Lithium salt electride with an excess electron pair--a class of nonlinear optical molecules for extraordinary first hyperpolarizability

A new lithium salt electride with an excess electron pair is designed, for the first time, by means of doping two sodium atoms into the lithium salt of pyridazine. For this series of electride molecules, the structures with all real frequencies and the static first hyperpolarizability (beta 0) are obtained at the second-order M?ller-Plesset theory (MP2). Pyridazine H 4C 4N 2 becomes the lithium salt of pyridazine Li-H 3C 4N 2 as one H atom is substituted by Li. The lithium salt effect on hyperpolarizability is observed as the beta 0 value is increased by about 170 times from 5 to 859 au. For the electride effect, an electride H 4C 4N 2...Na 2 formed by doping two Na atoms into pyridazine, the beta 0 value is increased by about 3000 times from 5 to 1.5 x 10 (4) au. Furthermore, combining these two effects, that is, lithium salt effect and electride effect, more significant increase in beta 0 is expected. A new lithium salt electride Li-H 3C 4N 2...Na 2 is thus designed by doping two Na atoms into Li-H 3C 4N 2. It is found that the new lithium salt electride, Li-H 3C 4N 2...Na 2, has a very large beta 0 value (1.412 x 10 (6) au). The beta 0 value is 2.8 x 10 (5) times larger than that of H 4C 4N 2, 1644 times larger than that of Li-H 3C 4N 2, and still 93 times larger than that of the electride H 4C 4N 2...Na 2. This extraordinary beta 0 value is a new record and comes from its small transition energy and large difference in the dipole moments between the ground state and the excited state. The frequency-dependent beta is also obtained, and it shows almost the same trends as H 4C 4N 2 < Li-H 3C 4N 2 < H 4C 4N 2...Na 2 < Li-H 3C 4N 2...Na 2. This work proposes a new idea to design potential candidate molecules with high-performance NLO properties.     

The structure and the large nonlinear optical properties of Li@calix[4]pyrrole

A new compound with electride characteristics, Li@calix[4]pyrrole, is designed in theory. The Li atom in Li@calix[4]pyrrole is ionized to form a cation and an excess electron anion. Its structure with C(4v) symmetry resembles a cup-like shape. It may be a stable organic electride at room temperature. The first hyperpolarizability of the cup-like electride molecule is first investigated by the DFT (B3LYP) method. The result shows that this electride molecule has a considerably large first hyperpolarizability with beta(0) = 7326 au (63.3 x 10(-30) esu), while the beta(0) value of the related calix[4]pyrrole system is only 390 au. Obviously, the Li atom doped in calix[4]pyrrole brings a dramatic change to the electronic structure, so that the first hyperpolarizability of Li@calix[4]pyrrole is almost 20 times larger than that of calix[4]pyrrole. We find that the excess electron from the Li atom plays an important role in the large first hyperpolarizability of Li@calix[4]pyrrole. The present investigation reveals a new idea and different means for designing and synthesizing high-performance NLO materials.     

Inorganic Molecular Electride Mg4O3: Structure,Bonding, and Nonlinear Optical Properties

Growing demands of material science and, in particular, in the field of nonlinear optics (NLO) encourage us to look for stable highly polarizable molecules with excess diffuse electrons. An unusual class of compounds called electrides comply with these requirements. Many attempts have been made, yet only few electrides have been synthesized as solids and none of them as molecular species. In this paper, a new theoretically designed molecular species with electride characteristics is reported. The idea of this molecular electride comes from the formation of electride-like features in the MgO crystal with defect F-centers. The geometry of the investigated molecule can be described as a Mg₄O₄ cube with one oxygen atom removed. In Mg₄O₃, two 3s electrons are pushed out from the inner area of the molecule forming a diffuse electride multicentered bond. Our calculations show that this electride-like cluster possesses a noticeably large first hyperpolarizability β=5733 au. At the same time, a complete cube Mg₄O₄ and Mg₄O₃²⁺ without electride electron pair have much smaller β: 0 au and 741 au, respectively. This fact indicates the decisive role of the electride electron pair in NLO properties. Additionally, vertical detachment energies of isomers (VDE), excitation energies ΔE, polarizabilities α, and IR spectra were calculated. These properties, including β, are supposed to be observable experimentally and can serve as indirect evidence of the stable molecular electride formation.     

