新型Salen型配合物的合成和表征及轴向配位热力学

采用金属模板法合成了四个新型Salen型单、双核金属配合物,并用元素分析、核磁共振(1HNMR)、电喷雾质谱(ESI-MS)、傅里叶变换红外光谱(FT-IR)等手段进行了表征.使用紫外-可见(UV-Vis)光谱滴定法和圆二色(CD)光谱研究了主体金属镍配合物与咪唑类含氮小分子的轴向配位反应热力学性质.结果表明:主体与咪唑(Im)和N-甲基咪唑(N-MeIm)的配位数是2,而与2-Et-4-MeIm和2-MeIm的配位数是1;轴配体系的热力学数据显示主体与咪唑类配体的平衡常数按K苓(Im)K苓(N-MeIm)K苓(2-Et-4-MeIm)K苓(2-MeIm)顺序依次减小;测得的△rHm苓和△rSm苓数据表明该轴向配位反应为放热、熵增加过程.     

手性不对称Salen Ni对咪唑类和二胺类客体的分子识别研究

用紫外-可见光谱滴定法研究了新型手性不对称Salen Ni主体(1和2)与咪唑类和二胺类客体的分子识别行为. 结果表明, 二胺类客体的缔合常数顺序为Kθ(乙二胺)>Kθ(丙二胺); 咪唑类客体的缔合常数顺序为Kθ(Im)>Kθ(N-MeIm)>Kθ(2-MeIm)>Kθ(2-Et-4-MeIm), 除主体2对2-乙基-4-甲基咪唑的配位数为1外, 其它体系的配位数均为2. 通过测定识别过程的热力学函数ΔrHθm和ΔrSθm发现, 反应为放热、熵减少过程; 利用圆二色光谱研究了识别过程中的主-客体结合能力的强弱; 用分子力学方法研究了主客体体系的最低能量构象, 并通过量化计算对实验事实做了进一步解释.     

新型手性双核Salen锰（III）配合物对咪唑、吡啶类客体的分子识别研究

合成并表征了新型手性双核Salen配体1及其锰（III）配合物2（主体2）。用 紫外-可见光谱滴定法研究了主体2与四种咪唑类、四种吡啶类客体在CHCl_3中的分 子识别行为。实验结果表明：对咪唑客体的缔合常数按K（Im） > K (2 - Melm) > K (N-MeIm) > K (EtMelm)顺序递减；吡啶类顺序为K （PyO） > K (4-PhPyO) > K (DMAP) > K(Py)，配位数n值均为2。测定了识别过程的Δ_rH_m，Δ_rS_m， 发现此类反应为放热、熵减小的过程，反应体系中存在焓熵补偿关系。与单核的 Salen锰（III）配合物3（主体3）进行比较，除EtMeIm与3的配位数为1外，其他唑 类客全的配位数均为2。就与客体的缔合能力而言，主体2比3大。用圆二色光谱（ CD）研究了主-客体的分子识别行为。     

新型手性双核Salen Mn的分子识别研究

合成了新型手性双Salen配体1及双核锰配合物2,并进行了表征.用紫外-可见光谱滴定法研究了主体双核Salen Mn（2）与咪唑、吡啶类客体的分子识别行为.结果表明:对咪唑类客体的缔合常数顺序为K(Im) > K(2-MeIm) > K(N-MeIm);对吡啶类客体缔合常数顺序为K(4-MePy) > K(3-MePy)> K(Py).主体与所有客体的配位数均为2.测定了识别过程的热力学函数ΔrHmθ, ΔrSmθ, 发现反应为放热、熵减过程.利用圆二色光谱研究了识别过程的Cotton效应.用分子力学方法研究了主客体的最低能量构象,结合量化计算结果对实验事实做了进一步解释.     

新型手性双核Salen锰（III）配合物对咪唑、吡啶类客体的分子识别研究

合成并表征了新型手性双核Salen配体1及其锰（III）配合物2（主体2）。用 紫外-可见光谱滴定法研究了主体2与四种咪唑类、四种吡啶类客体在CHCl_3中的分 子识别行为。实验结果表明：对咪唑客体的缔合常数按K（Im） > K (2 - Melm) > K (N-MeIm) > K (EtMelm)顺序递减；吡啶类顺序为K （PyO） > K (4-PhPyO) > K (DMAP) > K(Py)，配位数n值均为2。测定了识别过程的Δ_rH_m，Δ_rS_m， 发现此类反应为放热、熵减小的过程，反应体系中存在焓熵补偿关系。与单核的 Salen锰（III）配合物3（主体3）进行比较，除EtMeIm与3的配位数为1外，其他唑 类客全的配位数均为2。就与客体的缔合能力而言，主体2比3大。用圆二色光谱（ CD）研究了主-客体的分子识别行为。     

