Vibrational spectroscopy (FT-IR and FT-Raman) investigation, and hybrid computational (HF and DFT) analysis on the structure of 2,3-naphthalenediol

Design, structural, spectral, DFT and analytical studies of novel nano-palladium schiff base complex

A novel nano-palladium (II) Schiff base complex (C1) is synthesized by the reaction between palladium chloride and the Schiff base N, N'-1, 2-phenylene) bis (3 -aminobenzamide (A1). The prepared compounds were characterized by elemental analysis, Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Thermogravimetric Analysis (TGA). A combined solvent sublation-ICP OES methodology has been studied for the preconcentration, separation and determination of trace palladium (II) in media of diverse origin using the Schiff base ligand (A1). The different experimental variables that affect the sublation efficiency (S, %) were thoroughly investigated viz.: pH of sample solution; amounts of A1, Pd (II) and TBAB; type and amounts of surfactants, types of organic solvent, temperature and stirring time. The method involves the determination of trace palladium (II) after selective separation by solvent sublation, thus eliminating the effect of foreign ions and increasing the sensitivity. Also, palladium is determined directly in the organic phase, which decreases the determination time and its loss during determination. At optimum conditions, the linear range of Pd (II) was 10.0-100.0 ngmL^-1. The coefficient of determination, the limit of detection (LOD) and limit of quantification (LOQ) were 0.9943, 21.29 ngL^-1 and 64.5 ngL^-1, respectively. This sublation method was applied to real samples and recoveries of more than 95% were obtained in the spiked samples with a preconcentration factor of 100. The mechanism of solvent sublatation of the TBA.[Pd^II-(A1)₂] ion pairs is discussed. The computational studying was estimated to approve the geometry of the isolated solid compounds.

Synthesis, Covalency Sequence, and Crystal Features of Pentagonal Uranyl Acylpyrazolone Complexes along with DFT Calculation and Hirshfeld Analysis

Three uranyl acylpyrazolone complexes [UO₂(PCBPMP)₂(CH₃CH₂OH)] (complex I), [UO₂(PCBMCPMP)₂(CH₃CH₂OH)] (complex II), and [UO₂(PCBPTMP)₂(CH₃CH₂OH)] (complex III) were synthesized from σ-donating acypyrazolone ligands to analyze their sequence of covalent characteristics, reactivity, and redox properties (PCBPMP: p-chlorobenzoyl 1-phenyl 3-methyl 5-pyrazolone; PCBMCPMP: p-chlorobenzoyl 1-(m-chlorophenyl) 3-methyl 5-pyrazolone; PCBPTMP: p-chlorobenzoyl 1-(p-tolyl) 3-methyl 5-pyrazolone). An examination of the structure, pentagonal bipyramidal geometry, and composition of these complexes was conducted mainly through their single-crystal X-ray diffraction (XRD) data, ¹H nuclear magnetic resonance (NMR) δ-values, plots of thermogravimetric-differential thermal analysis (TG-DTA), significant Fourier transform infrared (FTIR) vibrations, gravimetric estimation, and molar conductivity values. The covalency order was found to be complex II > III > I, which mainly depends on values of stretching frequencies, average bond lengths of axial uranyl bonds, values of average bond lengths on the pentagonal equatorial plane, solvent coordination on the fifth site of a pentagonal plane, and the type of aryl group on the nitrogen of the pyrazolone ring. This was confirmed by FTIR spectroscopy and single-crystal spectral characterization. To verify experimental results by comparison with theoretical results, density functional theory (DFT) calculations were carried out, which further gives evidence for the covalency order through theoretical frequencies and the gap of highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energies. Theoretical bond properties were also examined by the identification of global index parameters. Intermolecular noncovalent surface interactions were studied by the Hirshfeld surface analysis. The irreversible redox behavior of uranyl species was identified through electrochemical cyclic voltammetry-differential pulse voltammetry (CV-DPV) plot analysis.

