UV-vis Absorption Studies Research Articles

Interaction Studies of PVP and CTAB Capped CuO Nanorods with Aldicarb and Chlorpyrifos

Copper oxide uncapped nanorods (UC-CuO), capped with cetyltrimethylammonium bromide (CTAB-CuO), and polyvinyl pyrrolidine (PVP-CuO) were utilized for interaction study of Aldicarb (A.D.) and Chlorpyrifos (C.P.) pesticides. Electron microscopy (FE-SEM & TEM) studies confirmed the nanocrystalline structure and nanorod morphology of UC-CuO, CTAB-CuO, and PVP-CuO. The contact angle study showed the hydrophilic nature of the UC-CuO and PVP-CuO with contact angle of 51° and 57°, respectively. While CTAB-CuO exhibited hydrophobic nature with a contact angle of more than 90°. Interaction study of UC-CuO, CTAB-CuO, and PVP-CuO with A.D. and C.P was conducted using UV–vis absorption study (in the 250–400 nm region). UC-CuO showed the specific detection with A.D., while CTAB-CuO have shown with C.P. without using any bio-recognition elements. PVP-CuO did not show systematic change with both pesticides confirming the capping agent-dependent specific interaction of the pesticides.

Nonlinear Optical Refraction and Absorption Features of Methyl Orange Dye in Polar Solvents.

Herein, we report the nonlinear optical (NLO) refraction and absorption features of azo dye namely, methyl orange (MO) dissolved in ethanol, methanol, acetone, 1-propanol, DMF and DMSO. The UV-Visible absorption study reveals that the maximum absorption spectrum of MO dye appeared towards longer wavelength by increasing the solvent polarizability is the result of red shift or bathochromic shift. The Z-scan method is utilized to measure the third-order NLO features of MO dye in different polar solvents. A continuous wave laser with 5-mW power and an excitation wavelength of 405nm is employed in the Z-scan technique. The NLO features including nonlinear index of refraction (n2), nonlinear coefficient of absorption (β) and third-order NLO susceptibility (χ3) are calculated to be the order of 10-7 cm2/W, 10-2cm/W and 10-7 esu, respectively. The NLO index of refraction shows peak-valley transmittance is the result of self-defocusing and NLO absorption coefficient exhibits both positive and negative nonlinearity owing to saturable absorption (SA) and reverse saturable absorption (RSA). The effect of solvent polarizability and dipole moment on third-order NLO susceptibility of MO dye is discussed. Based on the experimental results, an azo dye MO appears to be a promising option for NLO applications in the future.

A 1D Sb-containing hybrid organic-inorganic material: Synthesis, structural characterization, hirshfeld surface, thermal behavior, vibrational and optical properties

A novel interesting hybrid organic-inorganic material of Bis (2-amino-3-nitropyridinuim) pentachloroantimoinates (III) with the formula [C5H6N3O2]2SbCl5 was elaborated by slow evaporation at room temperature. This compound was crystallized in the monoclinic system with the P 21/c space group, as shown using the X-ray diffraction results. The parameters are the following: a = 16.484(6) Å, b = 7.7170 (19) Å, c = 16.159 (7) Å, β= 109.26(5)°, Z = 4 and V = 1940,5(14) Å3. The asymmetric unit consists of one Sb (III) cation surrounded by five Cl− and two protonated cations 2-amino-3-nitropyridinuim. The crystal packing cohesion was maintained by NH…Cl and NH…O hydrogen bonds to form a three- dimensional network. The infrared IR and Raman studies which were recorded at room temperature in the 4000–400 cm−1 and 0–4000 cm−1 frequency regions, respectively, confirmed the existence of vibrational modes that correspond to the organic and inorganic groups. The Hirshfeld analysis results show that the predominate interactions were H…Cl and O…H contacts (39.9, 14.5 % respectively). The Thermogravimetric analysis TGA shows that this compound remains stable up to about 150 °C. The optical properties were characterized experimentally by UV–visible absorption studies and photoluminescence measurements. The Photoluminescence spectrum manifests a broad and strong band of luminescence around 454 nm (2.73 eV), which can be even observed with the naked eye at room temperature and is due to exciton emission.

