UV Absorption Studies Research Articles

Mn-Catalyzed Ligand-Free One-Pot Synthesis of (E)-6,7-Dihydrodibenzo[b,j][1,7]phenanthrolines and (E)-1,2,3,4-Tetrahydrobenzo[b][1,6]naphthyridines through Dehydrogenative Friedlander Annulation/C(sp3)-H Functionalization.

An efficient, MnO2-catalyzed ligand-free synthesis of (E)-6,7-dihydrodibenzo[b,j][1,7]phenanthrolines, 13, and (E)-1,2,3,4-tetrahydrobenzo[b][1,6]naphthyridines, 15, utilizing, 2-amino-5-chloro-benzhydrol, 9, acridinol, 10, or 1-benzyl-4-piperidinol, 14, and benzyl alcohols, 11, is reported. The MnO2-catalyzed dehydrogenative Friedlander annulation utilizing ChCl/p-TSA (DES-1) and subsequent C(sp3)-H functionalization with TBAB/p-TSA (DES-2) was effected at 100 °C. The optimized reaction conditions gave excellent product yields, and the products were evaluated for their by UV absorption and fluorescence emission studies.

Host-Guest Mechanism via Induced Fit Fullerene Complexation in Porphin Receptor to Probe Salivary Alpha-Amylase in Dental Caries for Clinical Applications.

Salivary α-amylase is the most abundant protein of human saliva that potentially binds to streptococcus and other bacteria via specific surface-exposed α-amylase-binding proteins and plays a significant role in caries development. The detection of α-amylase in saliva can be used as a bioindicator of caries development. Herein, a facile strategy has been applied, tailoring the photochemical properties of 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine (TPPOH) and the fullerene C60 complex. The fluorescence emission of TPPOH is quenched by starch-coated fullerene C60 via charge-transfer effects, as determined by UV absorption and fluorescence spectroscopic studies. The starch-coated C60 has been thoroughly characterized via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), optical microscopy, thermal gravimetric analysis (TGA), static water contact angle measurements, and zeta potential measurements. The analytical response of the assay showed a linear fluorescent response in α-amylase concentrations ranging from 0.001-0.1 Units/mL, with an LOD of 0.001 Units/mL. The applicability of the method was tested using artificial saliva with quantitative recoveries in the range 95-100%. The practicability of the procedure was verified by inspecting saliva samples of real clinical samples covering all age groups. We believe that the proposed method can serve as an alternative analytical method for caries detection and risk assessment that would also minimize the cost of professional preventive measures and treatments.

Effect of molar concentration on optoelectronic properties of NiO nanoparticles for p-n junction diode application

In this work, fine nickel oxide nanoparticles (NiO NPs) were successfully made utilizing a straightforward co-precipitation approach at low temperature. The effects of precursor concentration on the structural, optical, and electrical characteristics of NiO nanoparticles were investigated. All indexed diffraction peaks in XRD demonstrate the production of NiO with cubic structure. An increase in NiO crystallite size above 16.8 nm was observed when the precursor concentration exceeds 2 M, suggesting the presence of nanostructure in the final product. In FT-Raman spectra, the band centered at ∼ 500 cm–1 is due to Ni-O stretching (LO) mode, and two-magnon (2 M) scattering mode causes the band at 1514 cm–1. The synthesized product is composed of almost rod-shaped particles with a size range of 10–20 nm, according to FESEM pictures. The UV absorption studies showed a high absorption at the fundamental absorption edges originating at 332 nm, which gradually shifted to a lower energy region up to 400 nm with increasing precursor concentration, which means a reduction in bandgap values. The effect of precursor concentration associated with the electrical characteristics of the produced NiO nanoparticles has been investigated for the temperature range 30 to 130 °C. The I-V characterization was used to compute the different photo-diode parameters including n, ФB, Io, PS, R, QE, and D* . The remarkable high photosensitivity of 1100% and specific detectivity of 4.324 × 10−10 Jones for the diode evaluated at 120 mW/cm2 was observed in a 2 M fabricated diode. These findings imply that all the fabricated diodes are exceptionally light-sensitive and are well-suited for upcoming UV photodetector applications.

