UV-vis Absorption Studies Research Articles

Magnetic and structural properties of Co doped ZnO nanowires prepared by heat treatment of electrospun PVA nanofibers containing Zn and Co acetates

We report the synthesis of inter-twined ZnO nanowires doped with Co by electrospinning polyvinyl alcohol along with metal oxide precursors followed by heat treatment in air at 550 °C for 90 min. This heat treatment removed PVA from the samples and ensured crystallization of 1-dimensional metal oxide nanostructure. X-ray diffraction (XRD) patterns also confirmed single phase wurtzite-type ZnO structure in samples with 3 wt% Co. Traces of Co3O4 could be observed in XRD patterns of samples with 5 wt% Co. However, micro-Raman spectra clearly indicate the presence of Co3O4 in samples with Co content more than 2 wt% which is also supported by electron paramagnetic resonance studies. UV–Vis absorption studies showed an increase in band gap energy with substitution of Co in ZnO structure. Field dependent magnetization curves recorded at room temperature revealed weak room temperature ferromagnetism with considerable paramagnetic component. The results are used to understand the origin of magnetism in this alloy and the extent of possible doping of Co in ZnO nanofibers.

Growth, characterization and estimation of lattice strain and size in CdS nanoparticles: X-ray peak profile analysis

This work is based on the growth, characterization and estimation of lattice strain and crystallite size in CdS nanoparticles by X-ray peak profile analysis. The CdS nanoparticles were synthesized by a non-aqueous solvothermal method and were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and UV–visible spectroscopy. XRD confirms that the CdS nanoparticles have the hexagonal structure. The Williamson–Hall (W–H) method was used to study the X-ray peak profile analysis. The strain–size plot (SSP) was used to study the individual contributions of crystallite size and lattice strain from the X-rays peaks. The physical parameters such as strain, stress and energy density values were calculated using various models namely, isotropic strain model, anisotropic strain model and uniform deformation energy density model. The particle size was estimated from the TEM images to be in the range of 20–40 nm. The Raman spectrum shows the characteristic optical 1LO and 2LO vibrational modes of CdS. UV–visible absorption studies show that the band gap of the CdS nanoparticles is 2.48 eV. The results show that the crystallite size estimated from Scherrer’s formula, W–H plots, SSP and the particle size calculated by TEM images are approximately similar.

Bay-Region Functionalisation of Ar-BIAN Ligands and Their Use Within Highly Absorptive Cationic Iridium(III) Dyes

We report the synthesis, UV-vis absorption, electrochemical characterisation, and DFT studies of five panchromatic, heteroleptic iridium complexes (four of which are new) supported by Ar-BIAN ligands. In particular, the synthesis of an ester-functionalised Ar-BIAN ligand was carried out by a mechanochemical milling approach, which was advantageous over conventional metal templating solution methods in terms of reaction time and product purity. The introduction of ester and carboxylate functionalities at the bay region of the acenaphthene motif increases each ligand’s π-accepting capacity and imparts grafting capabilities to the iridium complexes. These complexes have absorption profiles that surpass the renowned N3 dye [Ru(dcbpy)2(NCS)2] (dcbpy = 4,4′-dicarboxy-2,2′-bipyridine), making them of interest for solar-energy-harvesting applications.

Cobalt(II)–metformin complexes containing α‐diimine/α‐diamine as auxiliary ligand: DNA binding properties

The cobalt(II) complexes [Co(Cl)2(met)(o‐phen)] (1), [Co(Cl)2(en)(met)] (2) and [Co(Cl)2(met)(opda)] (3) (met = metformin, o‐phen = ortho‐phenanthroline, en = ethylenediamine, opda = ortho‐phenylenediamine) were synthesized and characterized using liquid chromatography–mass spectrometry, elemental analysis, molar conductance measurements, thermal analysis, infrared spectroscopy, magnetic moment measurements, electronic spectroscopy and X‐ray diffraction. The metal centre was found to be in an octahedral geometry. UV–visible absorption, fluorescence and viscosity measurements were conducted to assess the interaction of the complexes with calf thymus DNA. The complexes showed absorption hyperchromism in UV–visible spectra with DNA. The binding constants from UV–visible absorption studies were 1.38 × 105, 2.1 × 105 and 3.1 × 105 M−1 for 1, 2 and 3, respectively, and Stern–Volmer quenching constants from fluorescence studies were 0.146, 0.176 and 0.475, respectively. Viscosity measurements revealed that the binding of the complexes with DNA could be surface binding, mainly due to groove binding. The activities of the complexes in DNA cleavage decrease in the order 3 > 2 > 1. The complexes were docked into DNA topoisomerase II using Discovery Studio 2.1 software.

