Conformations of Epristeride（ 17-β-N-t-butylcarboxamide-androst-3,5-diene-3-carboxylic acid） and its analogs were analyzed with the random search method and compared by means of the methods for steroid conformers, ...Conformations of Epristeride（ 17-β-N-t-butylcarboxamide-androst-3,5-diene-3-carboxylic acid） and its analogs were analyzed with the random search method and compared by means of the methods for steroid conformers, Connolly surfaces, dihedral angles, and molecular accessibility probes with protons, hydroxyl and methyl groups contained simultaneously. Analog d is different from others, which is in accordance with the preliminary clinical trial results under double blind conditions.展开更多
cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher c...cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher cis-selectivity of NaBH4 reduction of 2- monosubstituted cyclododecanones was rationalized by the mode of ＂corner position carbonyl participation＂. Crystal data for 2c： Mr = 263.21, monoclinic, space group P21/c, a = 1.11140（7）, b = 2.62590（17）, c = 0.91360（6） nm, β= 106.1840（10）°, V = 2.5606（3） nm^3, Dc = 1.366 g/cm^3, Z = 8, F（000） = 1104, μ（MoKα= 3.182 mm^-1, S = 0.837, the final R = 0.0460 and wR = 0.1033. Crystal X-ray diffraction analysis for 2c showed that its ring skeleton adopts [3333] conformation, in which the OH group presents at the side-exo position and the other one at the corner carbon. The 1H NMR data of 2 showed that 1-corner-R-2-side-exo-OH [3333] and 1-corner-OH-2-side-exo-R [3333] conformations coexist in dynamic equilibrium in the solution, but only the former presents in the crystal.展开更多
Conformation analysis of the model compounds for tunicamycin V and its natural donor substrate, UDP-N-acetylglucose, is performed to reveal the detail of the inhibition process.
We present a comprehensive investigation of the vibrational spectra and conformational distribution of neutral and cationic monoethanolamine(MEA)in the gas phase.Using infrared-vacuum ultraviolet non-resonant ionizati...We present a comprehensive investigation of the vibrational spectra and conformational distribution of neutral and cationic monoethanolamine(MEA)in the gas phase.Using infrared-vacuum ultraviolet non-resonant ionization fragmentation detected IR spectroscopy(NRIFD-IR),we obtained vibrational spectra in the 2500-3800 cm^(−1)range for both neutral and cationic MEA.Density functional theory(DFT)calculations at the B3LYPD3(BJ)/def2-TZVPP level were employed to elucidate the molecular structures and vibrational modes.Our analysis revealed twelve distinct conformers for neutral MEA,with N1gʹGgʹbeing the most stable,while cationic MEA exhibited four conformers,among which C1gʹGt conformer was found to be the primary contributor to the observed spectra.The experimental spectra were interpreted through comparison with anharmonic calculations,allowing for detailed assignment of vibrational modes.Notably,we observed significant differences in the OH stretch region between neutral and cationic species,reflecting changes in intramolecular hydrogen bonding upon ionization.Furthermore,our study highlights the necessity for distinct scaling factors when calculating harmonic frequencies for neutral and cationic substances.展开更多
Monte-Carlo simulated annealing method (SA) was applied to the conformational analysis of flexible molecules such as peptides. The programs SAMM and SAPEP have been developed, using MM2 force field for organic molecul...Monte-Carlo simulated annealing method (SA) was applied to the conformational analysis of flexible molecules such as peptides. The programs SAMM and SAPEP have been developed, using MM2 force field for organic molecules and ECEPP/2 force field for peptides respectively.展开更多
The title compound,（E）-5-methoxy-2-（（4-methoxyphenylimino）methyl）phenol（C15H15NO3）,crystallizes in monoclinic,space group P21/c with a=9.4361（6）,b=10.6212（5）,c=12.9338（9）,β=93.064（5）o,V=1294.41（14）3...The title compound,（E）-5-methoxy-2-（（4-methoxyphenylimino）methyl）phenol（C15H15NO3）,crystallizes in monoclinic,space group P21/c with a=9.4361（6）,b=10.6212（5）,c=12.9338（9）,β=93.064（5）o,V=1294.41（14）3,Z=4,Dc=1.320 g/cm3,F（000）=544,Rint=0.116,T=296 K,μ=0.09 mm-1,the final R=0.051 and wR=0.148 for 1836 observed reflections with I2σ（I）.An extensive two-dimensional network of C–H…O hydrogen bonds and π-ring interactions are responsible for the crystal stabilization.Intermolecular hydrogen bonds and C–H…π interactions produce R22（14）,R44（30） and R44（31） rings.In addition to the molecular geometry from X-ray experiment,the molecular geometry of the title compound in the ground state has been calculated using the semi-empirical（AM1 and PM3） and density functional theory method（DFT）（B3LYP） with 6-31G（d） basis set.To determine the conformational flexibility,molecular energy profile of the title compound was obtained by semi-empirical（PM3 and AM1） and DFT/B3LYP calculations with respect to the selected degree of torsional freedom,which varied from –180° to ＋180° in a step of 10°.展开更多
A series of trans-4, 5-disubstituted -γ-butyrolactones are found to assume two different envelope conformations by means of nuclear magnetic resonance spectroscopy.
Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which...Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which is independent of fluorophore concentrations, scattering and bleaching, is a suitable tool to analyze membrane proteins in a single cell. Ferroportin（FPN）, a multi-ion exporter in vertebrates, was modulated by metal ions with unknown mechanism. Herein, we fused green fluorescence protein on Cterminal of FPN（FPN-eGFP） and applied fluorescence lifetime to monitor conformation changes of FPN in a live cell. The fluorescence lifetime distribution showed a shift to shorter lifetime upon Mn^（2＋） treatment,suggesting a preference conformation of FPN in Mn^（2＋） exposure. It is also observed that the lifetime（rather than intensity） measurement was not strongly influenced by laser power. The observed fluorescence lifetime changes of FPN-eGFP upon Mn^（2＋） treatments indicated that extracellular metal ions can modulate FPN through conformation exchanges between several different states.展开更多
Triadimefon(TDM)and cyproconazole(CPZ)are two triazoles widely used as fungicides.Several azoles were synthe-sised starting from commercial TDM and CPZ.The compounds were evaluated against phytopathogenic filamentous ...Triadimefon(TDM)and cyproconazole(CPZ)are two triazoles widely used as fungicides.Several azoles were synthe-sised starting from commercial TDM and CPZ.The compounds were evaluated against phytopathogenic filamentous fungi,including Aspergillus fumigatus(AF),A.niger(AN),A.ustus(AU),A.japonicus(AJ),A.terreus(AT),Fusarium oxyspo-rum and Botrytis cinerea isolated from grapevine in the province of San Juan,Argentina.Three of the synthesised compounds(1-(Biphenyl-4-yloxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one,1;2-(Biphenyl-4-yl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol,3;3-Cyclopropyl-2-(4’-fluorobiphenyl-4-yl)-1-(1H-1,2,4-triazol1-yl)butan-2-ol,4)presented remarkable in vitro fungicidal properties,with better effects than TDM and CPZ on some of the target fungi.Cytotoxicity was assessed using human lung fibroblasts MRC5.Derivative 1,with IC50 values of 389.4μM,was less toxic towards MRC-5 human lung fibroblasts than commercial TDM(248.5μM)and CPZ(267.4μM).Docking analysis and molecular dynamics simulations suggest that the compounds present the same interaction in the binding pocket of the CYP51B enzyme and with the same amino acids as CPZ.The derivatives investigated could be considered broad-spectrum but with some selectivity towards imperfect fungi.展开更多
The crystal structure of the title compound ((C 6H 5CONC 6H 4S) 2, M r =229) has been determined by X ray diffraction analysis. The crystal belongs to triclinic space group P 1 with cell parameters: a=...The crystal structure of the title compound ((C 6H 5CONC 6H 4S) 2, M r =229) has been determined by X ray diffraction analysis. The crystal belongs to triclinic space group P 1 with cell parameters: a=7.957(4), b=11.570(7), c=12 335(6), α=76.68(4), β=81.48(4), γ=87.26(4)°, V=1092.9 3, Z=2, D c =1 39g/cm 3, F(000)=476, μ (Mo Kα )=2.7mm -1 . The final R factor is 0.0373 for 3764 observed reflections. The result of X ray diffraction analysis indicates that all of these single bond lengths are obviously shorter than that of standard single bond. Those atoms might take part in a conjugate system. The electrons for sp 3 hybridized S(1) and S(2) move toward two sides and the densities of electronic cloud among them are reduced and can be easily broken. The obtained results can explain the reaction mechanism of the title compound.展开更多
Chemical investigation of Beouverio felina,a marine-derived entomopathogenic fungus,obtained two new destruxin hexadepsipeptides(1 and 2)containing an/.-Ala^(5)residue instead of the usual A/-Me-L-Ala^(5).Interestingl...Chemical investigation of Beouverio felina,a marine-derived entomopathogenic fungus,obtained two new destruxin hexadepsipeptides(1 and 2)containing an/.-Ala^(5)residue instead of the usual A/-Me-L-Ala^(5).Interestingly,the presence of the/.-Ala^(5)residue enabled two slowly-exchanging solution conformers with cis/trons(ILE^(3))-(A/-Me-Val^(4))amide bond for 1 and 2 with 1.5:1 and 1:1 cis/trans ratios,respectively,while only the conformer with c/s amide bond was found in the solid-state.The solution and solid-state conformers were studied by NMR,X-ray diffraction and solution and solid-state ECD measurements,as well as by TDDFT-ECD calculations.Structural(conformational)parameter-activity correlations suggested that the extended destruxin geometry with the preferred c/s(ILE^(3))-(A/-Me-Val^(4))bond probably resulted in improved bioactivity and reduced toxicity for the destruxin class.This was the first report on the interconversion phenomenon of cis/trans amide bonds of destruxin class,which could give insights in the development of bioactive destruxin agents with lower toxicity.展开更多