Pharmaceutical manifestation of Knoevenagel condensed metal (II) complexes through virtual, in vitro and in vivo assessments

Sulphur containing compounds possess a great deal of interest due to wide range of beneficial activities towards biotic species. This work also deals with the study of biological examination of newly synthesized sulphur containing Cu(II) and Zn(II) complexes derived from (E)-4-(phenylimino)-3-((E)-1-(phenylimino)ethyl)pent-2-ene-1-thiol Schiff bases. Moreover, the DNA nuclease efficiency of the synthesized metal complexes is studied by UV absorption studies, Fluorescence studies, Viscosity and CV titrations which confirm the intercalative mode of binding. Pharmacokinetic studies and drug like activity of these compounds are screened with the help of SWISS ADME online freeware. Their morphological nature is corroborated by various spectral techniques. Optimized geometry and biologically accessible nature of the synthesized compounds are investigated by Gaussian 09 W software. Interestingly, molecular docking studies are carried out against cancer DNA and 6J10 cancer cell. Anti–inflammatory and in vitro antioxidant activities have been studied to validate the theoretical prediction. Based on these preliminary pharmacological activities, the in vitro cytotoxicity and in vivo antitumor activities are examined using MCF-7, HeLa, Hep-2, HepG-2 and Ehrlich ascites carcinoma (EAC) cell lines. All the above examinations reveal that the nitro substituted transition metal complexes possess higher biological bustle. Communicated by Ramaswamy H. Sarma

Synthetic dimethoxyxanthones bind similarly to human serum albumin compared with highly oxygenated xanthones

Spectroscopic studies were carried out for the interaction of the bioactive compounds 2,3-dimethoxyxanthone (1) and 3,4-dimethoxyxanthone (2) with human serum albumin (HSA). The UV absorption, steady-state, and time-resolved fluorescence spectroscopy studies showed that 1 and 2 interact with HSA through a ground-state association. The decrease in the Stern-Volmer constant (KSV) values with increasing temperature, and the bimolecular quenching rate constant (kq) values in the order of 1012 M−1s−1 indicated a static fluorescence quenching mechanism, corroborating with time-resolved fluorescence decays. The association constant (Ka) values in the order of 104 M−1 indicated a moderate interaction between these xanthones and HSA. Circular dichroism experiments showed weak perturbation on the secondary structure of albumin after the interaction with 1 and 2. Thermodynamic parameters suggested that the binding is entropically (for HSA:1, ΔS° 0.012 ± 0.003 and for HSA:2 0.008 ± 0.002 J/molK) and enthalpically (for HSA:1, ΔH° -24.0 ± 0.99 and for HSA:2 -25.6 ± 0.67 kJ/mol) controlled, with a Gibbs free energy change (ΔG°) close to -28.0 kJ/mol in both cases. Competitive drug-displacement and molecular docking results showed that 1 and 2 could interact not only with subdomain IIA, where Trp-214 residue can be found, but also with subdomains IIIA and IB. Hydrogen bonding, electrostatic, and hydrophobic interactions were detected as the main binding forces to stabilize the association HSA:1 and HSA:2. Overall, the dimethoxyxanthones have similar binding affinity compared with highly oxygenated xanthones, e.g., mangiferin, gentiacaulein, and norswertianin.