Synthesis of Aziridinofullerene-Porphyrin Mediated by Triethyl Phosphite: Physicochemical and Electrochemical Properties

Aziridinofullerene-porphyrin (C60-TPP) dyad was synthesized using triethyl phosphite mediated [2+1] cycloaddition reaction. Structural elucidation of the compound was carried out using NMR and FT-IR spectroscopic methods. The synthesized C60-TPP was further characterized using UV-Vis absorption and photoluminescence emission studies. An optical study of the synthesized compound shows absorption maxima at 424 nm, around 516, 550, and 593 nm with small broad absorption peaks at 360 and at 480 nm. Photoluminescence studies of the compound shows emission maxima at around 597, 652 and 717 nm. Electrochemical studies of the compound shows oxidation potentials at 0.30, 0.52, 0.74 V and reduction potentials at−1.69,−2.07 and−2.42 V with respect to internal Fc/Fc+ reference corresponding to porphyrin and fullerene C60 moiety in the compound and the formation of C60-TPP. Furthermore, the absence of obtain XPS peaks corresponding to nitro group in C60-TPP confirms the conversion of nitro group to aziridine group.

Synthesis and Characterization of CdO–SnO2 Nanocomposites Prepared by Hydrothermal Method

In this work, (1−x)CdO–xSnO2 nanocomposites (≤ 0.15) have been synthesized via hydrothermal route. The structural study reveals that CdO nanostructures possess crystalline phase and cubic structure. The CdO–SnO2 nanocomposites possess both cubic and orthorhombic structure with good crystallinity. The crystallite size in the nanocomposites was found to be in the range of 9.6–19.6 nm. Field emission scanning electronic microscopy and high-resolution tunnelling microscopy analysis confirm the presence of both cubic and orthorhombic structures which is also confirmed from X-ray diffraction studies. Fourier transform infrared spectroscopy (FTIR) studies confirm that CdO–SnO2 nanocomposites possess the characteristics band of both CdO and SnO2 nanostructures. The UV–visible absorption studies confirm that the optical absorption band in CdO–SnO2 nanocomposites possesses both blue and red shift as compared to that of CdO nanostructures. Photoluminescence spectroscopy studies reveal the appearance of strong emission peak at 513, 469 and 369 nm corresponding to green, blue and violet emission spectrum, respectively, in CdO–SnO2 nanocomposites. The FTIR studies confirm the presence of hydroxyl and water functional group due to atmospheric water vapours and chemical bonding in CdO and CdO–SnO2 nanocomposites. Raman spectroscopy confirms the presence of Raman bands of both CdO and SnO2 phases in the CdO–SnO2 nanocomposites.

Non linear optical investigations of silver nanoparticles synthesised by curcumin reduction

Metal nanoparticles have considerable applications in assorted fields like medicine, biology, photonics, metallurgy etc. Optical applications of Silver nanoparticles are of significant interest among researchers nowadays. In this paper, we report a single step chemical reduction of silver nanoparticles with Curcumin both as a reducing and stabilising agent at room temperature. Structural, plasmonic and non linear optical properties of the prepared nanoparticles are explored using Scanning Electron Microscope, Transmission Electron Microscope, UV absorption spectrometry, Spectroflurometry and Z scan. UV–Vis absorption studies affirm the Surface Plasmon Resonance (SPR) absorption and spectroflurometric studies announce the emission spectrum of the prepared silvernanoparticles at 520 nm. SEM and TEM images uphold the existence of uniform sized, spherical silvernanoparticles. Nonlinear optical studies are accomplished with the open aperture z scan technique in the nanosecond regime. The nonlinearity is in virtue of saturable absorption, two-photon absorption and excited state absorption. The marked nonlinearity and optical limiting of the Curcumin reduced silvernanoparticles enhances its photonic applications.

