Zinc(ΙΙ) complexes with 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydrate and different N-donors: syntheses,crystal structures,and emission properties

Two new Zn^II complexes, {[Zn(L)(phen)(H₂O)]?·?H₂O}_∞ (1) and {[Zn(L)(4bpy)(H₂O)]?·?H₂O}_∞ (2) (L?=?5,6-dihydro-1,4-dithiin-2,3-dicarboxylate, phen?=?1,10-phenanthroline, and 4bpy?=?4,4′-bipyridine), have been prepared by in situ reaction of Zn(ClO₄)₂?·?6H₂O with 5,6-dihydro-1,4-dithiin-2,3-dicarboxylic anhydrate in the presence of lithium hydroxide, together with incorporating chelating phen or bridging 4bpy as co-ligands. Their structures were determined by single-crystal X-ray diffraction. Complex 1 takes a 1-D helical structure that is further assembled into a 2-D network by O–H?···?O, C–H?···?O hydrogen bonds, and weak S?···?S interactions, and then an overall 3-D supramolecular framework was formed by π?···?π stacking interactions. Complex 2 possesses a 2-D (4,4)-layered structure. The structural difference between 1 and 2 can be attributed to the different N-donor auxiliary co-ligands. Both 1 and 2 are photoluminescent materials whose emission properties are closely related to their intrinsic structure.     

Comment on: “FTIR,FT-Raman,scaled quantum chemical studies of the structure and vibrational spectra of 1,5-dinitronaphthalene” by Arivazhaga et al. [Spectrochim. Acta A72 (2009) 941–946]

The title paper [1] reports ab initio calculations of the structure and molecular vibrations of 1,5-dinitronaphthalene. The calculations are unminimised, the molecular structure is wrong and the vibrational spectra are misinterpreted. These errors have been corrected and the vibrational spectra of 1,5-dinitronaphthalene have been reassigned in agreement with the optical and neutron spectroscopic data.     

Synthesis,computational quantum chemical study,in silico ADMET and molecular docking analysis,in vitro biological evaluation of a novel sulfur heterocyclic thiophene derivative containing 1,2,3-triazole and pyridine moieties as a potential human topoisomerase IIα inhibiting anticancer agent

Computational quantum chemical study and biological evaluation of a synthesized novel sulfur heterocyclic thiophene derivative containing 1,2,3-triazole and pyridine moieties namely BTPT [2-(1-benzyl-5-methyl-1H-1,2,3-triazol-4-yl)-6-methoxy-4-(thiophen-2-yl) pyridine] was presented in this study. The crystal structure was determined by SCXRD method. For the title compound BTPT, spectroscopic characterization like ¹H NMR, ¹³C NMR, FTIR, UV–vis were carried out theoretically by computational DFT method and compared with experimental data. Druglikeness parameters of BTPT were found through in silico pharmacological ADMET properties estimation. The molecular docking investigation was performed with human topoisomerase IIα (PDB ID:1ZXM) targeting ATP binding site. In vitro cytotoxicity activity of BTPT/doxorubicin were examined by MTT assay procedure against three human cancer cell lines A549, PC-3, MDAMB-231 with IC50 values of 0.68/0.70, 1.03/0.77 and 0.88/0.98 μM, respectively. Our title compound BTPT reveals notable cytotoxicity against breast cancer cell (MDAMB-231), moderate activity with human lung cancer cell (A-549) and less inhibition with human prostate cancer cell (PC-3) compared to familiar cancer medicine doxorubicin. From the results, BTPT could be observed as a potential candidate for novel anticancer drug development process.     

