Synthesis of new condensed and cyclized coumarin derivatives

Condensation of 4-chloro-2-oxo-2H-chromene-3-carbonitrile with selected heteroarylamines in acetonitrile containing a catalytic amount of triethylamine, followed by intramolecular cyclization, gave the new coumarin derivatives with yields ranging from 43 % to 78 %. The novel compounds were subjected to acid hydrolysis giving the corresponding oxo derivatives in 66–70 % yield. The structural assignments of the synthesized compounds were based on elemental, IR, ¹H and ¹³C NMR analyses.     

Frontier orbital and density functional study of the variation of the hard–soft behavior of monoborane (BH3) and boron trifluoride (BF3) as a function of angles of reorganization from planar (D3h) to pyramidal (C3v) shape

In chemical response the BH₃ and BF₃ molecules undergo the physical process of planar (D_3h) to pyramidal (C_3v) reorganization in shape as the condition precedent to the event of chemical reaction under the requirement of symmetry. A frontier orbital and density functional study of the variation of the stability of electronic structures and chemical reactivity of associated with the physical process of D_3h to C_3v geometry reorganization has been performed. The theoretical parameters viz. eigenvalues of HOMO and LUMO, the HOMO and LUMO energy gap, the global hardness and global softness, the chemical potential, the condensed Fukui function, and local softness of B atom, the reaction site, have been computed over a wide range of ∠XBX angles. The nature of variation in the intrinsic chemical reactivity, global and local, of the molecules associated with their geometry reorganization during the chemical event of charge transfer interaction involving their frontier molecular orbitals has been quantitatively explored. The hardness profiles as a function of reaction coordinates are consistent with the principle of maximum hardness (PMH). Results demonstrate that the hardness and softness are not a static and invariable property of molecules but a dynamic and variable function of molecular structure. The hardness parameters and the HOMO–LUMO gap of the molecules are so modified with the distortion of molecular geometry that, after a certain stage of molecular deformation, the profiles of such parameters of the molecules intersect and cross each other, signifying that the relative order of the intrinsic hardness of their equilibrium geometry is reversed. The intrinsically hard molecule BF₃ becomes softer than the intrinsically soft molecule BH₃ as a consequence of structural distortion. The increase in chemical reactivity computed in terms of density functional parameters are transparent and justified in terms of the profiles of the eigenvalues of the frontier orbitals. The profiles of chemical potential reveal the inherent difference in the tendency of backdonation from two molecules. The computed values of Fukui functions and local softness parameters of the B atom site demonstrate that the concept of local softness can be exploited for a theoretical analysis and understanding of the characteristic chemical events of the molecules under consideration. The profiles of the Fukui functions and local softness parameters of the two molecules seem to reflect and reveal their intrinsic difference in the tendency of receiving donation in the LUMO (electrophilicity) and that of backdonation from the HOMO (nucleophilicity) and the inherent difference of overall reactivity of the two molecules by a simultaneous operation of two opposing processes of charge transfer. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

荧光香豆素衍生物的合成及其光电性能研究

香豆素类衍生物是一类具有抗病毒等许多生理活性的化合物[1-3],其合成和性质的研究一直受到关注[4].     

Synthesis,characterization, and emulsion polymerization of polymerizable coumarin derivatives

We describe the synthesis of a new polymerizable coumarin derivative, [6‐(β‐acryloxyethoxy)‐7‐isopropoxy‐4‐methyl coumarin ( 3 )], whose UV absorption spectrum significantly overlaps the emission spectrum of 9‐alkyl phenanthrene chromophore. This dye can serve several purposes in latex films. It can be a tracer for fluorescence microscopy experiments, or it can act as a donor or acceptor dye in nonradiative energy transfer experiments. Here we emphasize its role as an energy transfer acceptor in experiments with phenanthrene as the corresponding donor. Coumarin‐labeled poly(butyl methacrylate) latex dispersions could be synthesized by conventional batch emulsion polymerization with complete monomer conversion, complete dye incorporation, and uniform dye distribution. Attempts to extend this reaction to poly(vinyl acetate) copolymers failed because the dye inhibited monomer conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3479–3489, 2004     

