THE CALCULATION OF CHEMICAL SHIFTS IN DISUBSTITUTED NAPHTHALENES

<正> The principle and method for calculating the chemical shifts of substituted benzenes have been extended to the calculation of chemical shifts in disubstituted naphthalenes. We have set up a series of empirical parameters for the calculation of chemical shifts. The calculated results of 439 8 values from 78 compounds show that the standard deviation between the calculated and the experimental values is 0.08 ppm. The combination of this calculation with that of the coupling constants can be used to provide a criterion .for the determination of molecular structure in disubstituted naphthalenes as well as to assign NMR parameters for the experiment of proton simulated spectra of disubstituted naphthalenes.     

THE CALCULATIOM OF CHEMXCAL SHIFTS IN SUBSTITOTED PYRIDINES

<正> The principle and method for the calculation of chemical shifts of substituted benzenes have been extended to calculation of the cheiiical shifts in substituted pyridines. We have set up a series of empirical parameters for calculation of the chemical shifts. The calculated results of 154 δ values frou 54 compounds show that the standard deviation between the calculated and the experimental values is 0 . 09 ppm. The combination of the coupling constants can be used to provide a criterion for the determination of molecular structure in substituted pyridines and to assign NMR parameters for the experiment of proton simulated spectra of substituted pyridines.     

~(13)C NMR SUBSTITUENT EFFECTS IN A SERIES OF 2-PHENYL BENZOTHIAZOLES

According to ~(13)C NMR determinations and analyses of 14 compounds of 2-phenyl benzothiazole, we have studied the substituent effects on aromatic hetero rings. The different substituents have effects on the charge densities in the molecules. We have also analyzed the structural factors of effects on ~nJ_(13C-1H). The perturbations of benzothiazole to benzene ring were studied by the method of comparison analysis. The substituent induced chemical shifts of benzothiazole were obtained. The experiential calculations of ~(13)C chemical shifts for aromatic carbons have been done, the calculated velues agreed with the experimental ones. The theoretical calculations for the compounds 2, 3, 9 have been made using the EHMO method (the Enlarged Hiickel Molecular Orbital Method). The relationships between the ~(13)C experimental chemical shifts and the total charge densities of the corresponding carbon atoms were obtained by the regression analysis. The correlation coefficient is—0.96.     

Studies on the Synthesis and Complexing Behavior of Crown Ethers with External Coordination Center

Ligands capable of positioning two or more very different metal cations, like transition metal and alkali or alkaline earth metal cations, have been described recently1-3. Reinhoudt et al. have synthesized a number of ligands with the cavity for transition metal cations as well as the cavity for alkali metal cations and the corresponding comlexes with different kinds of metal ions4,5. It was anticipated that co-complexation of a hard cation closing to the complexed transition metal cation woul…     

Prediction of the ~(13)C NMR Chemical Shifts of 9,10-Dihydrophenanthrene Analogues by the GIAO Method

After the geometry optimizations at the B3LYP/6-31+G(d,p) level, the NMR calculations of a series of 9,10-dihydrophenanthrene analogues have been carried out by GIAO method at the HF/6-31+G(d) level. The calculated 13C NMR chemical shifts are in agreement with the observed values. By a series of linear correlation equations (δpred = a + bδcal.c) of the 13C chemical shifts, accurate prediction of 13C chemical shifts was achieved for the new 9,10- dihydrophenanthrene compound, for which the predicted 13C NMR chemical shifts are in quite good agreement with the experimental values. The linear correlation between δpred and δexptl is excellent, and the square of correlation coefficient, r2, is up to 0.9973. The maximum absolute difference between δpred and δexptl, Δδ, is 4.5 ppm, and the rms error between δpred and δexptl is 2.55 ppm. In the meantime, according to the theoretical predicted result, we could confirm that the new 9,10-dihydrophenanthrene analogue is erianthridin (2,7-dihydroxy-3,4-dimethoxy-9,10-dihydro-phenanthrene).     

Synthesis, Crystal Structure and Fluorescent Properties of 1-（4-（Dimethylamino）benzylidene）- 4-（naphthalen- 1-yl） Thiosemicarbazide

1 INTRODUCTION Recently, for the fluorescent properties, Schiff base has been more and more important and widely studied in density optical memories, nonlinear op- tics (NLO), organic light-emitting diodes (OLED), polymer LED and electrogenerated chemilumines- cence (ECL)[1~5]. Thiosemicarbazones are a kind of Schiff bases with thiourea and good ligands easily chelating with transition metal ions. Although they have been studied extensively for a long time due to their chemical and b…     

Synthesis and Crystal Structure of Tri-(2-mercaptopyridine N-oxide)bis(dimethyl sulfoxide) Dysprosium(III)

