7-甲氧基香豆素-3-甲酰二乙醇胺的电子结构和光谱性质的理论研究

采用密度泛函的B3LYP和单激发组态相互作用(CIS)方法分别对基态和第一、第二单重激发态(S1和S2)结构进行优化,均采用6-31G(d)基组.在优化的基态和第一单重激发态的结构基础上,用含时密度泛函理论(TD-DFT),成功模拟了7-甲氧基香豆素-3-甲酰二乙醇胺的吸收光谱和荧光发射光谱,并用极化连续模型考虑了溶剂的影响.利用前线轨道、电荷密度差(CDD)和态密度(DOS)图分析了电子跃迁的特性.计算结果与实验结果吻合得很好.该量子计算方法对此类化合物的定性和定量研究是有效的.     

新型4-羟基香豆素衍生物的微波合成及其光谱性质

以4-羟基香豆素(a)为原料微波辐射合成了具有独特的生理活性和荧光性能的3,3′,3″,3′″-亚乙四基-4-羟基香豆素(b)、3,3′-苯亚甲基-双-4-羟基香豆素(c)和4-羟基香豆素-1,4-萘醌(d)系列4-羟基香豆素衍生物, 采用元素分析、红外光谱、核磁共振及质谱表征了产物的结构, 并对其紫外-可见吸收光谱及荧光光谱性质进行了研究, 探索了化合物的微观结构与其光学性能之间的关系. 研究结果表明, 具有“近平面”、大π共轭和对称型结构的化合物b具有较大的摩尔吸光系数及强荧光特性, 且浓度在0.50~1.50×10^-4 mol/L范围时, 其荧光强度随着浓度的降低而呈线性增加; 在pH=1.81~6.09时, 荧光强度随pH降低而减弱, 在pH 8.36~11.98时, 荧光强度随pH升高而减弱. 此外, 牛血清白蛋白(BSA)及脱氧核糖核酸(DNA)可与该化合物发生相互作用, 进而敏化增强该分子的内源荧光.     

香豆素类肼荧光探针的合成及应用

以4-三氟甲基-7-羟基香豆素为荧光母体,4-溴丁酰基为识别基团,合成了一种基于分子内电荷转移机制的肼荧光探针XS-1,其结构经核磁共振氢谱(¹H NMR),核磁共振碳谱(¹³C NMR)和高分辨质谱(HRMS)确证,通过荧光发射光谱研究了探针对肼的响应性能。结果表明,在磷酸盐缓冲液(10 mmol,pH7.4)中,探针XS-1能通过荧光增强作用识别肼,并具有很好的选择性和抗干扰能力,检出限为0.11μmol/L。探针XS-1具有斯托克斯位移大(144 nm)、线性范围宽(0～400μmol/L)、合成简便以及能在水相中检测肼等优点,并已成功用于实际水样中肼的定量检测。     

3-吡咯烷基苯并蒽酮的电子结构和光谱性质

苯并蒽酮衍生物在新型荧光材料、非线性光学材料和液晶显示材料等领域有较大的应用前景.本文采用量子化学方法优化了3-吡咯烷基苯并蒽酮的基态几何结构和第一单重激发态的几何结构,并与X射线晶体衍射实验值进行了对比.利用含时密度泛函理论(TD-DFT)的不同泛函,计算了3-吡咯烷基苯并蒽酮在气相和溶剂中的吸收和发射光谱,考察了它的电子结构和光谱特征,并分析了不同泛函、基组以及溶剂效应对吸收和发射光谱的影响.计算结果表明:3-吡咯烷基苯并蒽酮的最强吸收和发射光谱都是具有π→π*跃迁特征的电荷转移(CT)态;泛函B3LYP能较好地重现实验吸收能;而对于具有分子内电荷转移特征的激发态,泛函MPWK能较好地重现实验发射能.溶剂效应的计算表明,不同极性的溶剂对3-吡咯烷基苯并蒽酮的吸收光谱和发射光谱的影响较小.理论预测的光谱与实验结果一致.     

