Dihydrate Complex Research Articles

Synthesis, electronic and vibrational properties, solvation effects, ADME and cytotoxic assay of aqua-(1,10-phenanthroline)-tyrosinato-copper(II) nitrate dihydrate complex: experimental and theoretical studies

Synthesis, electronic and vibrational properties, solvation effects, ADME and cytotoxic assay of aqua-(1,10-phenanthroline)-tyrosinato-copper(II) nitrate dihydrate complex: experimental and theoretical studies

Structural characterization, DNA interaction and pharmacological evaluation of Cu (II), Co (II), Ni (II), Fe (II) dihydrate complexes derived from pyridine-2,5-dicarboxylic acid and 2-methylimidazole as organic moieties

The study of Metal organic coordination polymers is one of the most emerging areas of research in coordination chemistry because of their wide technological and interesting applications in pharmacology, sensor studies, catalysis, hydrogen storage devices, magnetic and NLO materials, ion exchange adsorption, metallic conductivity and luminescence studies. In this research work, microcrystalline transition metal [Cu (II), Co (II), Ni (II) and Fe (II)] complexes of Pyridine-2,5-dicarboxylic acid and 2-Methylimidazole as organic moieties were synthesized and analyzed for DNA interaction, biological properties like anti-cancer, anti-oxidant and anti-microbial activities. Structural characterization were studied using Fourier Transform-Infra Red spectroscopy (FT-IR), X-ray Diffractions (XRD), Ultraviolet-Visible spectroscopy (UV–VIS), Field Emission Scanning Electron Microscopy (FE-SEM), Energy-Dispersive X-Ray analysis (EDX), Cyclic voltammetry (CV) and Thermo Gravimetric Analysis (TG-DTA). The copper complex demonstrates superior biological activity compared to alternative complexes, exhibiting antioxidant, antibacterial, and anticancer properties. From cytotoxicity results, it's evident that complexes (1–4) possess the capability to inhibit tumor cell growth while sparing normal cells, attributed to the metal atoms' strong affinity for cancer cells.

Hydrogen Bonding and Molecular Geometry in Isolated Hydrates of 2-Ethylthiazole Characterised by Microwave Spectroscopy.

Broadband microwave spectra of the isolated 2-ethylthiazole molecule, and complexes of 2-ethylthiazole⋅⋅⋅H2O and 2-ethylthiazole⋅⋅⋅(H2O)2 have been recorded by probing a gaseous sample containing low concentrations of 2-ethylthiazole and water within a carrier gas undergoing supersonic expansion. The identified conformer of the isolated 2-ethylthiazole molecule and the 2-ethylthiazole sub-unit within each of 2-ethylthiazole⋅⋅⋅H2O and 2-ethylthiazole⋅⋅⋅(H2O)2 have C1 symmetry. The angle that defines rotation of the ethyl group relative to the plane of the thiazole ring, ∠(S-C2-C6-C7), is -98.6(10)° within the isolated 2-ethylthiazole molecule. Analysis of molecular geometries and non-covalent interactions reveals each hydrate complex contains a non-linear primary, N⋅⋅⋅Hb-O, hydrogen bond between an O-H of H2O and the nitrogen atom while the O atom of the water molecule(s) interacts weakly with the ethyl group. The ∠(Hb⋅⋅⋅N-C2) parameter, which defines the position of the H2O molecule relative to the thiazole ring, is found to be significantly greater for 2-ethylthiazole⋅⋅⋅H2O than for thiazole⋅⋅⋅H2O. The distance between the O atoms is determined to be 2.894(21) Å within the dihydrate complex which is shorter than observed within the isolated water dimer. The primary hydrogen bond within 2-ethylthiazole⋅⋅⋅(H2O)2 is shorter and stronger than that in 2-ethylthiazole⋅⋅⋅H2O as a result of cooperative hydrogen bonding effects.

