Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) Studies on α(1A)-Adrenergic Receptor Antagonists Based on Pharmacophore Molecular Alignment

The α(1A)-adrenergic receptor (α(1A)-AR) antagonist is useful in treating benign prostatic hyperplasia, lower urinary tract symptoms, and cardiac arrhythmia. Three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed on a set of α(1A)-AR antagonists of N-aryl and N-nitrogen class. Statistically significant models constructed from comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were established based on a training set of 32 ligands using pharmacophore-based molecular alignment. The leave-oneout cross-validation correlation coefficients were q(2) (CoMFA) = 0.840 and q(2) (CoMSIA) = 0.840. The high correlation between the cross-validated/predicted and experimental activities of a test set of 12 ligands revealed that the CoMFA and CoMSIA models were robust (r(2) (pred) (/CoMFA) = 0.694; r(2) (pred) (/CoMSIA) = 0.671). The generated models suggested that electrostatic, hydrophobic, and hydrogen bonding interactions play important roles between ligands and receptors in the active site. Our study serves as a guide for further experimental investigations on the synthesis of new compounds. Structural modifications based on the present 3D-QSAR results may lead to the discovery of other α(1A)-AR antagonists.     

Molecular weight effect on theta-gel formation in poly(vinyl alcohol)–poly(ethylene glycol) mixtures

Injectable hydrogel formulations that undergo in situ gelation at body temperature are promising for minimally invasive tissue repair. This work focuses on the investigation of injectable poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) mixtures. The injectable PVA–PEG aqueous solutions form a hydrogel as temperature is reduced to near body temperature, while filling a defect in the injection site. Gamma sterilization of these solutions compromises injectability presumably due to crosslinking of PVA. We hypothesized that by modifying the PEG molecular weight and its concentration, injectability of radiation sterilized PVA–PEG hydrogels can be optimized without compromising the mechanical properties of the resulting gel. The use of a bimodal mixture of higher and lower molecular weight PEG (600 and 200 g/mol) resulted in lower PVA/PEG solution viscosity, better injectability, and higher gel mechanical strength. The PVA/bimodal-PEG had a lower viscosity at 2733 ± 149 cP versus a viscosity of 5560 ± 278 cP for PVA/unimodal-PEG (400 g/mol). The gel formed with the bimodal PEG mixture had higher creep resistance (61% total creep strain under 0.5 MPa) than that formed with unimodal PEG (84%). These hydrogel formulations are promising candidates for minimally invasive tissue repair. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Molecular Spin Ladders Constructed from [Ni(dmit)2]− Building Blocks: Synthesis, Structure and Physical Properties

Abstract  A new ion-pair complex [1-(4-bromobenzyl)-3-methylpyridinium][Ni(dmit)₂] (1), in which dmit = 4,5-dimercapto-1,3-dithiole-2-thione, has been synthesized and structurally characterized. The anions of [Ni(dmit)₂]⁻ stack into dimers, which further construct into a two-leg ladder through lateral S···S interactions. The weak H-bonding interactions of C–H···S and van de Waals interactions between anion and cations were observed. The magnetic susceptibilities measured from 2–300 K indicate an AFM exchange interaction domination and an AFM ordering below ~8 K. The best fit to magnetic susceptibility above 40 K, using a dimer model with s = ?, gives rise to Δ/k_B = 29.8 K, zJ′ = −0.72 K, C = 3.40 × 10⁻³ emu K mol⁻¹ and χ ₀ = −5.8 × 10⁻⁶ emu mol⁻¹ with a fixed g = 2.0. Cyclovoltammetry revealed two quasi-reversible one-electron steps, which are attributed to Ni(IV/III) and Ni(III/II) redox couples. Graphical Abstract  [A novel complex [1-(4-bromobenzyl)-3-methylpyridinium][Ni(dmit)₂] has been synthesized and structurally characterized. The anions of [Ni(dmit)₂]⁻ stack into dimers, which further construct into two-leg ladder through lateral S···S interactions. The weak H–bonding interactions of C–H···S and van de Waals interactions between anion and cations were observed. Moreover, its magnetic property and electrochemical property have been investigated] .     