香豆素酮染料光谱性质的研究

近年来,许多具有“推一拉”电子结构的分子内电行转移激光染料的光谱性质的研究引起人们极大的关注[1-5]．研究染料在不同条件下光物理性质行为不仅具有重要的理论意义,而且使激光染料能有效地应用于光功能材料．香豆素酮染料作为一种重要的激光染料,已经在光聚合、光固化等领域中得到广泛应用[6,7]．在这类化合物中不同位置的取代对其光物理性质的研究已有报导[8,9],但香豆素酮染料在不同的非质子传递溶剂中的光物理行为的研究至今未见报导．鉴于以前关于香豆素染料文献报导常涉及到用醇、水等质子传递溶剂,为了避免溶剂与溶质间的氢…     

苯并咪唑苯并异喹啉酮及其衍生物的电子结构和光谱性质的理论研究

采用密度泛函、含时密度泛函和单激发组态相互作用(CIS)方法研究了苯并咪唑苯并异喹啉酮(1)及其衍生物的电子结构特性和光谱性质,并用极化连续模型考虑了溶剂的影响.结果表明,化合物1及其衍生物的吸收和荧光发射过程的电子垂直跃迁是由于分子内的电荷迁移.化合物1中取代基的位置及给吸电子能力影响其HOMO-LUMO能隙和电荷迁移量.在分子中引入吸电子和给电子取代基,均使最大吸收波长和最大荧光发射波长红移,计算的结果与实验结果吻合得较好.     

香豆素-咪唑类荧光染料的设计与研究

合成了不同给电子取代基(羟基、丁氧基、二乙基氨基等)的菲并[9,10-d]咪唑(CA1~CA6)或4,5-二苯基咪唑(CB1~CB6)修饰的香豆素衍生物,初步考察了它们的溶液发光和固体发光现象.研究表明,当香豆素取代基为氨基时,化合物在二氯甲烷中的荧光较强,而羟基取代、丁氧基取代或者无取代的衍生物在二氯甲烷中的荧光都很弱,而菲并[9,10-d]咪唑修饰的衍生物CA1~CA5的溶液荧光要比4,5-二苯基取代咪唑修饰的衍生物CB1~CB5的溶液强.另外,染料分子的分子内氢键强度及咪唑基-香豆素环间二面角大小都会对染料分子的发光性能产生影响.     

苯并香豆素酯类衍生物的合成及荧光性质研究

以2-羟基-1-萘甲醛为原料,采用改进的Knoevenagel反应合成了苯并香豆素-3-羧酸中间体和4种不同链长的脂肪酯和芳香酯衍生物,采用元素分析和红外光谱对其结构进行了表征.对所有化合物固体粉末的发光性能进行了研究.     

新型香豆素类氟离子荧光探针的合成及细胞成像研究

设计合成了一类基于分子内电荷转移（Intramolecular Charge Transfer,ICT）的香豆素类F^-荧光探针CS1,CS2和CS3,经¹H NMR,¹³C NMR,IR和HRMS表征了相应探针的结构,并解析了探针CS3的晶体结构.通过核磁和质谱实验验证了探针与F^-的作用机理是氟化物脱硅基.光谱分析实验结果显示,CS1,CS2和CS3均具有较好的选择性和灵敏度,且均能成功实现人乳腺癌细胞（MCF^-7）中F^-的检测.     

四取代酞菁化合物的合成和光谱性质

以3(4)-硝基邻苯二腈为起始原料经过两步反应合成了α(β)-四苯氧基酞菁.通过谱学方法和元素分析表征了其结构,研究了中心离子和取代基位置对酞菁吸收波长、发射波长和荧光强度的影响.结果表明,取代位置对最大吸收波长、最大发射波长和荧光强度的影响较大,而中心离子对荧光强度的影响较大,可降低荧光强度甚至淬灭荧光.     

