI), the luminous efficiency of radiation (LER), and correlated color temperatures (CCT) of 89328 lm W -1 , and 4907 K, respectively with CIE coordinate (0.35,0.32).

Organic dyes generally suffer from small Stokes shift that usually leads to self‐quenching and ‐gaining errors during the fluorescent imaging process. Here, a through‐bond energy transfer (TBET) cassette is developed with large Stokes shift to pursue precise cell imaging. The TBET is constructed by covalently conjugated tetraphenylethene (acts as donor) and rhodamine (acceptor) through an acetylene bond. The constructed TBET cassette distinctly behaves as dual‐Stokes shifts, including a large pseudo‐Stokes shift caused by energy transfer, from donor's absorption to acceptor's emission (up to 260 nm) and a smaller Stokes shift of acceptor molecules itself. Due to the intrinsic dual‐Stokes shifts, TBET cassette exhibits specific “dual distinct absorbances, single shared emission” properties, which can be excitated under two different laser channels. By colocalization of the imaging readouts of these two channels, the precisely “double checked” fluorescent imaging is achieved in living cells. A through‐bond energy transfer (TBET) cassette is constructed with intrinsically “dual distinct absorbances, single shared emission” properties and realized precisely, “double checked” fluorescent imaging in living cells.

Finding narrow‐band, ultrapure blue thermally activated delayed fluorescence (TADF) materials is extremely important for developing highly efficient organic light‐emitting diodes (OLEDs). Here, spin–vibronic coupling (SVC)‐assisted ultrapure blue emitters obtained by joining two carbazole‐derived moieties at a para position of a phenyl unit and performing substitutions using several blocking groups are presented. Despite a relatively large singlet–triplet gap (∆EST) of >0.2 eV, efficient triplet‐to‐singlet crossover can be realized, with assistance from resonant SVC. To enhance the spin crossover, electronic energy levels are fine‐tuned, thereby causing ∆EST to be in resonance with a triplet–triplet gap (∆ETT). A sizable population transfer between spin multiplicities (>103 s−1) is achieved, and this result agrees well with theoretical predictions. An OLED fabricated using a multiple‐resonance‐type SVC‐TADF emitter with CIE color coordinates of (0.15, 0.05) exhibits ultrapure blue emissions, with a narrow full‐width‐at‐half‐maximum of 21 nm and a high external quantum efficiency of 23.1%. Spin‐vibronic coupling assisted ultrapure blue emitters demonstrate high external quantum efficiency of 23.1%, color coordinate of (0.15,0.05) and small full width at half maximum of 21 nm.

The enzyme soybean lipoxygenase (SLO) provides a prototype for deep tunneling mechanisms in hydrogen transfer catalysis. This work combines room temperature X-ray studies with extended hydrogen—deuterium exchange experiments to define a catalytically- linked, radiating cone of aliphatic side chains that connects an active site iron center of SLO to the protein—solvent interface. Employing eight variants of SLO that have been appended with a fluorescent probe at the identified surface loop, nanosecond fluorescence Stokes shifts have been measured. We report a remarkable identity of the energies of activation (Eₐ) for the Stokes shifts decay rates and the millisecond C—H bond cleavage step that is restricted to side chain mutants within an identified thermal network. These findings implicate a direct coupling of distal protein motions surrounding the exposed fluorescent probe to active site motions controlling catalysis. While the role of dynamics in enzyme function has been predominantly attributed to a distributed protein conformational landscape, the presented data implicate a thermally initiated, cooperative protein reorganization that occurs on a timescale faster than nano-second and represents the enthalpic barrier to the reaction of SLO.

