Search

This study presents a novel, facile, and low-cost method for the separation and sensing of two closely related antiparasitic drugs, abamectin (ABM) and ivermectin (IVM), which have significant applications in agriculture and medicine. The aim was to explore the potential of gold nanoparticles (Au NPs) conjugated with organosilicon compounds as effective optical sensors for these drugs. However, existing methods often involve complex procedures and excessive costs. The aim of this study is to develop a novel, facile, and low-cost method for the separation and sensing of abamectin and ivermectin by exploring the potential of gold nanoparticles (Au NPs) conjugated with organosilicon compounds as effective optical sensors for these drugs. Au NPs were extracellular photosynthesized using yeast extract and conjugated with 1-naphthol-based organosilicon compound (Naph-1-TBDPS) to form Au NP/Naph-1-TBDPS nano-photoactive composite. In addition, the application of the developed nanosensor on cellulose filter paper was achieved. The interaction of abamectin or ivermectin with the nanocomposite (nanosensor) was investigated using UV–Vis spectroscopy. Abamectin caused a red shift in the spectral line of the ABM/Au NPs/Naph-1-TBDPS nanocomposite, while ivermectin caused a blue shift of IVM/Au NPs/Naph-1-TBDPS nanocomposite, indicating distinct interactions. The mechanistic pathway of the observed phenomenon was explained by the formation of a silyl-based abamectin complex in the C22–C23 bond and the etching of Au NPs in the presence of ivermectin forming Au clusters. It was determined that the difference in spectral shifts enabled the selective detection of abamectin and ivermectin. For the first time, this study presents a novel and cost-effective method for the identification and sensing of ABM and IVM using the Au NPs/organosilicon composite. The method demonstrated high sensitivity and selectivity, offering potential for practical applications in drug analysis and quality control, thereby addressing the limitations of previous methods that often-involved complex procedures and high costs. [ABSTRACT FROM AUTHOR]

Chemical compounds belonging to the quinone class are known for their cyclic diketone structures. Anthraquinone derivatives have been used as sensing materials and dyes or pigments. The spectroscopic and voltammetric sensing capacity of 1-amino-4-hydroxy-9,10-anthraquinone was utilized to sense 2-bromobenzene-sulfonyl chloride, 4-nitrobenzene-sulfonyl chloride, benzoyl chloride, 2-chloro-benzoyl chloride and 4-bromo-benzoyl chloride. These substituted acyl chlorides and nitrobenzene sulfonyl chloride are important intermediates in various reactions, and the product formation is highly dependent on their concentration. Therefore, it is crucial to take special care as all these compounds are carcinogenic. All studies were carried out in ethanol solvent. Results showed that 1-AHAQ could be effectively used as a UV–visible sensor for sensing 2-bromo benzene sulfonyl chloride. 1-AHAQ demonstrates good results as a fluorescence sensor for sensing 4-bromobenzene-sulfonyl chloride and behaves as a good voltammetric sensor for sensing 4-nitrobenzene sulfonyl chloride. [ABSTRACT FROM AUTHOR]

The chemical reaction of 2-(methylsulfinyl)naphtho[2,3-d]thiazole-4,9-dione (3) using different amines, including benzylamine (4a), morpholine (4b), thiomorpholine (4c), piperidine (4d), and 4-methylpiperazine (4e), produced corresponding new tricyclic naphtho[2,3-d]thiazole–4,9–dione compounds (5a–e) in moderate-to-good yields. The photophysical properties and antimicrobial activities of these compounds (5a–e) were then characterized. Owing to the extended π-conjugated system of naphtho[2,3-d]thiazole–4,9–dione skeleton and substituent effect, 5a–e showed fluorescence both in solution and in the solid state. The introduction of nitrogen-containing heterocycles at position 2 of the thiazole ring on naphtho[2,3-d]thiazole-4,9-dione led to large bathochromic shifts in solution, and 5b–e exhibited orange-red fluorescence with emission maxima of over 600 nm in highly polar solvents. Staphylococcus aureus (S. aureus) is a highly pathogenic bacterium, and infection with its antimicrobial-resistant pathogen methicillin-resistant S. aureus (MRSA) results in serious clinical problems. In this study, we also investigated the antimicrobial activities of 5a–e against S. aureus, MRSA, and S. epidermidis. Compounds 5c with thiomorpholine group and 5e with 4-methylpiperazine group showed potent antimicrobial activity against these bacteria. These results will lead to the development of new fluorescent dyes with antimicrobial activity in the future. [ABSTRACT FROM AUTHOR]

Reactive dyes exhibit suitable opto-electronic properties, making them promising for dye-sensitized solar cell (DSSC) applications. The present study uses reactive orange 16 dye to design an efficient dye sensitizer for DSSC application using a donor–π–acceptor concept. The sensitizer structures and their electronic and optical properties were investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The molecular electrostatic potential maps, HOMO–LUMO distributions, and density of states plots were obtained for the optimized geometry. The analysis showed that the electronic properties of reactive orange 16 are enhanced due to the π-linkage, responsible for extending the conjugation length of the system. The TD-DFT calculations showed a bathochromic shift in the absorption spectra due to the introduction of the π-linker. The shift confirmed the conjugation's role in enhancing the sensitizers' electronic properties. The transitions were π → π* and n → π*, and the transition with maximum oscillator strength was assigned to the H → L excitation. The study showed that donor–π–acceptor concept-based sensitizers derived from reactive dyes favor DSSC applications. Hence, this study's findings could be used to design and develop more efficient dye sensitizers based on reactive dyes. [ABSTRACT FROM AUTHOR]