The crystal structure of the title compound cis 2 (P, P Diethoxy)phosphono( m nitro)benzyloxy 4 Phenyl 5,5 Dimethyl 1,3,2 Dioxaphosphorinane 2 Sulfide, C 22 H 29 NO 8P 2S, was determin...The crystal structure of the title compound cis 2 (P, P Diethoxy)phosphono( m nitro)benzyloxy 4 Phenyl 5,5 Dimethyl 1,3,2 Dioxaphosphorinane 2 Sulfide, C 22 H 29 NO 8P 2S, was determined by single crystal X ray diffraction. It crystallizes in the monoclinic system, space group P2 1/c, with M r=529.49, a=9.888(2), b=20.831(4), c=12.797(3) , β=94.42(3)°, V=2628(1) 3, Z=4, D x =1.338 g/cm 3 , λ=0.71073 , μ =0.2796 mm 1 and F(000) =556. The structure was solved by direct methods. The final R factor is 0.052 and R w is 0.057 for 1793 unique observed reflections I≥3σ(I) . A cis configuration and a preferred chair conformation for the molecule have been established by X ray diffraction analysis. The results presented also give a good explanation to the correlation between the configurational assignments and the regularity in the chemical shifts of C 4-H and 31 P NMR.展开更多
A new coordination compound Zn（2,4＇-bpt）2（H2O）（1） based on the versatile ligand 2,4＇-Hbpt（2,4？-Hbpt = 3-（2-pyridyl）-5-（4-pyridyl）-1H-1,2,4-triazole） was prepared by hydrothermal reactions. The structure...A new coordination compound Zn（2,4＇-bpt）2（H2O）（1） based on the versatile ligand 2,4＇-Hbpt（2,4？-Hbpt = 3-（2-pyridyl）-5-（4-pyridyl）-1H-1,2,4-triazole） was prepared by hydrothermal reactions. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, X-ray powder diffraction, IR spectrum analysis and thermogravimetric analysis. Single-crystal X-ray diffraction analysis indicates that the complex belongs to monoclinic system, space group C2/c with a = 23.877（3）, b = 0.7483（9）, c = 1.2492（2） A, b = 92.681（2）°, V = 2230.6（4） A^3, Z = 4, Dc = 1.572 g/cm^3, m = 1.143 mm^-1, Mr = 527.85 and F（000） = 1080. The final R = 0.0581 and wR = 0.0898 with I 〉 2s（I）. 1 is a 0D motif which is connected by hydrogen bonds to form a corrugated 1D pattern. In addition, 1 shows strong photoluminescent emissions in the solid state at room temperature which can be used as potential optical materials. Theoretical calculations based on density functional theory（DFT） were employed in order to explicate the stability and chemical reactivity of 2,4＇-Hbpt with different conformations. The results indicated that conformation I is more stable and prior to coordination in the reactions.展开更多
The need for the analysis of modern businesses is rapidly increasing as the supporting enterprise systems generate more and more data.This data can be extremely valuable for executing organizations because the data al...The need for the analysis of modern businesses is rapidly increasing as the supporting enterprise systems generate more and more data.This data can be extremely valuable for executing organizations because the data allows constant monitoring,analyzing,and improving the underlying processes,which leads to the reduction of cost and the improvement of the quality.Process mining is a useful technique for analyzing enterprise systems by using an event log that contains behaviours.This research focuses on the process discovery and refinement using real-life event log data collected from a large multinational organization that deals with coatings and paints.By investigating and analyzing their order handling pro-cesses,this study aims at learning a model that gives insight inspection of the processes and performance analysis.Furthermore,the animation is also performed for the better inspection,diagnostics,and compliance-related questions to specify the system.The configuration of the system and the conformance checking for further enhancement is also addressed in this research.To achieve the objectives,this research uses process mining techniques,i.e.process discovery in the form of formal Petri nets models with the help of process maps,and process refinement through conformance checking and enhancement.Initially,the identified executed process is reconstructed by using the process discovery techniques.Following the reconstruction,we perform a deep analysis for the underlying process to ensure the process improvement and redesigning.Finally,some recommendations are made to improve the enterprise management system processes.展开更多
Through complexation reaction of arynyl Fe-S complexes A(μ-p-CH_3C_6H_4C≡CS)(μ- RS)Fe_2(CO)_6 with Co_2(CO)_6, eight mixed cluster complexes B[μ-p-CH_3C_6H_4C_2Co_2(CO)_6S](μ- RS)Fe_2(CO)_6 have been synthesized....Through complexation reaction of arynyl Fe-S complexes A(μ-p-CH_3C_6H_4C≡CS)(μ- RS)Fe_2(CO)_6 with Co_2(CO)_6, eight mixed cluster complexes B[μ-p-CH_3C_6H_4C_2Co_2(CO)_6S](μ- RS)Fe_2(CO)_6 have been synthesized. Reactivity of the complexation reaction is approximately equi- valent to that of the reaction of diarylacetylene with Co_2(CO)_8. Conformational analysis has shown that R groups in complexes A are linked to sulfur atoms by a-and e-bond, whereas that in B only by art e-type of bond.展开更多
Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement...Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement Spectroscopy(NOESY)and two-dimensional homonuclear J-correlated Spectroscopy(COSY).The result indicates that the overall structure of the single-stranded d(TTGGGGTT)is a right-handed B-type helix.展开更多