Spectroscopic, Thermodynamic and Molecular Docking Studies on Interaction of Toxic Azo Dye with Bovine Serum Albumin

Investigation on interaction of azo dyes with bovine serum albumin as carrier protein will be important in the field of toxicology because of distribution and transportation of dyes in blood. In this regard, the interaction between the azo dye, trisodium (4E)-3-oxo-4-[(4- sulfonato-1- naphthyl) hydrazono] naphthalene-2,7-disulfonate (C20H11N2Na3O10S3), known as Amaranth and bovine serum albumin (BSA) was studied using UV-vis absorption, fluorescence spectroscopy, viscosity measurement and molecular docking studies . Also, the association behavior of Amaranth was investigated at its various concentrations and different ionic strength (NaCl) in 5 mM aqueous phosphate buffer of pH 7.0 at 25°C. Spectrophotometric studies of the interaction between Amaranth and BSA have shown that the binding constant was Kb = 7.1×104 M-1 at 298 K. Thermodynamic parameters (ΔH > 0 and ΔS > 0) indicated that hydrophobic forces play major roles in the interaction between Amaranth and BSA. Further, the fluorescent experiments revealed that the quenching mechanism of BSA by Amaranth was static. Also, no obvious increasing of BSA viscosity was observed by addition of Amaranth. The molecular docking method is also employed to understand the interaction of Amaranth with BSA. All these studies confirm that BSA has more affinity towards Amaranth and the groove binding must be predominant.

Spectroscopic investigations on the interaction of thioacetamide with ZnO quantum dots and application for its fluorescence sensing

The purpose of the present work was to develop a method for the sensing of thioacetamide by using spectroscopic techniques. Thioacetamide is a carcinogen and it is important to detect its presence in food-stuffs. Semiconductor quantum dots are frequently employed as sensing probes since their absorption and fluorescence properties are highly sensitive to the interaction with substrates present in the solution. In the present work, the interaction between thioacetamide and ZnO quantum dots has been investigated by using UV–visible, fluorescence and infrared spectroscopy. Besides, dynamic light scattering (DLS) has also been utilized for the interaction studies. UV–visible absorption studies indicated the bonding of the lone pair of sulphur atom of thioacetamide with the surface of the semiconductor. The fluorescence band of the ZnO quantum dots was found to be quenched in the presence of micromolar concentrations of thioacetamide. The quenching was found to follow the Stern-Volmer relationship. The Stern-Volmer constant was evaluated to be 1.20×105M−1. Infrared spectroscopic measurements indicated the participation of the NH2 group and the sulphur atom of thioacetamide in bonding with the surface of the ZnO quantum dots. DLS measurements indicated that the surface charge of the semiconductor was shielded by the thioacetamide molecules.

Optical spectroscopy of rare earth-doped oxyfluoro-tellurite glasses to probe local environment

$$\hbox {TeO}_{2}$$ -based glasses with a general formula $$65\hbox {TeO}_{2}{-}5\hbox {BaF}_{2}{-}30\hbox {ZnF}_{2}$$ (TBZ) (in mol%) were prepared by usual melt quenching technique. Three mol% of europium (Eu) or erbium (Er) were added to the prepared glass at the expense of $$\hbox {TeO}_{2}$$ . Raman, photoluminescence (PL), UV–visible absorption studies were carried out on the glass samples. Raman spectra of the undoped and doped glasses were analysed using the peak shift and the intensity variation along with full width at half-maximum (FWHM). It was found that Eu-doped TBZ glass has a greater tendency towards depolymerizing the glass matrix by influencing the conversion of $$\hbox {TeO}_{4}$$ to $$\hbox {TeO}_{3}$$ units compared to Er-doped and undoped glasses. PL spectra of the glass samples show emission due to different possible transitions. Position of the peak of the de-convoluted spectra shows the position of the particular Stark component and the FWHM is a measure of the inhomogeneous broadening. The UV–visible absorption spectra are used to calculate the optical density and to determine the band edge of the glass samples by fitting to the Mott equation. It is seen that Eu-doped TBZ glass has a lesser bandgap than that of Er-doped glass.