The chemical reaction of 2-(methylsulfinyl)naphtho[2,3-d]thiazole-4,9-dione (3) using different amines, including benzylamine (4a), morpholine (4b), thiomorpholine (4c), piperidine (4d), and 4-methylpiperazine (4e), produced corresponding new tricyclic naphtho[2,3-d]thiazole–4,9–dione compounds (5a–e) in moderate-to-good yields. The photophysical properties and antimicrobial activities of these compounds (5a–e) were then characterized. Owing to the extended π-conjugated system of naphtho[2,3-d]thiazole–4,9–dione skeleton and substituent effect, 5a–e showed fluorescence both in solution and in the solid state. The introduction of nitrogen-containing heterocycles at position 2 of the thiazole ring on naphtho[2,3-d]thiazole-4,9-dione led to large bathochromic shifts in solution, and 5b–e exhibited orange-red fluorescence with emission maxima of over 600 nm in highly polar solvents. Staphylococcus aureus (S. aureus) is a highly pathogenic bacterium, and infection with its antimicrobial-resistant pathogen methicillin-resistant S. aureus (MRSA) results in serious clinical problems. In this study, we also investigated the antimicrobial activities of 5a–e against S. aureus, MRSA, and S. epidermidis. Compounds 5c with thiomorpholine group and 5e with 4-methylpiperazine group showed potent antimicrobial activity against these bacteria. These results will lead to the development of new fluorescent dyes with antimicrobial activity in the future.

A facile one-pot four-component synthetic methodology is evolved to construct novel copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrins in good yields via a sequential reaction of copper(II) 2,3-diamino-5,10,15,20-tetraarylporphyrins, 2-hydroxynaphthalene-1,4-dione, aromatic aldehydes, and dimedone in the presence of a catalytic amount of trichloroacetic acid in chloroform at 65 °C. Further, the newly prepared copper(II) porphyrins were transformed to the corresponding free base and zinc(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrins under standard demetallation and zinc insertion conditions. The absorption and emission properties of the obtained porphyrins were investigated by using UV–visible and fluorescence spectroscopy. The preliminary photophysical results revealed a significant red-shift in their absorption and emission spectra as compared to the meso-tetrakis(4-methylphenyl)porphyrins due to the extended π-conjugation.

It is challenging to realize ultra‐pH‐responsive fluorescent carbon dots (CDs), especially reversibly adjustable multichromatic emission covering a broad wavelength range including deep‐red lasing. This study reports a one‐step solvothermal treatment of pyrogallol to obtain brilliant CDs with a substantial bathochromic shift (from blue to dark red emission) induced by pH changes. The CDs show an excellent reversible pH response: simple acid treatment instantaneously shifts their initial green emission by 140 nm to a deep‐red emission with high‐color‐purity and enhances brightness, subsequent alkali addition returned the green emission, suggesting smooth and reversible regulation of fluorescence. Detailed components analyses, morphology tracking, and photodynamic studies demonstrate the discrete, reversible shift of emission derived from structural transformations, which include protonation of the CDs and their subsequent assembly and partial aggregation triggered by hydrogen bonding. The abundant H‐bonds crosslink the network of CDs, ultimately raising the quantum yield from 11.3% to 16.0%. Furthermore, the aggregated CDs crystallized into sheet‐like structures that acted as a resonant cavity for lasing show excellent gain ability and lead to strong deep‐red lasing. This study draws together pH regulation, the effects of CD's assembly, and their lasing emission to demonstrate significant potential for the development of versatile CDs. [ABSTRACT FROM AUTHOR]

This study explores the vibrational and nuclear magnetic resonance spectra of free ions as well as those coordinated with sodium ions, which are commonly utilized to study ion-ion and ion-solvent interactions in electrolytic solutions of dipolar aprotic solvents. The spectral investigations suggested the origin of new bands due to solvent shell of sodium ions. The ion-solvent interactions were confirmed by the carbonyl symmetric stretch ring deformation bands in N,N-dimethylacetamide. The probability of new contact ion pairs between sodium and perchlorate ions with N,N-dimethylacetamide (DMA) increases on enhancing the increase in electrolytic concentration of sodium perchlorate in binary solvent mixtures. FTIR vibrational spectra and 13C-NMR spectra of several electrolytic concentration solutions of sodium perchlorate (NaClO4) were studied in pure DMA and its binary mixture with 2-aminoethanol (AE). The study investigates the vibrational spectra of free ions as well as those coordinated with Na+ ions, which are widely used to study ion-ion and ion-solvent interactions in electrolytic solutions of dipolar aprotic solvents. The solutions of the salt at different concentrations were prepared in the molar ratio of NaClO4/AE/DMA (4:4:4) from 0.25 to 1.0 m. The vibrational spectroscopic and 13C-NMR studies suggested the origin of new bands due to solvent shell of Na+ ions, which is due to O=C–N deformation behavior. The study revealed that the Na+ ions interacted through the coordinate bond to both N-atom of NH4+ structure as well as oxygen atom of the C=O (carbonyl group) of amide. The interaction between Na+ ions and solvent suggests preferential solvated by DMA in the binary solvent mixtures. The ion-solvent interactions were confirmed by the carbonyl symmetric stretch ring deformation bands in DMA. The new contact ion-pairs between Na+ and ClO4− ions are more probable with increase in the concentration of sodium perchlorate in binary solvent mixtures. [ABSTRACT FROM AUTHOR]

