Fluorescence Emission Spectroscopy Research Articles

Effects of ultraviolet radiation and reactive oxygen species on the structure and ligand-binding ability of human serum albumin for norfloxacin

To explore the influence of ultraviolet radiation (UV) and reactive oxygen species (ROS) on the structure and ligand-binding ability of human serum albumin (HSA) for norfloxacin (NFLX), HSA was treated with UV (HSAUV) and UV/H2O2 (HSAUV/H2O2), respectively. The structure difference of HSA, HSAUV and HSAUV/H2O2 were investigated by Fourier transform infrared, fluorescence (i.e., emission fluorescence, synchronous fluorescence and fluorescence lifetime) and circular dichroism spectroscopy. The intermolecular interactions of HSA, HSAUV and HSAUV/H2O2 with NFLX were studied at pH 7.4 and temperatures 291, 310, and 318 K, using fluorescence emission and synchronous fluorescence spectroscopy, and combined with molecular docking. The results suggested that UV and ROS could destroy the α-helix of HSA and induce the loose of HSA structure, and the average fluorescence lifetimes of HSA decreased from 6.12 ns to 3.76 ns (HSAUV) and 3.40 ns (HSAUV/H2O2). The conformational changes of HSA caused by UV and ROS allowed NFLX to get access to more potential binding sites and promoted the binding affinity of HSA for NFLX, while the temperature stability of the HSA-NFLX complex significantly decreased. The results are useful and valuable for evaluating the protein damage caused by UV and ROS in organisms.

Insights into the binding of buspirone to human serum albumin using multi-spectroscopic and molecular docking techniques

Buspirone is an anxiolytic drug that plays a significant role in managing anxiety disorders and alleviating their symptoms as well. Several techniques were utilized to study the interaction between buspirone and human serum albumin under physiological conditions, including UV–vis absorption spectroscopy, fluorescence emission spectroscopy, circular dichroism, Fourier transform infrared spectroscopy (FT-IR), equilibrium dialysis, and molecular docking. The results of this study demonstrated that buspirone quenched the intrinsic fluorescence of human serum albumin through a mixed mechanism. Moreover, the binding constants (Kb), the quenching constants (Ksv), and thermodynamic parameters were calculated at various temperatures. The binding process of buspirone to human serum albumin showed a cooperative binding pattern, confirmed by the Scatchard diagram and Hill coefficient. Molecular docking results showed that buspirone interacted with the IIA, IIIA, and IIB subdomains of human serum albumin and slightly changed its conformation. It was also found that hydrophobic forces played a major role in this interaction. This study consequently proves that BSH as a drug can be transported by blood albumin. Additionally, due to its ratiometric response in absorbance upon binding to a biological target, HSA can be used as a molecular probe to follow biomolecular interactions.

Erbium(III) complexes with fluoroquinolones: Structure and biological properties

Four erbium(III) complexes with the fluoroquinolones enrofloxacin, levofloxacin, flumequine and sparfloxacin as ligands were synthesized and characterized by a wide range of physicochemical and spectroscopic techniques as well as single–crystal X–ray crystallography. The compounds were evaluated for their activity against the bacterial strains Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Xanthomonas campestris, which was higher than that of the corresponding free quinolones. The interaction mode of the complexes with calf–thymus DNA is via intercalation, as suggested by diverse studies such as UV–vis spectroscopy, DNA–viscosity measurements and competitive studies with ethidium bromide. Fluorescence emission spectroscopy revealed the high affinity of the complexes for bovine and human serum albumin and the determined binding constants suggested a tight and reversible binding of the compounds with both albumins.