Synthesis, physicochemical properties, thermal analysis and biological application of phosphorescent cationic iridium(III) complexes

Cyclometalating iridium(III) complexes with formula, [Ir(cpy)2(biim)Cl] 1, [Ir(cpy)2(bpy)Cl] 2 and [Ir(cpy)2(dppe)Cl] 3 (where, cpy=9-(pyridine-2-yl)-9H-carbazole, biim=biimidazole, bpy=2,2′-bipyridine, dppe=1,2-bis(diphenylphosphino)ethane) were synthesized and characterized by elemental analysis, 1H, 13C NMR, and ESI-Mass spectral studies. The complex 1–3 show their emissions in green emitting region (λPL,max=536–580nm), and the emission maxima can be tuned by changing the ancillary ligand. The phosphorescent line shape indicates that the emissions originate predominantly from 3MLCT states with little admixture of ligand-based 3(π-π∗) excited states. These complexes exhibited biexponential phosphorescence decays with relatively short lifetimes of 0.40–12.35µs in solution state at room temperature and the relaxation dynamics of 1–3 are O2 dependent. The electrochemical and thermal properties were systematically evaluated. Binding of these complexes (1–3) with calf thymus DNA was investigated by UV–Vis, fluorescence, circular dichroic spectroscopy, viscosity measurements and computer aided molecular docking studies. The binding constant of complexes (1–3) with ct-DNA obtained by UV–Vis absorption studies were 2.28×104, 1.98×104 and 2.98×104M−1, respectively. The result indicated that the complexes (1–3) were able to bind to DNA with different binding affinity in the order: 3>1>2. Complexes (1–3) also exhibit a good binding propensity to bovine serum albumin (BSA). Gel electrophoresis assay demonstrated that complexes (1–3) cannot promote the cleavage ability of the pBR322 plasmid DNA or plasmid pBluescript II KS+ DNA or pUC19 DNA in the presence of the reducing agent 3-mercaptopropionic acid. The cytotoxicity studies of complexes 1–3 were tested in vitro on in human cervical cancer cell line (HeLa) and they found to be active. We propose that the phosphorescent iridium(III) complexes (1–3) are possible candidates for the green phosphors in organic light emitting diodes (OLEDs) applications as well as better anticancer agents.

Synthesis and Characterization of a Series of Bis-homoleptic Cycloruthenates with Terdentate Ligands as a Family of Panchromatic Dyes.

A series of six homoleptic bis-cyclometalated ruthenium complexes, Ru(N^N^C)2, is reported where N^N^C is a 6-(2,4-difluoro-3-R3-phenyl)-4-R2-4'-R1-2,2'-bipyridine with R3 = -H or -CF3 and R2 and R1 = -COOEt or -CF3. An effective synthesis of the ligands and the complexes is described. The UV-visible absorption studies demonstrate that these complexes are panchromatic dyes absorbing up to 900 nm. Importantly, the onset of absorption depends only on the substitution on the metalated phenyl, whereas the intensity of absorption throughout the spectra is a function of substituents on both the phenyl and the bipyridine moieties. The same trend is observed in electrochemistry as the redox gap depends only on the substitution on the metalated phenyl, whereas the oxidation and reduction potentials are a function of substituents on both the phenyl and the bipyridine moieties. Preliminary tests as sensitizer for dye-sensitized solar cells demonstrate that the number of anchoring groups on the dye has a major influence on the device efficiency.

Correlation of edge truncation with antibacterial activity of plate-like anisotropic silver nanoparticles.

The effect of silver nanoparticle anisotropy on the antibacterial properties has been studied against Escherichia coli, Staphylococcus aureus, Bacillus, Vibrio cholerae, and Streptococcus pyogenes. Anisotropic silver nanoparticles have been synthesized by solvothermal process. The UV-visible absorption, X-ray diffraction, and TEM studies show the anisotropic nature of silver nanoparticles. The results demonstrate that the anisotropic silver nanoparticles undergo a shape-dependent interaction with the bacteria, and the nanoparticles with higher anisotropy exhibit the superior antibacterial activity. Silver nanoparticles with sharp edges and corners displayed the stronger biocidal action, in comparison to the anisotropic nanoparticles with round edges and corners. The sharpness of the corners has been quantified using degree of truncation method. The variation in degree of truncation and the antibacterial activity follows the same pattern.