The Knoevenagel condensation of azulenyl ketones with malononitrile resulted in the synthesis of π-conjugated 1-mono- and 1,3-bis(phenyldicyanovinyl)azulenes, and the Kumada cross-coupling reaction of bromazulenes with PhMgBr gave 1-mono- and 1,3-biphenylazulene. The electronic spectra of dicyanovinylated azulenes showed strong absorption bands of intramolecular charge transfer in the visible region, as well as significant bathochromic shifts of the absorption maxima of phenylazulenes. [ABSTRACT FROM AUTHOR]

Development of organic fluorophore is an important theme. Especially, the fluorophores with longer fluorescence peaks are useful to biological probes. One of the methods to change the fluorescence peak is the introduction of substituents. However, opposing characteristics of the substituents lead to different changes in the fluorescence peaks. Furthermore, the introduction of the substituent also affects their electric properties. Thus, if the materials were developed with the substituent effect on the optical and electric properties separately, it will be useful to design the functional materials related to both optical and electric properties. Herein, we investigated the substituent effect of dipyrrolo[1,2-a:2′,1′-c]quinoxalines on fluorescence properties. We synthesized the compounds bearing electron-donating or electron-withdrawing substituents at the benzene ring on dipyrrolo[1,2-a:2′,1′-c]quinoxaline, which would have more direct influence on the optical properties. By introducing each substituent at the 6 position of dipyrrolo[1,2-a:2′,1′-c]quinoxaline, the bathochromic shift was observed in the fluorescence spectra. In the case of fluorine substituent, the change of the fluorescence peak reached was about 19 nm. Using a TDDFT calculation, we explained the reason for such a substituent effect that large on the increment of LUMO energy or decrement of HOMO energy occurred by introducing electron-withdrawing or electron-donating substituents at the 6 position, respectively. The substituent effect on the change of orbital energies is typical although the different characteristics of substituents resulted in the similar tendency about the change of fluorescence peak. Furthermore, with the introduction of phenyl substituents at the 3 and 10 positions, we achieved 40–50 nm longer fluorescence peaks compared with that of the original dipyrrolo[1,2-a:2′,1′-c]quinoxaline. [ABSTRACT FROM AUTHOR]

Surfactant–dye complexation between anionic dye: Alizarin Red S (ARS) and cationic surfactant:cetyltrimethylammonium bromide (CTAB) was investigated in an aqueous medium at 303.15 K employing various physicochemical characterization to offer an understanding of the micellization conduct. Here, micellization and thermodynamic parameters have been calculated using the tensiometry and conductivity approach. The critical micelle concentration (CMC) of CTAB is observed to decrease in presence of ARS. The Gibbs energy of micellization (∆Gmico) remains be negative on increasing the ARS content which indicated the spontaneity of the overall micellization process. Cyclic voltammetry (CV) reflected the impact of interactions between CTAB and ARS. ARS solubilization in CTAB micelles caused a red (bathochromic) shift in the ultraviolet–visible spectrum below the CMC thereby inferring that ARS undergoes J‐type aggregation in the pre‐micellar region. The intercept drawn following the Job's (corrected absorbance vs. CTAB volume ratio plot) method depicted the volume fractions of (equimolar) ARS (VARS) and CTAB (VCTAB) expressed in v/v occurring at VARS/VCTAB = 0.52/0.48, suggesting their stoichiometric ratio of 1:1 amid each molecule of ARS and CTAB leading to CTAB‐ARS ion‐pair complexation. A computational simulation method using molecular orbital energy calculations was used to evaluate the successive correlation between CTAB and ARS to comprehend the binding mechanism. The lower energy gap (ΔE) value of CTAB‐ARS indicated the favorable interaction of ARS with CTAB. Thus, the present work will reflect the significance of surfactant–dye systems in analytical and biochemistry research; and may open novel possibilities in dye absorption and their applications in the removal of dyes using surfactants. [ABSTRACT FROM AUTHOR]

Heavy metal ions pollution is posing a major danger to human health across the planet. We present a phenylhydrazone‐based colorimetric sensor for detecting Cu2+ ions in tap water and human blood plasma. The phenylhydrazone‐based sensor (Sensor 1) is extremely selective for recognizing Cu2+ ions over other similar metal ions by producing a colorimetric response. Upon interaction with Cu2+, the colorless sensor 1 changes to dark yellow within a minute producing a bathochromic shift in the absorption spectrum. The AFM, Zetasizer and FTIR spectroscopic techniques were used for Cu2+ detection and selectivity of sensor 1. The average size of sensor 1 is around 293.9 nm which changes to 2275 nm upon complexation with Cu2+. Sensor 1 was highly selective towards Cu2+ as no interference was recorded by various metals ions. The detection limit was found to be 0.1 μM with R2 equal to 0.9821. Furthermore, cytotoxic experiments showed that sensor 1 is nontoxic to various cell lines, which revealed that it could detect Cu2+ ions in the biological system. Moreover, sensor 1 gives satisfactory results for detecting Cu2+ ions in human blood plasma and real water samples. [ABSTRACT FROM AUTHOR]