Naphthotubes are a class of macrocycles with welldefined cavities and are appealing for molecular recognition and smart materials.In this research,we report two types of hybridized naphthotubes(HNT)which were synthesi...Naphthotubes are a class of macrocycles with welldefined cavities and are appealing for molecular recognition and smart materials.In this research,we report two types of hybridized naphthotubes(HNT)which were synthesized through the condensation of a phenyl-bis-naphthalene(PN)tweezer and a bisnaphthalene cleft.The naphthyls attached to the PN tweezer can rotate around the single bonds to form conformational mixtures.When substituents are present at the ortho positions of the naphthyls,four atropisomers are formed.The water-soluble HNT could recognize phenylpyrimidine,phenyltetrazine,and drug intermediates effectively by adopting a syn conformation in aqueous environments(up to 10^(5)M^(-1)).Moreover,a series of shear-induced hydrogels have been prepared with the newly developed hybridized naphthotube,PEGs,and different transition-metal ions,which showed much stronger gelation properties compared to the previously reported amide naphthotubes.展开更多
Fifteen new meroterpenoids, littoreanoids A—O (1—15), including three rearranged skeleton meroterpenoids (1—3), were isolated from the mangrove-derived fungus Penicillium sp. HLLG-122. Compound 1 was a novel berkel...Fifteen new meroterpenoids, littoreanoids A—O (1—15), including three rearranged skeleton meroterpenoids (1—3), were isolated from the mangrove-derived fungus Penicillium sp. HLLG-122. Compound 1 was a novel berkeleyacetal-derived meroterpenoid featuring an unusual spirocyclic 2-oxaspiro[5.5]undeca-4,7-dien-3-one moiety. Compound 2 possessed an unusual 6/6/6/6/6 pentacyclic system with a novel 1-hydroxy-7,7-dimethyl-2-oxabicyclo[2.2.2]octan-5-yl acetate moiety. Compound 3 was an unusual 6/7/6/5/6/5/4 polycyclic systems containing a β-lactone ring. The structures and absolute configurations of new compounds were elucidated by HRESIMS, NMR spectroscopy, single crystal X-ray diffraction analysis, and electronic circular dichroism calculations. The plausible biosynthetic pathways of 1—3 were also proposed. Compounds 6 and 11 exhibited anti-inflammatory effects with IC_(50) values of 30.41 and 19.02 μmol/L, respectively. The bioactive compound 11 was selected for the investigation of preliminary mechanism using molecular docking and Western blotting experiments. Compound 11 could suppress the levels of TNF-α and IL-6, and down-regulate the protein expression of iNOS and COX-2 in RAW 264.7 cells.展开更多
Tripodal 1,3,5-tris（phenoxymethyl）-2,4,6-triethylbenzene analogues have been synthesized and structurally characterized by IR, 1H NMR and 13C NMR spectroscopy and HRMS, and additionally, the single crystal structure...Tripodal 1,3,5-tris（phenoxymethyl）-2,4,6-triethylbenzene analogues have been synthesized and structurally characterized by IR, 1H NMR and 13C NMR spectroscopy and HRMS, and additionally, the single crystal structures of compounds bearing ortho- （7）, meta- （9） and para-hydroxymethyl （11） functions have been determined by X-ray diffraction analysis. The structural study revealed that compounds 7, 9, and II do not adopt the expected 1,3,5-alternate conformation in the solid state. The packing diagrams of compounds 7, 9, and 11 revealed that six hydrophilic hydroxymethyl groups from six individual molecules （7, 9 and 11） were arranged in close contact via intermolecular hydrogen-bond interactions. For compounds 7 and 9, the six hydroxyl groups formed a distorted hexagonal ring; however, formation of such a hexagonal ring was not clear in the case of compound 11. Compounds 9 and 11 were found to form hydrophobic cavities via intermolecular hydrogen-bond interactions in the solid state, and the cavities were occupied by two ethyl groups from the two cavity-forming molecules.展开更多
A DFT calculations are carried out at UB3LYP/6-311＋ ＋G （3df, 2p） levels of theory to study electrocyclic thermal cleavage of four （R） derivatives of unsaturated bicyclic diaziridines, Ix-R, to produce correspond...A DFT calculations are carried out at UB3LYP/6-311＋ ＋G （3df, 2p） levels of theory to study electrocyclic thermal cleavage of four （R） derivatives of unsaturated bicyclic diaziridines, Ix-R, to produce corresponding （Z） and （E） azomethine imides （2X-Z, 2X-E, 3X-Z and 3X-E）, where X=H, Me, t-Bu and Ph. Cleavage of 1X-R series to form the most stable 3X-Z product, （path 2） is found the favored procedure because of delocalized negative charge on five atoms and lower steric effect in related transition state. According to IRC calculations in paths 1 and 2, C6--N1 bond is cleaved before the rate determinating step （transition state）. The stability of unsaturated bicyclic diaziridines and their corresponding （Z） and （E） azomethine imides is in the following order in gas phase and chloroform, tetrahydrofuran, and acetone solvents： 3X-Z〈3X-F〈2X-Z 〈2X-E 〈 1X-R 〈 1X-S.展开更多
基金Supported by the National Natural Science Foundation of China(No. 30170808) and the Natural Science Foundation of Guang-dong Province(No. 010418).
