多羟基新咪唑鎓环番的合成及其与DNA相互作用

以咪唑鎓正电荷为结构单元构筑的咪唑鎓型环番可发挥大环效应、范德华力、氢键、π-π堆积及阳离子-π等相互作用而在主-客体化学、超分子化学及仿生研究中备受青睐.已有多个研究组从事该类化合物的设计、合成、分子识别、仿生及超分子性能研究.我们已研究了烷基、芳基、甾体、葡萄糖类等咪唑鎓型环番[1-5].在此我们报道多羟基新咪唑鎓型环番.羟基的引入可使咪唑鎓型环番发挥氢键、偶极-偶极等非共价键力相互作用,增强咪唑鎓环番对阴离子、中性分子特别是DNA等生物分子的识别作用.     

一种硫脲受体的合成及其对阴离子识别的研究

设计合成了一种阴离子受体分子1,4-(4-硝基苯基)-1-(3-氧代-3,4-二氢喹喔啉)氨基硫脲。通过UVVis和荧光光谱考察了其与AcO~-,H_2PO_4-,F~-,Cl~-,Br~-和I~-之间的相互作用。当加入F~-时主体溶液由淡黄色变为蓝色,而当加入AcO-和H_2PO_4~-的时主体溶液由淡黄色变为紫色,而Cl~-、Br~-和I~-的加入主体溶液基本没有变化,可以实现对阴离子的裸眼识别。     

手性联二萘咪唑鎓环番的对映选择性识别性能研究

近年来,咪唑鎓主体分子对客体分子识别性能研究受到越来越多的关注.Sato等首次报道了咪唑鎓主体分子对于卤阴离子的识别[1];Howarth等研究了以二茂铁咪唑鎓化合物对于Cl-,Br-,I-,NO3-以及HSO4-离子的识别和手性咪唑鎓化合物对于R-和S-2-丙氨酸钠的对映选择性识别[2];本课题组合成了一系列咪唑鎓环番,采用1H NMR和紫外光谱分析的手段,研究了它们对于卤阴离子的识别[3];Kim等报道了带有吸电基的三咪唑鎓化合物对于阴离子的识别[4].     

新型手性咪唑鎓环番的合成及对氨基酸的对映选择性识别

以L-氨基酸为手性源, 合成了一系列新型手性咪唑鎓环番, 并进行了结构表征. 在碱性条件下, L氨基酸和乙二醛、甲醛缩合生成了(S)-2-(1-咪唑)羧酸钠, 转化为甲酯后与乙二胺进行胺解反应制得开链手性咪唑二酰胺, 然后与二溴化合物在高稀淡技术和无水条件下进行季铵化关环反应, 再进行阴离子交换制得目标分子(4~6). 以手性咪唑鎓环番为主体分子, 研究了对氨基酸及其衍生物的对映选择性识别作用.     

洞状咪唑环番的合成和晶体结构

由1,3,5-三甲基-2,4,6-三(咪唑甲基)苯与1,3,5-三(溴甲基)苯直接季铵化反应高产率地合成了洞状咪唑环番3(C30H33N63+*Br－3*3H2 O), 对目标物的分子和晶体结构进行了表征. 该晶体属单斜晶系, 空间群为P21, 晶胞参数： a=0.863 4(2) nm, b=0.817 0(4) nm, c=1.088 4(2) nm, β=112.03(1)°, V=\{1.582 8(6)\} nm3, Z=2, R=0.033 6, F(000)= 780． 溴离子与水分子形成氢键． 分子和晶体结构表明化合物具有选择性识别一些阴离子或中性分子的适宜结构．     

吲哚-3-醛-邻硝基苯基半卡巴腙的阴离子识别

利用吲哚~-3~-醛和邻硝基苯基半卡巴肼设计合成了新型含内氢键的阴离子识别受体吲哚~-3~-醛~-邻硝基苯基半卡巴腙.利用核磁共振波谱、质谱和元素分析等手段对该受体进行了表征,利用荧光光谱滴定和核磁共振波谱滴定研究了该受体对Ac O~-,F~-,H_2PO~-_4,Cl~-,Br~-,I~-,HSO~-_4等阴离子的识别性能.结果表明,该受体与Ac O~-,F~-,H_2PO~-_4,Cl~-,Br~-,I~-,HSO~-_4的结合常数和结合比分别是6.98,1∶2;6.85,1∶2;5.40,1∶2;13.51,1∶2;6.34,1∶1;5.40,1∶1;2.88,1∶1.该受体由于具有内氢键,与具有适当体积、碱度的Cl~-很匹配,对Cl~-具有很强的结合能力和很高的选择性.     