• TCBPS and TBBPS have lower p K a values than BPS. • Cl or Br substitution increases sunlight absorption due to bathochromic effect. • TCBPS and TBBPS have higher photoreactivity due to "heavy atom" effect of halogens. • Half-lives of TCBPS and TBBPS were predicted by GCSOLAR. • Some photoproducts of BPS, TCBPS, and TBBPS have higher ecotoxicity. Bisphenol S (BPS), a widely used plasticizer, is known to have potential endocrine disrupting effects to organisms. Its tetrahalogenated derivatives, tetrachlorobisphenol S (TCBPS) and tetrabromobisphenol S (TBBPS), are flame retardants exhibiting high neurodevelopmental toxicity and cytotoxicity. Halogen substitution has been shown to significantly affect the optical and photochemical properties of organic compounds. In this study, we conducted a comparative investigation into the photochemical behaviors of BPS, TCBPS, and TBBPS in aqueous solutions under both laboratory UV and natural sunlight irradiation. Spectroscopic titration results indicated that the p K a of TCBPS (4.16) and TBBPS (4.13) are approximately 3.7 units smaller than that of BPS (7.85), indicating that the halogenated derivatives are mainly present as the phenolate anions under circumneutral conditions. The halogen substituents also cause a significant bathochromic shift in the absorption spectra of TCBPS and TBBPS compared to BPS, leading to the enhanced absorption of sunlight. Meanwhile, TCBPS and TBBPS showed higher quantum yields than BPS, attributed to the "heavy atom" effect of halogen substituents. GCSOLAR modeling predicted half-lives for BPS, TCBPS, and TBBPS in surface water in Nanjing (32°2′7.3′′N, 118°50′21′′E) under noon sunlight in clear mid-autumn days as 810.2, 3.4, and 0.7 min, respectively. Toxicity evaluation suggest potential ecological risks of BPS/TCBPS/TBBPS and their photoproducts to aquatic organisms. Our findings highlight direct photolysis as an important mechanism accounting for the attenuation of tetrahalogenated bisphenols in both sunlit surface waters and UV based water treatment processes.engineered (e.g., UV disinfection) and natural aquatic environments (e.g., surface fresh waters). [Display omitted] [ABSTRACT FROM AUTHOR]

Anthocyanins are attractive alternatives to colorants; however, their low color stability hinders practical application. Copigmentation can enhance both the color intensity and color stability of complexes. Herein, we report an investigation of copigmentation reactions between purple sweet potato anthocyanins (PSA1) and phenolic acids (tannic, ferulic, and caffeic acids) or fatty acids (tartaric and malic acids) at pH 3.5. The effects of the mole ratios of the copigment and the reaction temperature were examined. In addition, quantum mechanical computations were performed to investigate molecular interactions. The optimum PSA:copigment molar ratio was found to be 1:100. The strongest bathochromic and hyperchromic effects were observed for copigmentation with tannic acid (Tan), which might be attributable to the fact that its HOMO-LUMO energy gap was the smallest among the investigated copigments, and because it has a greater number of phenolic aromatic and groups to form more van der Waals and hydrogen bond interactions. However, the formation of the PSA-caffeic acid (Caf) complex was accompanied by the greatest drop in enthalpy (−33.18 kJ/mol) and entropy (−74.55 kJ/mol), and this was the most stable complex at 90 °C. Quantum mechanical calculations indicated that hydrogen bonds and van der Waals force interactions contributed to the color intensification effect of copigmentation. These findings represent an advancement in our understanding of the properties of PSA, expanding the application scope of this natural product.

Plasmonic metal nanoparticles due to their characteristic localized surface plasmon resonance (LSPR) in the optical region of the electromagnetic wave are of much interest right from the medieval ages. Herein, we present a robust single-step synthetic protocol for the synthesis of Au and Cu alloy nanoparticles, which are typically used in various catalytic and sensing applications. For alloy formation, co-reduction of Au and Cu salts was used in four different Au/Cu mass ratios (1:1, 1:2, 1:3, and 1:4) yielding "marigold" like nanostructures. The formation of the desired alloy composition was confirmed from their optical spectra giving an LSPR peak among the specific peak nature of Au and Cu and also, from the XRD pattern, displaying diffraction peaks corresponding to Au and Cu only, but not the copper oxides. Additionally, the effect of plasmonic damping due to inter-band transition and polydispersity in the formed alloys was also discussed. Moreover, their optical spectra confirm a broadband bathochromic shifted LSPR peak alongside a lowering intensity with the surge in Cu concentration. For the respective compositions of the alloy nanoparticles, optical spectra (compared with experimental data) and the electric field enhancement data were also simulated using the MATLAB-based boundary element method to investigate their application in antennas for SERS, SEIRA, etc. Furthermore, these AuCu nanoalloys were utilized in crystal violet dye degradation, which provides an enhanced catalytic character in comparison with that of pure Au nanoparticles. Subsequently, the turnover frequency of the degradation process provides the superlative AuCu composition. A similar enhanced nature was likewise obtained for simulated refractive index sensitivity for n = 1−1.5, establishing not only the inherent cost-effectiveness and single-step procedure of our versatile synthetic protocol, but also the formation of robust alloy with different combinations of nanoparticles. [ABSTRACT FROM AUTHOR]