Design, synthesis and bioactivity of novel ALS enzyme inhibitors (II)——Molecular mechanics, quantum chemistry and structure-activity relationship studies on the herbicidal heterocyclic sulfonamide

In view of quantum pharmacology, the structure-activity relationships of different kinds of fused heterocydic sulfonamides with the same mode of action were first investigated using molecular mechanics, quantum chemistry and discriminatory analysis. It has been found that the process of the interaction of the fused heterocydic sulfonamide with ALS enzyme involves the electropositive region of the sulfonyl bridge chain and the electronegative region of the heterocydic moiety. The herbicidal activity is related to the potency of electric charge translocation of the related regions.     

FR-IR spectroscopic studies of polyurethanes—Part II. Ab initio quantum chemical studies of the relative strengths of “carbonyl” and “ether” hydrogen-bonds in polyurethanes

Ab initio quantum chemical computations were carried out on (a) dimethyl ether, (b) N-methyl formamide, (c) dimethyl ether-N-methyl formamide complex, and (d) N-methyl formamide dimer to compute the strengths of hydrogen bonds (H-bonds) between the NH groups and CO and ether COC groups. The basis set used was the 3-21G set of the GAUSSIAN 80 program obtained from QCPE, Bloomington, IN. Variations in the strengths of these two H-bonds with the N . . O distance (where O is either carbonyl or ether group oxygen) were studied and found to be similar in behavior. The strength of the “ether” hydrogen bond is computed to be 10.32 kcal mol⁻¹, which is quite significant compared to the value of 10.11 kcal mol⁻¹ for the more accepted “carbonyl” hydrogen bond. The “ether” hydrogen bond is found to be directional, specific and non-negligible. Work with two more basis sets has indicated that the results so obtained are not dependent on their choice. Possible importance of such a hydrogen bond in polyurethanes, inhalation anesthetics, and depsi-peptides is indicated.     

Quantum mechanical calculations on cellulose–water interactions: structures,energetics, vibrational frequencies and NMR chemical shifts for surfaces of Iα and Iβ cellulose

Periodic and molecular cluster density functional theory calculations were performed on the Iα (001), Iα (021), Iβ (100), and Iβ (110) surfaces of cellulose with and without explicit H₂O molecules of hydration. The energy-minimized H-bonding structures, water adsorption energies, vibrational spectra, and ¹³C NMR chemical shifts are discussed. The H-bonded structures and water adsorption energies (ΔE_ads) are used to distinguish hydrophobic and hydrophilic cellulose–water interactions. O–H stretching vibrational modes are assigned for hydrated and dry cellulose surfaces. Calculations of the ¹³C NMR chemical shifts for the C4 and C6 surface atoms demonstrate that these δ¹³C4 and δ¹³C6 values can be upfield shifted from the bulk values as observed without rotation of the hydroxymethyl groups from the bulk tg conformation to the gt conformation as previously assumed.     

Theoretical studies on Lewis acidity scale and bonding character of boron trihalides BX_3(X=F, Cl, Br, I) by DV-X_α quantum chemical approach

The Lewis acidity scale of boron trihalides BX3 (X=F, Cl, Br, I) and character of the boron-halogen bonds have been studied by means of DV-Xa approach. Present results show that the acid strength of boron trihalides increases in the order BF3相似文献   

Spectroscopic (FT-IR,FT-Raman,UV–Vis), quantum chemical calculation and molecular docking evaluation of liquiritigenin: an influenza A (H1N1) neuraminidase inhibitor

Research on Chemical Intermediates - The vibrational spectroscopic analysis of anti-influenza agent liquiritigenin (LGN) was performed using Fourier-transform infrared (FT-IR) and Fourier-transform...     