洛汾碱衍生物的电子结构及光谱性质的理论研究

采用密度泛函理论(DFT)的B3LYP/6-31G*方法,对4种洛汾碱类化合物的几何构型进行了优化,在此基础上计算分子的电子结构,并结合有限场FF方法研究了二阶非线性光学(NLO)性质.用含时密度泛函理论(TD-DFT)对上述化合物分子进行吸收光谱的研究.研究表明在4,5-二-苯基-2-对甲酰苯基咪唑生色团中4,5苯环上引入硝基和3位N原子引入苄基改变分子的共轭平面,使二阶非线性极化率总有效值(βtot)减小,吸收峰总体蓝移.同时还发现,在CH2Cl2溶剂中a和c分子的λmax主要来源于HOMO→LUMO的π一π*跃迁,b和d分子的λmax主要来源于HOMO→LUMO+2的π→π*跃迁.     

六硝基六氮杂异伍兹烷结构和性质的理论研究

用abinitio和DFT方法,分别在HF/6-31G^*和B3LYP/6-31G^*水平下全优化计算了高能量密度材料六硝基六氮杂异伍兹烷(HNIW)的α(γ),β和ε型构象的分子几何构型、电子结构、IR谱和298～1000K温度下的热力学性质,细致分析比较了两种方法和相关的实验结果。理论计算几何参数与实验值相一致。分子中N—N键较长,N—N键Mulliken集居数较小,预示该键为热解和起爆的引发键。所得的IR谱形符合实验、指纹区频率与实验的平均绝对差值小于45cm^-1。由前线MO能级及其差值预示的热力学稳定性次序[ε＞α(γ)＞β]与实验排序相吻合。     

硫化反式聚异戊二烯电子性质的理论化学研究

应用量子化学计算方法,对反式聚异戊二烯本征态和硫化态结构的能量及电子性质等进行了计算.结果表明,当聚异戊二烯掺杂硫后,相邻两链之间的距离a⊥变窄,体系的总能量降低,从而使整个掺杂体系更加稳定.另外,在硫化聚异戊二烯分子中,S原子位于两个相邻聚异戊二烯链之间,并偏向于其中一个分子链的C C双键的一侧,即与相邻两链中相对应的两个C C双键形成π-p-π共轭体系,增加了电子在两个聚异戊二烯链间的流动性,从而使硫化的反式聚异戊二烯更加稳定.另外,根据固体能带理论,采用量子化学EHMO方法,对反式聚异戊二烯本征态和硫掺杂态的能带结构进行了计算,根据硫化前后能隙和带宽的变化,解释了反式聚异戊二烯掺杂后呈现电导率各向异性的原因.     

DFT/TDDFT studies on the electronic structures and spectral properties of rhenium(I) pyridinybenzoimidazole complexes

The electronic structures and spectral properties of three Re(I) complexes [Re(CO)3XL] (X = Br, Cl; L = 1-(4-5'-phenyl-1,3,4-oxadiazolylbenzyl)-2-pyridinylbenzoimidazole (1), 1-(4-carbazolylbutyl)-2-pyridinylbenzoimidazole (2), and 2-(1-ethylbenzimidazol-2-yl)pyridine (3)) were investigated theoretically. The ground and the lowest lying triplet excited states were fully optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ levels, respectively. TDDFT/PCM calculations have been employed to predict the absorption and emission spectra starting from the ground and excited state geometries, respectively. The lowest lying absorptions were calculated to be at 481, 493, and 486 nm for 1-3, respectively, and all have the transition configuration of HOMO-->LUMO. The lowest lying transitions can be assigned as metal/ligand-to-ligand charge transfer (MLCT/LLCT) character for 1, ligand-to-ligand charge transfer (LLCT) character for 2, and mixed MLCT/LLCT and intraligand pi-->pi* charge transfer (ILCT) character for 3. The emission of 1 at 551 nm has the MLCT/(3)LLCT character, 2 has the (3)MLCT/(3)LLCT character at 675 nm, and the 651 nm transition of 3 has the character of (3)MLCT/(3)LLCT/(3)ILCT. Ionization potentials (IP) and electron affinities (EA) calculations show that the comparable EA and smaller IP values and the relatively balanceable charges transfer ability of 2 with respect to 1 and 3 result in the higher efficiency of OLEDs. The calculated results show that the absorption and emission transition character and device's efficiency can be changed by altering the ancillary ligands.     