A series of 4‐NEt2‐appended salen−indium complexes bridged by different diimine units (ethylene [Et, 1], phenylene [Ph, 2], and benzonitrile [PhCN, 3]) with different electronic effects were prepared in high yields by a one‐pot synthetic procedure. Among them, the solid‐state structure of 1 was identified by X‐ray crystallography, featuring a square‐pyramidal structure around the indium center. Ultraviolet–visible (UV/Vis) absorption and emission spectra of 1–3 showed typical ππ* electronic transitions centered on the salen ligands, which underwent gradual redshifts as the electron‐withdrawing ability of the bridging units increased. Such bathochromic shifts resulted from lowering the energy levels of the lowest unoccupied molecular orbital (LUMO). In addition, the full width at half maxima for the emissions of 1–4 gradually decreased with increasing electron‐accepting property of the bridging units. The observed photophysical properties were further supported by theoretical calculations. [ABSTRACT FROM AUTHOR]

The performance of organic photodetectors (OPDs) sensitive to the short-wavelength infrared (SWIR) light lags behind commercial indium gallium arsenide (InGaAs) photodetectors primarily due to the scarcity of organic semiconductors with efficient photoelectric responses exceeding 1.3 µm. Limited by the Energy-gap law, ultralow-bandgap organic semiconductors usually suffer from severe non-radiative transitions, resulting in low external quantum efficiency (EQE). Herein, a difluoro-substituted quinoid terminal group (QC-2F) with exceptionally strong electron-negativity is developed for constructing a new non-fullerene acceptor (NFA), Y-QC4F with an ultralow bandgap of 0.83 eV. This subtle structural modification significantly enhances intermolecular packing order and density, enabling an absorption onset up to 1.5 µm while suppressing non-radiation recombination in Y-QC4F films. SWIR OPDs based on Y-QC4F achieve an impressive detectivity (D*) over 10 11 Jones from 0.4 to 1.5 µm under 0 V bias, with a maximum of 1.68 × 10 12 Jones at 1.16 µm. Furthermore, the resulting OPDs demonstrate competitive performance with commercial photodetectors for high-quality SWIR imaging even under 1.4 µm irradiation., (© 2024 Wiley‐VCH GmbH.)

An effectively selective colorimetric chemosensor BTV (2-methoxy-6-((E)-(((E)-3-methylbenzo[d]thiazol-2(3H)-ylidene)hydrazono)methyl)phenol) was synthesized for detecting Cu2+. The BTV having benzothiazole group showed a bathochromic shift (150 nm) with an explicit color variation from colorless to pink toward Cu2+. The BTV could detect Cu2+ down to 0.37 μM in solution. The binding ratio of BTV and Cu2+ was determined to be a 1:2 by Job plot and ESI-MS. Sensor BTV could distinctly sense Cu2+ without interference from other cations and distinguish it from diverse metal ions through the test strip. The sensing process of Cu2+ by BTV was presented by UV-visible titration, Job plot, 1H NMR titration, DFT calculation, FT-IR and ESI-MS. An effective colorimetric chemosensor BTV was synthesized for detecting Cu2+. Sensor BTV showed a bathochromic shift (150 nm) with an explicit color change from colorless to pink to Cu2+. In addition, it could detect Cu2+ down to 0.37 μM and distinguish it from various metal ions through the test strip. [ABSTRACT FROM AUTHOR]

Development of organic fluorophore is an important theme. Especially, the fluorophores with longer fluorescence peaks are useful to biological probes. One of the methods to change the fluorescence peak is the introduction of substituents. However, opposing characteristics of the substituents lead to different changes in the fluorescence peaks. Furthermore, the introduction of the substituent also affects their electric properties. Thus, if the materials were developed with the substituent effect on the optical and electric properties separately, it will be useful to design the functional materials related to both optical and electric properties. Herein, we investigated the substituent effect of dipyrrolo[1,2-a:2′,1′-c]quinoxalines on fluorescence properties. We synthesized the compounds bearing electron-donating or electron-withdrawing substituents at the benzene ring on dipyrrolo[1,2-a:2′,1′-c]quinoxaline, which would have more direct influence on the optical properties. By introducing each substituent at the 6 position of dipyrrolo[1,2-a:2′,1′-c]quinoxaline, the bathochromic shift was observed in the fluorescence spectra. In the case of fluorine substituent, the change of the fluorescence peak reached was about 19 nm. Using a TDDFT calculation, we explained the reason for such a substituent effect that large on the increment of LUMO energy or decrement of HOMO energy occurred by introducing electron-withdrawing or electron-donating substituents at the 6 position, respectively. The substituent effect on the change of orbital energies is typical although the different characteristics of substituents resulted in the similar tendency about the change of fluorescence peak. Furthermore, with the introduction of phenyl substituents at the 3 and 10 positions, we achieved 40–50 nm longer fluorescence peaks compared with that of the original dipyrrolo[1,2-a:2′,1′-c]quinoxaline.