Role of lignin in synergistic digestibility improvement of wheat straw by novel alkaline deep eutectic solvent and tetrahydrofuran pretreatment

A novel efficient pretreatment system containing alkaline deep eutectic solvent (DES) and tetrahydrofuran (THF) was developed in the present study. Under pretreatment conditions of 160 ℃ and 1 h, DES-THF pretreatment was more efficient (81.61%) in cellulose digestibility improvement than DES (choline chloride/monoethanolamine, 67.54%). To further explore lignin structural transformation and lignin-cellulase interaction after pretreatment, milled wood lignin (MWL) was extracted and characterized. Compared with DES-MWL, DES-THF-MWL showed an increased carboxyl group content (24.0%) and decreased condensed phenolic hydroxyl content (9.1%). In DES-MWL, β-O-4 content was 21.79%, while in DES-THF-MWL, β-O-4 accounted for 45.45%, indicating that the addition of THF alleviated cleavage of β-O-4 alkyl ether bonds. Fluorescence emission spectroscopy results showed that quenching mechanism of DES-THF-MWL and cellulase was dynamic, which was different from other lignin. Compared with DES-MWL, decreased Ka between DES-THF-MWL and cellulase indicated decreasing interaction between them. DES-THF pretreatment provides a novel pretreatment method for bioenergy.

Synthesis, Photophysical Properties and Self-Assembly of a Tetraphenylethylene-Naphthalene Diimide Donor-Acceptor Molecule.

The development of new π-conjugated molecular structures with controlled self-assembly and distinct photophysical properties is crucial for advancing applications in optoelectronics and biomaterials. This study introduces the synthesis and detailed self-assembly analysis of tetraphenylethylene (TPE) functionalized naphthalene diimide (NDI), a novel donor-acceptor molecular structure referred to as TPE-NDI. The investigation specifically focuses on elucidating the self-assembly behavior of TPE-NDI in mixed solvents of varying polarities, namely chloroform: methylcyclohexane (CHCl3 : MCH) and chloroform: methanol (CHCl3 : MeOH). Employing a several analytical methodologies, including UV-Vis absorption and fluorescence emission spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS), these self-assembled systems have been comprehensively examined. The results reveal that TPE-NDI manifests as distinct particles in CHCl3 : MCH (fMCH =90 %), while transitioning to flower-like assemblies in CHCl3 : MeOH (fMeOH =90 %). This finding underscores the critical role of solvent polarity in dictating the morphological characteristics of TPE-NDI self-assembled aggregates. Furthermore, the study proposes a molecular packing mechanism, based on SEM data, offering significant insights into the design and development of functional supramolecular systems. Such advancements in understanding the molecular self-assembly new π-conjugated molecular structures are anticipated to pave the way for novel applications in material science and nanotechnology.

Organofunctionalization of silica from rice husk ash with ESIPT dyes

Excited-state intramolecular proton transfer (ESIPT) dyes were immobilized on amorphous silica obtained from rice husk ash through surface modification methodology. The silanol groups present on the surface of silica were first functionalized with isocyanate groups to be reacted with ESIPT dyes. Scanning electron microscopy, infrared spectroscopy, thermogravimetric, nitrogen adsorption/desorption, powder X-ray diffraction, and solid-state fluorescence emission spectroscopy analysis have been carried out to characterize the materials. The synthesized silica-based fluorescent materials were used as latent fingerprint developer powders present on glass surfaces. The results showed that latent fingerprints were revealed with high contrast under ultraviolet light illumination.

Photocatalytic and antimicrobial studies of green synthesized Dy3+doped ZnO nanoparticles prepared from Rhododendron arboreum petal extract

