UV-vis Absorption Properties Research Articles

ZnO/NiO synthesis and its characterization using solvothermal method

This research aims to understand the influence of ZnO and NiO molarity towards its optical and morphological properties. ZnO/NiO was synthesized using solvothermal method with ZnO and (Ni(NO)3)2.6H2O as its main ingredients and dissolved in ethanol. The synthesis of ZnO/NiO using solvothermal method was carried out by modifying the variation of ZnO concentration with the ratio of ZnO and NiO were 1:1, 2:1, and 3:1. ZnO/NiO was used as a semiconductor material which will be analysed for optical properties that occur, one of which was band gap energy. The result was then characterized by X-Ray Diffraction (XRD) showed that the crystal size of the sample at 3:1 is the largest. Furthermore, the Fourier Transform Infrared Spectroscopy (FTIR) analyst indicated that the sample corresponds to C=C and C-H bonds. Moreover, the UV – Vis analyst showed that the absorption range is between 300-400nm indicated the extended UV-Vis absorption property of mixed oxide.

Synthesis and Photoelectrocatalytic Applications of TiO2/ZnO/Diatomite Composites

ZnO and TiO2 are semiconductor nanomaterials that are widely used in photocatalysis. However, the relatively high recombination rate and low quantum yield of photogenerated electron–hole pairs limit their practical applications. In this study, a series of TiO2/ZnO/diatomite composites with various compositions were successfully prepared via a two-step precipitation method. They exhibited stronger UV–visible absorption properties and substantially lower fluorescence intensities than those of ZnO and ZnO/diatomite, which was mainly due to the low recombination rate of the photogenerated electron–hole pairs in the composite system. The reaction intermediates of methylene blue were detected by liquid chromatography–mass spectrometry, and the degradation process was determined. The best composite catalyst was used for the degradation of gaseous methylbenzene and gaseous acetone. The gaseous acetone degradation product was determined to be acetaldehyde via gas chromatography–mass spectrometry. The results show that the composite catalyst exhibited a good photocatalytic degradation of both liquid pollutants and harmful volatile gases. When applied to the hydrogen and oxygen evolution reactions, the composite catalyst retained a good photoresponsivity and electrolytic efficiency.

Synthesis, UV-Vis Spectroscopic and Physico-chemical Characterization of Oxovanadyl Complexes of Lincomycin and Neomycin

Abstract: In the recent past, the pharmaceutical modification of drug molecules by complexation with biologically relevant metals to improve their properties such as stability, dissolution rate, absorption and bioavailability has been extensively studied. In order to achieve better and enhanced medicinal activity, vanadyl complexes of the widely used lincomycin (Lin-van) and neomycin (Neo-van) have been synthesized and their physico-chemical properties examined. The UV-Vis absorption properties of these complexes were determined and their antimicrobial activities were tested against some pathogenic organisms viz: Proteus vulgaris, Klebsiella pneumonae, Escherichia coli and Staphylococcus aureus. In all cases, Neo-van showed better antimicrobial activity than Lin-van while both complexes showed better activity than the antibiotic lincomycin and the previously reported Cu-Lin. Keywords: lincomycin, neomycin, UV-Vis spectroscopy, Physico-chemical, Oxovanadyl, synthesis

A novel BiOX photocatalyst for the “green” degradation of polymers used in oilfields

