含1,3-方酸苯螺旋共轭分子的设计及其电子光谱和非线性光学性质的理论研究

以量子化学半经验方法PM3优化构型为基础，利用INDO／CI方法研究了嵌入1，3－方酸的苯螺旋共轭分子的电子光谱。同时利用INDO／CI－SOS程度计算了它们的二阶非线性光学系数βijk和βμ值，从而探索分子结构与电子光谱及非线性光学性质的关系。理论计算结果表明：在苯螺旋共轭分子中适当地嵌入方酸后，其二阶非线性光学系数增大，与苯螺旋共轭分子和1，3－方酸的比较表明，方酸环处于左端的体系有很好的二阶非线性光学性质，可能成为较好的光学材料。     

螺旋共轭分子2，2‘—螺二茚—1，1’,3,3‘—四酮及其衍生物的二阶非线性光学性质与分子结构关系的研究

采用AM1和ZINDO系列方法研究了螺旋共轭分子2，2‘-螺二茚－1，1‘,3,3‘-四酮及其含氮衍生物的几何构型和各分子的稳定构型，并以稳定构型为基础，计算了这些分子的电子光谱、二阶非线性光学系数βμ，β0为电荷转移，考察了取代堪变化对βμ的影响。计算结果表明，所设计分子兼具较大的二阶非线性光学系数和较高的透过率，有希望成为一类新型的二阶非线性光学材料。     

硼羰基取代螺旋共轭化合物电子结构的理论研究

在AM1方法优化的几何结构基础上,用INDO/CI-SOS方法深入探讨硼羰基(B—CO)螺旋共轭化合物的二阶非线性光学性质,讨论了硼羰基的不同取代位置对螺旋共轭体系的电子光谱、二阶非线性光学系数的影响.结果表明硼羰基的引入可改善体系的非线性光学性质,随着硼羰基个数的增加,二阶非线性光学系数增大,大入射波长为1064nm时,β绝对值比未被取代的螺旋共轭化合物的β值增大一个数量级,达到13 84×10-40C·m.     

N-取代吩噻嗪衍生物分子的结构和二阶非线性光学性质的理论研究

在ZINDO方法基础上, 按完全态求和(SOS)公式, 编制了计算分子二阶非线性光学系数βijk的程序。研究了各种取代基在吩噻嗪的氮上取代后衍生物的结构和二阶非线性光学系数。结论是N上取代推电子基对增大二阶光学非线性有利, N上取代吸电子基对增大二阶光学非线性不利。扩大共轭范围对增大二阶光学非线性有利。对上述结果在微观上给予了解释。     

吩噻嗪侧环取代衍生物的二阶非线性光学性质的ZINDO－SOS研究

在ＺＩＮＤＯ方法基础上，按完全态求和（ＳＯＳ）公式编制了计算分子二阶非线性光学系数β＿（ｉｊｋ）、β＿μ的程序，研究了各种吩噻嗪侧环取代衍生物的结构和二阶非线性光学性质，结论是侧环上推、拉电子取代基（不太弱）对增大二阶光学非线性都有利，扩大共轭范围也对增大二阶光学非线性有利，并对上述结果在微观上给予了解释。     

螺旋共轭化合物及其相对应的多烯及联苯连接合物的结构,？…

用ＡＭ１和ＩＮＤＯ／ＣＩ方法研究了螺旋共轭化合物Ｉ的结构和电子光谱，并在此基础上，用完全态求和公式（ＳＯＳ，自编程序）计算了二阶非线性光学系数βμ，把结果与其对应的多烯及联苯连接的化合物Ⅱ和Ⅲ用同一方法计算得到的结果加以比较，发现螺旋共轭化合物Ⅰ的二阶非线性光学系数βμ虽然小于ⅡⅢ，但其透明性均比化合物Ⅱ和Ⅲ好。     

螺旋共轭化合物及其相对应的多烯及联苯连接化合物的结构、光谱和二阶非线性光学性质的比较研究

用ＡＭ１和ＩＮＤＯ／ＣＩ方法研究了螺旋共轭化合物Ⅰ的结构和电子光谱,并在此基础上,用完全态求和公式（ＳＯＳ,自编程序）计算了二阶非线性光学系数βμ．把结果与其对应的多烯及联苯连接的化合物Ⅱ和Ⅲ用同一方法计算得到的结果加以比较,发现螺旋共轭化合物Ⅰ的二阶非线性光学系数βμ虽然小于Ⅱ和Ⅲ,但其透明性均比化合物Ⅱ和Ⅲ好     

甲氧基苯基偶氮衍生物电子结构与二阶NLO性质的HF/FF方法研究

采用量子化学HF方法在6-31G水平上优化6个甲氧基苯基偶氮衍生物分子的几何构型，利用HF／6-31G。方法计算它们的偶极矩、电荷分布、前线分子轨道能级并结合有限场(FF)方法计算二阶非线性光学系数．结果表明，偶氮苯衍生物分子具有很好的共轭性，在给吸电子基团作用下，电荷转移明显，展现示出较强的极性．偶氮苯衍生物分子与苯乙烯、Schiff碱类衍生物相似，也具有很好二阶非线性光学活性，同时六元杂环取代的偶氮苯衍生物分子二阶非线性光学系数比未取代的大，五元杂环取代结果相反．     

新型非线性光学材料的分子设计: 系列螺旋共轭化合物的结构、光谱及二 阶非 线性光学性质的理论研究

采用AM1和ZINDO系列方法研究了螺旋共轭分子2,2'-螺二茚-1,1',3,3'-四酮及其腈基衍生物的几何构型,研究了各分子的稳定构型,并以稳定为基础,计算了这些分子的电子光谱,二阶非线性光学系数βμ,β0,及电荷转移,考察了取代基变化对βμ的影响,计算结果表明所设计分子兼具较大的二阶非线性光学系数和较高的透过率,有希望成为一类新型的二阶非线性光学材料。     

若干有机共轭分子二阶非线性光学系数和结构的关系

利用CNDO/S-CI程序计算了四类结构近似的有机共轭分子的二阶非线性光学系数,系统地研究了分子结构、共轭链链长、取代基的电子性质、取代位置等对有机共轭大分子二阶非线性光学性质的影响。研究结果表明,四类化合物的二阶非线性光学性质与其分子结构有着密切的关系。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.