In this study, the primary focus revolves around the synthesis of zinc oxide (ZnO) and dysprosium-doped zinc oxide (Dy-doped ZnO) nanoparticles utilizing a green chemistry approach, employing Rhododendron arboreum petal extract as a key component. A thorough characterization of nanoparticles has been carried out, involving a range of analytical techniques including UV–visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), and fluorescence emission spectroscopy. The structural examination confirmed the persistent hexagonal wurtzite structure of ZnO nanoparticles, which remained unaltered even with Dy doping. The XPS analysis corroborated the presence of lattice oxygen in addition to confirming the presence of Dy3+ and Zn2+. The results indicated that the incorporation of Dy3+ ions replaces Zn2+ ions in host ZnO leading to an increase in the defects inside ZnO. Based on HRTEM images, the particle size was determined to be 31 nm for ZnO nanoparticles and 39 nm for Dy-doped ZnO nanoparticles. FESEM imaging unveils a morphology reminiscent of pebbles, and EDX spectra provide additional evidence of the presence of Zn, Dy, and O elements within the nanoparticles, which aligns with the findings from XPS. Subsequently, these synthesized nanoparticles were harnessed for the remediation of novacron brown, a textile dye. Additionally, nanoparticles were explored for their antibacterial and antifungal properties which highlight the considerable potential of these nanoparticles in these specific domains.

Biodegradable Nanocomposite of ZnS(Mn) Quantum Dots Immobilized Graphene Oxide for Bioimaging Applications.

Developing a biocompatible and biodegradable graphene-based fluorescent nanoprobe with the ability to visualize live cells could be interesting for intracellular imaging and monitoring the efficiency of chemotherapy. Herein, we report a biodegradable and biocompatible hybrid fluorescent graphene oxide (GO)-ZnS(Mn) composite synthesized via in situ growth of ZnS(Mn) quantum dots (QDs) on the surface of GO in the aqueous medium. The prepared 'GO-ZnS(Mn)' composite was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and high-resolution transmission electron microscopy (HR-TEM) along with selected area electron diffraction (SAED). Further, the fluorescence properties of the GO-ZnS(Mn) composite were studied using fluorescence emission spectroscopy. The composite material exhibited a strong and broad visible light fluorescence from 500 to 600 nm by excitation with 365 nm (UV) light. The cytotoxic experiments of folic acid (FA) conjugated GO-ZnS(Mn) using MTT [(3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide)] assay revealed that the composite had excellent biocompatibility even at higher concentrations up to 200 µg/mL in HeLa cell lines. Next, the bioimaging experiments carried out using confocal fluorescence laser scanning microscopy (CLSM) revealed that GO-ZnS(Mn) composite was taken up by the HeLa cells effectively within 12 h of incubation via receptor (folate) mediated endocytosis with strong fluorescence throughout the cell surface. Finally, the biodegradability of GO-ZnS(Mn) composite was studied by treating it with human myeloperoxidase enzyme (hMPO) isolated from the primary immune cells, neutrophils, which is important to understand the in vivo fate of GO-Zns(Mn). The HR-TEM and Raman analyses confirmed the biodegradation of GO-ZnS(Mn) within 15 h of hMPO treatment. Thus, the biodegradable GO-ZnS (Mn) composite could be helpful for chemotherapy and bioimaging applications.

Synthesis, photo-physicochemical and biological properties of novel tetrahydropyrimidone-substituted metallo-phthalocyanines.

In this study, new peripherally substituted symmetric zinc and magnesium phthalocyanines (4 and 5) were successfully prepared by cyclotetramerization of the tetrahydropyrimidone (THPM)-linked phthalonitrile 3. The identity of the compounds were confirmed primarily through spectroscopic analysis including NMR, FT-IR, UV-Vis and MALDI-TOF mass spectroscopy. The photophysical and photochemical properties of the synthesized phthalocyanines (Pcs) were examined using UV-Vis absorption and fluorescence emission spectroscopy techniques. The quantum yields of singlet oxygen were found to be 0.50 and 0.33 for compounds 4 and 5 in DMSO, respectively. In addition to photo-physicochemical properties, the enhanced biological activities of compounds 4 and 5 were investigated using a range of biological assays, namely, antibiofilm, microbial cell viability, antioxidant, DNA cleavage, antimicrobial and photodynamic antimicrobial assays. The maximum DPPH inhibition of 4 and 5 was detected as 40.46% and 25.76% at 100 mg L-1, respectively. Fragmentation of the DNA molecule was observed at concentrations of 25 mg L-1, 50 mg L-1 and 100 mg L-1 for 4 and 5. Additionally, effective inhibition of microbial cell viability was observed with the targeted Pcs. The antibiofilm properties of these compounds were found to be concentration-dependent. The biofilm inhibition activities of 4 and 5 were found to be 96.01% and 92.04% for S. aureus, while they were 95.42% and 91.27%, for P. aeruginosa, respectively. The antimicrobial activities of 4 and 5 on different microorganisms were evaluated using the microdilution assay. In the case of photodynamic antimicrobial treatment, the newly synthesized Pcs showed more effective antimicrobial inhibition compared to the control. These findings suggest that compounds 4 and 5 can be used as promising photodynamic antimicrobial agents for the treatment of many diseases, particularly infectious diseases.

