Title Ligand Research Articles

Investigations on spectroscopic characterizations, molecular docking, NBO, drug-Likeness, and ADME properties of 4H-1,2,4-triazol-4-amine by combined computational approach

In this study, the spectroscopic characterization, frontier molecular orbital analysis, and natural bond orbital analysis (NBO) analysis were executed to determine the movement of electrons within the molecule and the stability, and charge delocalization of the 4H-1,2,4-triazol-4-amine (4-AHT) through density functional theory (DFT) approach and B3LYP/6-311++G(d,p) level of theory. Surface plots of the hybrids’ Molecular Electrostatic Potential (MEP) revealed probable electrophilic and nucleophilic attacking sites. The discussed ligand were observed to be characterized by various spectral studies (FT-IR, UV-Vis). The calculated IR was found to be correlated with experimental values. The UV-Vis data of the molecule was used to analyze the visible absorption maximum (λmax) using the time-dependent DFT method. Since the principle of drug-likeness is usually used in combinatorial chemistry to minimize depletion in pharmacological investigations and growth, drug-likeness and ADME properties were calculated in this research to establish 4-AHT molecule bioavailability. Furthermore, molecular docking studies were carried out. Molecular docking analysis was performed for the title ligand inside the active site of the Epidermal Growth Factor Receptor (EGFR). The title compound’s anti-tumor activity against the cancer cell, in which EGFR is strongly expressed, prompted us to conduct molecular docking into the ATP binding site of EGFR to predict whether this molecule has an analogous binding mode to the EGFR inhibitors (PDB: ID: 1M17).

Biosensitivity and Theoretical Electronic Structure Investigations on 3-(2-Hydroxyphenyl)-2-iminothiazolidin-4-one and Its Zn2+ and Cd2+ Metal Complexes

A two-step cyclocondensation reaction has been carried out using 2-aminophenol with 2-chloroacetyl chloride to produce o-hydroxyphenyl chloroacetamide followed by treatment with KSCN in CH3COCH3 to produce the heterocyclic ligand 3-(2-hydroxyphenyl)-2-iminothiazolidin-4-one. The Zn2+ and Cd2+ complexes with a metal : ligands ratio of 1 : 4 were synthesized in ethanol using respective metal precursors with the title ligand. Antimicrobial activities of the ligand and its complexes were checked against some bacterial and fungal strains. The result evidenced better bioactive performance of the metal complex (though lower than the standard drug) than the free ligand against Escherichia coli, Staphylococcus aureus, and Salmonella typhi bacteria, as well as Fusarium oxysporum and Aspergillus niger fungal strains. Theoretical investigations on ligand and metal complexes help to infer the electronic structure behavior of them. Molecular geometry and bond order analysis provides detailed information on the nature of chemical structure and bonding. Molecular Electrostatic Potential (MEP) and atomic charge analysis claims evidence on charge distribution and electrophilic, nucleophilic reactive sites. Natural bond orbital analysis provides second-order perturbed stabilization interactions, orbital population, and their energies. Other theoretical properties such as hardness, softness, electron affinities, and ionization potential were derived and discussed in detail.

Synthesis, crystal structure, Hirshfeld surface analysis, spectral characterizations and quantum computational assessments of 1‑hydroxy-3-methyl-11H-pyrido[2,1-b] quinazolin-11-one

