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1.
Quantitative relationships of the (31)P NMR chemical shifts of the phosphorus atoms in 291 phosphines with the atomic ionicity index (INI) and stereoscopic effect parameters (epsilon(alpha), epsilon(beta), epsilon(gamma)) were primarily investigated in this paper for modeling some fundamental quantitative structure-spectroscopy relationships (QSSR). The results indicated that the (31)P NMR chemical shifts of phosphines can be described as the quantitative equation by multiple linear regression (MLR): delta(p)(ppm)= -174.0197-2.6724INI+40.4755epsilon(alpha)+15.1141epsilon(beta)-3.1858epsilon(gamma), correlation coefficient R=0.9479, root mean square error (rms)=13.9, and cross-validated predictive correlation coefficient was found by using the leave-one-out procedure to be Q(2)=0.8919. Furthermore, through way of random sampling, the estimative stability and the predictive power of the proposed MLR model were examined by constructing data set randomly into both the internal training set and external test set of 261 and 30 compounds, respectively, and then the chemical shifts were estimated and predicted with the training correlation coefficient R=0.9467 and rms=13.4 and the external predicting correlation coefficient Q(ext)=0.9598 and rms=10.8. A partial least square model was developed that produced R=0.9466, Q=0.9407 and Q(ext)=0.9599, respectively. Those good results provided a new, simple, accurate and efficient methodology for calculating (31)P NMR chemical shifts of phosphines.  相似文献   

2.
A new method of quantitative structure‐retention relationship (QSRR) is proposed for estimating and predicting gas chromatographic retention indices of alkanes by using a novel molecular distance‐edge vector, called μ vector, containing 10 elements. The QSRR model (Ml), between the μ vector and chromatographic retention indices of 64 alkanes, was developed by using multiple linear regression (MLR) with the correlation coefficient being R = 0.9992 and the root mean square (RMS) error between the estimated and measured retention indices being RMS = 5.938. In order to explain the equation stability and prediction abilities of the M1 model, it is essential to perform a cross‐validation (CV) procedure. Satisfactory CV results have been obtained by using one external predicted sample every time with the average correlation coefficient being R = 0.9988 and average RMS = 7.128. If 21 compounds, about one third drawn from all 64 alkanes, construct an external prediction set and the 43 remaining construct an internal calibration set, the second QSRR model (M2) can be created by using calibration set data with statistics being R = 0.9993 and RMS = 5.796. The chromatographic retention indices of 21 compounds in the external testing set can be predicted by the M2 model and good prediction results are obtained with R = 0.9988 and RMS = 6.508.  相似文献   

3.
Luan F  Liu HT  Wen Y  Zhang X 《The Analyst》2008,133(7):881-887
A quantitative structure-property relationship (QSPR) methodology that involves multilinear (Hansch-type) and nonlinear (radial basis function neural network (RBFNN)) approaches was performed to correlate the quantitative molar calibration factors (f(M)) of 140 organic compounds against structural factors. The statistical characteristics provided by the multiple linear model (R(2) = 0.963; RMS = 0.089; AARD = 3.86% for test set) indicated satisfactory stability and predictive ability, while the predictive ability of the RBFNN model is somewhat superior (R(2) = 0.983; RMS = 0.075; AARD = 3.19% for test set). The multilinear model provided some insight into the main structure factors that modulate the quantitative calibration factor of the investigated compounds.  相似文献   

4.
1 INTRODUCTIONCurrently,consistenteffortshavebeenmadetotheinvestigationoforganicnonlinearoptical(NLO)materials〔1〕.Someofcinnamylideneacetophenonederivativeshavefairlystrongsecondharmonicgeneration(SHG)andthereforearepotentialusefulinNLOfields.Durin…  相似文献   

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The crystal of the title compound C, C30H30N2O3S has been prepared by reaction of 1,5-benzothiazepine with N-protected glycine and determined by X-ray single crystal diffraction. Crystal data: Mr=498.62, triclinic with P space group, a=10.880(2), b=13.955(3), c=9.537(2)(A), α=99.34(3)°, β=110.43(3)°, γ=88.56(3)°, V=1338.2(5)(A)3, F(000)=528, λ(MoKα)=0.71073(A), Z=2, Dc=1.237g/cm3, μ=0.154mm-1. Final R=0.0453, wR=0.1256 for 3491 observed reflections [I>2σ(I)]. Structure analysis reveals that the substituents at C(23) and C(7) in four-membered ring are located on the same side. The conformation of seven-membered ring is chair-like.  相似文献   