Theoretical Study of the Substituent Effects on the Nonlinear Optical Properties of a Room‐Temperature‐Stable Organic Electride

Excess‐electron compounds can be considered as novel candidates for nonlinear optical (NLO) materials because of their large static first hyperpolarizabilities (β₀). A room‐temperature‐stable, excess‐electron compound, that is, the organic electride Na@(TriPip222), was successfully synthesized by the Dye group (J. Am. Chem. Soc. 2005 , 127, 12416). In this work, the β₀ of this electride was first evaluated to be 1.13×10⁶ au, which revealed its potential as a high‐performance NLO material. In particular, the substituent effects of different substituents on the structure, electride character, and NLO response of this electride were systemically studied for the first time by density functional theory calculations. The results revealed that the β₀ of Na@(TriPip222) could be further increased to 8.30×10⁶ au by introducing a fluoro substituent, whereas its NLO response completely disappeared if one nitryl group was introduced because the nitro‐group substitution deprived the material of its electride identity. Moreover, herein the dependence of the NLO properties on the number of substituents and their relative positions was also detected in multifluoro‐substituted Na@(TriPip222) compounds.     

Organocatalyzed highly enantioselective direct aldol reactions of aldehydes with hydroxyacetone and fluoroacetone in aqueous media: the use of water to control regioselectivity

An organocatalyst prepared from (2R,3R)-diethyl 2-amino-3-hydroxysuccinate and L-proline exhibited high regio- and enantioselectivities for the direct aldol reactions of hydroxyacetone and fluoroacetone with aldehydes in aqueous media. It was found that water could be used to control the regioselectivity. The presence of 20-30 mol% of the catalyst afforded the direct aldol reactions of a wide range of aldehydes with hydroxyacetone to give the otherwise disfavored products with excellent enantioselectivities, ranging from 91 to 99% ee, and high regioselectivities. Aldolizations of fluoroacetone with aldehydes mediated by 30 mol% of the organocatalyst in aqueous media preferentially occurred at the methyl group, yielding products with high enantioselectivities (up to 91% ee); however, these additions took place dominantly at the fluoromethyl group in THF. Optically active 3,5-disubstituted tetrahydrofurans and (2S,4R)-dihydroxy-4-biphenylbutyric acid were prepared by starting from the aldol reaction of hydroxyacetone. Theoretical studies on the role of water in controlling the regioselectivity revealed that the hydrogen bonds formed between the amide oxygen of proline amide, the hydroxy of hydroxyacetone, and water are responsible for the regioselectivity by microsolvation with explicit one water molecule as a hydrogen-bond donor and/or an acceptor.     

Inorganic electride: theoretical study on structural and electronic properties

We report self-consistent ab initio calculations of structural and electronic properties for a kind of recently synthesized inorganic electride. The optimized geometry gives zigzag cesium chains within the sinusoidal channels of the zeolite. Among the wide energy gap of the zeolite, near the conduction bands, there are two interstitial electride bands mainly contributed by 6s electrons of Cs atoms, which have a delocalized real space distribution along the channels. For all different doping rates studied, we find that a finite density of states appears at the Fermi level, which predicts a metallic behavior of this material. Detailed electronic structure reveals all the essential properties of the electride model. The shift of Fermi level and the delocalization of the highest occupied bands cause this material to be a powerful reducing agent.     

超声辐射下水介质中一锅合成3-甲基-4-芳亚甲基-异噁唑-5(4H)-酮

报道了室温超声辐射下, 水相中通过乙酰乙酸甲酯、盐酸羟胺和芳香醛的三组分一锅反应, 合成了一系列3-甲基-4-芳亚甲基-异噁唑-5(4H)-酮衍生物. 在超声波辐射下, 参与反应的醛无论芳环上连有吸电子基或供电子基, 该一锅反应在室温下都能较好地进行; 对于α,β-不饱和醛、杂环芳醛以及二元芳醛与乙酰乙酸甲酯、盐酸羟胺的一锅反应也能在室温下顺利进行, 获得中等以上的收率. 产物的结构通过元素分析, IR, 1H NMR及单晶解析表征. 该方法具有操作简单和环境友好等优点.     