In this manuscript, a newly synthesized 1‑hydroxy-3-methyl-11H-pyrido[2,1-b] quinazolin-11-one molecule was analyzed in details for structural clarification by X-Ray crystallographic and FT-IR spectral data along with theoretical quantum chemical computations. The theoretical computations were performed by DFT/B3LYP method and 6–311++G(d,p) basis set in gas phase, and Potential Energy Distribution (PED) analysis of the DFT/B3LYP calculated IR spectrum of the compound was carried out by VEDA4 program. Hirshfeld surface analysis of the compound was performed to determine the most important contributions for the crystal packing. The 1H- and 13C- NMR chemical shift analyses were theoretically and experimentally studied for the compound. The existence of the n(O)→σ*(OH) hyperconjugative interaction resulted from the intra-molecular OH···O hydrogen bonding in the title compound were analyzed with NBO (Natural Bond Orbital) study. Additionally, the highest occupied molecular orbital (HOMO) - the lowest unoccupied molecular orbital (LUMO), the molecular electrostatic potential (MEP) and the non-linear optic values for the compound were found. Finally, the molecular docking study between the compound and macromolecule PDB:1EVE was done, and from the binding affinity value and the presence of inter-molecular interactions it was concluded that the title ligand compound may serve as a smart drug with nootropic property.

Synthesis and structural characterization of Zn2+, Cd2+ and Hg2+ complexes with tripyrrolidinophosphine chalcogenides

Six new complexes of zinc(II), cadmium(II) and mercury(II) chlorides with tripyrrolidinophosphine chalcogenides of the types [MCl2(Pyrr3PE)2] (M = Zn, E = S (1) or E = Se (2); M = Cd, E = S (3) or E = Se (4)) and [{HgCl(Pyrr3PE)}2(µ-Cl)2] (E = S (5) or Se (6)) have been prepared in yields of 66-92% by reaction of the ligands with metal chloride in ethanol and characterized by 1H and 31P NMR, IR, elemental analysis, conductivity, and single crystal X-ray diffraction analysis. The results show that the complexes are pseudo-tetrahedral containing coordinated chloride ions. Interestingly, the X-ray studies reveal that while the title ligands produce dinuclear complexes with Hg, their Cd and Zn complexes are mononuclear. The tetrahedral bond angles vary from 85.69(5)° to 126.25(4)° in dinuclear complexes 5 and 6 and from 93.51(3)° to 117.38(3)° in mononuclear species 2-4. The E = S bond lengths are in the range 1.999(9)-2.198(2) Å. The coordination properties of the title ligands are discussed and compared to those obtained for their bulkier counterparts.

Synthesis, structural, spectral, antioxidant, bioactivity and molecular docking investigations of a novel triazole derivative

The structural, spectroscopic and electronic properties of 4-(4-nitrophenyl)-5-(pyridin-3-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione have been analyzed by using single crystal X-ray diffraction (SCXRD), 1H and 13C NMR chemical shifts and FT-IR spectroscopic methods both theoretically and experimentally. The tautomeric (thiol and thione) energetic analysis results, structural optimization parameters (bond lengths and angles), vibrational wavenumbers, proton and carbon NMR chemical shifts, UV-Vis. parameters, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) analyses and Molecular Electrostatic Potential (MEP) surface have been calculated by using DFT/B3LYP quantum chemical method with 6-311++G(2d,2p) basis set to compare with the experimental results. The computed geometry parameters, vibrational wavenumbers, and NMR chemical shifts have been in good agreement with the experimental results. It should be noted that the radical scavenging activities of the title compound have been evaluated by using different test methods i.e. 2,2-Diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylenediamine (DMPD) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS). According to obtained results, the title compound displayed DPPH (SC50 19.42 ± 0.11 μg/mL), DMPD (SC50 21.13 ± 0.08 μg/mL) and ABTS (SC50 38.17 ± 0.25 μg/mL) scavenging activities. Also, these results have been compared with Butylated hydroxyanisole (BHA), Rutin (RUT) and Trolox (TRO) used as standard compounds. The physicochemical, pharmacokinetic, and toxicity features of the compound have been determined by using drug-likeness and in silico ADMET investigations. The interaction results with SARS-CoV-2 main protease (Mpro) of the title ligand compound have been analyzed via the help of molecular docking study. Communicated by Ramaswamy H. Sarma

Structural, spectral, electronic, and molecular docking investigations on N,N‐dimethyl‐2‐[(1E)‐({[(methylsulfanyl)methanethioyl]amino}imino)methyl]aniline

