ChemPhotoChem最新文献

There is a pressing need to develop fluorescent dyes with light emission peaks in the wavelength range of 650–950 nm for optical live-cell imaging applications. The advancement of fluorescent dyes with a large Stokes shift is imperative for their biological applications. A novel domino reaction is developed with success for the synthesis of diverse 9aH-benzoquinolizines in 65–95% yields through reaction of α-silylaryl triflates, pyridine derivatives, and activated alkynes at room temperature. This single-flask reaction involves completion of a 1,2-elimination, a 1,2-addition, and an intermolecular (4 + 2) cycloaddition in situ. Among 15 new products, diethyl 9aH-tribenzo[c,f,h]quinolizine-1,2-dicarboxylate with extension of π-conjugation is identified as the top-performing dye. It shows near-infrared fluorescent emission at 674 nm with the Stokes shift of 197 nm, ε_max = 5.62 × 10⁴M^–1cm^–1, Φ_fl = 15.2%, and τ_av = 10.1 ns. It also exhibits excellent photostability with only 4.97% decomposed under irradiation with an Hg lamp for 60 min. With a remarkable 96 ± 2% viability, minimal toxicity toward CT-26 cancer cells, and coupled with promising results from confocal microscopy, this 9aH-tribenzoquinolizine emerges as an ideal fluorescent dye for imaging live cells.

Ultrasensitive detection (LOD = 2 pM) of amyloid fibril is achieved using Pyridine 1 which exists as an ion-pair in water. A unique feature of amyloid-induced dissociation of this ion-pair and lack of hydrogen bonding inside the fibrillar grooves have been established to play a pivotal role for ultrasensitive colorimetric detection of amyloid fibrils. More information can be found in the Research Article by Aruna K. Mora, Sukhendu Nath, and co-workers (DOI: 10.1002/cptc.202400329).

Stimuli-responsive fluorescent materials are of great interest for sensing applications. Azulene-based molecular platforms feature a unique combination of optical, luminescence, and stimuli-responsive properties. In particular, they often display both pH- and excitation wavelength-dependent luminescent properties. Herein, the syntheses of two novel azulene derivatives 4-(azulen-2-yl)-N, N-dimethylaniline (1) and 4-(azulen-1-yl)-N, N-dimethylaniline (2) is presented via Suzuki–Miyaura cross coupling reactions. Combined experimental and theoretical investigations have been performed to elucidate the complex emissive properties exhibited by 4-(azulen-2-yl)-N, N-dimethylaniline and 4-(azulen-1-yl)-N, N-dimethylaniline, as well as those of their protonated forms. An in-depth understanding of their stimuli-responsive fluorescent properties is provided which is crucial for the future development of optical sensors.

Donor–acceptor systems are promising systems for applications in optoelectronics. The zwitterionic nature of betainoid pyridinium compounds allows a unique set of tunable electronic properties, but their rationalization remains challenging. Herein, the optical properties of a series of five derivatives are studied experimentally and computationally to unveil and rationalize their distinctive intramolecular charge transfer properties. These compounds consist of 4-functionalised-pyridine with H, tert-butyl, dimethylamino, trifluoroborate and oxo linked through their nitrogen atom to benzimidazole at its C2 position (1–5 respectively). The transitions responsible for the absorption and emission properties observed experimentally are investigated using density functional theory and time dependent-DFT. Calculated absorption energies systematically match the experimental λ_max, while the prediction of emission energy seems to be less straightforward. By use of the molecular orbitals, charge distribution evolution, change in electric dipole moment, and calculated vertical excitations, we are able to rationalize structure-properties relations involved in these transitions. This study allows us to gain insights into the optoelectronic properties of a series of unique donor–acceptor systems using computationally cost-effective methods.

Cyanostilbene derivatives constitute a variety of versatile molecular photoswitches and organic photofunctional materials, while prediction or control over their photochemical outcome represents yet a huge challenge. Here, in this work, two well-preorganized single molecular constrained bis-α-cyanostilbene derivatives 1,8-N-2CNS-C10 [1,8-naphthalene bis(decyloxy-α-cyanostilbene)] and 1,5-N-2CNS-C10 have been synthesized and fully characterized. Both 1,8-N-2CNS-C10 and 1,5-N-2CNS-C10 showed enantiotropic nematic liquid crystal (LC) mesophase and crystal polymorphism; more importantly, they exhibited distinct photophysical properties, especially the preorganization and condensed states-dependent varied photochemical reactions. Specifically, 1,8-N-2CNS-C10 in its U-shaped configuration in solution or molecular aggregates, the reversible intramolecular [2 + 2] photocycloaddition predominates, accompanied by characteristic fluorescence color and intensity modulation, which is promising for fluorescent photoswitch application. In the bulk nematic LC mesophase, mainly photopolymerization occurs through the intermolecular [2 + 2] cycloaddition reaction (irreversible); while in the crystalline solid state, the reaction efficiency is extremely low, in sharp contrast to the reported common nonliquid crystalline α-cyanostilbene derivatives, whereas for 1,5-N-2CNS-C10 in its extended but somewhat twisted stretching S-shaped configuration, in solution or aggregates, after a prerequisite Z/E photoisomerization, mainly photocyclization reactions occur. These findings provide valuable insights into the design of α-cyanostilbene-based multifunctional photoresponsive materials and offer an in-depth understanding of the underlying mechanisms of their varied photochemical reactions.