Self-assembly of heterogeneous bilayers stratified by Au-S and hydrogen bonds on Au(111)

The self-assembly of heterogeneous bilayers on Au substrates was investigated using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and infrared reflection absorption spectroscopy (IRAS). The formation of a well-defined bilayer including different types of functional groups would be one of the desired goals to create varying surface functionalities. In this study, we examined the assembly of a hydrogen-bonded molecular layer to another functional alkanethiolate self-assembled monolayer (SAM) on the Au(111) surface. The chemical properties and bond strength of the hydrogen bonds at the interlayer differ from those of the Au-S bonds at the anchor of thiolate SAMs, therefore the adsorbed molecules are expected to form a stratified bilayer. In this study, on one hand, we revealed that imidazole-terminated alkanethiolate SAMs (Im-SAMs) have an atomically smooth topography but chemically inhomogeneous Au-S anchors, rather incomplete than n-alkanethiolate SAMs, on the Au(111) surface. On the other hand, we confirmed the self-assembly of the heterogeneous bilayers including Im-SAMs on the Au(111) surface, even in a mixed solution containing two types of molecules. These results show that the self-assembly of the bilayer stratified by H bonds and Au-S bonds is flexible and adaptable.

New copper(II) μ-Alkoxo-μ-carboxylato double-bridged complexes as models for the active site of catechol oxidase: Synthesis, spectral characterization and DFT calculations

A series of four copper(II) μ-Alkoxo-μ-carboxylato double bridged complexes, [{Cu₂(L)}₂][(μ–O₂C–CO₂] 1, [{Cu₂(L)}₂(μ–O₂C–(CH₂)CO₂] 2, [{Cu₂(L)}₂(μ–O₂C–CH₂–CO₂] 3 and [{Cu₂(L)}₂(μ–O₂C–C₆H₄–CO₂] 4 (H₃L = 4-bromo-2-((E)-((3-(((E)-5-chloro-2-hydroxybenzylidene) amino)-2-hydroxypropyl) imino) methyl)-6-methoxyphenol and μ-dicarboxylate ions = oxalate, malonate, succinate and terephthalate) have been synthesized and characterized using several physicochemical techniques. The tridentate nature of H₃L is interpreted from IR spectra. The Epr spectra of these complexes are characteristic of the quintet state (S = 2) in central features and the triplet state (S = 1) of these tetranuclear complexes. The electrochemical potential of these complexes was investigated using CV (cyclic voltammetry) and DPV (differential pulse voltammetry). All complexes showed quasi reversible reduction peaks in the cathodic region. To explore the stability of these complexes, quantum chemical parameters like electronegativity, ionization potential, electron affinity, global hardness and softness, and electrophilicity were estimated and discussed. The synthesized complexes have been designed as structural and functional models of the catechol oxidase enzymes to investigate the catecholase activity. Additionally, superoxide dismutase activity data of all complexes have also been evaluated and compared with known SOD mimics.

A novel cerium(iii)–isatin Schiff base complex: spectrofluorometric and DFT studies and application as a kidney biomarker for ultrasensitive detection of human creatinine

A novel and promising Schiff base and Ce(iii)-complex were synthesized and fully characterized. A novel creatinine optical biosensor based on Ce(iii)-complex and could be a promising analytical tool and as a promising kidney biomarker.

A novel nano copper complex: potentiometry, DFT and application as a cancer prostatic biomarker for the ultrasensitive detection of human PSA

A novel analytical approach for cancer prostatic biomarker by PSA detection using nano-Cu(II)-complex.