Sol-Gel synthesis, characterization and photocatalytic activity of Cobalt doped ZnO nanoparticles

In the current study, Cobalt (Co) doped ZnO nanoparticles with different dopant concentrations are prepared using the sol-gel process. All the synthesized samples are characterised using a variety of instrumentation methods including XRD, FT-IR, UV-vis absorption spectroscopy, FE-SEM, EDAX, HRTEM and XPS. The XRD measurements revealed the crystallite sizes of the fabricated samples are reduced by increasing cobalt concentrations. The various functional groups present in the doped materials are identified using FT-IR spectra. According to the UV-vis absorption study, as Co dopant concentration rises, the energy band gap narrows down in comparison to pure ZnO. According to an FESEM image, Co doping in ZnO causes a shift in the morphology of the material, making for structures that resemble flowers almost exactly. The various elemental compositions are evaluated using EDAX. The results of analyses employing high-resonance transmission electron microscopy show that the two co-doped ZnO crystallites combine to produce spherical structures with a mean size of 16 nm. This is consistent with the crystallite size predicted by Scherrer's formula. According to the results of the XPS analysis, the Co ion was integrated into the ZnO lattice in a Co2+ oxidised form. The 0.3M Cobalt doped sample showed improved photocatalytic reaction efficiency of methylene blue. As the Co doping concentrations increased, the photocatalytic reaction's efficiency also increased.

SILAR deposited Cu2MnSnS4 thin films for sustainable energy applications

A heavy metal-free chalcopyrite (Cu2MnSnS4) thin film has been synthesized via the SILAR method by varying the adsorption and reaction time. The fabricated thin films are characterized by structural, spectral, and optical properties that are analyzed. The X-ray diffraction studies indicated the formation of Cu2MnSnS4 with grain size ranging from (16–18 nm). The Field Emission Scanning Electron Microscopic (FESEM) analysis revealed uniform film formation. Fourier Transformed Infrared Spectral (FTIR) analysis shows that sharp peaks are observed at 552 cm−1 and 1248 cm−1, indicating the presence of metal-sulfur bonds. The peak at 810 cm−1 is due to the resonance interaction of the sulfide ion. The band gap of Cu2MnSnS4 is in the range of 1.96–2.01 eV from UV–visible absorption studies.

Spectroscopic analysis of Cu doped and starch capped ZnS nanocrystals synthesized by microwave irradiation

The synthesis of undoped and copper doped ZnS nanoparticles (NPs) by a facile starch mediated microwave assisted hydrothermal route is reported in this work. Polycrystalline, cubic ZnS nanostructure of the samples were revealed by X-ray diffraction studies. High resolution transmission electron microscopy (HRTEM) analysis revealed the crystalline nature of NPs with size distribution in 2–7 nm range. Analysis of X-ray emission induced by particles of samples indicated presence of copper content in the sample. Cu doping showed a strong influence on the green emission properties of the ZnS NPs under UV light illumination. The band gap values determined from UV–Vis absorption studies were higher than that for bulk ZnS (3.68 eV), confirming quantum confinement effect. Further, starch capping and Cu doping confirmed by Fourier transform infra-red (FTIR) spectra. A strong PL emission around 507 nm observed due to carrier transition from conduction band of ZnS to Cu2+ t2 level. The intensity of this peak reduced at high dopant concentration due to quenching.

Bovine Serum Albumin as a Platform for Designing Biologically Active Nanocarriers-Experimental and Computational Studies.

Due to the specificity of their structure, protein systems are adapted to carry various ligands. The structure of many proteins potentially allows for two types of immobilization of a therapeutic agent, either on the outer surface of the protein or within the protein structure. The existence of two active sites in BSA's structure, the so-called Sudlow I and II, was confirmed. The conducted research involved determining the effectiveness of BSA as a potential carrier of 5-fluorouracil (5FU). 5-fluorouracil is a broad-spectrum anticancer drug targeting solid tumors. The research was carried out to estimate the physicochemical properties of the system using complementary measurement techniques. The optimization of the complex formation conditions made it possible to obtain significant correlations between the form of the drug and the effective localization of the active substance in the structure of the protein molecule. The presence of two amino groups in the 5FU structure contributes to the deprotonation of the molecule at high pH values (pH > 8) and the transition to the anionic form (AN1 and AN3). To investigate the binding affinity of the tautomeric form with BSA, UV-vis absorption, fluorescence quenching, zeta potential, QCM-D, and CD spectroscopic studies were performed. The experimental research was supported by molecular dynamics (MD) simulations and molecular docking. The simulations confirm the potential location of 5FU tautomers inside the BSA structure and on its surface.