Ab initio studies on vibrational spectra of XSO_2NCO (X=F,Cl):harmonic force fields and frequency assignments

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Molecular modeling on pyrimidine-urea inhibitors of TNF-α production: an integrated approach using a combination of molecular docking, classification techniques, and 3D-QSAR CoMSIA

Molecular docking, classification techniques, and 3D-QSAR CoMSIA were combined in a multistep framework with the ultimate goal of identifying potent pyrimidine-urea inhibitors of TNF-α production. Using the crystal structure of p38α, all the compounds were docked into the enzyme active site. The docking pose of each compound was subsequently used in a receptor-based alignment for the generation of the CoMSIA fields. "Active" and "inactive" compounds were used to build a Random Tree classification model using the docking score and the CoMSIA fields as input parameters. Domain of applicability indicated the compounds for which activity estimations can be accepted with confidence. For the active compounds, a 3D-QSAR CoMSIA model was subsequently built to accurately estimate the IC(50) values. This novel multistep framework gives insight into the structural characteristics that affect the binding and the inhibitory activity of these analogues on p38α MAP kinase, and it can be extended to other classes of small-molecule inhibitors. In addition, the simplicity of the proposed approach provides expansion to its applicability such as in virtual screening procedures.     

Incorporation of a 2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione unit into a donor–acceptor triad: synthesis and ion recognition features

A novel directly-linked donor–acceptor–donor (D–A–D) type system, which is based on 2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione as the A unit and thiophene as the D units, respectively, is designed, synthesized, and characterized by spectroscopic methods. This novel D–A–D system can be used for the fluorogenic detection of Cu²⁺ among other ions.     

Solvent effects on the molecular stability,intramolecular hydrogen bond,and π-electron delocalization in the simple RAHB systems with different donors and acceptors: a quantum chemical study

Structural Chemistry - In the present study, solvent effects on the molecular stability, intramolecular hydrogen bond (IMHB), and π-electron delocalization (π-ED) in some of the simple...     

Molecular complexes of cyclophanes,XVIII: Spectroscopic and thermodynamic studies on the charge-transfer complexes between 4-([2.2]paracyclophanoyl)amines and π-acceptors

The charge-transfer (CT) complexes of several substituted 4-([2.2]paracyclophanoyl)amines as donors with tetracyanoethylene (TCNE) and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as -acceptors have been studied spectrophotometrically. The role of the molecular structure of the donors on their Lewis basicities, the site and type of CT interactions are discussed. The thermodynamic properties of some CT complexes as well as the solvent effect on the CT complexation are reported.

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Molekulare Komplexe von Cyclophanenen, 18. Mitt.: Spektroskopische und thermodynamische Untersuchungen der Charge-Transfer-Komplexe von 4-([2.2]Paracyclophanoyl)aminen mit -Akzeptoren

Zusammenfassung Es wurden die Charge-Transfer-Komplexe einiger substituierter 4-([2.2]Paracyclophanoyl)amine als Donoren mit Tetracyanoethylen (TCNE) und 2,3-Dichlor-5,6-dicyanobenzochinon (DDQ) als -Akzeptoren spektrophotometrisch untersucht. Der Einfluß der Donor-Molekülstrukturen auf ihre Lewis-Basizitäten sowie Ort und Typ der CT-Wechselwirkung werden diskutiert. Es wird über die thermodynamischen Eigenschaften einiger CT-Komplexe und auch über Lösungsmitteleffekte bei der Komplexierung berichtet.

     

Silver(I) complex with 2-amino-4,4α-dihydro-4α,7-dimethyl-3H-phenoxazin-3-one (Phx-1) ligand: crystal structure,vibrational spectra and biological studies

The first metal complex of Phx-1 ligand, bis(2-amino-4,4α-dihydro-4α,7-dimethyl-3H-phenoxazin-3-one)nitratosilver(I), [Ag(Phx-1)₂NO₃], has been obtained and investigated by single crystal X-ray diffraction and vibrational spectroscopy methods. The Ag⁺ is bonded to heterocyclic nitrogen atoms of two organic ligands and one oxygen atom of a nitrate anion. The Phx-1 ligand coordination mode is supported by IR and Raman spectra, interpreted with the help of theoretical DFT studies. The antibacterial activity of the ligand and its Ag(I) complex as well as some reference compounds were screened against Gram-positive and Gram-negative bacteria, applying microdilution procedures. High sensitivity to the studied complex was found for Rhodococcus erythropolis and Bacillus licheniformis strains. Modified Phx-1 ligand preparation procedures are also presented.     