Theoretical studies on the electronic structures and spectra of single silicon-doped SWCNTs

The equilibrium geometries and electronic structures of a series of SWCNTs doped with a silicon atom were studied by using density function theory (DFT). The most stable doping site of silicon predicted at B3LYP/6-31G(d,p) level was located near the boundary of the SWCNTs. The energy gaps of (3,3) C₄₈, (3,3) C₆₀ and (3,3) C₇₂ were respectively decreased by 0.43, 0.25 and 0.14 eV after doping. Based on the B3LYP/6-31G(d) optimized geometries, the electronic spectra of the doped SWCNTs were computed using the INDO/CIS method. The first UV absorption at 973.9 nm of (5,5)-Si(L) (C₅₉Si) compared with that at 937.5 nm of (5,5) (C₆₀) was red-shifted. The ¹³C NMR spectra and nuclear independent chemical shifts (NICS) of the doped SWCNTs were investigated at B3LYP/6-31G(d) level. The chemical shift at 119.4 of the carbon atom bonded with the silicon atom in (3,3)-Si(L) (C₅₉Si) in comparison with that at 144.1 of the same carbon atom in (3,3) (C₆₀) moved upfield. The tendency of the aromaticity (NICS = −0.1) for (3,3)-Si(H) (C₄₇Si) with respect to that of the anti-aromaticity (NICS = 6.0) for (3,3) (C₄₈) was predicted.      

Hydrogen bond and the structures of 2-, 3-and 4-biphenylmethanols

Density functional theory (B3LYP/6-31G*) is applied to calculate structures, energy, dipole moment, polarizability, frequencies of normal vibrations in the harmonic approximation and intensities in vibrational spectra of 2-, 3-, and 4-biphenylmethanol molecules and their H-complexes that can form in crystalline, amorphous, and liquid phases. Based on the analysis of simulation results, the effect of the position of a methanol group in the molecule on its vibrational spectrum is discussed. The structure forming role of a hydrogen bonds in biphenylmethanols and the possibility of realization of two polymorphic modifications in 2-biphenylmethanol are stated. These modifications are: metastable monoclinic, in which each of four molecules of the unit cell is a link of a chain H-associate; and stable triclinic, in which four molecules of the unit cell organize an H-complex in the form of a cyclic tetramer. It is found that crystalline samples of 3-and 4-biphenylmethanols consist of chain H-associates. A glass-like sample of 2BPhM being a mixture of H-complexes consisting of cyclic tetramers and chain associates contains crystalline nuclei of triclinic and monoclinic polymorphous modifications in the supercooled state. In a liquid sample of 2BPhm, chain H-associates and free molecules are realized.     

Theoretical studies of structural and electronic properties of AlnAsn clusters

We present theoretical results of size dependent structural, electronic, and optical properties of ligand‐free stoichiometric Al_nAs_n clusters of zinc‐blende modification. The investigation is done using a simplified parametrized linear combination of atomic orbital–density functional theory‐local density approximation–tight‐binding (LCAO–DFT–LDA–TB) method and consider clusters with n up to around 100. Initial structures have assumed as spherical parts of infinite zinc‐blende structure and then allowed to relax to the closest local‐energy‐minimum structure. We analyze the radial distributions of atoms, Mulliken populations, electronic energy levels (in particular, HOMO and LUMO), bandgap, and stability as a function of size and composition. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

5,6,9,10-四脱氢苯并环辛烯结构和性质的理论研究

在RHF/6-31G^**,MP2/6-31G^**,B3LYP/6-31G^**水平下优化了5,6,9,10-四脱氢苯并环辛烯的平衡几何构型。用B3LYP/6-31G^**方法计算了该化合物的红外光谱、拉曼光谱、核磁共振谱。计算结果与实验结果吻合很好,从而在理论上证实了它的存在。用等键反应分析,自然键轨道方法对它的稳定性和共轭性分别进行了讨论。结果表明5,6,9,10-四脱氢苯并环辛烯分子平面刚性结构,可能稳定存在,但由于苯环共轭性的削弱和较高的张力,使得它易于分解。