AbstractIn this research, a joint theoretical and experimental investigation was performed on the structural and spectral data (FT‐IR, Laser‐Raman, NMR, and UV–vis) of N,N‐dimethyl‐2‐[(1E)‐({[(methylsulfanyl)methanethioyl]amino}imino)methyl]aniline molecule. The theoretical electronic structure analyses were fulfilled by the density functional theory at the B3LYP level with the 6‐311++G(d,p) basis set in the gas phase of the isolated compound at the ground state. The vibrational works were analyzed in terms of potential energy distribution analysis to make the assignments of fundamental vibrational frequencies and the assigned modes of the title compound were compared with the reported experimental vibrational data. Later, Hirshfeld surface analysis over crystalline structure of the title compound was made to define the possible inter‐molecular interactions. In addition, the HOMO (highest occupied molecular orbital), LUMO (lowest unoccupied molecular orbital), UV–vis, and molecular electrostatic potential analyses were done. The molecular docking investigation was done in order to analyze the presence of interactions between the title ligand compound and the receptor protein 2VN0.

Dinuclear gold(I) complexes with N-phosphanyl, N-heterocyclic carbene ligands: synthetic strategies, luminescence properties and anticancer activity.

A small library of dinuclear gold(I) complexes with the title ligands has been prepared, encompassing neutral, mono- and dicationic complexes. The luminescence properties of the complexes in the solid state have been evaluated, and it turns out that neutral and monocationic complexes not presenting a rigid metallamacrocyclic structure can exhibit rather strong emissions that extend towards the red region of the visible spectrum. The in vitro anticancer activity of the complexes has been also preliminarly evaluated; cytotoxicity seems to correlate with complex lipophilicity, whereas selectivity towards cancer cells can be apparently enhanced upon a judicious choice of the ligands.

Iron and Silver Complexes of 4‐(Imidazol‐1‐yl)‐2,6‐di(pyrazol‐1‐yl)‐pyridine (L), Including a [Fe3(µ‐F)2F6L8]+ Assembly

Treatment of 2,4,6‐trifluoropyridine with sodium imidazolate, then 2 equiv. sodium pyrazolate, in two reaction steps yields the title ligand L in 40 % overall yield. Crystalline [FeL2][BF4]2 and [FeL2][ClO4]2 are isostructural high‐spin complexes, with highly twisted six‐coordinate geometries and pendant imidazolyl groups. Conversely, [Ag(µ‐L)]BF4·0.5MeCN is a linear coordination polymer of distorted square planar silver ions linked by κ1:κ3,µ‐L ligands. Some samples of [FeL2][BF4]2 were contaminated by [FeIII3(µ‐F)2F6L8]BF4, which was prepared in pure form following reaction of Fe[BF4]2·6H2O, Na3[FeF6] and L in appropriate ratios. The linear [{trans‐FeFL4}2(µ‐F)2FeF4]+ assembly is supported by monodentate L ligands coordinated through their imidazolyl donors, and donating C–H····F interactions to the central [FeF6]3– moiety. The cluster exhibits moderate antiferromagnetic coupling between its iron(III) centres.

Synthesis, structural, molecular docking and spectroscopic studies of (E)-N'-(4-methoxybenzylidene)-5-methyl-1H-pyrazole-3-carbohydrazide