Five-membered 2,3-Dioxoheterocycles: LIX. Reaction of 3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with Acyclic β-Enaminoesters. Crystal and Molecular Structure of Ethyl 3-Benzoyl-4-hydroxy-1-o-hydroxyphenyl-5-oxo-2,3-dihydro-1H-pyrrolo-2-spiro-3′-(5-methyl-2-oxo-2,3-dihydro-1H-pyrrolo-4-carboxylate)

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones react with substituted alkyl 3-amino-2-propenoates to form substituted alkyl 3-aroyl-4-hydroxy-1-o-hydroxyphenyl-5-oxo-2,5-dihydro-1H-pyrrole-2-spiro-3′-(2-oxo-2,3-dihydro-1H-pyrrole-4-carboxylates). Crystal and molecular structure of ethyl 3-benzoyl-4-hydroxy-1-o-hydroxyphenyl-5-oxo-2,5-dihydro-1H-pyrrole-2-spiro-3′-(5-methyl-2-oxo-2,3-dihydro-1H-pyrrole-4-carboxylate) was investigated.     

A rhodamine hydrazide–4-nitroindole-3-carboxaldehyde based turn on Hg2+ chemosensor: cytoplasmic live cell imaging,logic gate and memory device applications and computational studies

A new, highly sensitive probe L² for the selective detection of Hg²⁺ in organo-aqueous (H₂O:CH₃CN, 1:1, v/v, HEPES buffer, pH 7.2) medium has been synthesized from rhodamine 6G-hydrazide and 4-nitroindole-3-carboxaldehyde. It was thoroughly characterized by physicochemical techniques including single crystal X-ray diffraction studies. The reaction of L² with Hg²⁺ gives a 1:1 stoichiometry resulting in a 146 fold fluorescence enhancement and a binding constant (K_f) of 3?×?10⁴ M^?1. The spirolactam form of the probe is non-fluorescent; however, it shows dual channel (absorbance and fluorescence) recognition of Hg²⁺ via CHEF effect through the opening of the spirolactam ring. The quantum yields of L² (0.00045) and L²-Hg²⁺ (0.29) show the higher stability of complex in the excited state over the free ligand. The 44.5?nM LOD value demonstrates the detection of Hg²⁺ at a very low concentration range. Cell imaging studies show the cytoplasmic recognition of Hg²⁺ by L². Experimental results are comparable with theoretical values obtained by DFT studies. The fluorescence emission of the complex was completely quenched by I^- and from the reversibility studies an advance level INHIBIT logic gate and memory device can be framed.     

Crystallographic studies and physicochemical properties of π-electron systems: Part VIII. Crystal and molecular structure of N,N-dimethyl-4-nitro-2, 6-xylidine. Application of the Walsh Rule to p-substituted nitrobenzenes

The crystal and molecular structure of N,N-dimethyl-4-nitro-2, 6-xylidine has been determined by X-ray diffraction. The compound crystallizes as tetragonal bipyramids, space group P4₁2₁2 with cell dimensions a=764.1(1), c=1807.9(2) pm. The absolute configuration was not determined. The structure was solved by direct methods and refined to R=0.042 for 578 observed reflections. The e.s.d. values of bond lengths between the heavy atoms are 0.3–0.4 pm and of the valence angles are 0.1–0.3°. The NO₂-plane is coplanar with e.s.d. 0.21° with the plane of the benzene ring, whereas the NMe₂-plane is twisted by 60.40(30)° outwards. The through resonance is hence hindered and in turn, the geometry of the ring exhibits less quinoidal character. These deformations are analyzed in terms of the Walsh rule applying parameters determined directly from bond lengths, as well as applying the HOSE-model. Comparison with 14 well solved structures for which the e.s.d. values for bond lengths are not higher than 0.5 pm of p-substituted nitrobenzenes, leads to the conclusion that consideration of the difference in length for bonds C2C3 and C1C2 describes the substituent effect on the geometry of the ring almost as well as the valence angle α at C1.     