A chalcone series (3a–f) with electron push–pull effect was synthesized via a one-pot Claisen–Schmidt reaction with a simple purification step. The compounds exhibited strong emission, peaking around 512–567 nm with mega-stokes shift (∆λ = 93–139 nm) in polar solvents (DMSO, MeOH, and PBS) and showed good photo-stability. Therefore, 3a–f were applied in cellular imaging. After 3 h of incubation, green fluorescence was clearly brighter in cancer cells (HepG2) compared to normal cells (HEK-293), suggesting preferential accumulation in cancer cells. Moreover, all compounds exhibited higher cytotoxicity within 24 h toward cancer cells (IC50 values ranging from 45 to 100 μM) than normal cells (IC50 value >100 μM). Furthermore, the antimicrobial properties of chalcones 3a–f were investigated. Interestingly, 3a–f exhibited antibacterial activities against Escherichia coli and Staphylococcus aureus, with minimum bactericidal concentrations (MBC) of 0.10–0.60 mg/mL (375–1000 µM), suggesting their potential antibacterial activity against both Gram-negative and Gram-positive bacteria. Thus, this series of chalcone-derived fluorescent dyes with facile synthesis shows great potential for the development of antibiotics and cancer cell staining agents.

Imidazo[1,5-a]pyridine is a stable scaffold, widely used for the development of emissive compounds in many application fields (e.g., optoelectronics, coordination chemistry, sensors, chemical biology). Their compact shape along with remarkable photophysical properties make them suitable candidates as cell membrane probes. The study of the membrane dynamics, hydration, and fluidity is of importance to monitor the cellular health and to explore crucial biochemical pathways. In this context, five imidazo[1,5-a]pyridine-based fluorophores were synthesized according to a one-pot cyclization between an aromatic ketone and benzaldehyde in the presence of ammonium acetate and acetic acid. The photophysical features of prepared compounds were investigated in several organic solvents and probes 2–4 exhibited the greatest solvatochromic behavior, resulting in a higher suitability as membrane probes. Their interaction with liposomes as artificial membrane model was tested showing a successful intercalation of the probes in the lipid bilayer. Kinetic experiments were carried out and the lipidic phase influence on the photophysical features was evaluated through temperature-dependent experiments. The results herein reported encourage further investigations on the use of imidazo[1,5-a]pyridine scaffold as fluorescent membrane probes.

A series of novel styrylquinolines with the benzylidene imine moiety were synthesized and spectroscopically characterized for their applicability in cellular staining. The spectroscopic study revealed absorption in the ultraviolet–visible region (360–380 nm) and emission that covered the blue-green range of the light (above 500 nm). The fluorescence quantum yields were also determined, which amounted to 0.079 in the best-case scenario. The structural features that are behind these values are also discussed. An analysis of the spectroscopic properties and the theoretical calculations indicated the charge-transfer character of an emission, which was additionally evaluated using the Lippert–Mataga equation. Changes in geometry in the ground and excited states, which had a significant influence on the emission process, are also discussed. Additionally, the capability of the newly synthesized compounds for cellular staining was also investigated. These small molecules could effectively penetrate through the cellular membrane. Analyses of the images that were obtained with several of the tested styrylquinolines indicated their accumulation in organelles such as the mitochondria and the endoplasmic reticulum.

In this review, we present a systematic and comprehensive summary of the recent developments in the synthetic strategies of 2-(2-hydroxyarylsubstituted)-benzothiazole (HBT) framework along with incorporation of various substituents on phenolic and benzothiazole rings which affect the emission process. The literature, spanning the years 2015–2024, on excited-state intramolecular proton transfer (ESIPT)-based studies of HBT derivatives comprising the effects of solvent polarity, substituents, and extended conjugation on fluorophores has been searched. ESIPT, intramolecular charge transfer, and aggregation-induced emissions enable these fluorescent probes to specifically interact with analytes, thereby altering their luminescence characteristics to achieve analyte detection. These fluorescent probes exhibit large Stokes shifts, high quantum yields, and excellent color transitions. Finally, the applications of HBTs as ESIPT-based fluorescent probes for the detection of cations, anions, and biomolecules have been summarized. We anticipate that this review will provide a comprehensive overview of the current state of research in this field and encourage researchers to develop novel ESIPT-based fluorophores with new applications.