Hirshfeld surface analysis, interaction energy calculations and in silico anti-SARS-CoV-2 potentials of metal (II) 3,4-dimethoxybenzoate with nicotinamide complexes

In this study, types of the intermolecular interactions, the intermolecular interaction energies, void analysis of diaquabis(3,4-dimethoxybenzoate)bis(nicotinamide)zinc(II) dihydrate (Complex 1), diaquabis(3,4-dimethoxybenzoate)bis(nicotinamide)nickel(II) dihydrate (Complex 2), diaquabis(3,4-dimethoxybenzoate)bis(nicotinamide)cobalt(II) dihydrate (Complex 3), whose crystal structures were characterized before, were investigated with the help of the CrystalExplorer program (Version 21.5). It has been determined that H…H, H…O/O…H, H…C/C…H, H…N/N…H, C…C, C…O/O…C, O…O, and C…N/N…C interactions are intermolecular interactions that contribute to the Hirshfeld surface of the complexes. According to the results of the interaction energy analysis calculated with the help of B3LYP/6-31G(d,p), B3LYP/6-31G(d), B3LYP/3-21G, HF/6-31G(d,p), HF/6-31G(d), HF/3-21G, DFT/6-31G(d,p), DFT/6-31G(d), DFT/3-21G, MP2/6-31G(d,p), MP2/6-31G(d), MP2/3-21G basis sets, the major amount of the total energy is contributed by electrostatic and polarization energies. The interactions between Complexes 1-3 and the main protease enzyme and the spike protein of Omicron variant of the SARS-CoV-2 were investigated by Molecular docking studies. It was determined that complexes 1-3 and the main protease enzyme and the spike protein of Omicron variant of the SARS-CoV-2 interact via attractive charges, hydrogen bonding, electrostatic contacts, and hydrophobic interactions. According to the obtained results, further in vivo/in vitro studies are recommended for complex 3. The results determined as a result of interaction energy analysis and molecular docking studies show that the hydrogen bonds formed by the hydrogen bond donor/acceptor groups in the structure of the complexes are an important factor in both the stability of the crystal package and inhibition of important enzymes of SARS CoV-2.

Investigation of initiator metal efficiency in the ring‐opening polymerization of lactones: an experimental and computational study

AbstractPoly(δ‐valerolactone) (PVL) was synthesized by ring‐opening polymerization (ROP), employing tin(II) acetate (SnAcet2), lead(II) acetate trihydrate (PbAcet2·3H2O) and cadmium(II) acetate dihydrate (CdAcet2·2H2O) complexes as initiators without any co‐initiator. The highest molecular weight PVL (45 438 g mol−1, 91% yield) was obtained with CdAcet2·2H2O. Characterization of the synthesized products was performed by FTIR, 1H NMR, 13C NMR, gel permeation chromatography (GPC), matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF/TOF MS), TGA and DSC. Electrostatic data (natural bond orbital and Hirshfeld) and lowest unoccupied molecular orbital (LUMO) of the initiators were obtained by using several density functional theory methods (B3LYP, ωB97X‐D, PBEPBE, BPV86, HSEH1PBE, MPW1PW91, M06 and M062X). In addition, the initiation stage of the ROP mechanism of δ‐valerolactone with these metal acetate complexes was investigated at the ωB97X‐D level with a mixed basis set. It was computationally determined that the most effective initiator was also CdAcet2. The molecular weight variation of PVLs synthesized with these initiators can be associated with the combined evaluation of atomic charge, LUMO and orbital overlap analyses. The computationally obtained reaction barriers for the initiators support this idea, also. In addition, toxicity tests carried out for PVLs synthesized with acetate complexes containing Sn, Cd and Pb revealed that the Sn and Cd complexes do not have a toxic effect on cell viability at some dilution rates. © 2021 Society of Industrial Chemistry.

Luminescent self-healing materials constructed via coordination between lanthanide ions and phenanthroline-tethered to polymer chain

Self-healing material with additional properties has constituted a great family of functional materials. Herein, self-healing and stretchable luminescent elastomers, Polymer-Phen-Eu3+, Polymer-Phen-Tb3+ and Polymer-Phen-Eu(tta)3, were prepared by linking Ln3+ (Eu3+/Tb3+) or tris(2-thenoyltrifluoroacetonato) europium (III) dihydrate complexes (Eu(tta)3·2H2O) with the polymer ligand based on PDMS chains and phenanthroline moieties. The dynamic Ln-ligand cross-linking and hydrogen bonds endow the as-prepared materials with fast self-healing capability as well as good mechanical property. Compared to Polymer-Phen-Ln3+, Polymer-Phen-Eu(tta)3 behaved higher elasticity and faster self-healing property due to its smaller steric hindrance owing to the presence of the β-diketone ligand (tta), which feature the polymer with loosely accumulated chains, and better luminescent behavior because of the coordinated water molecules being expelled by the coordination of tta to Eu3+ ions and energy transfer from tta to Eu3+. In addition, the resulting materials, Polymer-Phen-Ln3+ and Polymer-Phen-Eu(tta)3, can also be processed into flexible and self-healing conductors upon the embedding of silver nanowires, which was crucial to their applications in wearable intelligent devices, visualized force and sensing optical coating.