离子液体表面活性剂烷基硫酸1-丁基-3-甲基咪唑鎓盐的合成及其在水溶液中的聚集行为

采用离子交换法,由氯化1-丁基-3-甲基咪唑鎓(C_4mimCl)和烷基硫酸钠合成了一系列无卤素的阴离子表面活性离子液体—烷基硫酸1-丁基-3-甲基咪唑鎓盐[C_4mim][C_nH_(2n+1)SO_4](n=8,12,16),利用表面张力仪、稳态荧光光谱等手段考察了表面活性离子液体在水溶液表面及体相中的聚集行为。结果表明,与传统无机反离子相比,有机咪唑阳离子[C_4mim]~+作为反离子的离子液体型表面活性剂具有较高的表面活性,[C_4mim]~+产生的氢键引起的抑制分子规则排列的作用小于其促进分子有序排列的疏水作用。长烷基链的阴离子是界面膜及胶束的主要组成成分,阴离子疏水烷基碳链的增长虽然可促进胶束的形成,但却在一定程度上抑制[C_4mim]~+参与界面或胶束的形成;阴离子所带烷基链越长,越不利于阳离子[C_4mim]~+参与界面膜或胶束的形成,界面膜或胶束中表面活性剂排布越松散,即界面张力越大,体系中胶束聚集数较小。     

环钯化苯基咪唑啉-卡宾络合物的合成及催化Suzuki反应研究

以间硝基苯甲酸或苯甲酸和(S)-缬氨醇为起始原料,室温反应制得酰氨基醇1a和1b,在亚硫酰氯存在下,酰胺基醇与对甲苯胺关环反应得到苯基咪唑啉化合物2a和2b.通过对苯基咪唑啉配体2进行钯化反应、1,3-二苄基苯并咪唑盐解聚,得目标产物环钯化苯基咪唑啉-卡宾络合物3a和3b.通过1H NMR,13C NMR,IR,MS和元素分析等手段对新化合物3a和3b进行了表征.进一步通过单晶X射线衍射对3a进行了结构确证,络合物3a晶体结构表明该化合物通过分子间氢键形成一维链状结构.催化性能考察发现,络合物3a在萘硼酸和碘代甲氧基萘的Suzuki偶联反应中表现出较好的催化活性.     

咪唑鎓离子液体协同催化苯酚与碳酸丙烯酯的反应

在离子液体1-丁基-3-甲基咪唑乙酸盐([bmim]OAc)催化下,苯酚和碳酸丙烯酯一步合成了丙二醇苯醚.系统考察了反应温度、反应时间及催化剂用量对反应性能的影响,在优化的反应条件下,丙二醇苯醚的收率达79%.同时研究了不同咪唑鎓离子液体的阴阳离子的种类对催化反应的影响,发现咪唑鎓中的C2-H对反应有极大的促进作用,咪唑鎓通过提供氢键能力活化反应底物碳酸丙烯酯;同时,离子液体的阴离子也对反应有很大的影响,阴离子通过接受氢键能力活化另一反应底物苯酚.离子液体阴阳离子通过提供和接受氢键协同催化苯酚与碳酸丙烯酯的反应.离子液体循环使用5次,其活性未见明显降低.     

双-(3,5-二叔丁基-2-羟基苄基-3-异丙基咪唑基)五氯化镱的合成与结构

阴离子功能化的咪唑盐LCl(L=HO-4,6-di-tBu-C6H2-2-CH2{CH[NCHCHN]iPr})与无水YbCl3反应成功合成阴离子功能化的咪唑基五氯化物镱L3[YbCl5(THF)]2-Cl-,产物通过元素分析、IR、X-ray射线衍射法表征。晶体结构表明配合物属于三斜晶体,空间群P1,晶胞参数a=1.6082(4)nm,b=1.6522(4)nm,c=1.7778(5)nm,α=81.682(16)°,β=81.378(16),γ=68.172(10)°,V=4.315(2)nm3,Z=2,F(000)=1750,D=1.280Mg/m3,μ=1.32mm-1,R1=0.1076,wR2=0.2213。氢键的存在对空间网状结构的形成起着重要的作用。     

Imidazolium receptors for the recognition of anions

This tutorial review covers imidazolium receptors for anion recognition according to their topological and structural classification, and includes benzene tripodal, cyclophane and calix-imidazolium, fluorescent imidazolium, ferrocenyl imidazolium, cavitand and calixarene, and polymeric imidazolium systems.     