Novel 1,3-Indenedione-Based Azo Dyes: Synthesis, Characterization, Solvatochromic UV-Vis Absorption Study, and Biological Activity

Novel 1,3-Indenedione-Based Azo Dyes: Synthesis, Characterization, Solvatochromic UV-Vis Absorption Study, and Biological Activity

Bio-inspired benign synthesis of Cr doped ZnO nanoparticles towards electrochemical detection of Bovine Serum Albumin

In this study, we aimed to synthesize monodisperse chromium-doped zinc oxide (Cr-ZnO) nanoparticles (NPs) through green synthesis for the construction of a highly sensitive electrochemical biosensor for BSA detection. Characterization techniques such as X-ray diffraction, FTIR spectroscopy, UV-Vis absorption, and photoluminescence studies confirmed the structural, chemical, and optical properties of the synthesized NPs. FESEM and EDS analysis revealed a spherical nodular morphology with a cauliflower-shaped structure. Nano-bio interaction studies between Cr-ZnO NPs and BSA were conducted using UV-Vis absorption and PL measurements, indicating fluorescence quenching due to complex formation. The synthesized NPs were utilized as electrode material for an electrochemical sensor, demonstrating sensitivity and selectivity in detecting BSA concentrations within the range of 1.5 nM to 48 nM. The sensor's response was linear, showing a decrease in anodic peak current response from 5.08 µA to 3.48 µA for different BSA concentrations. Remarkably, the optical interaction results mirrored the electrochemical findings, emphasizing the consistency between the two methods. The linear response of the electrochemical sensor, coupled with its optical interactions, suggests the versatility and reliability of the synthesized NPs for biosensing applications. With a simple setup requiring minimal samples, the electrochemical sensor offers an inexpensive, rapid, and sensitive screening method for BSA. These findings underscore the potential of the synthesized NPs as a promising electrochemical surface for biosensors, with implications for diagnostic and therapeutic applications, particularly in the context of cattle-related research.

Furan-formulated benzothiazole based Schiff bases for highly selective visual and fluorometric detection of Cu2+ ion with density functional theory studies and its application for real-life samples

In this work, we describe the synthesis of a Schiff base (R1) derived from furfural and 2-hydrazinobenzothiazole which displayed turn-off selective fluorescent chemo-sensing properties for Cu2+ ions in THF: HEPES buffer (9:1, v/v) solution. The molecular structure of the Schiff base (R1) was characterized by various spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, and HRMS. Interestingly, R1 upon interaction with various metal cations displays highly selective colorimetric and fluorescent turn-off response to Cu2+ ions. The UV–Vis absorption study of the R1 with Cu2+ ions exhibits a noticeable color change from yellow to brown color with a redshift (∼60 nm). Upon the addition of Cu2+ ions emission quenching at 529 nm was observed in R1, and the limit of detection (LOD) and limit of quantification (LOQ) were found to be 3.23 × 10−9 M and 10.79 × 10−9 M. The mechanisms of probe R1 for sensing Cu2+ ions have been well demonstrated by Job's plot, Benesi-Hildebrand studies, and Density functional theory calculations (DFT). Owing to practical application, the Cu2+ ions were efficiently determined using a spike and recovery approach from real water and vegetable extract samples. Further, the developed R1 sensors were used for test strips application to detect the Cu2+ ions and achieved naked-eye detection. Therefore, these investigated results demonstrate that sensor R1 has great potential to detect Cu2+ ions in environmental analysis systems.