The Signature of the Northern Galactic Center Region in Low-velocity UV Absorption

The Galactic Center (GC) is surrounded by plasma lobes that extend up to ∼14 kpc above and below the plane. Until now, UV absorption studies of these lobes have only focused on high-velocity components (∣v LSR∣ > 100 km s−1) because low- and intermediate-velocity (LIV) components (∣v LSR∣ < 100 km s−1) are blended with foreground interstellar medium. To overcome this difficulty, we present a differential experiment to compare the LIV absorption between different structures within the GC region, including the Fermi Bubbles (FBs; seen in gamma rays), the eROSITA Bubbles (eBs; seen in X-rays), and the Loop I North Polar Spur (LNPS) association, an X-ray and radio feature within the northern eB. We use far-UV spectra from Hubble Space Telescope to measure LIV Si iv absorption in 61 active galactic nuclei sight lines, of which 21 pass through the FBs, 53 pass through the eBs, and 18 pass through the LNPS. We also compare our measurements to those in the literature from sight lines covering the disk–halo interface and circumgalactic medium (CGM). We find that the FBs and eBs have enhancements in measured columns of 0.22–0.29 dex in log. We also remove the contribution of a modeled disk and CGM component from the measured Si iv columns and find that the northern eB still retains a Si iv enhancement of 0.62 dex in log. A similar enhancement is not seen in the southern eB. Since a notable difference between the northern and southern eBs is the presence of the LNPS association in the nothern bubble, the northern eB enhancement may be caused by the LNPS.

CuO/NiO nano-composite synthesized from banana peels for grow light

The essential electromagnetic radiation spectrum required for plant growth is provided by grow lights, which replicate the solar spectrum's spectral radiations. In this study, CuO, NiO, and CuO/NiO nanocomposites were synthesized from discarded banana peels. The yields of CuO, NiO, and NiO/CuO were 1.00 g, 0.99 g, and 1.2 g, respectively. The structural and optical properties of the synthesized material were investigated using x-ray diffraction, Fourier transform infrared spectroscopy, UV absorption, and fluorescence spectroscopy. XRD analysis revealed that CuO, NiO, and CuO/NiO have crystalline monoclinic, cubic, and mixed phases, respectively. The average crystalline size was determined using the Scherrer formula and was found to be 18.89 nm, 11.27 nm, and 16.55 nm for CuO, NiO, and CuO/NiO, respectively. The FTIR spectrum showed that the Cu–O bond in the CuO structure is characterized by a broad band in the range of 480–486 cm−1, while the Ni-O bond stretching vibrations are assigned to a broad band in the range of 440–470 cm−1. The UV absorption study yielded an optical band gap of 1.74 eV for CuO, 3.60 eV for NiO, and 5.22 eV for NiO/CuO. The fluorescence spectroscopy results revealed similar emission spectra for CuO, NiO, and CuO/NiO, which are ideal for grow lights.

Microwave‐Assisted Tandem Copper‐Catalyzed Three‐Component Reaction for Synthesis of 2‐Iminopyrans

AbstractThe iminopyrans were synthesized by the CuAAC‐MCR approach, the coupling of enaminones, phenyl acetylenes, and sulfonyl, under microwave treatment. The mechanism of the formation of iminopyrans along with amidine has been studied in detail. Experiments to minimize amidine formation were explored, and unfortunately, these experiments were unsuccessful. Molar equivalents of enaminones, phenyl acetylenes, and sulfonyl were optimized to increase the yield of iminopyran. Fluorescent properties of iminopyrans were characterized using Frontier molecular orbital analysis, UV absorption, and emission studies.

Anthracene benzene conjugate (ABC): An asymmetric Schiff base for the selective detection of Ag+ ion using fluorimetry and its applications

Anthracene based chemosensor ABC has been synthesized and characterized through 1H, 13C NMR, mass spectral studies. UV absorption and emission studies performed to identify the sensing behavior of chemosensor ABC. The probe ABC, originally bright fluorescent, selectively sense Ag+ ion by the quenching the fluorescence intensity through a “Switch On-off” process and quench the fluorescence due to the heavy atom effect interaction with the free chemosensor. The binding constant of the probe ABC with Ag+ was calculated as 5.4 × 104 M−1 and the limit of detection upto 1.4 nM level. The practical utilization of the probe ABC was demonstrated by applying to the real water and soil sample analysis, latent finger print, and the sensor as a fluorescent ink.