The wastes from functional polymers (polyanionic cellulose, polyacrylamide, potassium polyacrylamide, and hydroxyethyl cellulose) generated during oil and gas exploration and development are harmful to biodiversity and human health. However, most traditional treatments are inefficient in degradation and cause secondary pollution. In this paper, BiOBr0.5Cl0.5 a 3D flower-like solid solution with in-situ deposition of elementary substance Bi and surface oxygen vacancies was synthesized by the hydrolysis and the redox methods. The chemical compositions, the morphologies, and the UV–visible absorption properties of Bi/BiOBr0.5Cl0.5 were characterized. Moreover, the photocatalytic activity of Bi/BiOBr0.5Cl0.5 and the kinetic behavior of the RhB photocatalytic degradation were investigated. The photocatalytic degradation of RhB followed a pseudo-first-order kinetic reaction, and Bi/BiOBr0.5Cl0.5-0.3 demonstrated the highest photocatalytic activity: The RhB degradation efficiency of Bi/BiOBr0.5Cl0.5-0.3 was 85%, and the COD removal rate of the functional polymers conducted by Bi/BiOBr0.5Cl0.5-0.3 was greater than 80%. The exciton photocatalytic processes of Bi/BiOBr0.5Cl0.5 was found through the electron spin resonance (ESR) and the active-species trapping analyses of the photocatalytic degradations of RhB by Bi/BiOBr0.5Cl0.5. In summary, in this paper, the synthesis methods of Bi/BiOBr0.5Cl0.5 photocatalyst and the photocatalytic activity of the Bi/BiOBr0.5Cl0.5 on the degradations of polymers used in oilfields were reported, addressing the shortcomings of the existing treatments for polymer waste fluids that are incorporated into the oil and gas exploration and development process.

Synthesis and Characterization of Schiff Bases Containing 1,2,3-Triazole Unit: Photophysical and Acetyl Choline (AChE) Inhibitory Properties

In this study, new salicylaldehyde derivatives containing a 1,2,3-triazole group (5a-c) and their Schiff bases (6a-c) were synthesized and their structures were characterized by FT-IR, 1H(13C) NMR and elemental analysis spectroscopic methods. The crystal structure of the triazole compound 5c was investigated by X-ray diffraction study. Then, UV-Vis absorption properties were studied and the effects of different solvents on absorption were investigated. In the UV-vis spectra, π-π* and n-π* transitions were observed in the range of 280-480 nm. Especially, the absorption band at 400-480 nm range for 6a-c in MeOH gave the idea that they were caused by tautomeric conversion from phenol-imine to keto-amine in their structure. Acetylcholinesterase Inhibitory activity studies are very important for research on the treatment of Alzheimer's disease, so the synthesized compounds were screaned for their AChE inhibitory activities. According to the results obtained, both 1,2,3-triazole compounds and Schiff bases showed comperable inhibitory activity. In particular, the activity of compound 6b (IC50: 12.85 ± 0.026 µM) was determined to be approximately considerably higher than the standard Galantamine (IC50: 139.4 µM).

Isoelectronic Pt(II) complexes of cyclometalating C^N^N ligands with phenyl/(benzo)thiophenyl and pyridyl/(benzo)thiazolyl moieties.

A series of cyclometalated Pt(II) complexes [Pt(C^N^N)X] (X = Cl, CCPh, CCC6F5) was synthesised from the protoligands HC^N^N containing either phenyl (ph), naphthyl (na) or (benzo)thiophenyl (b(th)) C aryl functions and either pyridyl (py) or (benzo)thiazolyl ((b)tz) peripheral N units, alongside the central 4-phenyl-pyridyl (ppy) or tBu2-phenyl-pyridyl (tbppy) N group. Depending on the combination of the peripheral N or C aryl building blocks, these square planar complexes reveal very different electrochemical, UV-vis absorption and emission behaviour. The reversible reductions shift anodically along the series th/py < ph/tz ≈ th/tz < ph/btz while the irreversible oxidations shift cathodically along the series Cl ≈ CCC6F5 < CCPh. Similar trends were observed for the long-wavelength UV-vis absorption and photoluminescence properties. The emission maxima range from 605 to 675 nm at 298 K in CH2Cl2 solution and from 555 to 655 nm at 77 K in glassy frozen CH2Cl2/MeOH matrices. Large differences in amplitude-weighted average lifetimes τav (up to 0.9 μs at 298 K, up to 12 μs at 77 K) and photoluminescence quantum yields ΦL (up to 0.15 at 298 K and up to 0.82 at 77 K) were found. TD-DFT calculations showed that the decomposition of the triplet excited states into LC (π-π*, centred in the individual parts of the C^N^N ligand) and LLCT (π-π*, between the individual parts of the C^N^N ligand + X-π* from coligand to C^N^N) contributions for the ligand-centred states as well as MLCT (dPt-to-π*C^N^N) and LMCT (pCl or πCCR-to-dPt) character for the charge-transfer states involving the metal is beneficial to assess the participation of the individual heteroaryl groups of the C^N^N ligands. In view of the modular synthesis of these ligands, this will allow the realisation of tailor-made Pt(II) triplet emitters in future work.