Synthesis, Characterization, Optical and Luminescence Properties of Copper Based Metal Organic Frame Works

Herein, we report synthesis of two new copper metal organic frameworks. The organic linkers were terephthalic acid with 6-Dihydroimidazo[2,1-b]thiazole-2-carbaldehyde and terephthalic acid with 3-benzothiazol-2-yl-malonaldehyde used in the copper nano metal organic framework (MOF). Both the Cu-MOF’s were characterized by XRD, UV-vis spectroscopy and FTIR. XRD crystallographic studies revealed the presence of copper metal at 2θ at 18.4°. Tauc plots were simulated to calculate the band gap of both Cu-MOF’s and result indicated the band gap energy of Cu-MOF 1 at 3.31 eV and for Cu-MOF 2 was at 3.57 eV. The UV-Visible absorption studies indicated two bands for Cu-MOF 1 and Cu-MOF 2 at 326 nm. However, the second band in Cu MOF 1 at 509 nm was slightly shifted to higher wavelength at 516 nm in Cu-MOF 2 due to the extension of π-π* transition. The photoluminescent properties of both Cu-MOF’s indicated a strong band at 505 nm. Thus, the optical properties of both the Cu-MOF’s infers that these can be a promising semiconductor material for various electronic applications.

Aggregation-induced Emission Active Naphthalimide Derived Schiff Base for Detecting Cu2+ and Its Applications.

Herein, an aggregation-induced emission (AIE) active Schiff base (NHS) was synthesized by condensing naphthalimide hydrazide with salicylaldehyde. The non-fluorescent solution of NHS in DMSO turned to emissive NHS upon increasing the HEPES fraction in DMSO from 70 to 95%. The UV-Vis absorption and DLS studies supported the self-aggregation of NHS that restricted the intramolecular rotation and activated the ESIPT process. The blue fluorescence of AIE luminogen NHS in DMSO:HEPES (5:95, v/v, pH = 7.4) was examined by adding different metal ions (Al3+, Ca2+, Cd2+, Co2+, Cu2+, Cr2+, Fe2+, Fe3+, Hg2+, Mg2+, Mn2+, Ni2+, Pb2+ and Zn2+). NHS showed a selective fluorescence switch-off response for Cu2+ due to the chelation enhancement quenching effect(CHEQ). The quenching of NHS by Cu2+ was explored by using density functional theory (DFT) and Stern-Volmer plot. The practical utility of NHS was examined by quantitative and qualitative analysis of Cu2+ in real water samples.

Nonlinear Absorption Features of Acid Blue 129 Dye in Polar Solvents: Role of Solvents on Solute Molecule.

This paper focuses the study of nonlinear absorption (NLA) features of anthraquinone dye namely, acid blue 129 with different polar solvents including ethanol, methanol, acetone, 1-proponal and DMSO. The acid blue 129 dye in polar solvents is characterized by UV-Visible absorption and fluorescence study. The NLA measurements of acid blue 129 dye is examined via open aperture (OA) Z-scan method employing at 650nm wavelength. The OA Z-scan curve of the experimental dye exhibits both saturable absorption (SA) and reveres saturable absorption (RSA) signature, which results from negative and positive NLA coefficient (β). The order of ground and excited state absorption cross-section is measured to be 10-22 m2 and 10-18 m2, respectively and proved the existence of RSA in acid blue 129 dye. The order of NLA coefficient and imaginary component of the third-order nonlinear susceptibility of acid blue 129 dye in polar solvents is calculated to be 10-3cm/W and 10-5 esu, respectively. The multi-parameter scale viz., Kamlet-Abboud-Taft is used to measure the influence of solvent parameters on solute molecule. The results from the experiments suggest that the acid blue 129 is a suitable candidate for nonlinear optical (NLO) applications.

Impact of Nd doping in Bi2S3 thin films coated by nebulizer spray pyrolysis technique for photodetector applications