1 INTRODUCTION Transition-metal thiolato complexes have been of interest for the simulation of many metallo- enzymes where the thiolato group mimics the ligation of cysteinyl residues in proteins. Numerous complexes of transition elements with 1,2-bidentate oxothiolate ligands have been prepared[1~4]. Re- cently, we have studied a few transition metal complexes of 2-mercaptopyridine N-oxide (Hmpo) as bactericidal and antifungal reagents[5～7]. Although Hmpo exhibits unusual versatility…     

Understanding the dehydrogenation mechanism over iron nanoparticles catalysts based on density functional theory

The conversion of chemical feedstock materials into high value-added products accompanied with dehydrogenation is of great value in the chemical industry.However,the catalytic dehydrogenation reaction is inhibited by a limited number of expensive noble metal catalysts and lacks understanding of dehydrogenation mechanism.Here,we report the use of heterogeneous non-noble metal iron nanoparticles(NPs) incorporated mesoporous nitrogen-doped carbon to investigate the dehydrogenation mechanism based on experiment observation and density functional theory(DFT) method.Fe NPs catalyst displays excellent performance in the dehydrogenation of 1,2,3,4-tetrahydroquinoline(THQ)with 100% selectivity and 100% conversion for 10-12 h at room temperature.The calculated adsorption energy implies that THQ prefers to adsorb on Fe NPs as compared with absence of Fe NPs.What is more,the energy barrier of transition state is relatively low,illustrating the dehydrogenation is feasible.This work provides an atomic scale mechanism guidance for the catalytic dehydrogenation reaction and points out the direction for the design of new catalysts.     

~(11)B NMR AND QUANTUM CHEMISTRY STUDIES OF BORATRANE COMPOUNDS

The ~(11)B chemical shifts of boratrane compounds were measured. Quantum chemistry calculations of some of the compounds wore carried out using the CNDO/2 method. Both experimental and calculated results confirmed the existence of the B←N dative bonds in boratranes. The exporimental results indicate that the ~(11)B chemical shifts are influenced by the size of the rings, the characteristics of substituents and steric factors. The calculated results indicate that the strengths of the B←N dative bonds in boratranes are about half of that of a purely "covalent two-electron bond" and therefore, the dative bonds B←N are stronger than those of Si←N in the analogous silatranes, and the boratranes are more stable than silatranes.     

Prediction of the 13C NMR Chemical Shifts of Stilbene Analogues by GIAO Method

After the geometry optimization at B3LYP/6-31+G(d,p) level,the calculations of the NMR chemical shifts of a series of stilbene analogues were carried out by means of Gauge Including Atomic Orbitals(GIAO) method at HF/6-31+G(d) level and B3LYP/6-311G+(2d,p) level,respectively.The 13C NMR chemical shifts calculated at both HF/6-31+G(d) and B3LYP/6-31+G(d,p) levels are in agreement with the observed values.By virtue of a series of linear correction equations(δpred.=a+bδcalcd.) of the 13C chemical shifts,accurate prediction of 13C chemical shifts was achieved for the new stilbene compounds.For the 13C NMR chemical shifts calculated at HF/6-31+G(d) level,the linear correlation of δpred.with δexptl.is excellent,and the square of correlation coefficient,r2,is 0.9985.The maximum absolute difference between δpred.and δexptl.,Δδ,is 2.3,and the root-mean-square error between δpred.and δexptl.is 0.98.In the meantime,for those obtained at B3LYP/6-31+G(d,p) level,the linear correlation of δpred.with δexptl.is also excellent,and the square of correlation coefficient,r2,is up to 0.9987.The maximum absolute difference between δpred.and δexptl.,Δδ,is 2.2,and the root-mean-square error between δpred.and δexptl.is only 0.88.     

Synthesis of 7,7’-Disubstituted BINAP and Their Application in Asymmetric Catalytic Reaction

The design of new chiral ligands plays a very important role in the development of transition metal catalyzed asymmetric synthesis. Many chiral diphosphine ligands have been prepared and applied in asymmetric catalytic reactions with excellent enantioselectivities. Among the chiral diphosphine ligands reported, BINAP was found to have been the widest application in the transition metal catalyzed reaction. Recently we have developed a novel oxovanadium (Ⅳ) complex catalyst for the oxidative …     

Synthesis and spectral properties of arylmercury derivatives of α-thiopicolinanilide

A series of thirteen arylmercury derivatives of α-thiopicolinanilide have been synthesizedand characterized by elemental analysis,IR,~1H NMR and MS.The intramolecular coordination andthe substituent effects on the MS and ~(199)Hg NMR behaviours have been studie6.It has been shownthat a linear correlation exists between the ~(199)Hg chemical shifts and the Hammett-Brown constantsσ~+,and the electron-donating groups cause the chemical shift to move upfield.     