Allylation Reactions of Aldehydes with Allylboronates in Aqueous Media: Unique Reactivity and Selectivity that are Only Observed in the Presence of Water

Zn(OH)₂‐catalyzed allylation reactions of aldehydes with allylboronates in aqueous media have been developed. In contrast to conventional allylboration reactions of aldehydes in organic solvents, the α‐addition products were obtained exclusively. A catalytic cycle in which the allylzinc species was generated through a B‐to‐Zn exchange process is proposed and kinetic studies were performed. The key intermediate, an allylzinc species, was detected by HRMS (ESI) analysis and by online continuous MS (ESI) analysis. This analysis revealed that, in aqueous media, the allylzinc species competitively reacted with the aldehydes and water. An investigation of the reactivity and selectivity of the allylzinc species by using several typical allylboronates ( 6a , 6b , 6c , 6d ) clarified several important roles of water in this allylation reaction. The allylation reactions of aldehydes with allylboronic acid 2,2‐dimethyl‐1,3‐propanediol esters proceeded smoothly in the presence of catalytic amounts of Zn(OH)₂ and achiral ligand 4d in aqueous media to afford the corresponding syn‐adducts in high yields with high diastereoselectivities. In all cases, the α‐addition products were obtained and a wide substrate scope was tolerated. Furthermore, this reaction was applied to asymmetric catalysis by using chiral ligand 9 . Based on the X‐ray structure of the Zn‐ 9 complex, several nonsymmetrical chiral ligands were also found to be effective. This reaction was further applied to catalytic asymmetric alkylallylation, chloroallylation, and alkoxyallylation processes and the synthetic utility of these reactions has been demonstrated.     

水介质中α,α-双(4-羟基香豆素-3-基)甲苯的洁净合成

在水介质中三乙基苄基氯化铵(TEBA)存在下, 芳醛与4-羟基香豆素反应为α,α-双(4-羟基香豆素-3-基)甲苯提供了一种快速、方便、高效和洁净的合成方法.     

A Simplified Wittig Synthesis Using Solid/Liquid Transfer Processes

The use of a solid-liquid phase transfer process led to the selective preparation of Z-olefins (ratio Z:E=4:1) in high yields from aromatic or aliphatic aldehydes and a phosphonium salt in alkaline media (1–4). A further advantage of the method is the possible use of non anhydrous solvents.     

Theoretical study of a novel organic electride with large nonlinear optical responses

The design of stable organic electrides with high nonlinear optical (NLO) properties is a challenge in organic and materials chemistry. Here we theoretically design of a novel organic molecular electride model, Li⁺(C₂₀H₁₅Li₅)e⁻, by modifying the lithiation and Li-doping based on dodecahedrane (C₂₀H₂₀). Its electride characteristic is verified by the quantum theory of atoms in molecules and electron localization function analyses. For the first time, the strategy of steric protection is applied to improve the stability of the organic electride Li⁺@(C₂₀H₁₅Li₅)e⁻, in which the closed C₂₀ cage serves not only as the ligand with a negative inner electric field to stabilize the Li cation but also as a barrier to prevent the Li cation from escaping. Meanwhile, the released excess electron is firmly captured in the cavity of Li₅. Moreover, Li⁺(C₂₀H₁₅Li₅)e⁻ displays a remarkably large first hyperpolarizability of 1.4 × 10⁴ au with potential application in organic second-order NLO materials.     

Enhanced Oxygen Reduction on Graphene via Y\begin{document}$_5$\end{document}Si\begin{document}$_3$\end{document} Electride Substrate: a First-Principles Study

Manipulating the chemical reactivity of graphene toward oxygen reduced reduction (ORR) is of particular interest for both fundamental research and practical application in fuel cell. Deposing graphene on selected substrate provides a structure-intact strategy to enhance its chemical reactivity due to substrate-induced charge and interface effect. Here, we report the graphene deposited on one-dimensional electride Y\begin{document}$_5$\end{document}Si\begin{document}$_3$\end{document} as an effective ORR catalyst in acidic media. Thermodynamic calculations suggest that depositing graphene on electride materials can facilitate the protonation of O\begin{document}$_2$\end{document}, which is the rate-determining step based on the four-electron reaction pathway and thus promote the ORR activity. Further electronic calculations reveal that low work function (3.5 eV), superior electrical conductivity and slight charge transfer from substrate to graphene result in the enhanced ORR performance of graphene. These findings shed light on the rational design of ORR catalysts based on graphitic materials and emphasize the critical role of substrates for energy-related electrochemical reactions.     

μ-Bis(cyanotrihydroborato)-tetrakis(triphenylphosphine) dicopper(I). A new,selective, pH dependent reducing agent

The title compound selectively reduces acid chlorides to aldehydes under neutral conditions and aldehydes and ketones to alcohols in acidic media. 4-$\text{tert}$-Butylcyclohexanone is reduced to the $\text{trans}$ alcohol with a high degree of stereoselectivity (94:6).     

Novel superalkali superhalogen compounds (Li3)+(SH)- (SH=LiF2, BeF3, and BF4) with aromaticity: new electrides and alkalides.