(E)-N'-4-methoxybenzylidene-5-methyl-1H-pyrazole-3-carbohydrazide (E-MBPC) has been synthesized and characterized by FT-IR, 1H & 13C NMR and ESI-MS spectroscopic methods. The (E)-configuration of hydrazonoic group was confirmed by single-crystal X-ray diffraction. Theoretical structures of E-MBPC in both gas phase and aqueous solution have been optimized by using hybrid B3LYP/6-311++G** calculations. Calculations in solution have shown that dipole moment increases from 7.97 D in the gas phase to 13.68 D in solution with solvation energy of −131.34 kJ/mol. Atomic charges have evidenced that the protonation of E-MBPC in solution could occur only in the N28 atom because those charges on this atom show negative values. Mapped MEP surfaces show that the nucleophilic sites is located on the O21 and N28 atoms including the N16 atom while the electrophilic sites are observed on the N24-H27 and N18-H19 bonds. NBO calculations support the high stability of E-MBPC in solution while frontier orbitals studies suggest low reactivity of E-MBPC in both media, as compared with the (E)-N'-(4-(dimethylamino)benzylidene)-5-methyl-1H-pyrazole-3-carbohydrazide derivative. The vibrational assignments of 93 vibration modes expected for E-MBPC were reported together with the corresponding force fields and force constants in both media. The predicted Raman and Ultraviolet-visible spectra were also reported for E-MBPC at the same level of theory. Good correlations were obtained between the predicted 1H- and 13C NMR spectra and the corresponding experimental ones. In addition, molecular docking studies between the title ligand and 4AMJ protein were performed. Docking results revealed that the title compound can be designed as a potential anti-diabetic agent.

Synthesis, crystal structure, hirshfeld surface analysis, DFT calculations, anti-diabetic activity and molecular docking studies of (E)-N’-(5-bromo-2-hydroxybenzylidene) isonicotinohydrazide

In this present work, the newly synthesized compound E)-N’-(5-bromo-2-hydroxybenzylidene)isonicotinohydrazide (2) has been synthesized and characterized by IR, 1H &13C NMR, ESI-MS and single crystal X-ray diffraction analysis using experimental and theoretical methods. The molecular geometry, vibrational frequencies, frontier molecular orbital (HOMO-LUMO) energies and thermodynamic properties of the title molecule were explored using Density Functional Theory (DFT) calculation via B3LYP method with 6–31++G (d,p) basis set. Moreover, Hirshfeld and Molecular electrostatic potential (MEP) surfaces analyses were investigated. In addition, the title compound was evaluated for their in vitro antidiabetic activity against α-glucosidase and α-amylase enzymes. Finally, Molecular docking studies were performed between the title ligand and 1CLV/2ZE0 enzymes. Docking calculations showed that the 2-2ZE0 complex is more stable than 2-1CLV complex, since it has the best inhibitory impact whose their total energy score equal to −108.68 kcal/mol. Docking results reveal that the main interaction forces are H-bond and van der Waals interactions.

Synthesis, characterization, crystal structures, Hirshfeld surface analysis and DFT computational studies of new Schiff Bases derived from Phenylhydrazine

In this research, four novel ligands were synthesized from hydrazine derivatives. The hydrazine compounds via reacting 2, 4-dinitrophenylhydrazine with 2-hydroxy-4-methoxybenzaldehyde (HL1), 2-hydroxy- 5-bromobenzaldehyde (HL2), 2-hydroxy-naphtaldehyde (HL3) and 4-nitrophenylhydrazine with 2-hydroxy-4-methoxybenzaldehyde (HL4) were synthesized, characterized using FT-IR, Raman and UV–Vis spectrum and it structure were confirmed by X-ray diffraction studies. Novel compounds were recovered to crystallize the systems in monoclinic, orthorhombic, triclinic and monoclinic, crystal structures with P21/n, Pbcn, P-1, and P21/c space groups in ligands (HL1), (HL2), (HL3) and (HL4), respectively. Afterwards, the present study compared the experimental parameters in the UV–Vis and FT-IR spectra with the theoretical values.The results showed that at B3LYP/6-311 + G (d, p) level, DFT was able to properly reproduce the structure of the title ligands. Moreover, Hirshfeld surface (HS) analyses, particularly dnorm surface and FPs (fingerprint plots), were employed to decode intermolecular interactions in the crystal system and contribution of component units in the construction of the 3D architecture. These examinations presented the general description of such inter-contact interactions by means of an attractive graphical approach by 3D Hirshfeld surfaces and 2D fingerprint plots derived from the surfaces. Hirshfeld surface analysis indicated the dominant role of various hydrogen intermolecular interactions such as H⋯H, C⋯H/H⋯C and O⋯H/H⋯O for all compounds and H⋯Br contacts for the HL2 (because of the) into the crystal packing which are discussed.