Self-healable luminescent materials via a supramolecular self-assembly design

Supramolecular self-assembly induced by lanthanide ions (Ln3+) provides a powerful route to construct advanced functional materials, owing to the highly predictable nature of the Ln-ligand coordination and unique physical property of Ln3+. Herein, we synthesized functional luminescent materials by incorporation of fluorescent centers into polydimethylsiloxane polymers via supramolecular self-assembly design, where the coordination connection and hydrogen bond endow the materials with fast self-healability and good mechanical performance at room temperature: (i) the self-healing material PIB-Ln prepared by introducing Ln3+ into the precursor exhibits response to stimuli of acid-base vapors on account of the inhibition or promotion of “antenna effect” upon stimulation (the as-prepared precursor is named as PIB). This reversibly responsive fluorochromic material displays promising application in smart sensors; (ii) the highly fluorescent material PIB-Eu-TTA was prepared by bonding Tris(2-thenoyltrifluoroacetonato) (TTA) europium(III) dihydrate complexes (Eu(TTA)3·2H2O) to the bipyridine groups on the precursor. Compared to PIB-Ln, PIB-Eu-TTA shows faster self-healing property and more high stretchable feature on account of the smaller steric hindrance of PIB-Ln-TTA and better fluorescent behavior because of the coordinated water molecules being expelled and energy transfer effectively from tris(2-thenoyltrifluoroacetonato) to Eu3+. On the basis of the superior performance, PIB-Eu-TTA demonstrates an exemplary application in a flexible and self-healable conductor and light-emitting diode (LED), thereby providing new insight into the future development of e-skin and smart optical devices.

Structural Features of 1,3,4-Thiadiazole-Derived Ligands and Their Zn(II) and Cu(II) Complexes Which Demonstrate Synergistic Antibacterial Effects with Kanamycin.

Classical synthetic protocols were applied for the isolation of three novel 1,3,4-thiadiazole derivatives which were then complexed with the biologically important Cu(II) and Zn(II) ions. All free ligands and their corresponding complexes were characterized using a number of spectroscopic techniques including Ultraviolet-visible (UV–vis), Fluorescence, Infrared (FT-IR), tandem liquid chromatography-mass (LC-MS), X-ray diffraction (XRD), and Nuclear Magnetic Resonance (NMR) spectroscopy (1H, 13C, HSQC, HMBC). The results obtained are consistent with the formation of dihydrate complexes, in which the chelation of the metal ion occurs via one of the thiadiazole nitrogen atoms and the deprotonated hydroxyl group of the neighboring resorcynyl moiety. The Zn(II) complexes utilize a 1:1 ligand–metal ratio, while in the Cu(II) complexes the ligand–metal ratio is 2:1. Although the antibacterial testing identified moderate activity of the compounds against the tested bacterial strains and additionally modest antioxidant activity, a strong synergistic antibacterial effect against Staphylococcus aureus, using concomitant treatment of thiadiazole derivatives with the commercial antibiotic kanamycin, was observed. The most active thiadiazole derivative demonstrated a minimal inhibitory concentration (MIC) of 500 μg/mL while it was 125 μg/mL in the presence of kanamycin. Moreover, in the presence of few thiadiazole derivatives the MIC value of kanamycin decreased from 0.39 μg/mL to 0.5 μg/mL. The antioxidant activity (IC50) of the most active thiadiazole derivative was determined as 0.13 mM which was nearly three-fold lower compared to that of TROLOX (0.5 mM).