文摘Conformations of Epristeride（ 17-β-N-t-butylcarboxamide-androst-3,5-diene-3-carboxylic acid） and its analogs were analyzed with the random search method and compared by means of the methods for steroid conformers, Connolly surfaces, dihedral angles, and molecular accessibility probes with protons, hydroxyl and methyl groups contained simultaneously. Analog d is different from others, which is in accordance with the preliminary clinical trial results under double blind conditions.
基金Presented in part at the Third National Symposium of the Chinese Chemical Society on Organic Chemistry, Lanzhou, China, August, 2004 (for abstract, see Chin. J. Org. Chem., 2004, Suppl. 365)This project was supported by the National Natural Science Foundation of China (No. 20072053)
文摘cis-1,2-Disubstituted cyclododecanes 2 were synthesized by sodium borohydride reduction of 2-monosubstituted cyclododecanones and their structures were confirmed by 1HNMR, ^13C NMR and elemental analysis. The higher cis-selectivity of NaBH4 reduction of 2- monosubstituted cyclododecanones was rationalized by the mode of ＂corner position carbonyl participation＂. Crystal data for 2c： Mr = 263.21, monoclinic, space group P21/c, a = 1.11140（7）, b = 2.62590（17）, c = 0.91360（6） nm, β= 106.1840（10）°, V = 2.5606（3） nm^3, Dc = 1.366 g/cm^3, Z = 8, F（000） = 1104, μ（MoKα= 3.182 mm^-1, S = 0.837, the final R = 0.0460 and wR = 0.1033. Crystal X-ray diffraction analysis for 2c showed that its ring skeleton adopts [3333] conformation, in which the OH group presents at the side-exo position and the other one at the corner carbon. The 1H NMR data of 2 showed that 1-corner-R-2-side-exo-OH [3333] and 1-corner-OH-2-side-exo-R [3333] conformations coexist in dynamic equilibrium in the solution, but only the former presents in the crystal.
文摘Conformation analysis of the model compounds for tunicamycin V and its natural donor substrate, UDP-N-acetylglucose, is performed to reveal the detail of the inhibition process.
基金the Dalian Coherent Light Source (DCLS) for support and assistancesurported by the National Natural Science Foundation of China (No.22288201)+1 种基金the Chinese Academy of Sciences (GJJSTD20220001)the Innovation Program for Quantum Science and Technology (No.2021ZD0303305)。
文摘We present a comprehensive investigation of the vibrational spectra and conformational distribution of neutral and cationic monoethanolamine(MEA)in the gas phase.Using infrared-vacuum ultraviolet non-resonant ionization fragmentation detected IR spectroscopy(NRIFD-IR),we obtained vibrational spectra in the 2500-3800 cm^(−1)range for both neutral and cationic MEA.Density functional theory(DFT)calculations at the B3LYPD3(BJ)/def2-TZVPP level were employed to elucidate the molecular structures and vibrational modes.Our analysis revealed twelve distinct conformers for neutral MEA,with N1gʹGgʹbeing the most stable,while cationic MEA exhibited four conformers,among which C1gʹGt conformer was found to be the primary contributor to the observed spectra.The experimental spectra were interpreted through comparison with anharmonic calculations,allowing for detailed assignment of vibrational modes.Notably,we observed significant differences in the OH stretch region between neutral and cationic species,reflecting changes in intramolecular hydrogen bonding upon ionization.Furthermore,our study highlights the necessity for distinct scaling factors when calculating harmonic frequencies for neutral and cationic substances.
文摘Monte-Carlo simulated annealing method (SA) was applied to the conformational analysis of flexible molecules such as peptides. The programs SAMM and SAPEP have been developed, using MM2 force field for organic molecules and ECEPP/2 force field for peptides respectively.
基金The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayis University, Turkey, for the use of the Stoe IPDSII diffractometer (purchased under grant No F279 of the University Research Fund)
文摘The title compound,（E）-5-methoxy-2-（（4-methoxyphenylimino）methyl）phenol（C15H15NO3）,crystallizes in monoclinic,space group P21/c with a=9.4361（6）,b=10.6212（5）,c=12.9338（9）,β=93.064（5）o,V=1294.41（14）3,Z=4,Dc=1.320 g/cm3,F（000）=544,Rint=0.116,T=296 K,μ=0.09 mm-1,the final R=0.051 and wR=0.148 for 1836 observed reflections with I2σ（I）.An extensive two-dimensional network of C–H…O hydrogen bonds and π-ring interactions are responsible for the crystal stabilization.Intermolecular hydrogen bonds and C–H…π interactions produce R22（14）,R44（30） and R44（31） rings.In addition to the molecular geometry from X-ray experiment,the molecular geometry of the title compound in the ground state has been calculated using the semi-empirical（AM1 and PM3） and density functional theory method（DFT）（B3LYP） with 6-31G（d） basis set.To determine the conformational flexibility,molecular energy profile of the title compound was obtained by semi-empirical（PM3 and AM1） and DFT/B3LYP calculations with respect to the selected degree of torsional freedom,which varied from –180° to ＋180° in a step of 10°.