Synthesis of New Aza-crown Ethers Containing Pyridine Ring and their Liquid Membrane Transport of Alkali Cations

IntroductionOxygen donor macrocycles such as crown ethers are well known to have strong complexation for alkali and alkaline earth ions1. On the other hand, polyazamacrocycles show a high affinity for transition metal ions. Nitrogen-oxygen mixed donor macrocycles can form stable complexes with both alkali and transition metal ions2~5. Most of the macrocycles with mixed donor sites bearing oxygen and sp3 nitrogen atoms, oxygen and sp2 nitrogen atoms, or oxygen and sp3 and sp2 nitrogen atoms hav…     

Synthesis and Crystal Structure of a Novel Organolanthanide Schiff Base Complex[(η~5-C_5H_5)Pr(acac)_2(μ_3-OH)]_2·4THF

1 INTRODUCTION It is well known that lanthanide metals are quite oxophilic and the oxygen-stabilized organolanthanide complexes are tractable for exploring their physical and chemical properties. Organolanthanide complexes involving -diketonato chelate ligands have been largely prepared and characterized[1~5]. The Schiff base complexes are some of the most important stereochemical models in transition metal coordination chemistry; however, the organolanthanide Schiff base complexes are …     

Prediction of the 13C NMR Chemical Shifts of Fluorenone Analogues by the GIAO Method

After the geometry optimization at B3LYP/6-31+G(d,p) level,the NMR calcula-tions of a series of fluorenone analogues have been carried out by GIAO method at HF/6-31+G(d) level and B3LYP/6-311G+(2d,p) level,respectively.The 13C NMR chemical shifts calculated at HF/6-31+G(d) level show better agreement with the observed values.By a series of linear correction equations (δpred=a + bδcalc),accurate prediction of 13C chemical shifts was achieved for the new fluorenone compound.The linear correlation of δpred with δexptl is excellent,and the square of correlation coefficient,r2,is up to 0.994.The maximum absolute difference between δpred and δexptl,Δδ,is 4.6 ppm,and the root-mean-square error between δpred and δexptl is only 2.6 ppm.     

DFT Studies on Thermal Stabilities,Electronic Structures,and ~（13）C Chemical Shifts of C_（24）O_2 Based on Fullerene C_（24）（D_6）

Quantum chemical calculations on some possible equilibrium geometries of C24O2 isomers derived from C24 (D6) and C24O have been performed using density functional theory (DFT) method. The geometric and electronic structures as well as the relative energies and thermal stabilities of various C24O2 isomers at the ground state have been calculated at the B3LYP/6-31G(d) level of theory. And the 1,4,2,5-C24O2 isomer was found to be the most stable geometry where two oxygen atoms were added to the longest carbon-carbon bonds in the same pentagon from a thermodynamic point of view. Based on the optimized neutral geometries, the vertical ionization potential and vertical electron affinity have been obtained. Meanwhile, the vibrational frequencies, IR spectrum, and 13C chemical shifts of various C24O2 isomers have been calculated and analyzed.     

Synthesis and Crystal Structure of Bis（barbiturato） triwater Complex of Copper（Ⅱ）

1 INTRODUCTION A variety of transition metal complexes with barbiturates have been prepared owing to their important roles in clinical detection and identi- fication of drug[1～5]. They have the general formula of M(Ⅱ)(barb)2L2, where M is a transition metal (Co, Cr, Zn, Cu etc), barb the anion of a substituted barbituratic acid and L an organic base, usually pyridine. In these complexes, the donor atom in the barbiturate anion is a deprotonated nitrogen atom and, the coordination …     

Synthesis of some novel divalent transition metal complexes as antimicrobials

A novel series of transition metal complexes have been synthesized from the reaction of 5-((3-(methylthio)-5-(pyridin-4-yl)-4H- 1,2,4-triazol-4-ylamino)melhyl)quinolm-8-ol with transition metal salts.The structures of these compounds have been elucidated by elemental and spectral analysis.Furthermore,compounds were screened for in vitro antimicrobial activity against the representative panel of two Gram-positive and two Gram-negative bacteria and two strains of fungus.The various compounds show potent inhibitory action against test organisms.     

Synthesis and Study on the Complexation of Dithidiaza 21-Cown-7- Bearing Appended Coumarin or 1-Aminonaphthene as Sidearms

The high toxicity of many transition and post-transition metal ions, especially Hg2+ and Pb2 + , is well recognized and a lot of attention has been paid to control contamination of water supplies by toxic metal ions and to monitor the level of these metal ions in the environment. For the application purpose in controlling and monitoring the concentrations of specific metal ions in a complex matrix continuously and remotely by using ion-selective sensory devices, chemical sensors based on the synthetic fluoroionophores and chromoionophores capable of signaling complexation of metal ions have been reported, [1～ 5], and a series of dithidiaza 21-rown-7 bearing appended coumarin or 1-aminonaphthene as sidearms was synthesized. [6]