Photoluminescence Quenching in Recyclable Water-Soluble Zn-Based Metal–Organic Framework Nanoflakes for Dichromate Sensing

Nanoflakes are materials with high dispersion, a large specific surface area, and a high number of active sites that can provide a good platform for various fluorescence sensors and are very popular among researchers. In this study, a nanoflake-like zinc metal–organic framework (Zn-MOF) was successfully synthesized from the organic ligand 1,2,4,5-tetra(1H-imidazol-1-yl)benzene and zinc nitrate. The synthesized Zn-MOF nanoflakes are extremely soluble in water and exhibit high fluorescence stability. Since Cr2O72– can significantly quench the fluorescence of Zn-MOF aqueous solution, a rapid detection method for Cr2O72– content in water was constructed with a linear range and linear correlation of 0.3–20 μM and 0.992, respectively. The fluorescence quenching constant of the Zn-MOF is KSV = 2.003 × 104 M–1, and the detection limit for Cr2O72– is as low as 0.09 μM. Through the study of fluorescence lifetime and UV absorption, it is proven that the mechanism of Cr2O72– quenching the fluorescence of the Zn-MOF is the inner filter effect. In addition, even after being applied five times, the Zn-MOF still maintained good detection performance for Cr2O72–. The proposed method was successfully applied to the determination of real water samples, confirming that it can be used as an alternative method for the detection of Cr2O72– in environmental samples.

Impact of erbium (Er) doping on the structural and magnetic properties of Ni-Cu (Ni0.1Cu0.9Fe2O4) nanoferrites

Rare earth erbium (Er) doped spinel Ni-Cu nanoferrites having chemical composition Ni0.1Cu0.9ErxFe2-xO4 (x = 0.00, 0.010, 0.015, 0.020, 0.025 and 0.030) were prepared by standard citrate-gel auto combustion (CGAC) technique. X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), UV–visible spectroscopy, and vibrating sample magnetometer (VSM) were used to characterize the structural, optical, and magnetic properties of these ferrites. X-ray diffraction spectra clearly revealed that the pure Ni-Cu ferrite shows a tetrahedral distortion due to John Tellar ion (Cu2+) subsequently erbium doping transformed the tetragonal phase in to the cubic spinel phase with minor traces of impurity phase. Using Scherer's equation, the average crystallite size was found to be between 7.39 and 27.78 nm. The average crystallite size (7.39–27.78 nm) obtained from XRD and average grain size (64.84–83.36 nm) measured from FESEM confirmed the nano structure of prepared samples. Energy dispersive analysis X-ray (EDAX) spectra with elemental analysis verified the existence of Ni, Cu, Er, Fe, and O elements without any impurities. Two prominent absorption bands detected in FTIR spectra within the wave number range of 575.54–586.73 cm−1 (υ1) and 370.24–372.53 cm−1 (υ2) indicate the stretching vibrations of Fe3+-O2− complexes in tetrahedral and octahedral sites of spinel structure respectively. TG and DTA techniques were used to analyze the thermal behavior of the composition x = 0.030. It was observed that exhibiting a rapid loss in weight after 900 °C promotes the formation of pure phase nanoferrite. Direct and indirect optical band gap values were computed from UV absorption studies with Tauc plots. The obtained band gap values revealed the semiconducting behavior of the prepared samples. VSM was used to explore the magnetization of samples as a function of field at temperatures of 15 K and 300 K. The maximum saturation magnetization (Ms) was observed for x = 0.030 composition and it was estimated as 31.18 emu/g at 15 K and 26.80 emu/g at 300 K temperatures. The experimental and theoretical values of lattice parameter and room temperature magnetic moment are good agreement with suggested cation distribution.