Effect of π-extension and halogenation on the optical limiting properties of meso-pyrenylBODIPYdyes

The lack of suitable optical limiters that cover the entire UV-visible-NIR region has motivated research to identify novel efficient and stable optical limiting materials. There has been a strong focus on attenuating the second harmonic of Nd:YAG pulsed lasers at 532 nm on the nanosecond timescale. The photophysicochemical processes of a series of mono- and di-(4-dimethylamino)styryl-meso-pyrenylBODIPY and mono- and di-(4-dimethylamino)buta-1,3-dienyl-meso-pyrenylBODIPY dyes were studied by UV-visible absorption and fluorescence emission spectroscopy, and by determining the fluorescence and triplet state lifetimes. Z-scan measurements were carried out at a fixed concentration of 10 [Formula: see text]M so that the effective nonlinear coefficients, third-order susceptibilities, second-order hyperpolarizabilities and limiting fluences of the dyes can be compared and trends in the structure-property relationships for these optical limiting parameters can be identified.

Characterization, modes of interactions with DNA/BSA biomolecules and anti-tumor activity of newly synthesized dinuclear platinum(II) complexes with pyridazine bridging ligand.

Platinum-based drugs are widely recognized efficient anti-tumor agents, but faced with multiple undesirable effects. Here, four dinuclear platinum(II) complexes, [{Pt(1,2-pn)Cl}2(μ-pydz)]Cl2 (C1), [{Pt(ibn)Cl}2(μ-pydz)]Cl2 (C2), [{Pt(1,3-pn)Cl}2(μ-pydz)]Cl2 (C3) and [{Pt(1,3-pnd)Cl}2(μ-pydz)]Cl2 (C4), were designed (pydz is pyridazine, 1,2-pn is ( ±)-1,2-propylenediamine, ibn is 1,2-diamino-2-methylpropane, 1,3-pn is 1,3-propylenediamine, and 1,3-pnd is 1,3-pentanediamine). Interactions and binding ability of C1-C4 complexes with calf thymus DNA (CT-DNA) has been monitored by viscosity measurements, UV-Vis, fluorescence emission spectroscopy and molecular docking. Binding affinities of C1-C4 complexes to the bovine serum albumin (BSA) has been monitored by fluorescence emission spectroscopy. The tested complexes exhibit variable cytotoxicity toward different mouse and human tumor cell lines. C2 shows the most potent cytotoxicity, especially against mouse (4T1) and human (MDA-MD468) breast cancer cells in the dose- and time-dependent manner. C2 induces 4T1 and MDA-MD468 cells apoptosis, further documented by the accumulation of cells at sub-G1 phase of cell cycle and increase of executive caspase 3 and caspase 9 levels in 4T1 cells. C2 exhibits anti-proliferative effect through the reduction of cyclin D3 and cyclin E expression and elevation of inhibitor p27 level. Also, C2 downregulates c-Myc and phosphorylated AKT, oncogenes involved in the control of tumor cell proliferation and death. In order to measure the amount of platinum(II) complexes taken up by the cells, the cellular platinum content were quantified. However, C2 failed to inhibit mouse breast cancer growth in vivo. Chemical modifications of tested platinum(II) complexes might be a valuable approach for the improvement of their anti-tumor activity, especially effects in vivo.