Physicochemical properties of cesium tetroxalate dihydrate single crystal: An efficient material for nonlinear optical applications

Herein we report the tunable optical limiting property of a metal–organic cesium tetroxalate dihydrate (CTD) complex. Temperature and pH were optimized to be 40°C and 3.5 respectively to grow CTD single crystal using the solvent evaporation method. The compound formation was confirmed by its response to single crystal and powder x-ray diffraction analysis. Thermal, mechanical, dielectric, linear optical, photoconductivity and photoluminescence properties of title crystal are reported. Nonlinear coupling between delocalized π-electrons of metal–ligand interaction and the oscillating electric field of a laser beam enhanced the nonlinear optical parameters. The third order nonlinear refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) of CTD complex under continuous-wave laser excitation are found to be (3.26±0.033)×10−8 cm2W−1, (10.33±0.41)×10−4 cmW−1 and (8.98±0.35)×10−5 esu respectively. Variation in two-photon absorption (2PA) coefficient measured under nanosecond pulsed laser excitation of different intensities confirmed the presence of sequential 2PA in CTD complex. The optical limiting threshold was investigated under different intensities were found to vary from (1.09±0.05)×1012 Wm−2 to (2.49±0.05)×1012 Wm−2 showing the intensity tunable optical limiting property of CTD material.

Specific Ion Effects on Hydrogen-Bond Rearrangements in the Halide-Dihydrate Complexes.

Small aqueous ionic clusters represent ideal systems to investigate the microscopic hydrogen-bonding structure and dynamics in ion hydration shells. In this context, halide-dihydrate complexes are the smallest systems where the interplay between halide-water and water-water interactions can be studied simultaneously. Here, quantum molecular dynamics simulations unravel specific ion effects on the temperature-dependent structural transition in X-(H2O)2 complexes (X = Cl, Br, and I), which is induced by the breaking of the water-water hydrogen bond. A systematic analysis of the hydrogen-bonding rearrangements at low temperature provides fundamental insights into the competition between halide-water and water-water interactions depending on the properties of the halide ion. While the halide-water hydrogen-bond strength decreases going from Cl-(H2O)2 to I-(H2O)2, the opposite trend in observed in the strength of the water-water hydrogen-bond, suggesting that nontrivial many-body effects may also be at play in the hydration shells of halide ions in solution, especially in frustrated systems (e.g., interfaces) where the water molecules can have dangling OH bonds.

Ion-mediated hydrogen-bond rearrangement through tunnelling in the iodide-dihydrate complex.

A microscopic picture of hydrogen-bond structure and dynamics in ion hydration shells remains elusive. Small ion-dihydrate molecular complexes are ideal systems with which to investigate the interplay and competition between ion-water and water-water interactions. Here, state-of-the-art quantum dynamics simulations provide evidence for tunnelling in hydrogen-bond rearrangements in the iodide-dihydrate complex and show that it can be controlled through isotopic substitutions. We find that the iodide ion weakens the neighbouring water-water hydrogen bond, leading to faster water reorientation than in the analogous water trimer. These faster dynamics, which are apparently at odds with the slowdown observed in the first hydration shell of iodide in solution, can be traced back to the presence of a free OH bond in the iodide-dihydrate complex, which effectively triggers the overall structural rearrangements within it. Besides providing indirect support for cooperative hydrogen-bond dynamics in iodide solutions, the analysis presented here suggests that iodide ions may accelerate hydrogen-bond rearrangements at aqueous interfaces, where neighbouring water molecules can be undercoordinated.

IN VITRO STUDY OF ANTIMICROBIAL AND ANTIOXIDANT ACTIVITIES OF OXALIC ACID-DERIVED BIOACTIVE CHELATING AGENT

Objective: The aim of this study is to evaluate the biological potentials of sodium cadmium oxalate dihydrate complex prepared by a single diffusion method in the silica gel medium.
 Methods: The present complex was derived by the oxalic acid using a single diffusion method in gel medium and tested for single-crystal X-ray diffraction, ultraviolet-visible (UV) spectrum (190–500 mm), and solubility (distilled water at 20–29°C) studies. Antioxidant activity was determined by 2, 2-diphenyl-1-picrylhydrazyl assay, and antimicrobial activity was measured by agar well diffusion method.
 Results: The present chelating complex was successfully synthesized by gel technique. The solubility of sodium cadmium oxalate dihydrate was moderately good for deionized warm water. The UV spectral studies confirmed the chelating O-H, Na-O, and C-O bonds of the newly synthesized complex for the optical and biological properties.
 Conclusions: The metal-oxygen and oxygen-hydrogen bonds of the present newly synthesized sample much improved its optical, antimicrobial, and antioxidant activities and find its applications in the field of pharmaceutical and biomedical applications.

The complete conformational panorama of formanilide-water complexes: the role of water as a conformational switch.