Investigating binding dynamics of trans resveratrol to HSA for an efficient displacement of aflatoxin B1 using spectroscopy and molecular simulation

Resveratrol is a polyphenol belonging to the class stilbenes. The active and stable form of resveratrol is trans-resveratrol. This polyphenol is bestowed with numerous biological properties. Aflatoxin B1 is a hepato-carcinogen and mutagen that is produced by Aspergillus species. In this study, the interaction of trans-resveratrol with HSA followed by competitive dislodging of AFB1 from HSA by trans-resveratrol has been investigated using spectroscopic studies. The UV-absorption studies revealed ground state complex formation between HSA and trans-resveratrol. Trans-resveratrol binds strongly to HSA with the binding constant of ~ 107 M−1 to a single binding site (n = 1.58), at 298.15 K. The Stern–Volmer quenching constant was calculated as 7.83 × 104 M−1 at 298.15 K, suggesting strong fluorescence quenching ability of trans-resveratrol. Site markers displacement assay projected subdomain IIA as the binding site of trans-resveratrol to HSA. The molecular docking approach envisages the amino acid residues involved in the formation of the binding pocket. As confirmed from the site marker displacement assays, both trans-resveratrol and AFB1 binds to HSA in the same binding site, subdomain IIA. The study explores the ability of trans-resveratrol to displace AFB1 from the HSA-AFB1 complex, thereby affecting the toxicokinetic behavior of AFB1 associated with AFB1 exposure.

DNA interaction perspectives of sulphur containing Knoevenagel condensed copper(II) complexes: Molecular docking, DFT, anti-biogram and insilico assessment

The present work describes the synthesis of a few novel Knoevenagel condensed copper(II) complexes from Schiff bases of thiosemicarbazide derivatives. The synthesized compounds have been characterized by various analytical and spectral techniques. The DFT calculations were carried on these compounds using Gaussian 09 W software which theoretically confirmed the change in UV–Vis electronic transitions after complexation. Interestingly, optimization and DFT calculations corroborated the stability and biological approachability of these copper complexes. Also, pharmacokinetic properties of the synthesized compounds have been computed using SWISS ADME online software which theoretically supports the oral mode of administration of the drug and its lead like activity. Moreover, all the copper complexes have the ability to undergo intercalative binding with CT-DNA, which has been confirmed by UV absorption studies, viscosity measurements, CV studies and molecular docking.

Synthesis, spectroscopic and thermal studies of Cu+2, Ni+2and Co+3complexes of Schiff base containing furan moiety. Antitumor, antioxidant, antibacterial and DNA interaction studies

Three mononuclear bioefficient imine‐based coordination complexes [Cu(FMIMBCP)2] (1), [Ni(FMIMBCP)2] (2), and [Co(FMIMBCP)3] (3) were synthesized using ligand [FMIMBCP = (((furan‐2‐yl)methylimino)methyl)‐6‐bromo‐4‐chlorophenol]. The formation of the complexes was ascertained by elemental analysis, Fourier transform infrared, UV–Visible, electrospray‐mass spectrometry, electron paramagnetic resonance, and thermogravimetric analysis. From the thermogravimetric curves, the kinetic and thermodynamic parameters of the thermal degradation steps were computed. The stability of the complexes has been calculated from quantum chemical parameters using HOMO‐LUMO energies. The comparative binding propensity profiles of above synthesized complexes with thecalf thymus‐DNA were investigated via UV absorption and fluorescence studies. On the basis of extended conjugation and increased chromophores, complex3exhibited superior bioactivity with greater calculated DNA binding constant values, (Kb) 5.73 × 104 M−1(3) as compared to complexes1(2.96 × 104 M−1) and2(8.38 × 103 M−1). The competitive binding titration with ethidium bromide (EB) revealed that metal complexes efficiently displace EB from the EB‐DNA system. The complexes were found to have pronounced cleavage efficiency as evaluated from agarose gel electrophoresis. The anticancer activity of the ligand and metal complexes against MCF‐7 and KB3 cells revealed that the complexes were more efficacious than the corresponding ligand. Further, in vitro antioxidant activity against DPPH proclaimed the remarkable bioefficiency of compounds, which makes them promising as an active chemotherapeutic agent. The complexes have strong antibacterial activity againstBacillus thuringiensis,Streptococcus pneumoniae,Escherichia coli, andPseudomonas putida.