Theoretical study of electrical and electrochemical properties of cyclopentanepentaone and its dicyanomethylene derivatives

Theoretical studies on anions of 1,2‐dihydroxycyclopentenetrione (croconic acid, H₂C₅O₅) and the whole series of dicyanomethylene derivatives in gas phase and in dimethyl formamide (DMF) solution are carried out using density functional theory (DFT) and self‐consistent reaction field (SCRF)‐DFT method at the B3LYP theory level for the first time. Natural bond orbital (NBO) analyses indicate that π‐electron delocalization in the series is quite strong. Based on the most stable conformations, linear correlations are observed between the oxidation potential measured by cyclic voltammetry and the highest occupied molecular orbital (HOMO) energy as well as ionization potential (Ip), which supports experimental results that systematic substitution of the oxygen atoms in the C₅O structure with C(CN)₂ groups causes a shift of both the oxidation potentials E and E toward more positive values. The correlations are also observed between experimental diffusion coefficient D and E_bind calculated in gas phase and DMF solution, the experimental electrochemical reducing potentials (E_R) and the electron affinity (Ea). © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

几种B环间位取代异黄酮衍生物的核磁共振谱理论研究(英文)

在B3LYP/6-31G**水平下优化了几种B环间位取代异黄酮衍生物的几何构型,在B3LYP/6-311G**水平下计算了该类化合物的核磁共振谱。研究结果表明:在1E!1H和2E～2H中的分子内氢键,其键长为0.1668nm,使整个分子形成一个四环的交叉共轭体系。从9位羟基取代对异黄酮衍生物NMR数据的影响来看,相邻的碳和相邻的氢化学位移的减少是由于电子云密度的增加和屏蔽作用的加强。而相邻碳的化学位移增加更大。此外,从取代基对化学位移的影响进行了讨论。邻对位氢的化学位移与取代基使苯环电子云密度增大的趋势相一致。A环和C环上的氢基本不受取代基的影响。对位碳的化学位移则与取代基使苯环电子云密度增大的趋势相反,邻位碳的化学位移变化趋势不明显。     

Theoretical study on tetrazole and its derivatives (3) MP2 and thermodynamic calculations of amino derivatives of tetrazole

Fully optimized geometries and electronic structures of amino derivatives of tetrazole are obtained at MP2/6-31G* level. The tetrazole rings are planar and aromatic for all the amino derivatives of tetrazole. The amino group is not co-planar with the ring and its conformation is mainly determined by the lone pair electronic repulsion between the substituent and the ring. N(4) atom is more negatively charged and is the most probable coordination site. The energy gaps between LUMOs and HOMOs of 2H-aminotetrazoles and C-aminotetrazole neutrals are smaller than those of the corresponding 1H-isomers and N-aminotetrazole neutrals respectively. The IR frequencies, thermodynamic properties and temperature-dependent functions for heat capacities in the form (a bT cT2) in the 300-1000K range are reported.     

Synthesis of coumarin derivatives in a microfluidic flow system employing the Pechmann condensation: A case study

For the synthesis of coumarin derivatives using the Pechmann condensation scheme, an acidic ionic liquid catalyst, abbreviated as [EBsImH][HSO ₄ ] , was prepared from the ring opening of 1,4-butanesultone by 1-ethylimidazole, followed by the addition of 1 equiv. H₂SO₄(c). The [EBsImH][HSO ₄ ] -catalyzed Pechmann condensation reactions proceeded smoothly in a batch setup, with recyclable [EBsImH][HSO ₄ ] showing great catalytic activity. The acidic ionic liquid catalyst [EBsImH][HSO ₄ ] was recovered from EtOAc/H₂O extraction of the product mixture, where the H₂O layer was worked up and dried for reuse in consecutive runs of the Pechmann condensation reactions, maintaining >85% conversion for four times. The catalytic reactions were also carried out in a microfluidic flow setup. The flow parameters, the reactant molar amounts, and the additional H₂SO₄ as a modifying acid catalyst were optimized in the current case study. A minimum conversion rate of 2.8 g/hr of coumarin derivatives was demonstrated.     