文摘A series of trans-4, 5-disubstituted -γ-butyrolactones are found to assume two different envelope conformations by means of nuclear magnetic resonance spectroscopy.
基金supported by the National Key R&D Program of China (Nos. 2016YFA0400900, 2017YFA0505300)the Instrument Developing Project of the Chinese Academy of Sciences (No. YZ201564)
文摘Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which is independent of fluorophore concentrations, scattering and bleaching, is a suitable tool to analyze membrane proteins in a single cell. Ferroportin（FPN）, a multi-ion exporter in vertebrates, was modulated by metal ions with unknown mechanism. Herein, we fused green fluorescence protein on Cterminal of FPN（FPN-eGFP） and applied fluorescence lifetime to monitor conformation changes of FPN in a live cell. The fluorescence lifetime distribution showed a shift to shorter lifetime upon Mn^（2＋） treatment,suggesting a preference conformation of FPN in Mn^（2＋） exposure. It is also observed that the lifetime（rather than intensity） measurement was not strongly influenced by laser power. The observed fluorescence lifetime changes of FPN-eGFP upon Mn^（2＋） treatments indicated that extracellular metal ions can modulate FPN through conformation exchanges between several different states.
文摘Triadimefon(TDM)and cyproconazole(CPZ)are two triazoles widely used as fungicides.Several azoles were synthe-sised starting from commercial TDM and CPZ.The compounds were evaluated against phytopathogenic filamentous fungi,including Aspergillus fumigatus(AF),A.niger(AN),A.ustus(AU),A.japonicus(AJ),A.terreus(AT),Fusarium oxyspo-rum and Botrytis cinerea isolated from grapevine in the province of San Juan,Argentina.Three of the synthesised compounds(1-(Biphenyl-4-yloxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one,1;2-(Biphenyl-4-yl)-3-cyclopropyl-1-(1H-1,2,4-triazol-1-yl)butan-2-ol,3;3-Cyclopropyl-2-(4’-fluorobiphenyl-4-yl)-1-(1H-1,2,4-triazol1-yl)butan-2-ol,4)presented remarkable in vitro fungicidal properties,with better effects than TDM and CPZ on some of the target fungi.Cytotoxicity was assessed using human lung fibroblasts MRC5.Derivative 1,with IC50 values of 389.4μM,was less toxic towards MRC-5 human lung fibroblasts than commercial TDM(248.5μM)and CPZ(267.4μM).Docking analysis and molecular dynamics simulations suggest that the compounds present the same interaction in the binding pocket of the CYP51B enzyme and with the same amino acids as CPZ.The derivatives investigated could be considered broad-spectrum but with some selectivity towards imperfect fungi.
文摘The crystal structure of the title compound ((C 6H 5CONC 6H 4S) 2, M r =229) has been determined by X ray diffraction analysis. The crystal belongs to triclinic space group P 1 with cell parameters: a=7.957(4), b=11.570(7), c=12 335(6), α=76.68(4), β=81.48(4), γ=87.26(4)°, V=1092.9 3, Z=2, D c =1 39g/cm 3, F(000)=476, μ (Mo Kα )=2.7mm -1 . The final R factor is 0.0373 for 3764 observed reflections. The result of X ray diffraction analysis indicates that all of these single bond lengths are obviously shorter than that of standard single bond. Those atoms might take part in a conjugate system. The electrons for sp 3 hybridized S(1) and S(2) move toward two sides and the densities of electronic cloud among them are reduced and can be easily broken. The obtained results can explain the reaction mechanism of the title compound.
基金the National Natural Science Foundation of China(31270104)the NSFC-Shandong Joint Fund for Marine Science Research Centers(U1606403)+2 种基金the Oceanographic Data Center at IOCAS.T.K.and A.M.thank the National Research,Development and Innovation Office(NKFI K120181 and FK134653)the Governmental Information-Technology Development Agency(KIFU for CPU time)B.-G.W.also acknowledged the support of the Taishan Scholar project from Shandong province.