Coumarins are an important class of phytochemicals, a chemical defense presumed to be secreted by plants. More recently, Coumarins have gathered popularity for their basis in anti-cancer agents. This paper dives into the organic synthesis of two 3-substituted coumarins from o-vanillin using the Knoevenagel condensation reaction. The 3-substituted coumarin were characterized using melting point analysis, 1H-NMR, and UV-Vis spectroscopy. In addition, the anticancer activity of synthesized 3-substituted coumarin compounds were assayed against topoisomeraseIIα, which is the target enzyme of FDA approved anti-cancer drug etoposide since it is an active enzyme in cancer cell replication. The demonstrated procedures can be used as an undergraduate senior project that traverses through several classes that chemistry majors take. [ABSTRACT FROM AUTHOR]

Nitrogen‐containing polycyclic heteroaromatics have exhibited fascinating multi‐resonance (MR) characteristics for efficient narrowband emission, but strategies to bathochromic shift their emissions while maintaining the narrow bandwidths remain exclusive. Here, homogeneous hexatomic rings are introduced into nitrogen‐embedded MR skeletons to prolong the π‐conjugation length for low‐energy electronic transitions while retaining the non‐bonding character of the remaining parts. The proof‐of‐the‐concept emitters exhibit near unity photoluminescence quantum yields with peaks at 598 nm and 620 nm and small full‐width‐at‐half‐maximums of 28 nm and 31 nm, respectively. Optimal organic light‐emitting diodes exhibit a high external quantum efficiency of 18.2 %, negligible efficiency roll‐off, and ultra‐long lifetime with negligible degradation at an initial luminance of 10 000 cd m−2 after 94 hours. [ABSTRACT FROM AUTHOR]

Treatment of p‐toluenesulfonic acid on bipyrenol in PhCl gave a pyrene‐fused furan. The expansion of the molecule induced a narrow HOMO‐LUMO gap, multiple redox processes showing both oxidation and reduction, and a bathochromic shift in the absorption spectrum. A small Stokes shift was caused by the rigidity of the molecule. The structures and electronic states were estimated by theoretical considerations. We found that the heteroatom containing a [5]helicene molecule shows racemization through a planar transition state. [ABSTRACT FROM AUTHOR]

Three new 1,3,4,5-tetrahydro-2H-1,5-benzodiazepin-2-one oximes were synthesized and characterized by the methods of 1H- and 13C-NMR, IR and elemental analysis. Along with previously described compounds bearing one additional methyl group on the 5th nitrogen atom, the new compounds were characterized in bulk by UV–Vis and fluorescence spectroscopy in various solvents. The influence of the nature of the organic solvent on the spectra of the title compounds was investigated and is discussed.

Modulation of molecular features of metal free organic dyes is important to present sensitizers with competing electronic and optical properties for dye sensitized solar cells (DSSCs). The D-A2-π-A1 molecular design based on phenothiazine skeleton (D) connected with benzothiadiazole (A2) linked with furan π-spacer and acceptor unit of cynoacrylic acid (A1) were fabricated and examined theoretically for possible use as DSSCs. Density functional theory (DFT) and time dependent density functional theory TDDFT were used to study the effect of additional donors on the photophysical properties of the dyes. Eight (8) different donor subunits were introduced at C7 of phenoxazine based dye skeleton to extend the π-conjugation, lower HOMO-LUMO gap (Eg) and improve photo-current efficiency of the dye sensitizer. All the dye sensitizers (except P3 and P4) exhibited capability of injecting electrons into the conduction band of the semiconductor (TiO2) and regenerated via redox potential (I−/I3-) electrode. Attachment of 2-hexylthiophene (P2) remarkably lowered the Eg, extended π-electron delocalization, hence, gives higher absorption wavelength (λmax) at 752 nm. The donor subunit containing 2-hexylthiophene (P2) presented the best chemical hardness, open circuit voltage (Voc), and other comparable electronic properties, making P2 the best DSSC candidate amongst the optimized dyes. The reported dyes would be interesting for further experimental research.

[Display omitted] New spiropyrans with chromene and indoline cores bearing alkoxycarbonyl group and cationic π-acceptor in the chromene moiety were synthesized in one step from 1,2,3,3-tetramethylindolinium and isophthalic dialdehyde derivatives. The appending of a 8′-positioned conjugated cationic fragment causes a significant red-shift of the photoinduced isomers absorption maxima and provides them with extremely long lifetimes up to 75 min. The obtained spiropyrans exhibit both positive and negative photochromism in solutions, demonstrating the properties of 'photochromic balance'. [ABSTRACT FROM AUTHOR]

Aggregation induced photoluminescent quenching of graphene quantum dots (GQDs) is a well-known effect, although there are limited reports of multicolour light emissions from such aggregates. In the present work, we demonstrate a novel aggregation induced bathochromic shift in emission similar to J-aggregates observed in dye molecules. Nitrogen-doped graphene quantum dots (N-GQDs) prepared in the presence of diethylenetriamine show blue emission which is attributed to monomers at low concentration (58 μg/ml) while cyan (1.75 mg/ml), and greenish yellow (3.5 mg/ml) emissions are observed at higher concentrations under 365 nm UV lamp. These materials for the first time show yellow and orange emission from drop cast film of N-GQDs under 365 nm UV-light while the parent powder gives orange emission. The variety of emission colours that could be made simply by controlling the degree of aggregation presents exciting possibilities in a range of applications such as sensing, bioimaging, solar harvesting and forensic science. Image 1 [ABSTRACT FROM AUTHOR]