Investigating ESIPT and donor-acceptor substituent effects on the photophysical and electrochemical properties of fluorescent 3,5-diaryl-substituted 1-phenyl-2-pyrazolines

This paper describes the synthesis, structural study, and evaluation of electrochemical and photophysical properties by UV–Vis absorption and fluorescence emission analysis (solution and solid-state) of a series of eight 3,5-aryl-substituted 1-phenyl-2-pyrazolines (5), where 3-aryl = 2-OH-C6H4 (5a-g) or Ph (5h), and 5-aryl = Ph (a, h), 1-naphthyl (b), 4-Br-C6H4 (c), 4-F-C6H4 (d), 4-OCH3-C6H4(e), 4-NO2-C6H4 (f), 4-(N(CH3)2)-C6H4(g). The UV–Vis absorption properties of 2-pyrazolines were evaluated in DCM, MeCN, AcOEt, EtOH, and DMSO as the solvent and showed a fluorescence shift for the polar aprotic solvents. The steady-state fluorescence emission exhibited a band in the blue region when excited at the least energetic transition of each compound, although the excited-state intramolecular proton (ESIPT) effect was not detected. In the solid state, compounds presented similar behavior regarding absorption and emission properties compared to the solution assays. With the electrochemical analyses performed for the synthesized 2-pyrazolines, it was possible to conclude that the redox potentials were influenced by the electronic and steric effects of the substituents on the aryl rings and, according to the electronic nature of the substituents, which electron-donating groups were favored. Finally, the TD-DFT analyses revealed that all compounds had delocalized electron density throughout the 2-pyrazolines unit and were not influenced by the substituent bonded at C-5. Nonetheless, LUMO orbital analysis showed that only derivatives 5b and 5f have this localized density over the substituents.

Dendritic Iron(III) Carbazole Complexes: Structural, Optical, and Magnetic Characteristics.

This paper focuses on the synthesis, structural characterization, and study of the optical, magnetic, and thermal properties of novel architectures combining metal ions as magnetoactive centers and photoactive blocks formed by carbazole units. For this purpose, a series of azomethine complexes of the composition [Fe(L)2]X (L = 3,6-bis[(3′,6′-di-tert-butyl-9-carbazol)-9-carbazol]benzoyloxy-4-salicylidene-N′-ethyl-N-ethylenediamine, X = NO3−, Cl−, PF6−) were synthesized by the reaction of metal salts with Schiff bases in a mixture of solvents. The UV–Vis absorption properties were studied in dichloromethane and rationalized via time-dependent density functional theory (DFT) calculations. Upon excitation at 350 nm, the compounds exhibited an intense dual fluorescence with two emission bands centered at ~445 and ~485 nm, which were assigned to πcarb–π* intraligand and πcarb–dFe ligand-to-metal charge-transfer excited states. EPR spectroscopy and SQUID magnetometry revealed solid-state partial spin crossover in some compounds, and antiferromagnetic interactions between the neighboring Fe(III) ions.

The enhanced photocatalytic activities of TiO2 nanobelts prepared by hydrothermal method

In this paper, the hydrothermal method was employed to synthesize TiO2 nanobelts, which performed enhanced photocatalytic activity compared with TiO2 nanoparticles. The structures, morphologies and surface chemical components of the as-prepared samples were systemically characterized, as well as the UV-Vis absorption properties. Also, the photocatalytic properties of the catalysts were evaluated through degrading MB dye under the simulated solar-driven irradiation. From the comparison, TiO2 nanobelts sample behaved a better photocatalytic degradation of 20 mg/L MB solution within 120 min, more than 0.2 times of TiO2 nanoparticles, which was attributed to more surface oxygen vacancies generated in TiO2 nanobelts during their synthesis process. This finding enables TiO2 nanobelts the feasibility to be used or to be constructed heterostructures applying in the field of water pollutant decontaminations.