手性锌卟啉对咪唑类客体的分子识别及圆二色光谱的研究

研究了手性α,α,α,β－四－[邻（叔丁氧羰L－酪氨酸）氨基苯基]卟啉 锌[α,α,α,β-ZnT(o-Boc)TyrTAPP](1)和手性α,α,α,β－四－[邻（叔 丁氧羰L－丙氨酸）氨基苯基]卟啉锌[α,α,α,β-ZnT(o-BocAla)TAPP](2)对 咪唑、2－甲基咪唑、N－甲基咪唑和2－乙基－4－甲基咪唑的分子识别行为,分别 求得主体（1）对咪唑类分子识别的缔合常数顺序为K（Im)>K(2-MeIm)>K(N-MeIm) >K(2-Et-4-MeIm),主体（2）对咪唑类分子识别的缔合常数顺序为K（2－MeIm)>K (Im)>K(2-Ek-4-MeIm)>K(N-MeIm),并用圆二色光谱（CD）研究了主体1和2对咪唑 在客体在CHCl3中分子识别的光谱行为,与热力学的结果做了比较。     

新型手性Salen双核锌配合物的分子识别研究

合成了新型手性Salen配体（H3L）及新型手性Salen双核锌配合物（主体）.通过研究主体对咪唑类客体及氨基酸酯类客体的分子识别行为,测定了这些配位反应的缔合常数.主体对咪唑类客体分子识别的缔合常数顺序为:K(Im) >K(2-MeIm) >K(2-Et-4-MeIm).主体对氨基酸酯类客体分子识别的缔合常数顺序为:K(LeuOCH3) >K(ValOCH3) >K(AlaOCH3) >K(SerOCH3),配位数均为2.主体与D、 L型氨基酸酯分子识别反应在不同温度下的缔合常数结果表明,随着温度的升高,对映选择性下降.实验发现反应体系中存在焓熵补偿关系. CD光谱的研究结果也反映了主体对不同客体识别能力的差异.     

手性SalenZn配合物的合成及对咪唑类、吡啶类客体的分子识别研究

合成并表征了手性Salen配体1及其Zn配合物2。详细讨论了配体及配合物的电 子光谱和圆二色光谱性质。用紫外—可见光谱滴定法测定了主体2与4种咪唑、5种 吡啶客体轴向配位反应的平衡常数，研究了主体分子2的分子识别行为。实验结果 表明：各种客体的缔合常数，咪吡类按K(Im)＞K(2—MeIm)＞K(SMIm)＞K(EMIm)顺 序递减;吡啶类按K(Py)＞K(3-Py)＞K(3，5-Py)＞K(2，4—Py)＞K(2，4，6—Py)顺 序递减。测定了识别过程的△rGm^-,△rHm^-,△rSm^-，发现该反应是放热、熵减 小的过程。采用分子力学的方法考察了主客体的最低能量构象，并对该构象进行量 子化学计算，从理论上对实验事实给予较好的解释。     

新型水溶性手性Salen配合物的合成及性质研究

合成并表征了新型水溶性手性Salen 配体(R,R)-N,N’-二{4-[2-(三甲胺基)乙氧基]水杨醛}-1,2-环己二胺二高氯酸盐(L)及金属配合物ML [M＝Zn(II), Cu(II), Ni(II), Co(II), Fe(III), Mn(III)]. 讨论了手性配体L及配合物ZnL的电子光谱和圆二色光谱性质, 用UV-Vis光谱滴定和CD光谱滴定法研究了ZnL对手性氨基酸对映异构体的分子识别. 测定了主体ZnL与客体氨基酸轴向配位反应的配位数(n)、缔合常数(K)及热力学函数 测得缔合常数的大小顺序为KPhe＞KVal＞KThr. 研究发现反应是放热、熵减小的过程. 用凝胶电泳的方法初步研究了此类手性金属配合物在H2O2存在下对DNA的裂解作用.     

新型手性酪氨酸卟啉锌对咪唑类客体的分子识别研究

合成了两种新型手性锌卟啉Zn(o-BocTyr)TAPP和Zn(p-BocTyr)TAPP.通过元素分析、紫外可见光谱及核磁共振谱对其性质进行了表征.研究了这两种锌卟啉对咪唑类的分子识别行为,识别的缔合常数顺序均为K(2-MeIm)>K(Im)>K(N-MeIm)>K(2-Et-4-MeIm).同时,采用理论计算和圆二色谱研究了咪唑类小分子在与锌卟啉分子识别时进攻主体位置的变化,这对于研究卟啉分子识别起到一定的作用.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.