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The nitroprusside ion [Fe(CN)(5)NO](2-) (NP) reacts with excess HS(-) in the pH range 8.5-12.5, in anaerobic medium ("Gmelin" reaction). The progress of the addition process of HS(-) into the bound NO(+) ligand was monitored by stopped-flow UV/Vis/EPR and FTIR spectroscopy, mass spectrometry, and chemical analysis. Theoretical calculations were employed for the characterization of the initial adducts and reaction intermediates. The shapes of the absorbance-time curves at 535-575 nm depend on the pH and concentration ratio of the reactants, R=[HS(-)]/[NP]. The initial adduct [Fe(CN)(5)N(O)SH](3-) (AH, λ(max) ≈570 nm) forms in the course of a reversible process, with k(ad)=190±20 M(-1)s(-1) , k(-ad)=0.3±0.05 s(-1) . Deprotonation of AH (pK(a)=10.5±0.1, at 25.0 °C, I=1 M), leads to [Fe(CN)(5)N(O)S](4-) (A, λ(max)=535 nm, ε=6000±300 M(-1) cm(-1) ). [Fe(CN)(5)NO](.)(3-) and HS(2)(.)(2-) radicals form through the spontaneous decomposition of AH and A. The minor formation of the [Fe(CN)(5)NO](3-) ion equilibrates with [Fe(CN)(4)NO](2-) through cyanide labilization, and generates the "g=2.03" iron-dinitrosyl, [Fe(NO)(2)(SH)(2)](-) , which is labile toward NO release. Alternative nucleophilic attack of HS(-) on AH and A generates the reactive intermediates [Fe(CN)(5)N(OH)(SH)(2)](3-) and [Fe(CN)(5)N(OH)(S)(SH)](4-) , respectively, which decompose through multielectronic nitrosyl reductions, leading to NH(3) and hydrogen disulfide, HS(2)(-) . N(2)O is also produced at pH≥11. Biological relevance relates to the role of NO, NO(-) , and other bound intermediates, eventually able to be released to the medium and rapidly trapped by substrates. Structure and reactivity comparisons of the new nitrososulfide ligands with free and bound nitrosothiolates are provided.  相似文献   

10.
A mercury(Ⅱ) iodide complex with organosulfide [Hg(pymt)(pymtH)I] 1 (pymt = the anion of pyrimidine-2-thiolate) has been synthesized by slow evaporation of the solution at room temperature and structurally characterized by single-crystal X-ray diffraction. Basic ideas and data collected are given. X-ray diffraction analysis reveals that complex 1 is mononuclear. Crystallographic data: C8H7HgIN4S2, Mr = 550.79, monoclinic system, space group P21/c, a = 11.218(4), b = 9.551(3), c = 15.877(4) A^°, β = 129.697(15)°, V = 1308.9(7) A^°^3, Z = 4, Mr = 550.79, Dc = 2.795 g/cm^3, F(000) = 995, μ(MoKa) = 14.415 mm^-1, 2(MoKa) = 0.71073 A^°, T= 293(2) K, 2θmax = 54.9°, GOOF= 1.053, the final R = 0.0310 and wR = 0.0742 for 2547 observed reflections with I 〉 2σ(I) (refinement on F^2). Complex 1 is connected through hydrogen bonds to give a one-dimensional supramolecular chain structure. Furthermore, π-π interactions are also found between the pyrimidine rings with the center-to-center distances of 3.439(4) and 3.603(4) A^°, so complex 1 expands the chains into a two-dimensional network.  相似文献   

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The complex [Cd(tren)(meim)](ClO4)2 was synthesized and characterized by elemental analysis, IR and X-ray single-crystal diffraction. The compound crystallizes in monoclinic system, space group P21/m with a=0.786 8(2) nm, b=0.834 2(2) nm, c=1.496 2(4) nm, Mr=538.64, Z=2, F(000)=542, Dc=1.822 g·cm-3, T=298(2) K, μ=1.435 mm-1 and λ=0.071 073 nm. The structure was refined to R=0.045 8 and wR=0.123 1 for 1 489 observed reflections with I>2σ(I). The complex was valued for its antimicrobial activity against bacterial strands using the agar diffusion method. It was found to be active against the four test bacterial organisms. CCDC: 600198.  相似文献   

13.
1 INTRODUCTIONInrecentyears,therehasbeenmuchinterestinphosphoranescontainingonlyonephosphorus-phosphorusbondandthestructuresofmostofthesecompoundshavebeenidentifiedbyX-raycrystallography[1~6].In1990,anewtypeofphosphoraneinvolvingtwoP-Pbondswassuccessfullysynthesized[7],butthecrystalstructurewasnotdetermined.Wehavesuccessfullysynthesizedthenovelphosphorane3bear-ingthreeP-Pbonds.Hereitscrystalstructureisreported.2 EXPERIMENTAL2.1 PreparationAllprocedureswereperformedunderN2atmos…  相似文献   