The microsolvated complexes of formanilide, generated in a supersonic expansion, have been observed by Fourier transform microwave spectroscopy. Three 1 : 1 and one 1 : 2 formanilide-water adducts have been observed and their structures characterized by the measurement of isotopologue rotational spectra. In one of the monohydrated complexes and in the dihydrated complex, formanilide adopts a cis-configuration. In these species water closes sequential cycles with the cis amino and carbonyl groups through a network of N-HO and O-HO hydrogen bonds. Furthermore, in these complexes cis-formanilide has almost the same non planar configuration observed in the monomer. In the two monohydrated complexes detected with trans-formanilide, a planar skeleton is detected with water interacting solely with either the amino (N-H··O bond) or the carbonyl group (O-HO[double bond, length as m-dash]C bond). The observed tunnelling splittings show a rich intermolecular dynamics in those complexes. The results seem to indicate that complexation with water switches the configuration of formanilide from trans, which is more stable for the bare monomer, to cis, which is more stable for the hydrated complexes.

Experimental design for optimizing MALDI-TOF-MS analysis of palladium complexes

This paper presents optimization of matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometer (MS) instrumental parameters for the analysis of chloro(2,2'',2"-terpyridine)palladium(II) chloride dihydrate complex applying design of experiments methodology (DoE). This complex is of interest for potential use in the cancer therapy. DoE methodology was proved to succeed in optimization of many complex analytical problems. However, it has been poorly used for MALDI-TOF-MS optimization up to now. The theoretical mathematical relationships which explain the influence of important experimental factors (laser energy, grid voltage and number of laser shots) on the selected responses (signal to noise ? S/N ratio and the resolution ? R of the leading peak) is established. The optimal instrumental settings providing maximal S/N and R are identified and experimentally verified.

Exploring acetylene chemistry in superbasic media: A theoretical study of the effect of water on vinylation and ethynylation reactions with acetylene in KOH/DMSO and NaOH/DMSO systems

A rapidly developing approach adding new dimensions to acetylene chemistry relying on employment of high basicity media such as alkali metal hydroxide suspensions in dimethyl sulfoxide (DMSO) has been, for the first time, investigated theoretically using ab initio models. Extending our recently introduced model of superbase catalysis with a nondissociated KOH (or NaOH) participation, we present here a model for a superbasic reaction center with the first solvation shell explicitly included. The alkali metal hydroxides in a DMSO solution were found to form KOH·5DMSO and NaOH·4DMSO complexes that are stabilized due to the interligand interaction. Our present MP2/6-311++G**//B3LYP/6-31+G* computations show that 1 and 2 water molecules can build themselves into the MOH close surrounding without substantially perturbing the DMSO ligands and easily travel between different insertion positions. Our results predict that the activation energies in the series of reactions of nucleophilic addition to a triple bond with water, methanol, methanethiol, sodium hydrosulfide, and acetone in the presence of dihydrated complexes should be larger than those obtained with the participation of monohydrated ones, which is in fair agreement with the experimental findings. The present model also explains an increase in the ethynylation reaction yield in the presence of water by suppression of the competitive enolization reaction.

Spectroscopic and structural studies of the first complex formed between salinomycin and organic amine

For the first time, the crystalline complex of salinomycin with benzylamine was obtained and its molecular structure was studied using single crystal X-ray diffraction, FT-IR, 1H NMR, 13C NMR, 2D NMR and ESI MS methods. These studies provided evidence that the proton from the carboxylic group of salinomycin (SAL) is transferred to the amine group of benzylamine (BnA) forming the host-guest complex (SAL-BnA). It was shown that the SAL-BnA complex both in solid state and in chloroform solution is stabilized by the intramolecular O—H⋯O hydrogen bonds and also by the intermolecular hydrogen bonding interactions of the carboxylate, ketone and/or hydroxyl groups of SAL with water molecules present in the investigated system. The solvated acetonitrile molecules are additionally located in the voids between the SAL-BnA complex molecules in the crystal structure, while water molecules involved in the dihydrated crystalline SAL-BnA complex partially move into the solvent upon dissolution in chloroform.