Molecular surface studies of adsorption and catalytic reaction on crystal (Pt,Rh) surfaces under high pressure conditions (atmospheres) using sum frequency generation (SFG) – surface vibrational spectroscopy and scanning tunneling microscopy (STM)

Sum frequency generation (SFG) – surface vibrational spectroscopy and the scanning tunneling microscope (STM) have been used to study adsorption and catalyzed surface reactions at high pressures and temperatures using (111) crystal surfaces of platinum and rhodium. The two techniques and the reaction chambers that were constructed to make these studies possible are described. STM and SFG studies of CO at high pressures reveal the high mobility of metal atoms, metal surface reconstruction, ordering in the adsorbed molecular layer, and new binding states for the molecule. CO oxidation occurs at high turnover rates on Pt(111). Different adsorbed species are observed above and below the ignition temperature. Some inhibit the reaction, and others are reaction intermediates since their surface concentration is proportional to the reaction rate. The dehydrogenation of cyclohexene on Pt(100) and Pt(111) proceeds through a 1,3‐cyclohexadiene surface intermediate. The higher dehydrogenation rate is related to the higher surface concentration of these molecules on the (100) crystal face. This revised version was published online in August 2006 with corrections to the Cover Date.     

Small-Molecule Inhibitors Targeting Sterol 14α-Demethylase (CYP51): Synthesis,Molecular Modelling and Evaluation Against Candida albicans

Fungal infections are a global issue affecting over 150 million people worldwide annually, with 750 000 of these caused by invasive Candida infections. Azole drugs are the frontline treatment against fungal infections; however, resistance to current azole antifungals in C. albicans poses a threat to public health. Two series of novel azole derivatives, short and extended derivatives, have been designed, synthesised and investigated for CYP51 inhibitory activity, binding affinity and minimum inhibitory concentration (MIC) against C. albicans strains. The short derivatives were more potent against the C. albicans strains (e. g., MIC 2-(4-chlorophenyl)-N-(2,4-dichlorobenzyl)-3-(1H-imidazol-1-yl)propanamide ( 5 f ) <0.03 μg/mL, N-(4-((4-chlorophenyl)sulfonamido)benzyl)-2-phenyl-3-(1H-1,2,4-triazol-1-yl)propanamide ( 12 c ), 1 μg/mL, fluconazole 0.125 μg/mL) but both displayed comparable enzyme binding and inhibition ( 5 f K_d 62±17 nM, IC₅₀ 0.46 μM; 12 c K_d 43±18 nM, IC₅₀ 0.33 μM, fluconazole K_d 41±13 nM, IC₅₀ 0.31 μM, posaconazole K_d 43±11 nM, IC₅₀ 0.2 μM). The short series had poor selectivity for CaCYP51 over the human homologue, whereas the selectivity of the extended series, for example, compound 12 c , was higher (21.5-fold) than posaconazole (4.7-fold) based on K_d values, although posaconazole was more selective (615-fold) than 12 c (461-fold) based on IC₅₀ values. Based on inhibitory activity and selectivity profile, the extended series are the better of the two series for further development.     

Molecular control of polystyrene in the reverse iodine transfer polymerization (RITP) – Suspension process

The reverse iodine transfer polymerization (RITP)-suspension polymerization of styrene was carried out in the presence of molecular iodine (I₂) using AIBN as an initiator and polyvinylalcohol (PVA) as a stabilizer under argon atmospheres at 70 °C for 10 h in the absence of light. The effect of iodine and styrene contents on the molecular characteristics was investigated. The result was summarized into three categories; (1) the two different polymerizations, the emulsion and suspension, simultaneously occurred in the RITP-suspension polymerization. (2) The emulsion fraction decreased, whereas the suspension fraction increased with the I₂ content from 0 to 0.25 mmol, resulting in the decreased molecular weight of the resultant polymer from 320,000 to 59,000 g/mol, respectively. This was arisen from the higher reaction rate of the RITP-suspension polymerization due to the better solubility of AIBN in the monomer droplet in the suspension phase than in the micelle in the emulsion phase upon the increased I₂ content. (3) As the styrene content increased up to 40 wt% under fixed I₂ content, the suspension fraction dominated, resulting in the reduced molecular weight from 59,000 to 38,000 g/mol, respectively. This was rationalized that the temperature increment upon the relatively small amount of solvent, which means due to the large amount of monomer, induced the rapid polymerization in the monomer droplets where the suspension polymerization was favorable. Thus, the RITP-suspension process dramatically decreased the molecular weight of PS not only by the presence of I₂, but also by the dominated suspension fraction.     