Nitric oxide functionalized molybdenum(0) pyrazolone Schiff base complexes: thermal and biochemical study

This work describes the synthesis and characterization of three molybdenum dinitrosyl Schiff base complexes of the general formula [Mo(NO)₂(L)(OH)], where L is N-(dehydroacetic acid)-4-aminoantipyrene (dha-aapH), N-(4-acetylidene-3-methyl-1-phenyl-2-pyrazolin-5-one)-4-aminoantipyrine (amphp-aapH) or N-(3-methyl-1-phenyl-4-propionylidene-2-pyrazolin-5-one)-4-aminoantipyrine (mphpp-aapH). The complexes were formulated on the basis of spectroscopic analyses, elemental composition, magnetic susceptibility measurements, molar conductance behaviour and determination of the respective decomposition temperatures. A comparative experimental-theoretical approach was followed to elucidate the structure of the complexes. Fourier transform infra-red (FT-IR) spectroscopy, thermo-gravimetry (TG) and electronic spectral insights were mainly focused on the confirmation of the formation of the complexes. The computational density functional theory (DFT) calculations evaluated in the study involve the molecular specification for the use of LANL2DZ/RB3LYP formalism for metal atoms and 6-311G/RB3LYP for the remaining non-metal atoms. The study reveals a suitable cis-octahedral geometry for the complexes. The TG curve of one of the representative complexes was evaluated to find the respective thermodynamic and kinetic parameters using various physical methods. The Freeman & Carroll (FC) differential method, the Horowitz and Metzger (HM) approximation method, the Coats–Redfern method and the Broido method were employed to present a comparative thermal analysis of the complex. The Broido method proved the best fit to the results for the compound under question. In addition to structural and thermal analyses, the study also deals with the in vitro antimicrobial and anticancer sensitivity of the complexes. The results revealed potent biological properties of the representative complex containing dha-aapH. Cell toxicity tests against COLO-205 human cancer cell line using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay showed an IC₅₀ value of 53.13 μgm mL⁻¹ for the Schiff base and 10.51 μgm L⁻¹ for the respective complex. Similarly the same complex proved to be an effective antimicrobial agent against Aspergillus, Pseudomonas, E. coli and Streptococcus. The results indicated a more pronounced activity against Pseudomonas and Streptococcus than the other two microbial species.

This work describes the thermal and biological implications of three pyrazolone-dinitrosylmolybdenum(0) complexes.

Density functionalized [RuII(NO)(Salen)(Cl)] complex: Computational photodynamics and in vitro anticancer facets

Photodynamic therapy (PDT) is a treatment that uses photosensitizing agents to kill cancer cells. Scientific community has been eager for decades to design an efficient PDT drug. Under such purview, the current report deals with the computational photodynamic behavior of ruthenium(II) nitrosyl complex containing N, N'-salicyldehyde-ethylenediimine (SalenH₂), the synthesis and X-ray crystallography of which is already known [Ref. 38,39]. Gaussian 09W software package was employed to carry out the density functional (DFT) studies. DFT calculations with Becke-3-Lee-Yang-Parr (B3LYP)/Los Alamos National Laboratory 2 Double Z (LanL2DZ) specified for Ru atom and B3LYP/6-31G(d,p) combination for all other atoms were used using effective core potential method. Both, the ground and excited states of the complex were evolved. Some known photosensitizers were compared with the target complex. Pthalocyanine and porphyrin derivatives were the compounds selected for the respective comparative study. It is suggested that effective photoactivity was found due to the presence of ruthenium core in the model complex. In addition to the evaluation of theoretical aspects in vitro anticancer aspects against COLO-205 human cancer cells have also been carried out with regard to the complex. More emphasis was laid to extrapolate DFT to depict the chemical power of the target compound to release nitric oxide. A promising visible light triggered nitric oxide releasing power of the compound has been inferred. In vitro antiproliferative studies of [RuCl₃(PPh₃)₃] and [Ru(NO)(Salen)(Cl)] have revealed the model complex as an excellent anticancer agent. From IC₅₀ values of 40.031mg/mL in former and of 9.74mg/mL in latter, it is established that latter bears more anticancer potentiality. From overall study the DFT based structural elucidation and the efficiency of NO, Ru and Salen co-ligands has shown promising drug delivery property and a good candidacy for both chemotherapy as well as light therapy.