Metal-Free Catalyzed Synthesis of Fluorescent Indolizine Derivatives.

A mild and high efficient method to prepare indolizines by two-component reaction with the acid as the catalyst was developed. In this reaction, a new ring efficiently formed in one-step reaction. A wide range of substrates could be applied and the desired products were obtained in 8-95% yields under metal-free conditions. Different indolizine derivatives (compounds 3a-3n) were synthesized by general conditions and microwave irradiation conditions, and compound 3a gave the best results with an isolated yield of 95% and 82%, respectively. The structures of synthesized compounds were characterized by spectral analysis, and compound 3m was confirmed by single crystal X-ray analysis. UV-vis absorption and fluorescence properties of these compounds were correlated with substituent groups on indolizine rings.

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties.

Acridine derivatives have attracted considerable interest in numerous areas owing to their attractive physical and chemical properties. Herein, starting from readily available anthranilic acid, an efficient synthesis of 2,4-bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine derivatives was accomplished via a one-pot double Sonogashira cross-coupling method. The UV-visible absorption and emission properties of the synthesized molecules have been examined. Additionally, theoretical studies based on density functional theory (DFT/B3LYP/6-31G(d)) were carried out.

Synthesis, structure, electronic characterization, and halogenation of gold(III) phlorin complexes

The metalation chemistry of the phlorin, which is a non-aromatic tetrapyrrole macrocycle containing a single sp3-hybridized meso-carbon has remained underdeveloped, as compared to that of more traditional tetrapyrroles such as porphyrins, corroles and phthalocyanines. There have been few prior efforts to prepare metallophlorins, and those that have been reported have relied on either reduction or nucleophilic attack of parent metalloporphyrins, rather than direct metalation of freebase phlorin constructs. In this work, an alternate synthetic approach for preparation of gold(III) phlorin complexes that involves the first direct metalation of two different freebase phlorin derivatives (3H(Phl[Formula: see text] and 3H(Phl[Formula: see text] with AuBr3to produce the stable and fully isolable gold(III) phlorin complexes Au(Phl[Formula: see text] and Au(Phl[Formula: see text] is reported. The first structural characterization of a metallophlorin bearing geminal dimethyl substituents at the sp3-hybridized meso-carbon via X-ray crystallography is also reported. In addition to the preparation of Au(Phl[Formula: see text] and Au(Phl[Formula: see text], the UV-vis absorption and redox properties of these two gold(III) phlorins in comparison to those of their freebase homologues is also detailed. Notably, the metallophlorins are characterized by panchromatic absorbance profiles and intense and broad bands that span the long-visible and into the near-IR regions, as well as two fully reversible oxidation and reduction waves as probed by cyclic voltammetry. Finally, the chlorination of Au(Phl[Formula: see text] using PhI(Cl[Formula: see text] was probed and it was found that this regioslective reaction generates monochlorinated (Au(Phl[Formula: see text]Cl)) and dichlorinated (Au(Phl[Formula: see text]Cl[Formula: see text] products, which were both structurally characterized by X-ray crystallography.

Characterization of carbon nanotube decorated silver nanoparticles

Silver nanoparticles (Ag NPs) prepared using the exploding wire process has been decorated with carbon nanotubes (MWCNTs, SWCNTs). Well dispersion of silver NPs is achieved by a simple chemistry process on the surface of CNTs. The structure, optical and morphology of silver nanoparticles decorated with carbon nanotubes were characterized by x-ray diffraction, Atomic force microscopy, and field emission scanning electron microscopy. The illustrated outcome that the UV-Visible absorption and electrical conductivity properties effectively improved for CNT/Ag NPs. The absorption spectrum of silver nanoparticles shows absorption at ultraviolet wavelength zone and there is low peak between (300-900nm) while the absorption of CNT/silver nanoparticles (Ag NPs) increased significantly from UV to near IR region. Field emission scanning electron microscopy analysis shows that silver nanoparticles are decorated on carbon nanotubes without any impurities, with average particle size about (50-80nm) for Ag-NPs, 44nm for MWCNTs/Ag-NPs and 30 nm for SWCNTs/Ag NPs. It was observed that Ag NPs enhanced the electrical conductivity of CNTs from (2.36 ×10-1 (1/Ω.cm) to (1.03×104 (1/Ω.cm)) for SWCNTs/Ag NPs and (8.83×104 (1/Ω.cm)). It is observed that Ag NPs adding enhanced the electrical properties of CNTs. The results show that Ag-coated CNTs have important optoelectronic applications such as solar cell and photodetector.