Investigations on structural, optical and electrical properties of holmium doped rubidium titanyl phosphate single crystals

The holmium doped rubidium titanyl phosphate single crystal was grown using a high-temperature flux method using rubidium polyphosphate as a flux compound. The structural nature of the grown Ho: RTP single crystal has been confirmed by powder XRD analysis. The addition of Ho dopant shows variations in the diffraction peaks refer to the combination of holmium with the RTP lattice. The UV absorption and transmittance study show no visible absorption induced by holmium. The electrical parameters like, dielectric constant, dielectric loss, AC conductivity and impedance have been studied up to the Curie point level of the material, and the results indicating that the doping of holmium reduces the electrical activities in the RTP single crystal, and there is no change in the Curie point of the Ho: RTP single crystal compared to pure RTP. The ferroelectric result shows that the polarization and coercive field of material have a lower value than the pure RTP single crystal due to the presence of holmium in the RTP, which is very useful for periodically poled device applications. Ferroelectric fatigue test on Ho: RTP shows that the grown crystal does not undergo polarization decay up to 5000 frequency cycles.

Structure–property relationship and spectroscopic studies of BaO–B2O3 oxide glasses containing ZnO for optical applications

In the present work, samples of barium borate glasses containing different molar ratios of ZnO were prepared using the conventional melt-quenching technique. X-ray diffraction studies confirmed the amorphous nature of the studied materials. Structural analysis using FT-Infrared confirmed the incorporation of the Zn atom in the glass matrix as a ZnO4 unit and the existence of ZnO in the tetrahedral interstitial sites. TEM images for the studied materials show that the average particle size is about 20nm and the ZnO4 structural units reside in the glass matrix with high homogeneity. Density and molar volume studies manifested an increase in the density as the amount of ZnO increases and a subsequent decrease in the molar volume. UV absorption studies showed a blue shift in the absorption peak from 343nm to 315nm. Additionally, an observed reversible behavior around 338nm divides the absorption range into high energy and low energy regions. In the high energy region, both absorbance, absorption coefficient, and refractive index increased with ZnO content increment. In the low energy region, this behavior was reversed, and the calculated values of the refractive index agreed with the measured ones in this region. Studies of optical dielectric parameters showed a Debye-type relaxation process in which increasing the ZnO content shortens the sample relaxation time. Our results, collectively, suggest the studied materials for several optoelectronic device applications such as high-energy optical filters, optical switches, and frequency converters.

A Near-infrared Search for Molecular Gas in the Fermi Bubbles

Abstract We present Gemini/NIFS near-IR integral field spectroscopy of the fields-of-view around two AGNs behind the Fermi Bubbles (PDS 456 and 1H1613-097 ) to search for molecular gas in the Milky Way’s nuclear wind. These two AGN sightlines were selected by the presence of high-velocity neutral and ionized gas seen in UV absorption. We do not detect any extended emission from the H2 rovibrational S(0) and S(1) lines at 2.224 and 2.122 μm in either direction. For the H2 1-0 S(1) line, the 3σ surface brightness limits derived from spectra extracted across the full 3″ × 3″ NIFS field-of-view are 2.4 × 10−17 erg cm−2 s−1 Å−1 arcsec−2 for PDS 456 and 4.9 × 10−18 erg cm−2 s−1 Å−1 arcsec−2 for 1H1613-097. Given these non-detections, we conclude that CO emission studies and H2 UV absorption studies are more promising approaches for characterizing molecular gas in the Fermi Bubbles.

Molecular Interactions of Diphenhydramine-hydrochloride with Some Imidazolium-Based Ionic Liquids in Aqueous Media at T = 293.15-313.15 K: Volumetric, Acoustic, and UV Absorption Studies.