Photoinduced E to Z isomerization of tetraphenylethylene derivatives within organometallic supramolecular assemblies

Isolation of E-1,2-bis(4-bromophenyl)-1,2-diphenyl-ethylene from the E/Z isomer mixture obtained by a Mc Murry coupling reaction and reaction of this isomer with imidazole followed by N-alkylation with n Bu Br and anion exchange yielded the bisimidazolium tetraphenylethylene (TPE) derivative H_2-E-1(PF_6)_2.The reaction of H_2-E-1(PF_6)_2 with Ag_2O yielded the dinuclear metallarectangle[Ag_2(E-1)_2](PF_6)_2 where the two bis-NHC donors E-1 bridge two silver atoms.Irradiation of[Ag_2(E-1)_2](PF_6)_2 leads to E/Z isomerization of the di-NHC ligand and formation of Z-1 in the mononuclear complex[Ag(Z-1)]PF_6.Demetallation of the di-NHC ligand with NH_4Cl/NH_4PF_6 yielded bisimidazolium salt H_2-Z-1(PF_6)_2.The unique isomerization of the E-TPE derivative into its Z-isomer via metal complex formation/irradiation/demetallation cannot be achieved by irradiation of the individual imidazolium salt.The emissive properties of the TPE complexes[Ag_2(E-1)_2](PF_6)_2 and[Ag(Z-1)]PF_6 have been investigated.     

Size selective supramolecular cages from aryl-bisimidazolium derivatives and cucurbit[8]uril

A series of bisimidazolium salts were synthesized as novel guests for the macrocyclic host molecule cucurbit[8]uril (CB[8]). These bisimidazolium-CB[8] binary complexes exhibited a unique cage structure with the imidazolium rings acting as lids, leading to a size-dependent binding selectivity by altering the hydrophobic linker between the two imidazolium moieties. This new class of CB[8] complexes was also capable of binding small solvent molecules, including acetone, acetonitrile, diethyl ether, and tetrahydrofuran (THF) in an aqueous environment.     

Tripodal nitro-imidazolium receptor for anion binding driven by (C-H)+- - -X- hydrogen bonds

[structure: see text] A positively charged tripodal receptor with nitro groups in the imidazolium rings was designed, synthesized, and characterized for its anion binding strength. The receptor shows strong affinity and high selectivity for Cl- through (C-H)+- - -X(-) hydrogen bonds wherein charge-charge and charge-dipole electrostatic interactions dominate. The association constant with chloride anion in a 9:1 mixture of acetonitrile-d3 and DMSO-d6 is measured to be 1.1 x 10(6) M(-1). The receptor also shows reasonably high affinity toward H2PO4-.     

Anion Receptor with Two Imidazolium Rings on the Glycoluril

We have synthesized an anion receptor with two imidazolium groups on the glycoluril. This receptor showed high affinity for Y-shaped anions such as acetate and benzoate. Although the association constants of these anions for the receptor 4 are too large to be estimated from ¹H NMR titration, the receptor 4 has at least 560-fold selectivity for acetate or benzoate over iodide and 360-fold selectivity over nitrate.     

Bile acid-based cyclic bisbenzimidazolium receptors for anion recognition: highly improved receptors for fluoride and chloride ions

The anion binding properties of bile acid-based cyclic bisbenzimidazolium receptors 6-8 bridged with m-xylene, p-xylene, and 2,6-dimethylpyridine have been studied. Receptors 6 and 7 exhibit much higher binding affinity for fluoride and chloride ions, respectively, as compared to the imidazolium receptors 1 and 2. Receptor 8, however, shows high selectivity but very low binding affinity for anions due to the presence of pyridyl nitrogen. The single-crystal X-ray structure of imidazolium receptor 10-(Br)2 containing pyridyl spacer reveals the binding pattern.     

1,3‐Alternate Tetraamido‐Azacalix[4]arenes as Selective Anion Receptors

Six tetraaza[1.1.1.1]cyclophane derivatives bearing peripheral amide groups were prepared according to two distinct synthetic strategies that depend on the connection pattern between the aryl units. NMR experiments combined with the X‐ray structures of two tetraamide derivatives 4 b and 10 show that these cavitands adopt a 1,3‐alternate conformation both in solution and in the solid state. Consequently, the four amide groups of the aza[1.1.1.1]‐m,m,m,m‐cyclophane isomer 10 can contribute to the same recognition process towards neutral water molecules or anion guests. NMR experiments, mass spectrometry analyses and single‐crystal X‐ray structures confirm the anion‐binding ability of this receptor. Absorption spectrophotometric titrations in nonpolar solvents provided evidence for the selectivity of 10 to chloride anions in the halide series, with a corresponding association constant K_a reaching 2.5×10⁶ m ^?1.     