Monophosphite coordination and hydrolysis by Pt(II) bearing 1,1′-bis(di(o-methoxyphenyl)phosphanyl)ferrocene

Neutral and bis-cationic platinum(II) complexes, which bear the chelating ligand 1,1′-bis(di(o-methoxyphenyl)phopsphanyl)ferrocene have been employed to mono-coordinate different tertiary phosphites. The coordination mode of the “in situ” obtained compounds as well as the influence of the nature of the counter-anion mainly on the 1JPtP (phosphite) was proved by 31P{1H} NMR spectroscopy. The stability of the obtained compounds in the presence of excess phosphite as well as under real phosphite hydrolysis reaction conditions conducted under neutral conditions has been studied spectroscopically. In order to corroborate the role of the o-methoxy substituents of the title ligand in phosphite coordination, analogous reactions were carried out with 1,1’-bis(diphenylphosphanyl)ferrocene and studied by 31P{1H} NMR spectroscopy.

Structural, spectroscopic (NMR, FTIR, UV), Quantum chemical calculations and drug docking studies of 6-amino benzoxazol-2(3H)-one

Abstract The aromatic organic benzoxazole molecule seems to have a wide variety of biological activities. The benzoxazole derivatives are pharmaceutically active ingredients and a vital building block in the field of medicine and agricultural sciences. An amine derivative of 2-Benzoxazoline having an empirical formula C7H6N2O2 was chosen for the present study. The chemical structure and composition of the title molecule have been investigated by using numerous techniques like UV-visible, FT-Raman, FT-IR, 1H, 13C NMR. The study of single crystal X‒ray diffraction reports that the compound is crystallized in monoclinic P21 space group with cell dimensions a=4.292 A, b=12.333 A, c=6.398 A, α=90°, β=103.605°, γ=90°. The Density Functional Theory (DFT) has been used to know the electronic structure of the molecule. The structural parameters of the title compound have been obtained from the experimental findings and compared with DFT theoretical values. The DFT model predicted a possible existence of tautomers for 6-Amino benzoxazol-2(3H)-one which is further confirmed with the help of vibrational and NMR spectral studies. These results suggested that the tautomers are the key factors to determine the overall chemical significance of the title compound. Further, the drug docking studies were also employed with Auto Dock tool to conclude its efficiency, binding mode, and nature of chemical interactions of title ligand molecule by the target proteins. The binding efficiency of the Lactam form of ligand on the receptor was found to be superior to the Lactim form of 6-Amino Benzoxazol-2(3H)-one.

Synthesis, characterisation, thermal properties and biological activity of coordination compounds of novel selenosemicarbazone ligands

A series of novel metal complexes with bidentate selenosemicarbazone Schiff-base ligands HL1 and HL2 are reported. The reaction of 2-(((3-nitrophenyl)amino)(phenyl) methyl)cyclohexan-1-one and 2-((4-methoxyphenyl)(phenylamino)methyl)cyclohexan-1-one with an ethanolic mixture of KSeCN and NH2NH2 afforded the preparation of the novel selenosemicarbazone ligands (E)-2-(2-(((3-nitrophenyl) amino)(phenyl)methyl)cyclohexylidene)hydrazine-1-carboselenoamide (HL1) and (E)-2-(2-((4-methoxyphenyl)(phenylamino)methyl)cyclohexylidene)hydrazine-1-carboselenoamide (HL2), respectively. The reaction of ligands with Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions resulted in the formation of mononucleating complexes of general formula K2[ML2Cl2] and [M’L2], (M = Mn(II), Co(II) and Ni(II); M’ = Cu(II), Zn(II) and Cd(II)). The mode of bonding and predicted geometry of complexes were determined through their physico-chemical and spectroscopic measurements. These data indicated the formation of the following; (i) a distorted octahedral geometry about Mn(II), Co(II) and Ni(II), (ii) a distorted square planar around Cu(II), and (iii) a tetrahedral arrangement about Zn(II) and Cd(II) ions. The thermal properties and biological activity of ligands and their metal complexes were studied. The title ligands and their metal complexes were screened against Gram negative bacterial strains; Escherichia coli (E. coli), Bacillus sabtuius and Klebsiella pneumoniae and Gram positive bacterial strain Staphylococcus aureus that revealed the metal complexes become more potentially resistive to the microbial activities, compared to the free ligands. Further, selenosemicarbazone ligands and their complexes were examined for their antifungul activity towards Candida albicans, Candida glabrata, Candida tropicalis and Candida parapsilsis, which generally showed complexes are more active compared to the free ligands.