In this study, cost effective & scalable nebulizer spray pyrolysis approach was used to produce varying concentrations of Bi2S3:Nd (0, 1, 3, 5 wt%) thin films on glass substrates and the effect of Nd dopants on the crystalline, morphological, optical and photo sensing properties of the Bi2S3 thin films were studied. From the XRD results, the diffraction pattern of the prepared Bi2S3:Nd thin films exhibits an orthorhombic structure for all concentrations of Nd dopants with a predominant peak along (130) plane. Upon increasing the concentration of Nd dopants up to 3 wt% the predominant peak intensity increases with an increase in crystallite size of 25 nm and decreases with a further increase in the incorporation of Nd dopant. The surface morphological studies showed uniform nanocrystalline morphology for all the Bi2S3 thin films. The UV–Vis absorption studies revealed higher absorption of the prepared thin films over UV region and narrowing of the energy gap from 2.18 to1.63 eV with the incorporation of Nd dopant from 0 to 3%, repectievely. The photo sensing properties of the fabricated devices showed higher responsivity (R), detectivity (D*), EQE, and rapid rise/fall time of 1.36 × 10−1 A/W, 3.05 × 1010 Jones, 43%, and 0.1/0.2 s for Bi2S3:Nd 3 wt% thin film photodetector confirming the suitability of the device for commercial photodetector applications.

Fabrication, Characterization of Basic Blue 7 Dye-Doped PVA Films and Their Third-Order Nonlinear Optical Properties.

In this work, we report on the fabrication, characterization and the third-order nonlinear optical (NLO) properties of basic blue 7 (BB 7) dye‒doped polyvinyl alcohol (PVA) polymer thin films. The absorption spectra of BB 7 dye‒PVA films were measured by UV‒visible absorption studies. The functional groups of BB 7‒PVA films have been identified by FT‒IR spectroscopic analysis. The surface morphology was examined by AFM and SEM analysis which shows that the BB 7 dye‒doped PVA films have a homogenous and smooth surface. The nonlinear absorption and refraction of BB 7‒PVA films were respectively explored by open aperture and closed aperture Z‒scan technique using a 5 mW semiconductor diode laser of 635nm wavelengths. The BB 7‒PVA films exhibit the reverse saturable absorption (RSA) and self-defocusing effect and the measured third‒order nonlinear susceptibility χ(3) values of these films were found to be of the order of 10- 5 esu. The present experimental results show that BB 7‒PVA films may have potential applications in future photonic and NLO devices.

Ba3GeTeS4: A new quaternary heteroanionic chalcogenide semiconductor

We report the synthesis and characterization of a new quaternary heteroanionic chalcogenide phase, Ba3GeTeS4. A single-crystal X-ray diffraction study of a yellow-colored crystal of Ba3GeTeS4 shows that the compound is stoichiometric and crystallizes in the orthorhombic Cmcm space group having cell parameters of a ​= ​6.8583(12) Å, b ​= ​16.207(3) Å, c ​= ​9.6239(19) Å, with four formula units (Z ​= ​4) per unit cell. The unit cell of the structure consists of two Ba, one Ge, one Te, and two S sites. All the crystallographically independent atoms occupy special positions. The Ba3GeTeS4 structure is made up of zero-dimensional [GeS4]4– anionic units along with Ba2+ cations, each of that is surrounded by the Te and S atoms. An optical UV–Vis absorption study on a polycrystalline sample of Ba3GeTeS4 establishes its semiconducting nature with a direct bandgap of 2.5(2) eV consistent with the yellow color of the sample. The polycrystalline Ba3GeTeS4 shows an extremely low value of thermal conductivity (∼0.46 W/mK) at 723 ​K. The ab-initio DFT calculations predict a high value of the thermoelectric figure of merit (zT ​> ​1) for the hole doped-Ba3GeTeS4 sample. The crystal orbital Hamilton population (COHP) analysis shows that the Ge–S bonds are strongest in the structure, while the strengths of the Ba–S and Ba–Te interactions are similar.

New azo-azomethine derivatives: Synthesis, characterization, computational, solvatochromic UV‒Vis absorption and antibacterial studies

In this research investigation, new azo-azomethine derivatives (3a-j) were synthesized by a conventional azo coupling process at 0–5 °C. Several spectroscopic methods, including FT-IR, NMR, and HRMS, were used to precisely conduct the structure elucidation. To obtain a deeper understanding of the molecular characteristics, computational analysis of molecular geometry, Mulliken atomic charges, and global reactive descriptors was conducted. Molecular electrostatic potential (MEP) and reduced density gradient analysis (RDG) were also examined. Utilizing various solvents, a solvatochromic UV‒Vis absorption investigation was conducted. A molecular docking study was used to investigate the binding type and energies of synthesized molecules with bacterial proteins. After testing for antibacterial activity, it was discovered that the compounds had excellent antibacterial activity.