A theoretical study of the microhydration of iodic acid (HOIO2)

The structures, energetics, and thermodynamic properties of HIO3 isomers (HOOOI, HOOIO, HOIO2, and HIO3) have been computed using CCSD(T)/CBS theoretical method. The spin orbit corrections (SOC) have also been evaluated for the each iodine-containing molecule. The SOC value decreases as the iodine valence increases within the molecule. The results revealed that HOIO2 was the most stable form and that HOOOI was the next most stable isomer. The standard enthalpies of formation at 298K have been derived from IO+HO2 and OH+OIO dissociation pathways. At the CCSD(T)/CBS level on B3LYP geometries, the recommended ΔfH°298K is (−95.4±0.3)kJmol−1 for HOIO2, and its computed S°298K andCp (300K) values are respectively 339.12 and 75.28Jmol−1K−1. Further, monohydrated and dihydrated complexes of iodic acid have been investigated using DFT and wavefunction methods. Three and six mono- and di-hydrated complexes, respectively, have been identified. The hydrogen bonded complexes (HOIO2_1wa and HOIO2_2wa) are the lowest lying structures. The thermodynamics of dihydrates have been calculated from the total hydration of iodic acid (HOIO2+2H2O). Mono- and di-hydration of iodic acid is a favored process at tropospheric and ambient conditions with the formation of HOIO2_1wa and HOIO2_2wa at T⩽310K. The positive Gibbs free energies at high temperatures indicate that gas-phase iodic acid would not be present in a hydrated form inside the nuclear containment building of a pressurized water reactor.

On 2:1 melamine – Squaric acid dihydrate complex: The structure and vibrational spectra

In the present paper we would like to describe the structural and dynamical properties of crystalline dihydrated complex of melamine (2,4,6–triamino-1,3,5–triazin-1-ium) with squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione) abbreviated as MH·SQ. The X-ray diffraction studies show the presence of deprotonated units (C4O4)2- and single protonated melamine cations surrounded by tetrameric water assemblies (H2O)4. The formation of the water tetramers deserves a special attention. IR absorption and Raman spectra reflect a richness of structural units and numerous hydrogen bonds. The presence of the continua in the IR spectra, with a characteristic presence of the Hadži's trio enriched by a numerous submaxima, may be ascribed to the structural units and to the various types of hydrogen bonds. The density functional theory calculation with the periodic boundary conditions was use to precise analysis of experimental data.

Investigation of Electrochemical Oxidation of Methanol at a Carbon Paste Electrode Modified with Ni(II)‐BS Complex and Reduced Graphene Oxide Nano Sheets

AbstractIn the present research, the electro oxidation of methanol was investigated by different electrochemical methods at a carbon paste electrode (CPE) modified with bis(salicylaldehyde)‐nickel(II)‐dihydrate complex (Ni(II)‐BS) and reduced graphene oxide (RGO) (which named Ni(II)‐BS/RGO/CPE) in an alkaline solution. This modified electrode showed very efficient activity for oxidation of methanol. It was found that methanol was oxidized by NiOOH groups generated by further electrochemical oxidation of nickel (II) hydroxide on the surface of the modified electrode. The rate constant and electron transfer coefficient were calculated to be 2.18 s−1 and 0.4, respectively. The anodic peak currents revealed a linear dependency with the square root of scan rate. This behaviour is the characteristic of a diffusion controlled process, so the diffusion coefficient of methanol was found to be 1.16×10−5 cm2 s−1 and the number of transferred electron was calculated to be 1. Moreover, differential pulse voltammetry (DPV) investigations showed that the peak current values were proportional to the concentration of methanol in two linear ranges. The obtained linear ranges were from 0.5 to 100.0 µM (R2=0.991) and 400.0 to 1300.0 µM (R2=0.992), and the detection limit was found to be 0.19 µM for methanol determination. Generally, the Ni(II)‐BS/RGO/CPE sensor was used for determination of methanol in an industrial ethanol solution containing 4.0 % methanol.

Tautomeric transformation of temozolomide, their proton affinities and chemical reactivities: A theoretical approach

The gas-phase geometry optimizations of bare, mono- and dihydrated complexes of temozolomide isomers were carried out using density functional calculation at the M06−2X/6−31+G(d,p) level of the theory. The structures and protonation energies of protonated species of temozolomide are reported. Chemical indices of all isomers and protonated species are also reported. Energies, thermodynamic quantities, rate constants and equilibrium constants of tautomeric and rotameric transformations of all isomers I1↔TZM↔HIa↔HIb↔I2↔I3 in bare and hydrated systems were obtained.