Syntheses,magnetic properties,and reactivity of dinuclear oxovanadium (IV) and copper (II) complexes with (μ-diphenylphosphinato)-bridges

Novel dinuclear oxovanadium (IV) complexes having the formula [(VO)₂(dpp)₃(bpy)₂]NO₃·2H₂O (1), [(VO)₂(dpp)₃(phen)₂]-NO₃·H₂O (2), [(VO)₂(bmp)₃(bpy)₂]NO₃·H₂O (3), and [(VO)₂(bmp)₃(phen)₂]NO₃·H₂O (4), and copper (II) complexes having the formula [Cu₂(bmp)₂(phen)₂](NO₃)₂·MeOH·H₂O (5), and [Cu₂(bmp)₂(bpy)₂](NO₃)₂ (6) (where Hdpp=diphenylphosphinic acid, Hbmp=bis(4-methoxyphenyl)phosphinic acid, bpy=2,2^′-bipyridine, and phen=1,10-phenanthroline) with (μ-phosphinato)-bridges, 1–6, have been prepared and characterized. Crystal structure of complex 2 reveals that two vanadium ions are linked by tris(μ-phosphinato)-bridges. The magnetic susceptibility data for 1–3, and 6 conform to the usual dimer equation with −2J values of 16–24 cm⁻¹, indicating a weak antiferromagnetic interaction between vanadium(IV) ions.The oxidation of cinnamyl alcohol was studied using complexes 1–6 as catalyst and molecular oxygen as an oxidant. In the presence of complex 3 as a catalyst, cinnamyl alcohol was oxidized to cinnamaldehyde 61% yield in 7 h. Consequently, complex 3 activates oxygen, and then alcohol was quite efficiently oxidized by activated oxygen.     

加热炉(F1101,F1102, 1203,F1501)

(一)概述(1)石脑油过热炉(F1101)作予脱硫石脑油加热用,即石脑油+弛放气混合经 E1101 A,B,C,D 四组热交换器后,使温度达310℃,进入加热炉使其过热到380℃送第一Co—Mo 加氢反应     

(K,Na) (Nb,Ta,Sb)O3粉体制备及陶瓷介电性能研究

Ta/Sb掺杂的K0.5Na0.5Nb0.7TaxSb0.3-xO3(KNNSTx,x＝0.06,0.09,0.12,0.15,0.18,0.21, 0.24)粉体经水热合成,Ta、Sb对粉体物相、微观结构的影响被系统研究,烧结后陶瓷的微观结构、介电性能表明:陶瓷物相均具有纯钙钛矿结构;随着Ta含量的增加陶瓷晶粒尺寸逐渐增大,x＝0.09、0.12时较小粒径颗粒均匀分布在大颗粒的空隙之间,陶瓷密度增加;样品的介电常数随着Ta含量的增加x＝0.06～0.12逐渐降低,x＝0.15～0.24逐渐增加,居里温度均在350 ℃左右,且x＝0.09、0.12时陶瓷介电损耗较小.     

亚砷酸钠(偏亚砷酸钠,NaAsO_2)

正1)性质。工业品亚砷酸钠不是单一组分,它是由偏亚砷酸钠(NaAsO_2)、三氧化二砷(As_2O_3)、正亚砷酸钠(Na_3AsO_3)、酸式亚砷酸钠(Na_2HAsO_3)等组成,但其基本分子式可以写成NaAsO_2,也可以用NaAsO_2·nAs_2O_3表示,其中0.305n0.34。工业品亚砷酸钠中偏亚砷酸钠约占65%(质量分数),游离白砒霜(As_2O_3)约占31%(质量分数),但两者并不是机械的混合,而是以化合物的形态出现。亚砷酸钠为白色粉末,但为了     

Influence of Al-substitution on structures,resistivity and magnetic properties of LaxSr(2−x)Fe(1+y)Mo(1−y)O6 (x=3y,y=0.05, 0.1, 0.15, 0.2)