Redox interactions between structurally different alkylresorcinols and iron(III) in aqueous media: frozen-solution 57Fe Mössbauer spectroscopic studies,redox kinetics and quantum chemical evaluation of the alkylresorcinol reactivities

Iron(III)-containing aqueous solutions of 5-methylresorcinol (5-MR), 5-n-propylresorcinol (5-n-PR) and 4-n-hexylresorcinol (4-n-HR) at pH ~ 3 were studied by means of ⁵⁷Fe transmission Mössbauer spectroscopy. Kinetic considerations were applied to the redox reactions. Density Functional Theory (DFT) calculations were performed for the alkylresorcinol (AR) molecules and their non-alkylated analogue (resorcinol). Mössbauer spectra consisted of quadrupole doublets assigned to high-spin Fe(III) and Fe(II) species. From changes in their relative spectral areas, a gradual reduction of Fe(III) by all the ARs studied was observed. However, significant differences were found for the reduction rates among the ARs. The following series of the reduction rates was established by means of Mössbauer spectroscopy: 4-n-HR ? 5-MR > 5-n-PR, supplemented by rate constants calculated using a kinetic model. DFT calculations resulted in the following series: 4-n-HR ? 5-n-PR > 5-MR ? resorcinol (the latter is not oxidised under the conditions applied). The reversed order of the experimentally observed 5-MR and 5-n-PR oxidation rates may be explained in terms of their different kinetic parameters related to their structure.     

Crystal structure of 1,9-dimethyl-4,5-dihydro-6H-pyrido[3’,2’:4,5]thieno[2,3-f] pyrrolo[1,2-a][1,4]diazepin-6-one

A new tetracyclic compound, 1,9-dimethyl-4,5-dihydro-6H-pyrido[3’,2’:4,5]thieno[2,3-f]pyrrolo[l,2-a][1,4]diazepin-6-one (2) was isolated and studied by X-ray crystallography. Compound 2 crystallizes in the orthorhombic system, space group Pna2₁, a = 11.1098(8) ?, b = 8.4815(6) ?, c = 28.367(2) ?, V= 2673.0(3) ?³, Z=8. The crystal structure comprises two crystallographically independent molecules of the compound. They relate as stereoisomers; in each the diazepine ring exhibits a boat conformation. The crystal packing reveals zigzag H-bonded chains with two distinct hydrogen bonds. The H…O distances and N-H…O angles for N3-H3…O1’ are 2.012? and 174°, and for N3’-H3’…O1 are 1.974? and 154°, respectively.     

Molecular structure and electron density distribution in the crystals of 3,6-dimethoxy-1,2,4,5-tetrazine and 3-phenyl-1,2,4,5-tetrazine based on X-ray diffraction data at 120 and 150 K. “Bent” bonds in the six-membered heterocycle

Characteristic features of the molecular geometry and electron density distribution in the crystals of 3,6-dimethoxy-1,2,4,5-tetrazine and 3-phenyl-1,2,4,5-tetrazine have been studied by X-ray structural analysis and quantum-chemical (RHF and MP2) and molecular mechanics (MM3) calculations. An unusual shift of the maxima of the deformation electron density from the N-N bonds toward the center of the heterocycles was found, which may be interpreted as a bending of the corresponding bonds. This bending was confirmed by calculations of characteristics of the electron density distribution within the multipole model.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2443–2450, December, 1995.The work was supported by the International Science Foundation (Grant No. M1F 000) and the Russian Foundation for Basic Research (Project No. 94-03-08338). We thank Dr. P. Mallinson (Chemistry Department, University of Glasgow, Scotland) for help in performance of multipole calculations.