放热型金属合金化对钒基贮氢材料性能影响的理论研究

利用电荷自洽离散变分Xα(SCC-DV-Xα)方法计算了放热型金属合金化对钒基贮氢材料性能的影响。研究结果表明:在钒氢化物V₆₃H₆₄中加入放热型金属后，钒原子的净电荷都减少，而氢原子的净电荷既有增加又有减少，加入Ti、Ca以后，H原子的净电荷减少，而加入Mg、Zr以后，H原子的净电荷增加。研究还表明放热型金属合金化以后，V4s轨道电子态密度峰发生分裂，与H1s和H2s轨道电子态密度重叠程度增大，V-H之间相互作用增强;差分电荷密度还表明M-H之间也有较强的相互作用。Mg合金化导致氢化物V₅₁M₁₂H₆₄的费米能增加，氢化物稳定性减弱;Ca、Ti、Zr合金化导致氢化物V₅₁M₁₂H₆₄的费米能减少，氢化物更稳定。     

Syntheses and Crystal Structures of Two New Pentaborates Templated by Transition-Metal Complexes

Two new pentaborates [M(dap)₃][B₅O₆(OH)₄]₂·H₂O (M = Co (1) and Ni (2); dap = 1,2-diaminopropane) have been hydrothermally synthesized. Both structures were determined by single crystal X-ray diffraction and further characterized by elemental analysis, FT-IR, thermogravimetric analysis and photoluminescence spectroscopy. Two compounds are isostructural and consist of isolated pentaborate [B₅O₆(OH)₄]^? anions and [M(dap)₃]²⁺ complex cations. The anionic [B₅O₆(OH)₄]^? groups are linked by extensive hydrogen bonds to form a 3-D supramolecular framework with large channels, in which the transition-metal complex templates are located. The luminescent properties of 1 and 2 were studied, and blue luminescence occurs with an emission maximum at 405 and 408 nm upon excitation at 332 and 328 nm respectively. Crystal data: 1, monoclinic, space group P2₁/c (No. 14), a = 9.7159(5) Å, b = 29.3372(19) Å, c = 11.5121(6) Å, β = 103.286(5)°, V = 3193.6(3) ų, Z = 4; 2, monoclinic, space group P2₁/c, a = 9.7264(4) Å, b = 29.3810(16) Å, c = 11.5185(6) Å, β = 103.249(4)°, V = 3204.0(3) ų, Z = 4.     

Synthesis,Structural Characterization and Properties of Two Strontium Borates Constructed from Oxo Boron Clusters

Two strontium borates Sr₂[B₆O₉(OH)₄] (1) and Sr₂B₅O₉(OH)·H₂O (2), with acentric structures have been synthesized under hydro/solvothermal conditions. Compound 1 is reported for the first time in the strontium borates system, and it crystallizes in the monoclinic space group P2₁ with unit cell parameters a = 6.8445(5) Å, b = 8.7033(6) Å, c = 8.4632(6) Å, β = 100.581(6)°, V = 495.58(6) ų and Z = 2. Its structure consists of unusual borate layers of 3, 11-membered rings, which are interconnected via Sr–O ionic bonds and hydrogen bonds to generate a 3D supramolecular network. Compound 2 is a known strontium borate, crystallizing in the monoclinic space group C ₂ with a = 10.161 (13) Å, b = 7.965(4) Å, c = 6.393(11) Å, β = 128.0(2)°, V = 407.7(14) ų and Z = 2. Second-harmonic generation measurements on the powder samples reveal that 1 and 2 exhibits good SHG efficiency about 1.5 and 2 times that of KDP (KH₂PO₄) powder respectively.     