Highly selective ratiometric estimation of fluoride ion based on a BINOL imidazolium cyclophane with dual-channel

A novel imidazolium cyclophane S-1, which displays a high selectivity for the recognition toward fluoride ion, has been constructed by using BINOL as scaffold. The fluoride ion induced remarkable red shift both in absorption and emission spectra, which might allow S-1 to be employed as a ratiometric receptor with dual-channel. The chiral recognitions of S-1 with chiral carboxylates were also examined.     

Azolium-linked cyclophanes: effects of structure, solvent, and counteranions on solution conformation behavior

This paper describes the synthesis, structural characterization, and solution behavior of some xylyl-linked imidazolium and benzimidazolium cyclophanes decorated with alkyl or alkoxy groups. The addition of alkyl/alkoxy chains to the cyclophanes allows for studies in chlorinated solvents, whereas previous solution studies of azolium cyclophanes have generally required highly polar solvents. The azolium cyclophanes may exist in a syn/syn conformation (azolium rings mutually syn, arene rings mutually syn) or a syn/anti conformation (azolium rings mutually syn, arene rings mutually anti). The preferred conformation is significantly affected by (i) binding of bromide (ion pairing) to the protons on the imidazolium or benzimidazolium rings, which occurs in solutions of bromide salts of the cyclophanes in chlorinated solvents, and (ii) the addition of alkoxy groups to the benzimidazolium cyclophanes. These structural modifications have also led to cyclophanes that adopt conformations not previously identified for similar azolium cyclophane analogues. Detailed (1)H NMR studies for one cyclophane identified binding of bromide at two independent sites within the cyclophane.     

Switching of pseudorotaxanes and catenanes incorporating a tetrathiafulvalene unit by redox and chemical inputs

An acyclic polyether 1a, incorporating a central tetrathiafulvalene (TTF) electron donor unit and two 4-tert-butylphenoxy groups at its termini, has been synthesized. Two macrocyclic polyethers containing two different electron donors, namely a TTF unit with, in one case, a 1,4-dioxybenzene ring (2a), and, in the other case (2b), a 1,5-dioxynaphthalene ring system, have also been synthesized. These two macrocyclic polyethers have been mechanically interlocked in kinetically controlled template-directed syntheses with cyclobis(paraquat-p-phenylene) cyclophane (3(4+)) to afford the [2]catenanes 2a/3(4+) and 2b/3(4+), respectively. X-ray crystallography reveals that the [2]-catenane 2b/3(4+) has the TTF unit of 2b located inside the cavity of 3(4+). The spectroscopic (UV/vis and 1H NMR) and electrochemical properties of compounds 1a, 2a, 2b, 2a/3(4+), and 2b/3(4+) and of the [2]pseudorotaxane 1a.3(4+) were investigated. The absorption and emission properties of the mono- and dioxidized forms of the TTF unit in these various species have also been studied. The results obtained in acetonitrile solution can be summarized as follows. (a) While TTF2+ exhibits a strong fluorescence, no emission can be observed for the TTF2+ units contained in the polyethers and in their pseudorotaxanes and catenanes. (b) A donor-acceptor absorption band is observed upon two-electron oxidation of the TTF unit in the macrocyclic polyethers 2a and 2b. (c) The spontaneous self-assembly of 1a and 3(4+) to give the [2]pseudorotaxane 1a.3(4+) is strongly favored (Kass. = 5 x 10(5) L mol-1) but slow (at 296 K, k = 11.3 L mol-1 s-1 and delta G++ = 15.9 kcal mol-1) because of the steric hindrance associated with the bulky end groups of 1a. (d) In the pseudorotaxane 1a.3(4+), the reversible displacement of the cyclophane from the TTF unit in the threadlike substrate occurs on oxidation/reduction of its electroactive components. (e) Switching between the two translational isomers of the catenanes 2a/3(4+) and 2b/3(4+) occurs by cyclic oxidation and reduction of the TTF unit contained in 2a and in 2b, respectively. (f) Addition of o-chloroanil to the pseudorotaxane 1a.3(4+) and to the catenanes 2a/3(4+) and 2b/3(4+) causes the displacement of the TTF unit from the cavity of the cyclophane 3(4+) because of the formation of an adduct between the TTF unit and o-chloroanil.