Two series of single-phased La_xSr_(2−x)Fe_(1+y)Mo_(1−y)O₆ and La_xSr_(2−x)Fe_(1+0.5y)Al_0.5yMo_(1−y)O₆ (x=3y, y=0.05, 0.1, 0.15 and 0.2) double perovskites were prepared by solid-state reaction. The effects of Al-substitution on the structures, resistivity and magnetic properties of La_xSr_(2−x)Fe_(1+y)Mo_(1−y)O₆ were investigated. Although Al-replacement exhibits a negligible influence of on the B-site ordering degree, it results in the suppression of magnetisation caused by non-magnetic Al³⁺ ions. Reduction of grain sizes leads to increased resistivity, thus an optimised magnetoresistance (MR) behaviour is observed. The greatest MR extent improvement can be obtained when y is 0.15 and the MR% of the Al-doped ceramics reaches −10.5% (10 K, 1 T), which is 2 times greater than that of the undoped ceramics (−4.6%, 10 K, 1 T). Interestingly, the Curie temperature (Tc) of both Al-doped and undoped samples maintained relatively constant values of approximately 420 K and 405 K, respectively, which were different results from the data obtained for similar electron-doping systems in the literature.     

Special issue on “Molecular Sensors and Molecular Logic Gates”

This issue of Frontiers of Chemical Science and Engineering highlights recent progress toward fluorescent probes that was originally conceived to coincide with 7th Conference on Molecular Sensors and Molecular Logic Gates(MSMLG 2020)to celebrate the career of Seiji Shinkai and hosted by Anthony Czarnik at the University of Nevada in Reno.Sadly,that meeting was cancelled due to the pandemic associated with COVID-19.However,this collection of research and review papers will now serve as an introduction to MSMLG 2022 which will be in Dublin,Ireland on 7–10 June 2022,where Thorfinnur Gunnlaugsson will be the local host.The collection of papers contained in this special issue covers in vitro and in vivo applications and illustrates the potential for practical sensing and imaging of disease-related species.     

COSMO-CAMPED – Solvent Design for an Extraction Distillation Considering Molecular,Process, Equipment,and Economic Optimization

For an extraction process to be economically feasible, selecting a suitable solvent is imperative. This work extends the computer-aided molecular and process design (CAMPD) framework COSMO-CAMPD for solvent design in an extraction-distillation process by replacing a pinch-based process model with a hybrid, rate-based extraction-distillation process model. The resulting CAMPD framework is able to evaluate solvent candidates by investment costs in addition to operating costs in a fully predictive manner. In a case study for purifying acetone, we show that our framework's guided exploration of a vast design space yields solvents with superior performance compared to a benchmark solvent from the literature.     

Effect of functionlization of N,N-dibenzyldithiocarbamate: synthesis,spectral and structural studies on bis(N-benzyl-N-(4-methoxybenzyl)dithiocarbamato-S,S′)zinc(II) and bis(N-benzyl-N-(4-cholrobenzyl)dithiocarbamato-S,S′)cadmium(II) and their use for the preparation of MS (M = Zn,Cd)

Bis(N-benzyl-N-(4-methoxybenzyl)dithiocarbamato-S,S′)zinc(II) (1) and bis(N-benzyl-N-(4-chlorobenzyl)dithiocarbamato-S,S′)cadmium(II) (2) have been prepared and characterized by elemental analysis, IR and NMR (¹H and ¹³C) spectroscopy and single-crystal X-ray analysis. Complexes 1 and 2 exist as monomer and dimer, respectively. Crystal structures of 1 and 2 confirm the presence of four coordinated zinc in a distorted tetrahedral arrangement and five coordinated cadmium in a distorted square pyramid arrangement, respectively. Both the complexes are further stabilized by various interactions such as C–H···S, C–H···N, C–H···O and C–H···π (chelate). C–H···O interaction leads to the formation of dimer in complex 1. In complex 2, C–H···π (chelate) interaction runs in opposite directions which results in the polymeric chain. ZnS and CdS have been prepared from 1 and 2, respectively, and characterized by powder X-ray diffraction, SEM, UV–Vis and fluorescence spectroscopy. The X-ray diffraction pattern confirms the wurtzite phase of as-prepared ZnS and CdS.     