A novel indolino-spironaphthooxazine as the highly sensitive and selective probe for colorimetric detection of Au3+

A novel colorimetric probe in a spironaphthooxazine class, SPNO, was successfully synthesized. The single crystal and spectroscopic analyses were utilized to confirm its molecular structure and photo properties. The results showed that SPNO in a 1,4-dioxane-H2O solution displayed remarkable selectivity and sensitivity for colorimetric detection of Au3+ over other competing cations. Based on the UV–vis absorption study, the mixtures of SPNO and Au3+ exhibited a new absorption band at 580 nm due to the structural isomerization of SPNO into its merocyanine form which acts as a ligand to form an SPNO–Au3+ complex. The stoichiometric ratio of SPNO to gold(III) cations in the complexes was determined using Job's plot and the results indicated that the complexes were formed at a 1:2 mol ratio. The detection limit of Au3+ in 1,4-dioxane-H2O was investigated to be 335 nM. Moreover, the SPNO-coated test strips were also prepared to demonstrate that this probe can be used practically as a tool for highly sensitive detection of Au3+ in mixed 1,4-dioxane:water solutions. Finally, the sensitivity of SPNO toward Au3+ in drinking water was determined to verify its applicability in real samples.

Heterometallic Mo–Ti oxo clusters with metal–metal bonds: Preparation and visible-light absorption behaviors

In this work, two heterometallic clusters, namely Ti^IV₄Mo^V₄Mo^VI₂O₁₆(OCH₃)₁₆ (<strong>1</strong>) and Ti^IV₄Mo^V₄O₁₀(OC₂H₅)₁₄ (C₆H₅COO)₂ (<strong>2</strong>) are successfully constructed to improve the solar absorption and performance of titanium oxo clusters (TOCs). The <strong>1</strong> and <strong>2</strong> structures are determined well by single-crystal X-ray diffraction analysis and found to feature the common presence of Mo–Mo interactions. The solid-state UV–vis absorption studies indicate that these structures exhibit enhanced visible-light absorption and significantly reduced optical band gaps, which should be dominantly attributed to the introduction of electron-rich Mo–Mo pairs as heterometals. This work demonstrates an effective strategy of regulating the light absorption behaviors of TOCs by importing electron-rich heterometals.

DNA groove binder and significant cytotoxic activity on human colon cancer cells: Potential of a dimeric zinc (II) phthalocyanine derivative

The interaction of a multi-component system consisting of benzene-1,4-diyldimethanimine-bridged dimeric zinc-phthalocyanine groups (4OMPCZ) with calf thymus DNA (ct-DNA) was investigated using UV–Vis absorption, fluorescence emission spectroscopy methods, and viscosity measurements. The binding constant, Kb, which is an important parameter to gain information about the binding mode, was found as 9.7 × 107 M−1 from the UV–Vis absorption studies. Another important spectrophotometric tool is competitive displacement assays with Ethidium bromide and Hoechst 33342. Through this experiment, a higher KSV value was obtained with Hoechst for the phthalocyanine derivative, 4OMPCZ, and the ct-DNA complex than with ethidium bromide. Additionally, molecular docking studies were conducted to calculate the theoretical binding constant and visualize the interactions of 4OMPCZ with a model DNA. According to docking results, although the interactions are mainly located in the major groove of the DNA helix, due to the wrapping, these interactions can also be extended to the minor groove of the DNA. Spectrophotometric, molecular docking, and viscosity studies revealed that the interaction of 4OMPCZ with DNA is likely to be via the major and minor grooves. The in vitro cytotoxic activity of 4OMPCZ was evaluated by MTT assay on human colon cancer cells (HT29) after 72 h of treatment. 4OMPCZ indicated significant cytotoxic activity when stimulated with UV light compared to the standard chemotherapy drugs, fluorouracil (5-FU), and cisplatin on HT29 colon cancer cells. The IC50 value of 4OMPCZ displayed considerably lower concentrations compared to the standard drugs, 5-FU, and cisplatin.