Pd(ii)-Complexes of a novel pyridinone based tripeptide conjugate: solution and solid state studies.

A novel peptide conjugate (H(L2)) incorporating N-donors of the peptide backbone and an (O,O) donor set of a hydroxypyridinone moiety is synthesized and characterized. This ambidentate chelating ligand is intended to develop Co(iii)/Pt(ii) heterobimetallic multitargeted complexes with anticancer potential. To explore its metal ion binding ability the interaction with Pd(ii) (as a Pt(ii) model but with faster ligand exchange reactions) was studied in aqueous solution by the combined use of pH-potentiometry, NMR and HR MS. In an equimolar solution H(L2) was found to bind Pd(ii) via the terminal amino group and increasing number of peptide nitrogens of the peptide backbone over a wide pH range. Around physiological pH an (N,N) and (O,O) chelated 2 : 2 minor species was also identified. At a 2 : 1 Pd(ii) to ligand ratio the formation of dinuclear species, [Pd2H-x(L2)] (x = 1-4), with high stability and with the involvement of the (O,O) chelating set of the ligand too, was demonstrated. Reaction of H3(L2)2+ with Pd(ii) in the presence of chloride ions at pH ∼ 2.0 afforded [PdH(L2)Cl2]·2H2O (3) in a solid state whose molecular structure was assessed by single crystal X-ray diffraction. The structure of 3 revealed that Pd(ii) is coordinated by a (NH2, Namide) chelate of the ligand in a square planar fashion. It also indicates that under suitable conditions a 2N coordinated Pd(ii) complex can also be obtained even in the presence of four available nitrogen donors in the chelatable position in the ligand most likely due to its neutral charge and the decreased conditional stability of the amide-involved chelate(s) under acidic conditions. Reaction of H(L2) with [Co(tren)]3+ (tren = tris(2-aminoethyl)amine) revealed the exclusive coordination of (L2)-via its (O,O) chelate to the metal core while treatment of the Co-complex with Pd(ii) resulted in the formation of a Co/Pd heterobimetallic complex in solution with (NH2, Namide) chelated Pd(ii). Reaction of 3 with 9-methylguanine indicated the N7 coordination of this simple DNA model to Pd(ii) in a 1 : 1 ratio.

Solvent Extraction Investigations on Pu(IV) and Th(IV) Complexes with Hydrophilic SO3-Ph-BTP and SO3-Ph-BTBP Ligands

ABSTRACT Complexation of Pu(IV) and Th(IV) cations by the title ligands – hydrophilic sulfophenyl triazinyl derivatives of bis-triazinyl-pyridine and -bipyridine – was studied in solvent extraction systems containing a TODGA extractant and one of these hydrophilic ligands. Stoichiometries and stability constants of the complexes formed in an acidic (HNO3) aqueous phase have been determined. The Pu(IV) complexes are significantly stronger than their Th(IV) analogues. Only two complexes of each metal with SO3-Ph-BTP (1:1 and 1:2) have been detected, and only one (1:1) with SO3-Ph-BTBP; both numbers being less than expected based on the coordination numbers of the metal ions and on the denticities of the ligands. Possible reasons of this discrepancy are discussed.