Theoretical investigations on absorption and fluorescence of perylene and its tetracarboxylic derivatives

Summary Theoretical molecular geometries of the perylene derivatives 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA), 3,4,9,10-perylene tetracarboxylic diimide (PTCDI), N,N-dimethyl 3,4,9,10-perylene tetracarboxylic diimide (MePTCDI), and 3,4,9,10-perylene tetracarboxylic disulfide (PTCDS) are presented for the electronic statesS ₀ andS ₁. On this basis, the electronic absorption properties can be interpreted and compared with experimentel data. The vibronic structure ofS ₀ S ₁ absorption andS ₁ S ₀ fluorescence has been reproduced. The analysis of the active vibrational modes shows a corresponding behaviour of derivatives and perylene.

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Theoretische Untersuchungen der Absorption und Fluoreszenz von Perylen und seinen Tetracarbonsäure-Derivaten

Zusammenfassung Theoretische Molekülgeometrien der Perylen-Derivate 3,4,9,10-Perylentetracarbonsäuredianhydrid (PTCDA), 3,4,9,10-Perylentetracarbonsäurediimid (PTCDI), N,N-Dimethyl-3,4,9,10-Perylentetracarbonsäurediimid (MePTCDI) und 3,4,9,10-Perylentetracarbonsäuredisulfid (PTCDS) für die elektronischen ZuständeS ₀ undS ₁ werden vorgestellt. Auf dieser Grundlage können die elektronischen Absorptionseigenschaften interpretiert und mit experimentellen Daten verglichen werden. Die vibronische Struktur derS ₀ S ₁-Absorption und derS ₁ S ₂-Fluoreszenz konnte reproduziert werden. Die Analyse der aktiven Schwingungsmoden zeigen ein gegenüber Perylen vergleichbares Verhalten der Derivate.

     

二阶非线性光学活性分子——咪唑类衍生物的设计与性质的理论研究

采用B3LYP方法在6-31G*水平上优化了6种F,Cl和Br取代的咪唑类衍生物分子几何构型,在此基础上采用TD-DFT的方法计算了它们的前线轨道能级和电子光谱,并用CPHF方法研究了此类衍生物二阶非线性光学系数性质.计算结果表明:此类化合物具有平面结构,共轭性较强;分子内设计的推拉电子基团增强分子内电荷转移,使前线分子轨道间的电子跃迁更容易;各体系具有较大的vβec和良好的透明性;咪唑环的引入增强了体系的热稳定性.这些结论对分子设计具有一定的指导意义.     

DFT-based molecular modeling, NBO analysis and vibrational spectroscopic study of 3-(bromoacetyl)coumarin

The NIR-FT Raman and FT-IR spectra of 3-(bromoacetyl)coumarin (BAC) molecule have been recorded and analyzed. Density functional theory (DFT) calculation of two BAC conformers has been performed to find the optimized structures and computed vibrational wavenumbers of the most stable one. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. Characteristic vibrational bands of the pyrone ring and methylene and carbonyl groups have been identified. The lowering of HOMO–LUMO energy gap clearly explains the charge transfer interactions taking place within the molecule.     