14.
The syntheses and ambient-temperature 19F NMR data are reported for 27 asymmetric ethanes of the general formula RCF2CXYZ, including a complete series of 10 compounds with R = Cl and all combinations of the 5 ligands H, F, Cl, Br and Ph. Within the theoretical framework of a previously proposed heuristic mathematical model the geminal 19F chemical shift differences are fitted to chirality functions X = ?R (λx - λy) (λy - λz) (λz - λx) to yield acyclic conformational ligand constants λ and substituent parameters ?. It is demonstrated that the λ constants already reported for an analogous series of 10 compounds with R = Br are transferable to the Cl series with ?Cl = 0.63 ± 0.07. Crude first approximations are also reported for the normalised (according to ?Br = 1) ligand constants λCh3, λOH, λOCH3 and λ1 and for the substituent parameter λH. It is argued that the λ values thus ext play a role in the conformational analysis of asymmetric ethanes that is conceptually analogous to the conformational free energies in monosubstituted cyclohexanes.  相似文献   

15.
The silver-dppm complex, [Ag2(dppm)2(NMP)2](SbF6)2·4H2O·3CH2Cl2 1 (NMP = 2- (4-dimethylaminophenyl)imidazo(4,5-f)(1,10)phenanthroline, dppm = diphenylphosphinomethane), was synthesized and its structure was determined by X-ray diffraction. The crystal belongs to mono- clinic, space group C2/c, Mr = 2461.61, a = 21.57(10), b = 22.48(6), c = 22.53(6) (A), β = 101.29(2)o, V = 10713(64) (A)3, Z = 4, Dc = 1.526 g/cm3, μ = 1.141 mm-1, F(000) = 4920, R = 0.0664 and Wr = 0.1774 for 8524 observed reflections (I > 2σ(I)). Complex 1 exists as a centrosymmetric dimmer. The two dppm molecules bridge two AgNMP moieties to form an eight-membered Ag2P4C2 metal- lacyclic ring with ligand NMP chelating to each Ag. It appears photoluminescence λ(max = 625 nm) at room temperature and makes red shift compared with free ligand NMP λ(max = 522 nm). DFT calculation indicates that the emission of 1 originates from singlet metal-perturbed ILCT excited state.  相似文献   

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在水相中,FeCl3催化对甲基苯胺聚合合成了对甲基苯胺三分子聚合物——(N,N′E,N,N′E)-N,N′-(2-氨基-5-甲基-2,5-环己二烯-1,4-二亚基)二(4-甲基苯胺)(1),其结构经X-射线单晶衍射仪表征。1属六方晶系,R3空间群,晶胞参数:a=21.116(2),b=21.116(2),c=10.364(2),α=90°,β=90°,γ=120°,Mr=315.41,Z=9,V=4002.1(10)3,Dc=1.178 g.cm-3,μ=0.070 mm-1,λ=0.710 73,F(000)=1 512,R=0.067 8,wR=0.112 6。  相似文献   

18.
In this study we compared the prediction abilities of the variable connectivity index 1chi(f) (not included in CODESSA) with topological indices available from CODESSA. We selected the boiling points of n = 100 alcohols as the property and examined the pool of 56 topological indices. Prediction capabilities of the developed models were evaluated by classical training/test set approach. RMS errors calculated from the prediction set for the MLR models obtained from CODESSA software with 1, 2, 3, 4, and 5 parameters were 9.06, 5.69, 5.40, 4.9, and 3.37 degrees C, respectively. Using the variable connectivity index with weights x = 0.10 and y = -0.92 for carbon and oxygen atom respectively, we obtain regression BP = 38.12 1chi(f) - 37.56 with the correlation coefficient r = 0.9915, RMS error 4.21 degrees C calculated from the test set, and Fisher ratio F = 5691. Prediction capability of the variable connectivity index was better than for MLR regression model with up to four parameters.  相似文献   

19.
IntroductionNitrobenzene derivatives have been used as organ-ic chemical materials and intermediates for many yearsin the chemical industry. Many of those chemicals arereleased into environment and especially into aquaticsystems, and thus have a high pote…  相似文献   

20.
The conversion of glucose and fructose into gluconic acid (GA) and sorbitol (SOR) was conducted in a batch reactor with free (CTAB-treated or not) or immobilized cells of Zymomonas mobilis. High yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/L (glucose plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 U/L. The concentration of the products varied hyperbolically with time according to the equations (GA)=t(GA)(max)/(W(GA) +t), (SOR)=t (SOR)(max)/(W(Sor)+t), v(GA)=[W(GA) (GA)(max)]/(W(GA)+t)(2) and V(SOR)=[W(SOR) (SOR)(max)]/(W(SOR)+t)(2). Taking the test carried out with free CTAB-treated cells as an example, the constant parameters were (GA)(max)= 541 g/L, (SOR)(max)=552 g/L, W(GA)=4.8h, W(SOR)=4.9h, upsilon(GA)=112.7 g/L. and upsilon(SOR)=112.7 g/L.  相似文献   

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