Molecular and crystal structure of poly(tetramethylene adipate) α form based on synchrotron X-ray fiber diffraction

The molecular and crystal structure of the α form of poly(tetramethylene adipate) (PTMA) was analyzed using synchrotron X-ray fiber diffraction data. The crystals belong to the monoclinic system of space group P2₁/n. The unit cell constants are a=0.6776(6), b=0.7904(6), c (fiber axis)=1.442(1) nm and β=135.6(1)°. The final crystal structure was obtained by the linked-atom least-squares refinement, which gave an R-factor of 0.130 for 103 observed spots and 64 unobserved reflections. The molecular structure deviates slightly from the fully extended conformation in the ester part. The torsional angle CH₂-CH₂-O-C(O) was found to be 155°. The CO groups of the corner and center chains in a unit cell are closely located along the c-axis and are related by the crystallographic 2₁-axes along the b-axis at z=1/4 and z=3/4. The total dipole moment arising from the CO groups is oriented in one direction at z=1/4, and in the opposite direction at z=3/4. Owing to the close arrangement of the CO groups between neighboring chains along the fiber axis, the c-projected cell dimensions and the setting angle of the polymer chain are different from those of the orthorhombic form of polyethylene and the β form of PTMA.     

线形聚(D,L-乳酸)和星形聚(D,L-乳酸)的合成研究

在辛酸亚锡Sn(Oct)₂催化下，分别用丙炔醇和季戊四醇引发D,L-丙交酯(DLLA)的开环聚合(ROP),合成了具有末端炔基的线形聚(D,L-乳酸)(PDLLA)和四臂星形聚(D,L-乳酸)(S-(PDLLA)₄),通过核磁共振氢谱(¹H NMR)和凝胶渗透色谱(GPC)对聚合物的结构和相对分子质量进行了表征。合成产物可用于后续制备基于聚乳酸的两亲性嵌段共聚物，为生物可降解性高分子材料的开发应用提供实验依据。     

层状LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(1.95)Y_(0.05)(Y=O,F,Cl,Br)正极材料的合成及高温电化学性能研究

采用溶胶-凝胶法合成层状LiNi1/3Co1/3Mn1/3O1.95Y0.05(Y=O,F,Cl,Br)正极材料,在850℃空气氛围下煅烧20h得到晶型较好的正极材料。以XRD、SEM和充放电测试等手段对材料的晶体结构、表观形貌和电化学性能进行表征。XRD显示F-和Cl-掺杂材料具有高度有序的二维层状结构;充放电测试表明,掺杂F-和Cl-的材料放电比容量、循环性能和倍率性能均优于未掺杂材料,特别是掺杂F-材料在55℃,电压范围为2.0～4.6V,0.15mA电流下首次放电比容量高达207.5mAh/g,且0.9mA电流下第60次循环的容量仍达到165.1mAh/g。掺杂Br-的材料结构稳定性、循环性能和放电比容量均比未掺杂材料差。     

M_(0.5)Co_(2.5)O_4(M=La,Ce,Pr,Nd)尖晶石型复合氧化物催化剂催化分解N_2O性能

采用共沉淀法制备了M_(0.5)Co_(2.5)O_4(M=La,Ce,Pr,Nd)钴基尖晶石型复合氧化物催化剂,运用XRD、SEM、H_2-TPR和O_2-TPD-TG等对催化剂物化性能进行表征,并在固定床微型反应器中评价催化剂催化分解N_2O性能。结果表明,稀土金属掺杂改性的钴基尖晶石型复合氧化物催化剂粒径明显减小,比表面积增加,氧化还原性能得到改善,催化分解N_2O活性提高,其中,M_(0.5)Co_(2.5)O_4催化剂催化分解N2O温度低,T10和T95分别为342℃和499℃。     

20%BaCO_3/La_(0.8)Sr_(0.2)MO_3(M=Fe,Co,Mn)催化分解NO的研究

通过NO程序升温吸附脱附(NO-TPD)分析测试手段,研究了20%BaCO3/La0.8Sr0.2MO3(M=Fe、Co、Mn)催化分解NO的机理,解释La0.8Sr0.2MO3(M=Fe、Co、Mn)与BaCO3简单混合后催化分解NO的性能提升的原因。