冰片及其酯/酰胺类衍生物的合成和活性研究进展

冰片是重要的芳香开窍类中药,具有开窍醒神,清热止痛等功效,常被作为佐药与其他中药配伍使用。目前,冰片及其衍生物广泛用于医药、农药、化工及香料领域,市场前景好,研究和开发价值高。本文对天然冰片、合成冰片及其酯/酰胺类衍生物的主要合成方法和生物活性方面进行了系统总结,并对冰片酯类衍生物未来的研究方向进行了展望,以期为冰片及其酯/酰胺类衍生物的进一步的研究提供有益参考。     

Electrospray ionization ion-trap multistage mass spectrometric study of sodium cationized aldobiuronic and pseudoaldobiuronic acid derivatives

Fragmentation mechanisms of electrospray ionization (ESI) mass spectrometry of aldobiuronic and pseudoaldobiuronic acid derivatives were elucidated by multistage mass spectrometric (MS(n), n = 2-5) measurements of selected ions. Characteristic under the conditions of ESI-MS analysis is the production of alkali metal (Na and K) cationized adducts. The probability the of locations of Na cations in per-O-methylated compounds was proved by quantum chemical calculations, using the Jaguar program. The most probably position of alkali metal attachment is the carboxy group of the methoxycarbonyl C-5 group of the uronic acid unit. Characteristic cleavages vary according the kind of O-derivatization. In most cases they take place on the acidic part of the dimer and at the interglycosidic oxygen atom. As a result, the criteria for the differentiation of aldobiouronic and pseudoaldobiouronic acids derivatives were elucidated.     

19F NMR study of relative polarities and reactivities of N-H,N-Hg,and N-Au bonds in 2-(4-fluorophenyl)benzimidazole and its PhHg and Ph3PAu derivatives in intermolecular exchange

It has been shown by the¹⁹F NMR method that the relative polarities of nitrogenelement bonds in 2-(4-fluorophenyl)benzimidazole and its PhHg and PPh₃Au derivatives increase in the order N-H19F NMR. It has been found that these reactions occur by a bimolecular associative mechanism and that the N-H bond is substantially less reactive than the N-Hg and N-Au bonds, which have identical reactivities within the limits of sensitivity of the method used.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1574–1580, August, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No. 93-03-5528).     

Synthesis of porous divinylbiphenyl copolymers and their sorptive properties towards phenol and its derivatives

Seven porous divinylbiphenyl polymers having the same nominal crosslinking degree (51.8 wt.%) have been synthesized using suspension polymerization method in the presence of the following inert diluents or their mixtures: toluene, heptane, dodecane, isooctane. The use of various inert diluents was aimed at changing the extent of polymeric network-diluent interactions. The obtained polymers have specific surface area in the range 50-300 m²/g depending on the type and amount of inert diluents used during polymerization. Their sorptive properties have been studied using dilute (0.5 mmol/l) aqueous solutions of phenol and its derivatives (2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,6-dimethylphenol, 4-hydroxyphenol). It has been found that sorption, at low equilibrium concentration, follows the order: 2,4,5-trichlorophenol > 2,4-dichlorophenol > 2-chlorophenol > 2,6-dimethylphenol > phenol > 4-hydroxyphenol. Full characteristic of the porous structure of polymers has been obtained by nitrogen adsorption at 77K.     

Chemiluminescence determination of melatonin and some of its derivatives using potassium permanganate and formaldehyde system

It was found that melatonin and its derivatives, such as N-acetyl- 5-methoxytryptamine (MT), N-acetyl-5-hydroxytryptamine (NAS), 5-Methoxytrypt- amine (5-MT), 5-Methoxyindolyl acetic acid (5-MIAA) and N-acetyl-5-methoxy- 6-hydroxytryptamine (6-HMT) would give chemiluminescence in the acidic potassium permanganate solution, and formaldehyde would enhance this chemiluminescent reaction greatly. The optimum conditions for this chemiluminescent reaction were studied in detail by a flow injection system. A new simple rapid method has been developed under the optimum conditions for determination of melatonin. This method has the advantages of high sensitivity, wide range of linear response and low detection limit. On the basis of investigation of chemiluminescent, fluorescent and UV spectra of melatonin in acidic solution containing potassium permanganate and formaldehyde, a possible mechanism of this reaction was proposed.