Oxovanadium(IV) complexes with Knoevenagel Schiff base condensate as impending chemotherapeutic agents: Synthesis, characterization, biological screening and anti-proliferative assay

Two novel oxovanadium(IV) complexes [VOL1]SO4(1) and [VOL2]SO4(2) containing Knoevenagel condensate Schiff base ligand (L1/L2) have been synthesized and characterized by physical, spectral and analytical methods. These complexes are reported as ionic in nature on the basis of elemental composition and molar conductance, and possess square pyramidal geometry around the central metal ions. The binding interactions of (1) and (2) with calf thymus DNA (CT DNA) were explored by absorption spectrophotometric titration, cyclic voltammetry data and viscosity measurements. The calculated intrinsic binding constant values (Kb) for (1) and (2) obtained from UV–Vis absorption studies are 0.4×105 and 5.6×105 (M−1) respectively. These experimental results indicate that (1) and (2) are intercalative binders and avid binder to CT DNA with different affinities. These complexes exhibit significant oxidative cleavage of supercoiled plasmid (pUC18) DNA in the presence of activators. In particular, the in vitro antimicrobial efficacy of oxovanadium(IV) complexes reveal that they are more active than free ligands. Besides, the in vitro cytotoxic effect of the titled complexes were examined on a bundle of human tumor cell lines such as MCF-7 and HeLa cancerous cell lines by the MTT method. Interestingly, complex (2) exhibits more potent cytotoxic activity than the other complex and standard drug (cisplatin). The mode of cell death was assessed by Hoechst 33258 staining morphological studies.

Activation of catalase by pioglitazone: Multiple spectroscopic methods combined with molecular docking studies.

Pioglitazone is an important prescription antidiabetic drug with positive roles in controlling high blood sugar in patients with type 2 diabetes. In the present study, we investigated the effects of pioglitazone on the structure and function of bovine liver catalase (BLC) using different spectroscopic and theoretical methods. UV-Vis absorption, fluorescence spectroscopy, synchronous fluorescence, and circular dichroism studies revealed conformational changes in the BLC structure and heme group in the presence of different concentrations of pioglitazone. Kinetic studies indicated that pioglitazone can increase BLC activity by approximately threefold compared with free enzyme. The fluorescence quenching data showed one binding site for pioglitazone, and the binding constants at 298, 304, and 310K were calculated as 5.01×107 M-1 , 5.8×107 M-1 , and 6.6×107 M-1 , respectively. The static type of quenching mechanism was mainly involved in the quenching of intrinsic emission of the enzyme. Thermodynamic data suggested that hydrophobic interactions played a major role in the binding reaction of pioglitazone with BLC. The molecular docking studies indicated that pioglitazone interacts with the cavity in the middle of the β-barrel and wrapping domain of BLC. Thus, pioglitazone can increase catalase activity by changing the BLC structure.

Computational and experimental studies of 4-thiazolidinone-cyclopropyl hybrid

Thiazolidi-4-one is a significant pharmacophore and has been known to exhibit a diverse range of biological activities for a long time. A new compound (6), thiazolidi-4-one was synthesized and characterized by spectroscopic techniques and X-ray single crystal structure. The stereochemistry of compound (6) was determined theoretically (DFT level) and experimentally (single crsytal X-ray structure) both. The DNA binding ability of the compound 6 has been assessed as using UV–Visible absorption studies and docking studies, MTT-assay study on MCF-7 cell line revealed non-toxic nature of the compound (6) in the concentration range 10–320μM.

Photoresponsive Organogelator: Utilization of Boron(III) Diketonate as a Building Block To Construct Multiresponsive Materials

A class of dithienylethene-containing boron(III) diketonates with long alkoxy chains, together with their corresponding β-diketone ligands, has been prepared and characterized. The photophysics, electrochemistry, and photochromism of the compounds have been investigated. Some of them exhibit gelation behavior, which has been explored by variable-temperature UV–vis absorption studies, and the morphology of the gels has been studied by electron microscopy. In addition, the organogels have been found to be photoresponsive with color changes under photoexcitation, leading to the construction of multiresponsive boron(III) diketonate-based materials.