From the density (ρ) and speed-of-sound (u) measurements, the interactions of the drug diphenhydramine-hydrochloride (DPH) with three imidazolium-based ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C4mim][Cl], 1-hexyl-3-methylimidazolium chloride1, [C6mim][Cl], and 1-methyl-3-octylimidazolium chloride, [C8mim][Cl]) have been investigated in aqueous medium at T = 293.15–313.15 K and experimental pressure p = 0.1 MPa. From the density calculations, the apparent molar volume (Vϕ) and the apparent partial molar volumes of transfer (ΔtVϕo) have been determined for various solutions of DPH in aqueous solutions of different ILs. In addition, from the speed-of-sound data, the apparent molar isentropic compressibility (Kϕ), apparent partial molar isentropic compressibility (Kϕo), and apparent partial molar isentropic compressibility of transfer (ΔtKϕο) have been calculated. The pair and triplet interaction coefficients are derived from apparent partial molar volumes of transfer. For the present mixtures, the absorption spectra have been also recorded using a UV–visible spectrophotometer. Using Hepler’s constant, the structure-making nature of the solute has been confirmed. All these calculated parameters provide detailed insights into various physicochemical interactions prevailing in the ternary system and confirm the presence of a strong attractive interaction between DPH and ILs.

Structural, optical and magnetic properties of Co(Cobalt) doped SnO2 nanoparticles by one stepmethod

Cobalt doped SnO2 nanoparticles were prepared for different molar concentration 2%, 4% &amp; 6% of Co by Chemical co precipitation method. The prepared samples were characterized by X-ray diffraction (XRD), UV-visible absorption spectra, Photoluminescence (PL), High Resolution transmission electron microscopy (HRTEM) and Vibrating sample magnetometer for their Structural, Optical and Magnetic Properties. The doping concentration of Co induces crystal phase, crystallite size, lattice distortion, optical and magnetic properties were investigated. XRD Results showed that Co2+ replaces Sn4+ in the crystal lattice of SnO2, which enhanced the growth of crystallite size and suppressed the transformation from anatase to rutile phase due to lattice distortion produced in SnO2. The UV absorption studies concluded the band gap of Co doped SnO2 nanoparticles decreased from 3.79 eV to 3.62 eV in visible region. PL spectra exhibit only a broad emission peak in the range of 420 nm to 540 nm and excitation is observed at the wavelength of 385 nm. New energy levels are not formed in the band structure to produce new emission due to Co doping and also indicates that the substitution of Co2+ ions for Sn4+ ions without the formation of other additional energy levels. Due to increasing Co concentration in SnO2, the emission energies are decreasing the peak intensities. An efficient method for inducing the ferromagnetic behavior from increasing the Co concentration from 2% to 6 % was known from the magnetization versus magnetic field (M–H) curves at room temperature of the Co doped SnO2 samples. The dominant magnetic interaction between Co ions, and hence, the ferromagnetic behaviour increases for increase in Co2+ doping concentration.Consequently, to achieve the good ferromagnetic character in these materials, the concentration of Co dopant has to be properly optimized.

Re(η6‐C6H5‐benzimidazole)2]+ and Derivatives as Dye Mimics; Synthesis, UV Absorption Studies and DFT Calculations

AbstractFunctionalizations of highly oxidation and hydrolysis stable mono‐cationic rhenium bis‐arene complexes [Re(η6‐C6H6)2]+ are of great interest. We directly built up structural features of the well‐known Hoechst Dye on the coordinated arenes as a model for prospective DNA minor groove binding studies. Extensions of the aromatic bis‐arene unit with functionalized and derivatized benzimidazole moieties resulted in a deep orange colour of the complexes, showing UV/Vis absorption spectra with multiple transition maxima. These have been assigned with support of DFT calculations to gain information about their charge transfer natures. The different transitions of the complexes, which are either intra‐ligand, ligand‐to‐ligand or metal‐to‐ligand charge transitions, were additionally compared and discussed with the spectra of the corresponding free ligands.