Quantum chemical and spectroscopic investigations of 4-Hydroxy-7-methyl-1,8-naphthyridine-3-carboxylic acid

The FTIR (4000–400[Formula: see text]cm[Formula: see text]) and the FT-Raman spectra (4000–50[Formula: see text]cm[Formula: see text]) of 4-Hydroxy-7-methyl-1,8-naphthyridine-3-carboxylic acid are recorded and investigated. The spectra are interpreted using anharmonic frequency computations by VPT2, VSCF and PT2-VSCF methods within DFT/6-311G(d,p) framework. The root mean square (RMS) values indicate that VSCF computed frequencies are in close agreement with the observed frequencies. The combination and overtone bands are also identified in the FTIR spectrum. The intermolecular O-H[Formula: see text]O hydrogen bonding interactions are discussed in the dimer structure of the molecule. The magnitudes of the coupling between pair of modes are also computed. The electronic spectra in water and ethanol solvents are analyzed using TD-B3LYP/6-311[Formula: see text]G(d,p) level of theory. Molecular electrostatic potential (MEP) and HOMO-LUMO analysis are also performed.

Synthesis and investigation of the properties of novel azocalix[4]arenes

The azocalix[4]arenes molecules such as methylphenylazocalix[4]aren (MPcalix[4]) and methoxyphenylazocalix[4]aren (MOPcalix[4]) have been synthesized and characterized by experimental FT-IR and (1)H NMR spectral analyses. The fundamental vibrational transitions have been addressed by experimental FT-IR (4000-400 cm(-1)) technique and density functional theory (DFT) employing B3LYP level with the 6-31G(d) and 6-311G(d,p) basis sets. The (1)H NMR spectra of the studied compounds have been recorded in chloroform, and compared with computed data obtained by using gauge including atomic orbital (GIAO) method. Furthermore, thermodynamic properties (heat capacity, entropy, and enthalpy changes) and frontier molecular orbitals of the molecules in the ground state have been calculated by using the same method and basis sets. The non-linear optical properties such as the first order hyperpolarizability (β0), related properties (α0 and Δα) are also computed. Information about the charge density distribution of the molecules and its chemical reactivity has been studied by mapping molecular electrostatic potential surface (MEPs). The scaled vibrational frequency values have been compared with experimental FT-IR spectroscopic data. The correlations between the observed and calculated frequencies are in good agreement with each other as well as the correlation of NMR data. The linear polarizability and first hyperpolarizability of the studied molecules indicate that the compounds are a good candidate of nonlinear optical materials.

Experimental and theoretical studies of (FT-IR, FT-Raman, UV-Visible and DFT) 4-(6-methoxynaphthalen-2-yl) butan-2-one

In this work, the vibrational spectral analysis was carried out by using FT-Raman and FT-IR spectroscopy in the range 4000-50 cm(-1) and 4000-450 cm(-1) respectively for 4-(6-methoxynaphthalen-2-yl) butan-2-one (abbreviated as 4MNBO) molecule. Theoretical calculations were performed by density functional theory (DFT/B3LYP) method using 6-311G(d,p) and 6-311++G(d,p) basis sets. The difference between the observed and calculated wavenumber value of most of the fundamentals were very small. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The UV-Vis spectrum was recorded in the methanol solution. The energy, wavelength and oscillator's strength were calculated by Time Dependent Density Functional Theory (TD-DFT) and matched to the experimental findings. The intramolecular contacts have been interpreted using natural bond orbital (NBO) and natural localized molecular orbital (NLMO) analysis. Thermodynamic properties of 4MNBO at different temperature have been calculated. The molecular electrostatic potential surface (MESP) and Frontier molecular orbital's (FMO's) analysis were investigated using theoretical calculations.