Synthesis and characterization of silver tungstate/iron phthalocyanine nanocomposite for electronic applications

Silver tungstate/iron phthalocyanine nanocomposite (Ag2WO4/FePc) was prepared by simple solvent evaporation method. Thermodynamic stability of the synthesized nanocomposite was studied by thermogravimetric analysis. The nanocomposite was structurally characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. The results confirm the formation of Ag2WO4/FePc nanocomposite. The size and morphology of the prepared nanocomposite were analyzed by scanning electron microscopy and high-resolution transmission electron microscopy. The optical properties were analyzed by ultraviolet-visible and photoluminescence spectroscopic techniques. UV-visible absorption studies indicate that Ag2WO4/FePc nanocomposite has extended visible absorption in the wavelength range 662 to 782 nm. The nanocomposite shows high emission intensity and greenish-blue emission when excited with near-ultraviolet light. The resistivity of the sample was measured at different temperatures. The dielectric constant, dielectric loss and AC conductivity values were measured in the frequency range 100 Hz–20 MHz. The results obtained from thermal, structural, optical and electrical characterization suggests that the synthesized Ag2WO4/FePc nanocomposite can be used as a potential material for varied optoelectronic and solid state applications. The present study constitutes the first report for the synthesis and characterization of Ag2WO4/FePc nanocomposite.

Biocompatible zwitterionic phosphorylcholine polymers with aggregation-induced emission feature

Two novel zwitterionic phosphorylcholine polymers (MTP1 and MTP2) with aggregation-induced emission (AIE) feature were prepared through reversible addition fragmentation chain transfer polymerization between an AIE monomer with vinyl end group and a zwitterionic phosphorylcholine monomer. The synthesized copolymers were characterized and confirmed by 1H NMR, FT-IR, and X-ray photoelectron spectra. By introduction of the zwitterionic phosphorylcholine component, the synthesized copolymers showed amphiphilic properties and tended to self-assemble into fluorescent polymeric nanoparticles (FPNs) in water. The dynamic light scattering results indicated the size distribution of the MTP1 FPNs was 345±22nm, and that of the MTP2 FPNs was 147±36nm. The transmission electron microscopy results demonstrated spherical nanoparticle morphology for the FPNs. The high dispersibility of the FPNs in water was proved by the UV–vis absorption study with high transmittance of the solution. Fluorescent spectra of the prepared FPNs revealed bright green fluorescence with high fluorescence quantum yield of 45% for MTP1 and 34% for MTP2. More importantly, the FPNs showed excellent particle stability with low critical micelle concentration of 0.008mgmL−1 for MTP1 and 0.007mgmL−1 for MTP2. The cytotoxicity evaluation confirmed high cytocompatibility of the prepared FPNs at different concentrations, and demonstrated excellent biocompatibility for cell imaging. In virtue of the high-performance MTP1 and MTP2 FPNs, including high water dispersion, good particle stability, and excellent cytocompatibility, this work would inspire more researches about high-performance biocompatible fluorescent polymers for biomedical application.

An Efficient Molecular Tool with Ferrocene Backbone: Discriminating Fe3+ from Fe2+ in Aqueous Media

Two novel molecular probes with ferrocene backbone have been designed and synthesized for the first time, and they were subsequently found capable of distinguishing Fe3+ and Fe2+ ion in aqueous media. The discrimination of both the oxidation states (II/III) of iron by these receptors can be established either from a striking shift in redox potential (1: ΔE1/2 ≈ 90 mV and 2: ΔE1/2 ≈ 59 mV) for Fe2+ ion or from UV–vis absorption studies (using light-absorption ratio variation approach (LARVA)). Moreover, the discrimination of Fe2+ and Fe3+ cations could be performed by naked-eye observation because of the development of different colors upon interaction with these probes which act as indicators for the in situ qualitative detection of Fe3+ and Fe2+. The limits of detection of Fe2+ and Fe3+ cations with receptor 2 were found to be as low as 30 and 15 parts per billion (ppb), respectively. The probable binding modes of these receptors with Fe2+ have also been suggested on the basis of the 1H NMR spectroscopic titration, electrospray ionization mass spectrometry (ESI-MS), Job’s plot, and computational (DFT) studies along with electrochemical and spectro-photochemical data. Single crystal X-ray diffraction analysis of 1 revealed that its solid-state structure was stabilized via intermolecular C–H/O and O–H/N hydrogen bonds and by C–H/π interactions. Interestingly, detailed theoretical calculations (DFT) indicated that hydroxymethyl (−CH2OH) group attached to naphthalene unit plays a pivotal role in sensing Fe2+/3+ ion selectively and in the stabilization of 2 in unusual eclipsed configuration through C–H···O type hydrogen bonding.