Synthesis and Molecular Structure of a C-iso-Butyl-cavitand Bowl with Trimethyl and Methylol Groups

A C-iso-butyl-cavitand bowl with trimethyl and methylol groups was isolated from the acetoxymethyl hydrolysis of mono-methylbromo-cavitand in THF. The molecular structure of the present cavitand compound was determined by single-crystal X-ray diffraction. The compound (C56H70N2O9) crystallizes in orthorhombic, space group Pnma with a = 19.5060(15), b = 19.8136(15), c = 12.9508(10) ?, V = 5005.3(7) ?3, Z = 4, Mr = 915.14, Dc = 1.214 g/cm3, F(000) = 1968, μ = 0.081 mm?1, S = 1.012, the final R = 0.0789 and wR = 0.1488 for 2298 observed reflections with I > 2σ(I) and 322 variable parameters. The structure exhibits a rigid bowl-cavity with an available functional hydroxyl group. The bowl of cavitand contains a CH3CN solvent molecule, and the depth of the bowl-shaped cavity is ca. 2.42 ?.

State-of-the-art and recent progress in resorcinarene-based cavitand

Compartmentalization in the biological world brings excellent efficiency and specificity to the formation of complex compounds,inspiring supramolecular chemists to continuously search for defined spaces that can mimic such natural binding sites.Bowl-shaped cavitands built up from resorcinarenes(RA)present rigid and preorganized concave surfaces,which are capable of mimicking the molecular recognition properties of enzymes.The versatile scaffold of RA endows the cavitand with terrific variety and excellent binding behavior.This review provides a comprehensive overview over the structural modification to date in the high attention field of RA-based cavitands development.Different strategies for synthesizing diverse cavitands,such as small cavity cavitands,wider cavity cavitands,deep cavity cavitands,biscavitands,and asymmetric cavitands,are discussed in details.Furthermore,insights into their applications including catalysis,separations and sensing are provided.

Shape Selectivity of a Metallo Cavitand Host Allows Separation of n-Alkanes from Isooctane

The use of a metallo cavitand for the selective sequestration of n-alkanes from their mixtures with isooctane is described.Competition experiments and NMR spectroscopy are used to show the preference of a water-soluble cavitand host for guests that are hydro-phobic and have narrow or flat shapes.The host showed selectivity for trans 1,4-dimethylcyclohexane over the cis-isomers.The sep-arations of n-alkanes from isooctane by gas/liquid adsorption and a liquid/liquid extraction are detailed.

Metal coordination to a deep cavitand promotes binding selectivities in water

One goal of supramolecular chemistry is the creation of synthetic receptors that have a high affinity for hydrophilic molecules in water.We found that cavitands with upper rims extended by pyridyl groups coax hydrophilic guests into the cavity where they are shielded from the aqueous environment.The ability of Pd(Ⅱ)to coordinate adjacent pyridyl groups leads to increased selectivity for highly hydrophilic solvent molecules such as acetone,1,4-dioxane and tetrahydrofuran in water.Analysis of the binding behavior indicated that metal-coordination restricts the container entrance,shrinks the effective cavity volume and increases the energetic barrier to guest exchange.

Synthesis and Structure of a Host-Guest Inclusion System between C-propyl-o-toluidine-methyl-resorcin[4]arene and Ethanol Solvate

Tetra-bromo-methyl-resorcin[4]arene cavitands were synthesized and C-2 position amine functionalized to obtain C-propyl-o-toluidine-methyl-resorcin[4]arene cavitand 4, and the crystal containing one solvate molecule of ethanol was obtained in a dichloromethane-ethanol solvent system, its structure crystallized in the monoclinic space group P21/n, with a = 12.521(3) Å, b = 21.738(6) Å, c = 25.353(6) Å, α = 90˚, β = 102.372(4)˚, γ = 90˚, and Z = 4. The compound was determined by single-crystal X-ray diffraction and characterized by 1H NMR, FT-IR and elemental analyses.

类杯芳烃孔穴桥联双芘分子开关化合物

利用构型可变的分子开关类杯芳烃孔穴化合物(Cavitand)作为母体,合成了2种具有不同臂长的双芘Cavitand化合物.在室温及中性状态下,2种双芘Cavitand化合物均可检验出分子内激基复合物荧光,其中短臂双芘Cavitand化合物的荧光明显强于长臂Cavitand化合物.经三氟乙酸酸化后,2种双芘化合物的分子内激基复合物荧光消失;而继续使用碱中和至中性,则荧光恢复.这个荧光出现-消失-出现的过程验证了Cavitand母体化合物分子构型闭合-打开-闭合可有效调控分子激基复合物荧光开关过程.此外,通过高斯计算模拟了2种化合物的理论分子构型,发现长臂双芘化合物在Cavitand母体构型处于闭合状态时2个芘基团重叠部分较少是其分子内激基复合物荧光较弱的关键原因.

C-H…X-C bonds in alkyl halides drive reverse selectivities in confined spaces

Binding of non-activated alkyl halides(2-20)in water-soluble cavitand(1)through supramolecular forces is here reported,with emphasis on the role of size and polarizability of the halogen atom in the formation of intramolecular C-H hydrogen bonds in confined spaces.Rare reverse affinity in water(RI<RBr<RCl)is surprisingly observed for the more water-soluble short alkyl halides in dynamic open-ended containers.Competitive bindings and theoretical calculations confirm the unusual selectivity and the presence of C-H hydrogen bonds in non-activated systems for the first time,pointing out the importance and effect of subtle forces on molecular recognition in confined spaces.

巨型给-受体分子开关化合物的合成及性质研究

以构象可变的间苯二酚杯[4]芳烃孔穴化合物(Cavitand)为分子开关母体,合成了一种新颖的给-受体(D-A)型分子开关化合物(化合物1),该分子是目前已知分子量最大的D-A型间苯二酚杯[4]芳烃Cavitand(分子量为3064.9966).其中,以卟啉为给体,富勒烯为受体.在pH诱导下,化合物1可发生构象变化,即由原来的关闭状(vase)转为打开状(kite);而在降低温度和引入Zn^(2+)的条件下,不能促使化合物1发生构象变化.p H诱导构象发生变化的原因,是酸的加入会导致喹喔啉手臂上的N原子发生质子化,从而使得形成的静电排斥作用促使手臂之间相互远离.此外,对化合物1的光物理性质研究表明,存在卟啉向富勒烯的单线态能量转移,其单线态能量转移速率常数为1.1×10^(7)s^(-1),单线态能量转移效率为9.63%.