In this study, we designed and synthesized novel 6‐(thiophen‐2‐yl) indolizino[3,2‐c]quinolines (IQs) guided by density functional theory (DFT) calculations and explored the optical properties of the IQ derivatives together with fractional atomic orbital contribution (FAOC) analysis. In accordance with the DFT predictions, the designed compound, IQ‐C9, with a methoxycarbonyl (MC) group attached to the C9 position of the IQ scaffold, displayed improved fluorescence quantum yields (QY) in solution and in the solid state along with bathochromic shifts compared to previous analogues. TEM images demonstrated that IQ‐C9 forms well‐defined nanoparticle structures (dimensions: 20×50 nm, aspect ratio: 2.3) in aqueous solution. Confocal images of IQ‐C9‐treated MCF7 cells revealed colocalization of IQ‐C9 with lipid droplets, highly dynamic subunits within cells involved in various metabolic disorders and cancers. Our results demonstrated that the analyses based on the FAOC coefficients and molecular orbital (MO) energy levels can be used as a computational method to predict spectral shifts for fluorophores and to design novel fluorescent probes for tracking dynamic cellular processes. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) is a class of zero-dimensional carbon nanomaterials with favorable stability and optical properties. However, CDs in solid state often suffer from fluorescence quenching due to π-π stacking of conjugated systems, like most small molecules or organic dyes. Herein, we prepared the CDs that generate bright yellow luminescence in solid state without any additional matrix, meanwhile the solid CDs are inclined to assembly into spherical structure. While the CDs are dissolved in aqueous solution, the photoluminescence (PL) emission from blue to green can be realized by regulating the concentration of CDs. With the concentration increasing, the self-assembly behavior of CDs is observed in solution, which leads to the bathochromic shift of photoluminescence. Besides, the mechanism of PL conversion in this process was proposed based on the characterization results, that with the concentration of CDs rising in solution, π-π interaction was restrained while electron redistribution was induced. Consequently, a localized state II caused by electron rearrangement gradually becomes the predominant emission state, resulting in the PL emission shifting to long-wavelength region. Moreover, CDs have shown favorable potentials in the field of anti-counterfeit and multicolor bioimaging, making the CDs highly attractive for a wide variety of applications. [ABSTRACT FROM AUTHOR]

New 2-cyclohexenone derivatives were synthesized via the Michael reaction in the presence of potassium carbonate. These derivatives containing the acetyl substituent in position 6 are of special interest due to the ability to form boron chelate complexes, 1,3-dioxaborines, possessing luminescence properties. The dependence of the position of the absorption and luminescence absorption band maxima on the donor properties of the substituents was found. [ABSTRACT FROM AUTHOR]

[Display omitted] • The photovoltaic properties of PTTD2-PTTD9 were explored. • Their key electronic properties were studied at M06/6-311G(d,p) level. • Time dependent density functional theory (TD-DFT) analysis was performed for FMOs and UV–Vis analyses. • TDM and DOS analyses supported FMO based findings. Nowadays, researchers are interested in developing efficient photovoltaic (PV) materials to fulfill the demand of advanced technology. Herein, a series of A-π-A configured fused ring chromophores (PTTD2-PTTD9) was designed by structural modulation of peripheral acceptor entities via PTTR1. The theoretical approach comprising DFT functional i.e. , M06/6-311G(d,p) was used to acquire valuable information involving their chemical, photonic, structural and electronic properties. The structural modulation disclosed considerable electronic influence on HOMO and LUMO for all the derivatives with reduced band gaps. All the designed chromophores showed wider absorption spectra of 722.09–778.69 nm with small energy difference range (2.07–2.23 eV) as compared to the reference compound (709.82 nm) with energy difference (2.26 eV). Moreover, comparable V oc values as well as less reorganization energies were observed in all the derivatives. Interestingly, PTTD8 was revealed to be the leading candidate due to its least energy gap, highest softness and lowest value of binding energy possessing remarkable bathochromic shift among all the derivatives. These fused chromophores with A-π-A architecture might be considered as potential competitors in efficient photovoltaic materials in the future. [ABSTRACT FROM AUTHOR]

The solvent effect can be determined by Solvent polarity scale,solvatochromic parameter which has different position of UV-Visibile absorption band in the range between 300 nm to 600 nm. The spectral characteristics of this azo dyes( QAPA) in different solvents at room temperature was analyzed which is the aim of studying the effect of solvents on the absorption spectra of this dyes in organic solvent of different characters. The solvatochromic behaviors of (QAPA) dye and solvent ̸ solute interactions can be analyzed by means of linear( solvation). The absorption spectra was( QAPA) dyes found to be two main bands at which 435nm which saw that Transition π-π* of the - N=N- group show a hypsochromic shift and550nm with n-π* transition This band is found to be highly dependent on solvent polarity and it shows a bathochromic shift with increasing solvent polarity, which may be indicated in azo- enaminetautomers. So, the absorption at longer wavelengths may be assigned to the hydrazone tautomer or common anion form. Absorption maxima of dyes are dependent on solvent polarity. Solvation of dye molecules probably occurs via dipole-dipole interactions in non-hydrogen-bond donating solvents, In hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature. [ABSTRACT FROM AUTHOR]