Mechanistic Insights into S-Depalmitolyse Activity of Cln5 Protein Linked to Neurodegeneration and Batten Disease: A QM/MM Study.

Ceroid lipofuscinosis neuronal protein 5 (Cln5) is encoded by the CLN5 gene. The genetic variants of this gene are associated with the CLN5 form of Batten disease. Recently, the first crystal structure of Cln5 was reported. Cln5 shows cysteine palmitoyl thioesterase S-depalmitoylation activity, which was explored via fluorescent emission spectroscopy utilizing the fluorescent probe DDP-5. In this work, the mechanism of the reaction between Cln5 and DDP-5 was studied computationally by applying a QM/MM methodology at the ωB97X-D/6-31G(d,p):AMBER level. The results of our study clearly demonstrate the critical role of the catalytic triad Cys280-His166-Glu183 in S-depalmitoylation activity. This is evidenced through a comparison of the pathways catalyzed by the Cys280-His166-Glu183 triad and those with only Cys280 involved. The computed reaction barriers are in agreement with the catalytic efficiency. The calculated Gibb's free-energy profile suggests that S-depalmitoylation is a rate-limiting step compared to the preceding S-palmitoylation, with barriers of 26.1 and 25.3 kcal/mol, respectively. The energetics were complemented by monitoring the fluctuations in the electron density distribution through NBO charges and bond strength alterations via local mode stretching force constants during the catalytic pathways. This comprehensive protocol led to a more holistic picture of the reaction mechanism at the atomic level. It forms the foundation for future studies on the effects of gene mutations on both the S-palmitoylation and S-depalmitoylation steps, providing valuable data for the further development of enzyme replacement therapy, which is currently the only FDA-approved therapy for childhood neurodegenerative diseases, including Batten disease.

Monitoring of cellulose-rich biowaste co-digestion with 3D fluorescence spectroscopy and mass spectrometry-based metabolomics

Anaerobic digestion (AD) is a promising waste management strategy that reduces landfilling while generating biogas. Anaerobic co-digestion involves mixing two or more substrates to enhance the nutrient balance required for microorganism growth and thus improve the degradation. Monitoring AD is crucial for comprehending the biological process, optimizing process stability, and achieving efficient biogas production. In this work, we have used three dimensional excitation emission fluorescence spectroscopy and mass spectrometry metabolomics, two complementary techniques, to monitor the anaerobic co-digestion (AcoD) of cellulose, ash wood or oak wood with food waste. The two approaches were compared together and to the biogas production records. Results of this experiment demonstrated the complementarity of both analytical techniques with the measurement of the biogas production since 3D fluorescence spectroscopy and MS metabolomics revealed the earlier molecular changes occurring in the bioreactors, mainly associated with the hydrolysis step, whereas the biogas production data reflected the biological activity in the last step of the digestion. Moreover, in all cases, the three data sets effectively delineated the differences among the substrates. While the two wood substrates were poorly degradable as they were richer in aromatic compounds, cellulose was highly degradable and was characterized by the production of several glycolipids. Then, the three tested AcoDs resulted in a similar 3D EEM fluorescence and metabolomics profiles, close to the one observed for the AD of food waste alone, indicating that the incorporation of the food waste drove the molecular degradation events in the AcoDs. Substrate-specific differences were appreciated from the biogas production data. The overall results of this research are expected to provide insight into the design of guidelines for monitoring AcoD.