The selective oxidation of organic substances is today considered one of the greenest strategies to synthesize important starting materials in different technological applications. This study investigates the sono-enhanced selective oxidation of coniferyl alcohol, a lignin-based model compound, under visible light by integrating sonophotocatalysis in a continuous flow system. The process utilizes a CuBi₂O₄/TiO₂ heterostructure as photocatalyst which is prepared by a simple and low-cost method. The heterostructure demonstrates significant improvements in catalytic performance due to its effective charge separation and extended light absorption range with a conversion and selectivity of 92% and 46%, 30%, respectively, for coniferyl aldehyde and ferulic acid after 4 h under visible-light irradiation by using acetonitrile as the solvent. The synergistic combination effects of ultrasonic irradiation and photocatalysis are explored to enhance the efficiency and selectivity of the oxidation reaction with 54% conversion with significant selectivity of ferulic acid measured 65%. Additionally, the continuous flow setup offers advantages in scalability and operational stability, making this method a promising approach for sustainable biomass valorization. The results highlight the potential of combining sonication and photocatalysis to achieve efficient and selective chemical transformations in renewable energy and green chemistry applications, and specially contribute to the sustainable transformation of lignin-based compounds into high-value chemicals, aiding in the utilization of biomass.

The nanorod morphology of the wurtzite crystal structure generally exhibits coexistence of polar and nonpolar surfaces, which play a different function in the photoelectrochemical water splitting (PEC-WS). In this study, both polar c-surface-dominated InGaN nanorods (NRs) and nonpolar m-surface-dominated InGaN nanorods are successfully fabricated using halide chemical vapor deposition. Experimental observations combined with density functional theory calculations reveal that the absence of a polarization field on the nonpolar surface samples causes a greater bending of energy bands at the semiconductor/electrolyte interface compared to samples with mainly exposed polar surfaces. Furthermore, the nonpolar surfaces are prone to form gallium oxynitride, thereby resulting in the reduction of the energy barrier for the oxygen evolution reaction process. The nonpolar surfaces sample in the synergistic impact of the above two factors yields a photocurrent density 7.2 times greater than that of the polar surface sample at 1.23 V vs. reversible hydrogen electrode (RHE). Due to the attribute of the polarization field absence of the nonpolar surface, CuBi₂O₄ was selectively grown on the nonpolar surfaces of NRs, the photocurrent density of the CuBi₂O₄/InGaN composite sample reached 6.7 mA cm⁻². This study presents an innovative method to boost PEC-WS efficiency by adjusting crystalline facets.

New xylene-bridged naphthalene-based fluorescent chemosensing system consisting of two structurally homologous probes, OHN and MHN, is synthesized for the selective and sensitive sensing of Fe³⁺ ions in a MeOH:H₂O (1:1, v/v) 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer solution through fluorimetric analysis. Both probes are highly intrinsically fluorescent, which is greatly quenched after coordination with Fe³⁺ ions. The probe alone exhibits strong fluorescence emission. However, upon binding with Fe³⁺, a significant quenching of fluorescence is observed. This quenching can be attributed to three key mechanisms: i) inhibition of photoinduced electron transfer, ii) restriction of CO bond rotation, and iii) electron transfer facilitated by the paramagnetic nature of the Fe³⁺ ion. Job's plot analysis substantiates a 1:2 (ligand:metal) binding stoichiometry for both OHN and MHN to Fe³⁺ ions. The binding constants (Ksv) are calculated, and the complex formation is further confirmed by electrospray ionization time-of-flight mass spectrometry and density functional theory calculations. Both complexes display outstanding sensitivity, with detection limits in the picomolar range. The utility of these probes in a practical sense is showcased by a smartphone-based colorimetric assay by using the Color Grab app and utilized effectively for detection of Fe³⁺ ions detection in environmental and nutritional samples.

The rapid advancement of display technology is inseparable from organic light-emitting diodes (OLEDs). As a critical component of OLEDs, the performance of emissive materials in the emitting layer directly determines their developmental potential. In recent years, macrocyclic luminescent materials have garnered increasing attention due to their distinctive photophysical properties with unique cavities and 3D structures. As nonterminal counterparts of polymers, macrocyclic emitters can synergize with diverse luminescence mechanisms (e.g., fluorescence or thermally activated delayed fluorescence) to achieve highly efficient OLEDs. This review systematically examines recently reported macrocyclic systems, elucidating their emission mechanisms, key factors influencing photophysical and electronic performance, and provides design strategies for macrocyclic emitters.

This study reports thecharacterization and photophysical properties of 4-(diphenylamino)phenyl-ethynyl naphthalimide, which is synthesized via Sonogashira coupling reactions. This compound exhibits sensitive fluorogenic responses to solvent polarity and viscosity, with fluorescence intensities and quantum yields decreasing as solvent polarity increases. Computational calculations indicate a significant increase in the excited-state dipole moment when transitioning from toluene to dimethyl sulfoxide, suggesting enhanced stabilization in polar solvents. Additionally, fluorescence enhancement is observed in glycerol-ethanol mixtures, particularly at glycerol concentrations of 80% and above, where increased viscosity extends fluorescence lifetimes and reduces particle sizes. The compound also demonstrates low cytotoxicity, high biocompatibility, and selective lipid droplet affinity in live cells, enabling precise visualization of cellular viscosity changes. These findings highlight the potential of this dual-function fluorescent probe as a valuable tool for investigating the microenvironmental properties of lipid droplets and other cellular structures.