New complexes of chelating Schiff base: Synthesis, spectral investigation, antimicrobial, and thermal behavior studies

The new bidentate Schiff base ligand (E)-1-(4-((E)-(4-(diethylamino)-2-hydroxybenzylidene)amino)phenyl)ethanone oxime [HL], has been synthesized via condensation equal amounts of 1-(4-aminophenyl)ethanone oxime and 4-Diethylaminosalicylaldehyde. The title ligand characterized by using (IR, UV-Vis) spectroscopies, (1H, 13C) NMR spectra, Mass spectrum and X-Ray crystallography. Chelated complexes of prepared ligand with Co(II), Ni(II) and Cu(II) ions, have been also prepared with a ratio of (1:2), (M:L) and characterized by (IR, UV-Vis) spectroscopies, magnetic susceptibility, molar conductivity and flame atomic absorption measurements. Results of spectral studies proved the chelation behavior of this ligand, which coordinated to metal ions as a monobasic N,O bidentate ligand, via imine and phenolic oxygen atom, after losing its proton. Tetrahedral geometry has been proposed for Co(II) complex and square planar geometry has been proposed for Ni(II) and Cu(II) complexes, respectively. The analysis studies of (TG/DTG/DTA) data reflected potential and good thermal stability of [HL] and its metal complexes. We also obtained the biological activity of the prepared compounds against two Gram-positive bacteria (Staphylococcus aureus & Staphylococcus epidermidis), four Gram-negative bacteria (Salmonella, E-coli., Pseudomonas aeruginosa & Klebsiella spp.) and one fungal (candida albicans).

Coordination chemistry of gold with N-phosphine oxide-substituted imidazolylidenes (POxIms)

Diverse gold complexes are found to be accessible with the title ligands, which exhibit peculiar structural features and promising catalytic performances.

Insight into Stereo-Induction by Minor Modification in the Ligand in DNA-Based Hybrid Catalysis

A pair of bisbenzimidazole derivatives as catalytic ligand was evaluated in DNA-based hybrid asymmetric reaction. Similar structure of both ligands induced entirely different stereoselectivity in Diels–Alder reaction and Friedel–Crafts alkylation. The binding mode of the two Cu2+ complexes to st-DNA was elaborated by circular dichroism, UV–vis, IR, Raman spectroscopy, and singular value decomposition analysis. The coordination mode of ligand to Cu2+ substantially impacted on dominant conformation of complex. The major binding mode depended on the steric chemistry of complex, directly regulating chiral microenvironment in hybrid catalytic system. Although the title ligand did not present considerable enantioselectivity in catalysis, the current research provided a feasible approach to insight into catalytic microenvironment of chiral scaffold. It will help to reveal the mechanism of stereo-induction in DNA-based hybrid asymmetric reaction.

4-[(4-acetylphenyl)amino]-2-methylidene-4-oxobutanoic acid, a newly synthesized amide with hydrophilic and hydrophobic segments: Spectroscopic characterization and investigation of its reactive properties

The FT-IR and FT-Raman spectra of 4-[(4-acetylphenyl)amino]-2- -methylidene-4-oxobutanoic acid were recorded. The vibrational wave numbers were computed by DFT quantum chemical calculations and the vibrational assignments were realized using the potential energy distribution. The theoretically predicted geometrical parameters were in agreement with the XRD data. Determination and visualization of molecule sites prone to electrophilic attacks were performed by mapping the average local ionization energies (ALIE) to the electron density surface. Furthermore, determination of possible reactive centres of title molecule was realized by calculation of the Fukui functions. Intramolecular non-covalent interactions were also determined and visualized. In addition, prediction of molecule sites possibly prone to autoxidation was performed by calculation of the bond dissociation energies (BDE), while the stability of the title molecule in water was assessed by calculation of radial distribution functions (RDF) obtained after molecular dynamics (MD) simulations. The docked title ligand compound forms a stable complex with insulin receptor kinase and gives a binding affinity of ?10.2 kcal* mol-1.