Development and evaluation of anti-reflux functional-oral suspension raft composed of sodium alginate-mung bean protein complex

This study aimed to develop a sodium alginate (Na alginate) and mung bean protein (MBP) raft complex to improve gastric reflux symptoms. Na alginate and MBP complexes with different ratios (1:1, 2:1, and 3:1, respectively) were used for raft formulations through a wet Maillard reaction. Structural properties of raft strength, reflux resistance, intrinsic fluorescence emission spectroscopy, and Fourier transform infrared spectroscopy (FTIR) were investigated for rafts. The suspension 1:1 Na alginate/MBP with 0 h Maillard reaction time exhibited the lowest sedimentation volume among the suspensions. In contrast, 3:1 Na alginate/MBP with 6 h Maillard reaction time showed the highest sedimentation volume. Based on the results, the 3:1 Na alginate/MBP rafts had the best results, and the results were within acceptable limits. Functional properties, including antioxidant properties, the Helicobacter pylori inhibition assay, the pancreatic lipase inhibition assay, and angiotensin-converting enzyme (ACE) inhibition, were investigated for rafts. The Na alginate/MBP raft has similar characteristics to Gaviscon syrup and can be used for obesity, Helicobacter pylori infection, high blood pressure, and gastric reflux.

Wittig Synthesis, Optical Properties and Electrochemical Behaviors of Some Conjugated Derivatives of 4-Pyrones

The novel hetero-stilbene derivatives were synthesized by the Wittig reaction between 2-formyl-4-pyrones and polysubstituted imidazole-based phosphonium salts in the presence of a base. The optical properties of the products were investigated via UV–Vis absorption and fluorescent emission spectroscopy in dilute ethanol solution. Electrochemical properties were also studied by the cyclic voltammetry in CH2Cl2 solutions. The phosphorus ylides obtained from α-halocarbonyls were also condensed with 2-formyl-4-pyrone to give two electrochemically inactive and non-emitting products.

Novel strategy toward color-tunable and glow-in-the-dark colorless smart natural wooden window

Smart windows that use photochromic colorless wooden materials are an intriguing and urgent area of research. Herein, we create afterglow transparent woods with UV-induced photochromic capability. Infiltrating a lignin-modified wood (LMW) with a solution of methyl acrylate (MA) and rare-earth strontium aluminum oxide (SrAl2O4: Eu2+, Dy3+; SAOED) yielded afterglow and photochromic translucent wood. Preparing photoluminescent transparent wood effectively requires dispersing SAOED phosphor nanoparticles (NPs) in pre-polymerized MA without clumping. CIE (Commission Internationale de ĺEclairage) Lab colorimetric studies indicated that this transparent timber substrate changed color from colorless in daylight to greenish when exposed to ultraviolet rays. Micrographs taken using a transmission electron microscope (TEM) were analyzed to learn more about the morphology of the synthesized SAOED NPs. Different characterization techniques were applied on the photochromic translucent wood samples, including scanning electron microscopy (SEM), energy-dispersive X-ray analyzer (EDX), hardness properties, wavelength-dispersive X-ray fluorescent spectroscopy (WD-XRF), and absorption and emission spectroscopy. Absorption maximum wavelength was detected at 365 nm. Both 436 nm and 517 nm were observed as emission wavelengths in the developed photoluminescence wood. The results displayed that the manufactured transparent wood introduced superior protection from UV radiation and superhydrophobic activity. UV light triggered a rapid and reversible photochromic reaction in the transparent luminous wood.

New anthracene-based Oxime-Palladium complexes loaded on albumin nanoparticles, in vitro cytotoxicity, mathematical release mechanism studies and biological macromolecules interaction investigation