Photocatalytic degradation of organic pollutants through conjugated poly(azomethine) networks based on terthiophene-naphthalimide assemblies.

A conjugated poly(azomethine) network based on ambipolar terthiophene–naphthalimide assemblies has been synthesized and its electrochemical and UV-vis absorption properties have been investigated. The network has been found to be a promising candidate for the photocatalytic degradation of organic pollutants in aqueous media.

A zero dimensional hybrid organic- inorganic perovskite CuCl4 based: Synthesis, crystal structure, vibrational, optical properties, DFT and TDFT calculations, dielectric properties and biological activity

The paper reports the preparation and structural characterization of a new complex (C6H16N2)[CuCl4] grown by slow evaporation technique in aqueous solution and characterized by X-ray diffraction, spectroscopy measurement, DTA-TG analysis, and photoluminescence properties. The crystal structure determination shows that the title compound crystallizes in the C 2/c space group of the monoclinic system. The unit cell dimensions at T=150K are as follows: a = 14.500(5) Å, b = 14.619(5) Å, c = 5.9173(17) Å, β = 107.419(11) °, V = 1196.8(7) Å3 and Z = 4. The atomic arrangement can be described by thick layers of inorganic entities, made up from CuCl4 anions, developed parallel to the (a, c) planes at y = 0 and 1/2. The organic cations are anchored onto successive layers and connect them via N-H...Cl hydrogen bonds, to form an infinite three dimensional network. In addition, the nature and proportion of contacts in the crystal packing were studied by the Hirshfeld surfaces. The vibrational properties were investigated experimentally by means of IR and Raman spectroscopy and theoretically by DFT calculations. Furthermore, the UV-Visible optical absorption and photoluminescence properties were explored by experimental techniques and TDDFT calculations. Good agreement was found between theoretical and experimental results. Thermal analysis reveals the decomposition of the compound at 511 K. The bioassay results showed that the structure exhibits significant antibacterial activity.

Syntheses, crystal structures and photoluminescent properties of dinuclear and tetranuclear zinc complexes with 1,4-bis(2,2':6',2″-terpyridine-4'-yl)benzene

Two zinc complexes, [(HCOO)2Zn(μ-bteb)Zn(OOCH)2]·2H2O (1) and {[(HCOO)Zn(μ-bteb)Zn(OOCH)]2(μ-O)2}·DMF·6H2O (DMF = dimethylformamide) (2), containing a π-conjugated “back to back” bis-terpyridine ligand 1,4-bis(2,2':6',2''-terpyridin-4'-yl)benzene (bteb) have been solvothermally synthesized and characterized via elemental analysis, infrared spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction, and powder X-ray diffraction. 1 and 2 are dumbbell-like dinuclear and rectangle tetranuclear ZnII complexes, respectively. It is interesting that these complexes were synthesized by adjusting the ratio of DMF and H2O. The X-ray crystal structure reveals that ZnII metal centers in 1 are five-coordinate by three nitrogens from bteb and two oxygens from monodentate formate ions, while ZnII metal centers in 2 are five-coordinate containing three nitrogens from bteb, one oxygen from a monodentate formate and the other one from a bridging O. Hirshfeld surface analyses and 2-D fingerprint plots display that the main interactions are O···H/H···O and H···H intermolecular interactions in 1 and 2. The thermal decomposition behaviors of 1 and 2 were studied by using thermogravimetric analysis. UV-Vis absorption and photoluminescent properties of 1 and 2 were also investigated.