Abstract Through the replacement of the β -diketonate Hbtfa (Hbtfa =4,4,4-trifluoro-3-hydroxy-1-phenylbutanone) with the bis- β -diketonate ligand H 2 btp (H 2 btp =1,3-bis(4,4,4-trifluoro-1,3-dioxobutyl)benzene), structure converts from mononuclear [Ir(iqbt) 2 (btfa)] (1) (Hiqbt =1-(benzo[ b ]-thiophen-2-yl)-isoquinoline) to asymmetric dinuclear [(iqbt) 2 Ir-(btp)-Ir(iqbt) 2 ] (2) framework toward larger molecule conjugation. Upon a significant bathochromic shift into the restrictive near-infrared (NIR) regime (λ em =722 nm for complex 2 and 698 nm for complex 1), the superior phosphorescence (Φ em =0.15 and τ = 1.27 μs) of complex 2 to that (Φ em =0.08 and τ = 0.78 μs) of complex 1 is also approached. Moreover, within the realization of their solution-processed NIR polymer light-emitting diodes (NIR-PLEDs-I-II), complex- 2 -doped NIR-PLED-II in the presence of TmPyPB-assisted (TmPyPB=1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene) carrier balance, exhibits the attractive electroluminescent (EL) performance with both η EQE max= 3.11% and almost negligible efficiency-roll-off. Graphical abstract Based on the bathochromic shift into the NIR region (λ em =722 nm, Φ em =0.15 and τ = 1.27 μs) for asymmetric dinuclear complex [(iqbt) 2 Ir-(btp)-Ir(iqbt) 2 ] (2), its solution-processed NIR-PLED-II-2 in the presence of TmPyPB-assisted carrier balance exhibits efficient (η EQE Max=3.11%) and almost negligible efficiency-roll-off (<5%). fx1 Highlights • Asymmetric dinuclear Ir3+-complex with NIR phosphorescence is obtained. • Ir3+-complex-doped NIR-PLED-II exhibiting the good EL performance is realized. [ABSTRACT FROM AUTHOR]

Abstract The effect of inclusion complex on the spectral response, molar extinction coefficient and the conduction mechanism of some organic dyes were studied. β- cyclodextrin inclusion complex strategy was examined on 3 different azo dyes, 2-(10-Hydroxy-anthracen-9-ylazo)-benzoic acid, 10-((4-hydroxyphenyl)diazenyl)anthracene-9-ol and N -(4,6-dimethylpyrimidin-2-yl)-4-(8-hydroxyquinolin-5-yl)diazenyl)benzenesulfonamide. The chemical structure of the obtained dyes was characterized by FTIR, 1H NMR and mass spectral studies. Inclusion complex strategy leads to get organic dyes with broader spectral response and higher molar extinction coefficient. [ABSTRACT FROM AUTHOR]

• Halogenated chloroxylenols absorb light more efficiently due to bathochromic effect. • Halogenated chloroxylenols have higher photoreactivity due to "heavy atom" effect. • Di-halogenated products are more photoreactive than the mono-halogenated ones. • Halo-derivatives are more toxic than the parent chloroxylenol. Trace organic contaminants usually go through multiple treatment units in a modern water treatment train. Structural modification triggered by pretreatment (e.g., prechlorination) may influence the further transformation and fate of contaminants in downstream units. However, knowledge on this aspect is still limited. In this contribution, we investigated the chlorination of chloroxylenol (PCMX), an antimicrobial agent extensively used during COVID-19 pandemic, and the photoreactivity of its halogenated derivatives. Results indicate that chlorination of PCMX mainly proceeded through electrophilic substitution to give chlorinated products, including Cl- and 2Cl-PCMX. The presence of bromide (Br−) resulted in brominated analogues. Owing to the bathochromic and "heavy atom" effects of halogen substituents, these products show increased light absorption and photoreactivity. Toxicity evaluation suggest that these halo-derivatives have higher persistence, bioaccumulation, and toxicity (PBT) than the parent PCMX. Results of this contribution advance our understanding of the transformation of PCMX during chlorination and the photochemical activity of its halogenated derivatives in subsequent UV disinfection process or sunlit surface waters. [Display omitted] [ABSTRACT FROM AUTHOR]

The nonfluorescent pullulan matrix was fabricated via an electrospinning technique with intriguing dual emitting 2-(2-fluorophenyl)-3-hydroxy-4 H -chromen-4-one as a dopant. The single crystal X-ray diffraction data of the dopant revealed the orientation of the molecules in the crystal lattice. The reduced diameter of the pullulan nanofiber from 328 nm to 32 nm upon fabrication was attributed to the improved crystallinity. The higher moisture resistance of the pullulan/dopant composite nanofiber mat was evidenced by an enhanced water contact angle from 29° to 65.9°. The pullulan/dopant composite nanofiber mat exhibited a bathochromic shift in absorption profile from 250 nm to 296 nm. The subsequent dual emission at 426 nm (Blue) and 532 nm (Green) was accompanied by the large Stoke's shift value of 90–236 nm. The redshift of the emission profile in the pullulan/dopant composite mat from 400 nm to 426 nm could be due to the J-aggregation of the dopant molecules in the pullulan matrix. The band gap of the composite nanofiber mat ranged from 2.41 to 2.91. The optimum quantum yield of 32.1–36.72% and enhanced refractive index value suggested the potential application of fabricated pullulan mat as a dual emissive layer in organic light emitting diode (OLED) material which could be an alternative option for multilayer emissive material in OLED device architecture. • Crystal structure of 2-(2-fluorophenyl)-3-hydroxy-4 H -chromen-4-one was studied. • Pullulan matrix was fabricated with fluoro-substituted dopant via electrospinning. • J-aggregation of dopant was observed in pullulan/dopant composite nanofiber mat. • Nanofiber composite mat displayed dual emission with a large Stoke's shift value. • It could be used as a dual emissive layer in OLED material. [ABSTRACT FROM AUTHOR]