Optimized structures, with all real frequencies, of superalkali superhalides (Li(3))(+)(SH)(-) (SH=LiF(2), BeF(3), and BF(4)), are obtained, for the first time, at the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ computational levels. These superalkali superhalides possess three characteristics that are significantly different from normal alkali halides. 1) They have a variety of structures, which come from five bonding mode types: edge-face, edge-edge, face-face, face-edge, and staggered face-edge. We find that the bonding mode type closely correlates with the Li(3)-SH bond energy. 2) The valence electrons on the Li(3) ring are pushed out by the (SH)(-) anion, and become excess electrons, conferring alkalide or electride characteristics on these Li(3)-SH species, depending on the bonding mode type. 3) The highest occupied molecular orbital of each Li(3)-SH species is a doubly occupied delocalized sigma bonding orbital on the Li(3) ring, which indicates its aromaticity. It is noticeable that the maximum negative nucleus-independent chemical shift value (about -10 ppm) moves out from the center of the Li(3) ring, owing to repulsion by the SH(-) anion. We find that these superalkali superhalides are not only complicated "supermolecules", but are also a new type of alkalide or electride, with aromaticity.     

Highly efficient solvent-free synthesis of quinazolin-4(3H)-ones and 2,3-dihydroquinazolin-4(1H)-ones using tetrabutylammonium bromide as novel ionic liquid catalyst

<正>A simple and efficient procedure for the synthesis of 2-arylquinazolin-4(3H)-ones has been developed through cyclocondensation of 2-aminobenzamide with aromatic aldehydes using tetrabutylammonium bromide(TBAB) as novel neutral ionic liquid catalyst in the presence of copper(Ⅱ) chloride(CuCl_2) as oxidizing agent under solvent-free conditions at 100℃.In the absence of CuCl_2 and under a nitrogen atmosphere,the unoxidized intermediates,2-aryl-2,3-dihydroquinazolin-4(1H)-ones,were isolated. Treatment of these intermediates with CuCl_2 in TBAB media gave the oxidized products 2-arylquinazolin-4(3H)-ones.On the other hand,cyclocondensation of 2-aminobenzamide with aromatic aldehydes in TBAB under microwave irradiation directly gave 2- arylquinazolin-4(3H)-ones.     

Efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by titanium silicon oxide nanopowder in aqueous media

An efficient synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives is accomplished in aqueous media by a three-component reaction of isatoic anhydride, primary amines or ammonium acetate, and aldehydes catalyzed by titanium silicon oxide nanopowder. A variety of 2,3-dihydroquinazolin-4(1H)-one derivatives were synthesized using this methodology in good to excellent yields. The catalyst was recovered and recycled up to four times without significant loss in the catalytic activity.     

Cetyltrimethylammonium chloride (CTAC) catalyzed one-pot synthesis of novel coumarin-4H-pyran conjugates in aqueous media

Novel fluorescent coumarin-4H-pyran conjugates were achieved by three-component reactions of various synthetic β-ketoesters with aldehydes and malononitrile in aqueous media.Besides mild reaction conditions,operational simplicity,absence of tedious separation procedures,using of inexpensive and nontoxic commercially available cationic surfactant cetyltrimethylammonium chloride(CTAC) as a catalyst are the prominent advantage of this method.     

微波辐射下氨磺酸催化水相合成3,3-亚芳基双(4-羟基香豆素)

在水介质中, 用氨磺酸作催化剂并经微波辐射, 使芳醛与4-羟基香豆素反应合成3,3-亚芳基双(4-羟基香豆素), 具有催化剂易得、环境友好、后处理简便、反应时间短和产率高等优点.     

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by zirconium(Ⅳ) chloride as a mild and efficient catalyst

2,3-Dihydroquinazolin-4(1H)-ones have been synthesized in the high to excellent yields via condensation of 2-aminobenzamide with aldehydes and ketones in the presence of catalytic amount of ZrCl_4 in EtOH at room temperature.Mild reaction conditions, clean reaction media,simple workup and easy purification are advantages of this methodology.     

Pictet-spengler reaction in the synthesis of condensed benzodiazepines. 2.* Synthesis of new derivatives of 11,12-dihydroquinazoline-[3,2-<Emphasis Type="Italic">c</Emphasis>][2, 3]benzodiazepin-14(6H)-ones

New derivatives of dihydroquinazoline[3,2-c][2, 3]benzodiazepin-14(6H)-ones were synthesized using the Pictet-Spengler reaction of 3-amino-2-(3,4-dimethoxybenzyl)quinazolin-4(3H)-one with aliphatic and heterocyclic aldehydes in acid media.