文摘Chemical investigation of Beouverio felina,a marine-derived entomopathogenic fungus,obtained two new destruxin hexadepsipeptides(1 and 2)containing an/.-Ala^(5)residue instead of the usual A/-Me-L-Ala^(5).Interestingly,the presence of the/.-Ala^(5)residue enabled two slowly-exchanging solution conformers with cis/trons(ILE^(3))-(A/-Me-Val^(4))amide bond for 1 and 2 with 1.5:1 and 1:1 cis/trans ratios,respectively,while only the conformer with c/s amide bond was found in the solid-state.The solution and solid-state conformers were studied by NMR,X-ray diffraction and solution and solid-state ECD measurements,as well as by TDDFT-ECD calculations.Structural(conformational)parameter-activity correlations suggested that the extended destruxin geometry with the preferred c/s(ILE^(3))-(A/-Me-Val^(4))bond probably resulted in improved bioactivity and reduced toxicity for the destruxin class.This was the first report on the interconversion phenomenon of cis/trans amide bonds of destruxin class,which could give insights in the development of bioactive destruxin agents with lower toxicity.
文摘The crystal structure of the title compound cis 2 (P, P Diethoxy)phosphono( m nitro)benzyloxy 4 Phenyl 5,5 Dimethyl 1,3,2 Dioxaphosphorinane 2 Sulfide, C 22 H 29 NO 8P 2S, was determined by single crystal X ray diffraction. It crystallizes in the monoclinic system, space group P2 1/c, with M r=529.49, a=9.888(2), b=20.831(4), c=12.797(3) , β=94.42(3)°, V=2628(1) 3, Z=4, D x =1.338 g/cm 3 , λ=0.71073 , μ =0.2796 mm 1 and F(000) =556. The structure was solved by direct methods. The final R factor is 0.052 and R w is 0.057 for 1793 unique observed reflections I≥3σ(I) . A cis configuration and a preferred chair conformation for the molecule have been established by X ray diffraction analysis. The results presented also give a good explanation to the correlation between the configurational assignments and the regularity in the chemical shifts of C 4-H and 31 P NMR.
基金Supported by the National Natural Science Foundation of China(Nos.21263019 and 51364038)
文摘A new coordination compound Zn（2,4＇-bpt）2（H2O）（1） based on the versatile ligand 2,4＇-Hbpt（2,4？-Hbpt = 3-（2-pyridyl）-5-（4-pyridyl）-1H-1,2,4-triazole） was prepared by hydrothermal reactions. The structure of complex 1 has been characterized by X-ray single-crystal diffraction, elemental analysis, X-ray powder diffraction, IR spectrum analysis and thermogravimetric analysis. Single-crystal X-ray diffraction analysis indicates that the complex belongs to monoclinic system, space group C2/c with a = 23.877（3）, b = 0.7483（9）, c = 1.2492（2） A, b = 92.681（2）°, V = 2230.6（4） A^3, Z = 4, Dc = 1.572 g/cm^3, m = 1.143 mm^-1, Mr = 527.85 and F（000） = 1080. The final R = 0.0581 and wR = 0.0898 with I 〉 2s（I）. 1 is a 0D motif which is connected by hydrogen bonds to form a corrugated 1D pattern. In addition, 1 shows strong photoluminescent emissions in the solid state at room temperature which can be used as potential optical materials. Theoretical calculations based on density functional theory（DFT） were employed in order to explicate the stability and chemical reactivity of 2,4＇-Hbpt with different conformations. The results indicated that conformation I is more stable and prior to coordination in the reactions.
文摘The need for the analysis of modern businesses is rapidly increasing as the supporting enterprise systems generate more and more data.This data can be extremely valuable for executing organizations because the data allows constant monitoring,analyzing,and improving the underlying processes,which leads to the reduction of cost and the improvement of the quality.Process mining is a useful technique for analyzing enterprise systems by using an event log that contains behaviours.This research focuses on the process discovery and refinement using real-life event log data collected from a large multinational organization that deals with coatings and paints.By investigating and analyzing their order handling pro-cesses,this study aims at learning a model that gives insight inspection of the processes and performance analysis.Furthermore,the animation is also performed for the better inspection,diagnostics,and compliance-related questions to specify the system.The configuration of the system and the conformance checking for further enhancement is also addressed in this research.To achieve the objectives,this research uses process mining techniques,i.e.process discovery in the form of formal Petri nets models with the help of process maps,and process refinement through conformance checking and enhancement.Initially,the identified executed process is reconstructed by using the process discovery techniques.Following the reconstruction,we perform a deep analysis for the underlying process to ensure the process improvement and redesigning.Finally,some recommendations are made to improve the enterprise management system processes.
文摘Through complexation reaction of arynyl Fe-S complexes A(μ-p-CH_3C_6H_4C≡CS)(μ- RS)Fe_2(CO)_6 with Co_2(CO)_6, eight mixed cluster complexes B[μ-p-CH_3C_6H_4C_2Co_2(CO)_6S](μ- RS)Fe_2(CO)_6 have been synthesized. Reactivity of the complexation reaction is approximately equi- valent to that of the reaction of diarylacetylene with Co_2(CO)_8. Conformational analysis has shown that R groups in complexes A are linked to sulfur atoms by a-and e-bond, whereas that in B only by art e-type of bond.