低分子肝素/壳聚糖/海藻酸钠复合微囊的制备及释药性能

低分子肝素/壳聚糖/海藻酸钠复合微囊的制备及释药性能;壳聚糖; 海藻酸钠; 低分子肝素; 微囊; 释药性能     

5-氟尿嘧啶壳聚糖微球的制备及其释药性能

5-氟尿嘧啶壳聚糖微球的制备及其释药性能;药物缓释剂     

电化学还原二氧化碳合成碳材料电催化还原氧气合成过氧化氢北大核心CSCD

研究了3种不同阳极(铜丝,镀锌铁丝和镍丝)材料对在熔盐中电化学还原CO_(2)制备的碳材料结构和形貌的影响,并探究了制备的3种碳材料,中空四面体碳(HQC,Cu作为阳极时的还原产物)、碳纳米片(CNS,Fe作为阳极时的还原产物)和海绵状多孔碳(SPC,Ni作为阳极时的还原产物),对2电子氧还原反应(2e;ORR)的电催化性能。研究表明,使用镀锌铁丝作为阳极材料制备的CNS由大量的碳纳米片构成,且该纳米片上具有丰富的孔洞结构以及较大的I_(D)/I_(C)(Raman光谱中D峰与G峰的强度之比,其比值反映材料的缺陷程度)值(0.996)。与HQC和SPC相比,CNS表现出最高的2e;ORR电催化活性和H_(2)O_(2)选择性(接近90%)。CNS的高活性和高选择性归因于其高的I_(D)/I_(C)值和高C—O/C=O比值,说明结构缺陷和C—O/C=O官能团对CNS催化性能至关重要。此外,CNS还具有非常优异的电催化稳定性,在长达14 h的恒电压电化学催化测试后,环电流几乎无衰减。这种以CO_(2)为碳源合成可用于电催化合成过氧化氢(H_(2)O_(2))的碳材料的方法,不仅可以作为缓解温室效应的潜在选项,也为CO_(2)衍生碳的实际应用提供了新的思路。     

The Tri(imidazole)-Derivative Moiety: A New Category of Electron Acceptors for the Design of Crystalline Hybrid Photochromic Materials

The intermarriage of neutral and tripodal imidazole ligand, tris(4-(1H-imidazol-1-yl)phenyl)amine (TIPA), with zinc phosphite yields two hybrid phosphites, [Zn₂(HPO₃)₂(TIPA)]⋅2 H₂O ( 1 ) and [Zn₃(HPO₃)₃(TIPA)]⋅6 H₂O ( 2 ). Compound 1 has a hybrid sheet with neutral zinc-phosphite chains as supramolecular building blocks (SBBs), whereas 2 exhibits a 3D hybrid architecture with other neutral zincophosphite chains as supramolecular building blocks. The structural discrepancy between 1 and 2 is mainly due to the distinct linkage modes between organic TIPA ligands and inorganic zincophosphite chains. Interestingly, compounds 1 and 2 feature fast photochromism in response to UV light irradiation under ambient conditions. The discrepancy of photochromic performance between 1 and 2 is mainly due to the different geometrical configuration of the TIPA ligand. Different to majority of reported hybrid photochromic compounds driven by photochromic active units, the photochromism in 1 and 2 is derived from the electron transfer (ET) between phosphite and non-photochromic triimidazole-derivative ligand TIPA. Compared with the widely explored nonphotochromic polypyridine-derivative as electron acceptors (EAs), our work provides a new EA model for the design of hybrid photochromic materials based on the ligand-to-ligand ET mechanism. A multiple anti-counterfeiting application based on 1 and 2 was investigated.     

Asymmetric [2,3]-Wittig rearrangement of the dienolates of chiral secondary alcohol-substituted β-pyrrolidinyl-γ-allyloxyl-α,β-unsaturated esters: total synthesis of (+)-eldanolide

The asymmetric [2,3]-Wittig rearrangement of the dienolates of various chiral β-pyrrolidinyl-γ-allyloxyl-α,β-unsaturated esters was investigated using different chiral secondary alcohol substitutions. When (1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2,2,1]heptane-1-carboxylic acid diisopropylamide was used as chiral auxiliary, it provided the best enantioselectivity in the rearrangement. When various γ-allyloxy substitutions underwent temperature and additive studies, 1,1-dimethylpropenoxy substitution was found to give the best enantioselectivity. The methodology was applied to the total synthesis of (+)-eldanolide.     

环氧化蓖麻油的合成及表征

采用酸性氧化铝做催化剂对蓖麻油(CO)进行环氧化,探索环氧化反应时间、反应温度和催化剂等不同条件对蓖麻油环氧化的影响,从而优化出合适的反应条件,采用傅立叶变换红外光谱法(FTIR)、热重分析法(TG)对制备的环氧化蓖麻油(ECO)的结构和性质等进行了研究。利用盐酸-丙酮法对环氧化产物进行环氧值的测定,结果表明,在优化条件下,即采用酸性氧化铝做催化剂,H₂O₂的滴加温度保持在50～55 ℃,反应温度65 ℃,反应时间控制在11.5 h,同时同时加入尿素做稳定剂,可以提高H₂O₂的利用率,使环氧化蓖麻油的环氧值达到2.094×10_-3 mol/g。 对ECO的性能表征结果表明,ECO粘度随着环氧值的增大而增大,随着温度的升高而降低。 ECO在250 ℃前能够基本保持稳定,而后开始分解,有3个明显的热分解阶段：250~390 ℃、390~470 ℃、470~580 ℃,ECO的热稳定性较好。