In this research work, two new palladium complexes [trans-Pd(C15H10NOCH3)2]Cl2 (1) and [cis- Pd(C15H10NOCH3)(PPh3)2Cl]Cl (2) were synthesized using an alkoxyme ligand named isophethalaldoxime. Then structure characterization has been done by FT-IR and different NMR (1H, 13C and 31P) spectroscopy. Then, their interactions with biological macromolecules including deoxyribonucleic acid and bovine serum albumin were studied using various spectroscopic methods such as UV–Vis absorption, fluorescence emission spectroscopy and circular dichroism. The results showed the binding of the prepared complexes to the deoxyribonucleic acid via grooves and different binding sites of bovine serum albumin. Fluorescence emission data showed that the mechanism of extinction of albumin emission by these compounds is static. Competitive titration was performed on albumin with eosin-Y, ibuprofen and digoxin as site markers I, II and III. The antitumor activity and toxicity of these compounds were evaluated on cancer cell lines A549 (leukemia) and K562 by in-vitro cytotoxicity test. The IC50 values showed the good activity of these complexes in inhibiting cancer cells. In the last section, the release mechanism of synthesized complexes from albumin nanoparticles (BNPs) was investigated and theoretical calculations were performed that showed Korsmeyer-Peppas mechanism for complex (1) and Quadratic mechanism for complex (2).

Photoluminescence Properties of Polythiophene/Tin Oxide (PTh/SnO2) Polymer Nanocomposites

In the present work, we have synthesized, polythiophene/tin oxide (PTh/SnO2) polymer nanocomposites through an in-situ chemical polymerization of thiophene monomers using anhydrous FeCl3 as an oxidant. The structural, thermal and optical characterization of PTh/SnO2 nanocomposites were investigated using X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analyzer and fluorescence emission spectroscopy. XRD spectra show the formation of pure polythiophene and incorporation of SnO2 nanofiller into the polythiophene matrix. FESEM images depict the formation of irregular rod and chain like structures with incorporation of SnO2 are noticed. TGA results reveal that the thermal stability of polymer nanocomposites is higher than that of pure polythiophene due to the strong interaction between nanofiller and polymer matrix. Fluorescence emission spectra show the emission intensity of polymer nanocomposites decreases as the concentration of SnO2 nanofiller increases due to the variation of rate of electron-hole recombination and conjugation length of polymer chain. Our results of fluorescence emission analyses suggest the PTh/SnO2 polymer nanocomposites could be a potential material for photonic devices.

Synthesis and characterization of hyperbranched conjugated polymers based on triphenylamine, phenoxazine, and benzothiadiazole for optoelectronic applications

In this work, two novel hyperbranched conjugated polymers poly(tris(4-(10-(2-ethylhexyl)-10H-phenoxazin-3-yl)phenyl)amine) (P1) and poly (tris(4-(7-(benzo[c][1,2,5]thiadiazol-4-yl)-10-(2-ethylhexyl)-10H-phenoxazin-3-yl)phenyl)amine) (P2) have been successfully synthesized via Direct polycondensation in the presence of Pd(OAc)2 as a catalyst. The chemical structures of novel conjugated polymers then were determined via Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR). Subsequently, the optical properties of conjugated polymers in different solvents were investigated via UV–Vis absorption and fluorescence emission (PL) spectroscopies, and were analyzed for optoelectronic applications.

Experimental and theoretical insights on the photophysical properties of ester-substituted indolizines

In this report, we present our latest results on the photophysical properties of substituted indolizines, which were previously obtained through the utilization of ultrasound (US) irradiation, in a one-pot and multicomponent strategy, allowing for a streamlined and straightforward preparation process. The photophysical properties of these derivatives were evaluated in solution using UV–Vis absorption and steady-state fluorescence emission spectroscopy. Our results reveal that these compounds exhibit absorption maxima in the UV-A-violet region. The electronic transitions could be related to spin and symmetry allowed ¹π→π* electronic transitions. The indolizines present fluorescence in the violet-to-green region. Both ground and excited states were shown to be tailored by the substituents in the indolizine core. In addition, the role of the solvent in the deactivation of the excited state proved to be critical in the successful exploration of these compounds as optical sensors for benzene. When benzene was added to the ethanolic solution, the indolizines usually exhibited fluorescence quenching, with a linear relationship between the amount of benzene and the emission intensity. Theoretical calculations were also employed to gain a deeper understanding of the solute-solvent interactions.