文摘Two-dimensional NMR study on the single-stranded octadeoxynucleotide,d(TT- GGGGTT)is presented.Assignments of the base protons,the H1′,H2′ and H2″ protons were made by two-dimensional Nuclear Overhauser Enhancement Spectroscopy(NOESY)and two-dimensional homonuclear J-correlated Spectroscopy(COSY).The result indicates that the overall structure of the single-stranded d(TTGGGGTT)is a right-handed B-type helix.
基金supported by the National Natural Science Foundation of China(grant no.22101125).
文摘Naphthotubes are a class of macrocycles with welldefined cavities and are appealing for molecular recognition and smart materials.In this research,we report two types of hybridized naphthotubes(HNT)which were synthesized through the condensation of a phenyl-bis-naphthalene(PN)tweezer and a bisnaphthalene cleft.The naphthyls attached to the PN tweezer can rotate around the single bonds to form conformational mixtures.When substituents are present at the ortho positions of the naphthyls,four atropisomers are formed.The water-soluble HNT could recognize phenylpyrimidine,phenyltetrazine,and drug intermediates effectively by adopting a syn conformation in aqueous environments(up to 10^(5)M^(-1)).Moreover,a series of shear-induced hydrogels have been prepared with the newly developed hybridized naphthotube,PEGs,and different transition-metal ions,which showed much stronger gelation properties compared to the previously reported amide naphthotubes.
基金supported by the National Natural Science Foundation of China(Nos.22177023 and 41866005)the Key Sci-ence and Technology Program of Hainan Province(No.ZDKJ202008)+3 种基金the Hainan Provincial Natural Science Foundation of China(221RC1054)the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province(YSPTZX202030)the Innovation Platform for Academicians of Hainan Province,the Central Government Guides Local Science and Technology Devel-opment(ZY2022HN08)the research was also supported by the Innovative Research Project of Hainan Graduate Students(Qhyb2022-105).
文摘Fifteen new meroterpenoids, littoreanoids A—O (1—15), including three rearranged skeleton meroterpenoids (1—3), were isolated from the mangrove-derived fungus Penicillium sp. HLLG-122. Compound 1 was a novel berkeleyacetal-derived meroterpenoid featuring an unusual spirocyclic 2-oxaspiro[5.5]undeca-4,7-dien-3-one moiety. Compound 2 possessed an unusual 6/6/6/6/6 pentacyclic system with a novel 1-hydroxy-7,7-dimethyl-2-oxabicyclo[2.2.2]octan-5-yl acetate moiety. Compound 3 was an unusual 6/7/6/5/6/5/4 polycyclic systems containing a β-lactone ring. The structures and absolute configurations of new compounds were elucidated by HRESIMS, NMR spectroscopy, single crystal X-ray diffraction analysis, and electronic circular dichroism calculations. The plausible biosynthetic pathways of 1—3 were also proposed. Compounds 6 and 11 exhibited anti-inflammatory effects with IC_(50) values of 30.41 and 19.02 μmol/L, respectively. The bioactive compound 11 was selected for the investigation of preliminary mechanism using molecular docking and Western blotting experiments. Compound 11 could suppress the levels of TNF-α and IL-6, and down-regulate the protein expression of iNOS and COX-2 in RAW 264.7 cells.
文摘Tripodal 1,3,5-tris（phenoxymethyl）-2,4,6-triethylbenzene analogues have been synthesized and structurally characterized by IR, 1H NMR and 13C NMR spectroscopy and HRMS, and additionally, the single crystal structures of compounds bearing ortho- （7）, meta- （9） and para-hydroxymethyl （11） functions have been determined by X-ray diffraction analysis. The structural study revealed that compounds 7, 9, and II do not adopt the expected 1,3,5-alternate conformation in the solid state. The packing diagrams of compounds 7, 9, and 11 revealed that six hydrophilic hydroxymethyl groups from six individual molecules （7, 9 and 11） were arranged in close contact via intermolecular hydrogen-bond interactions. For compounds 7 and 9, the six hydroxyl groups formed a distorted hexagonal ring; however, formation of such a hexagonal ring was not clear in the case of compound 11. Compounds 9 and 11 were found to form hydrophobic cavities via intermolecular hydrogen-bond interactions in the solid state, and the cavities were occupied by two ethyl groups from the two cavity-forming molecules.
文摘A DFT calculations are carried out at UB3LYP/6-311＋ ＋G （3df, 2p） levels of theory to study electrocyclic thermal cleavage of four （R） derivatives of unsaturated bicyclic diaziridines, Ix-R, to produce corresponding （Z） and （E） azomethine imides （2X-Z, 2X-E, 3X-Z and 3X-E）, where X=H, Me, t-Bu and Ph. Cleavage of 1X-R series to form the most stable 3X-Z product, （path 2） is found the favored procedure because of delocalized negative charge on five atoms and lower steric effect in related transition state. According to IRC calculations in paths 1 and 2, C6--N1 bond is cleaved before the rate determinating step （transition state）. The stability of unsaturated bicyclic diaziridines and their corresponding （Z） and （E） azomethine imides is in the following order in gas phase and chloroform, tetrahydrofuran, and acetone solvents： 3X-Z〈3X-F〈2X-Z 〈2X-E 〈 1X-R 〈 1X-S.