Synthesis and polarity-sensitive fluorescent properties of a novel water-soluble polycyclic aromatic hydrocarbon (PAH)

We report the successful synthesis and spectroscopic characterization of a novel, water soluble anthanthrene-based derivative, 6,12-bis(TEG)anthanthrene 3. The presence of the two long ethylene glycol side chains gives this large, six-membered polycyclic aromatic compound a high aqueous solubility. It exhibits UV–vis absorption properties similar to those of anthanthrene itself, indicating that the side chains do not have a significant effect on the electronic structure of the central chromophore. The compound exhibits strong, polarity-sensitive fluorescence in aqueous solution in the blue–green region of the spectrum, with a fluorescence quantum yield of 0.13 and a polarity sensitivity factor (PSF) of 2.0. The utility of this new fluorescent molecule as a probe of supramolecular complexation was demonstrated by its inclusion into the molecular host hydroxypropyl-β-cyclodextrin in aqueous solution. Strictly 1:1 inclusion was observed, with a moderately strong binding constant K of 650 M−1. This new fluorescence probe has significant potential applications in fluorescence-based studies of aqueous biochemical and supramolecular systems.

Modeling Photonastic Materials: A First Computational Study.

Photonastic materials present a directional and repeatable deformation of the material shape due to transduction from light energy to mechanical energy. Among these materials, light-responsive polymers, composed of photochromic molecules embedded in a polymer matrix, are of high interest. The present work aims at laying the foundation stone of the modeling of the photomechanical behavior of such systems by proposing a computational strategy that is able to investigate (i) the impact of the polymer matrix on the photochromic properties of a dithienylethene (DTE) switch and (ii) the impact of the photochromic reaction on the polymer environment. Contrary to previous approaches, the present model is able to propose a realistic arrangement of the photochrome embedded in the polymer film, thanks to the adaptation of the so-called "controlled-like polymerization algorithm" [Lemarchand, C. A.; J. Chem. Phys. 2019, 50, 224902]. Our strategy relies on molecular dynamics (MD) simulations and time-dependent density functional theory (DFT) calculations. Careful analysis of MD trajectories and comparison with simulations in solution have shown the rigidification of the DTE molecule due to the presence of the polymer chains, which hindered the interconversion between the DTE open-form isomers and can probably modify the photocyclization quantum yield. Besides, the UV-vis absorption properties of the DTE open-form isomers are more impacted by the polymer embedding than its closed-form counterpart. Concerning the impact of the photoreaction on the polymer matrix, the time evolution of the pressure tensor and of the atomic displacements in the matrix have shown that (i) the cyclization reaction has a negligible impact; (ii) the cycloreversion reaction induces a locally large and anisotropic pressure increase and leads to a collective displacement of the polymer matrix away from the reactive center; and (iii) the characteristic time scale associated with these coupled processes is below 1 ps. Therefore, the two processes involved in photonastic motions, namely, the photoreaction and the relaxation of the polymer matrix after the photoswitch structural change, cannot be decoupled.

Spectroscopic Studies of CDPy Molecule in Different Protic and Aprotic Solvents and Investigation of Antioxidant Property.

The properties of 3-Cyano-4, 6-Dimethyl-2-Pyridone (CDPy) were analyzed to study the antioxidant behavior. The UV-Visible absorption and fluorescence properties of CDPy have been studied in two protic (water and methanol) and two aprotic (acetonitrile and dimethyl sulfoxide) solvents. Its antioxidant properties were compared with well known antioxidant ascorbic acid. This compound, CDPy was found to exhibits moderate antioxidant properties. The experimental results were reproduced by theoretical density functional methods, which helped to understand the experimental result better.

Structural characterization and DNA binding properties of a new imine compound

In this study, a new imine compound (M) was prepared from the reaction of o-vanillin and 4-isopropylaniline. The structure of the compound was characterized by the spectroscopic and analytical methods. Single crystals of the compound were grown and solid-state structure of the compound was further characterized by X-ray diffraction study. The UV-Vis absorption and emission properties of the compound were studied in different solvents. Moreover, DNA binding ability of the compound was investigated and compared with the standard DNA binding agents. The compound showed similar binding constant (4 x 105 M-1) to those spermine and ethidiumbromide.