Preparation and unique circular dichroism phenomena of urea-functionalized self-folding resorcinarenes bearing chiral termini through asymmetric hydrogen-bonding belts
摘要:
通过相应的八胺衍生物分别与(R)-和(S)-α-甲基苄基异氰酸酯的反应,制备出了在间苯二酚骨架上有八个(R)-和(S)-甲基苄基脲残基的手性大环,这些残基通过具有酰胺键的己基或十二烷基间隔物连接。在氯仿中,带有己基间隔的脲官能化间苯二酚通过将脲和酰胺残基以环状方式捆绑在一起形成分子内氢键,从而得到一种自折叠空穴剂。脲和酰胺残基在同一方向上相互配合,形成不对称的氢键带。在大环骨架的吸收波长范围内,会出现独特的圆二色性(CD)带,这是由于在自折叠构象中,手性脲末端通过己基间隔产生了手性传递。另一方面,具有较长十二烷基间隔的脲官能化间苯二酚由于氢键形成的倾向性较弱,在大环上不会显示出这种独特的 CD 带。脲官能化自折叠大环与氯化物和溴化物等阴离子络合后,其特征性 CD 带消失,这反映了分子内氢键带的断裂。
Macrocyclic amphiphiles. Part 2.†—Multi-point adsorptivity of the crown conformer of calix[4]resorcinarenes and their derivatives on surfaces of amorphous polar substrates
The adsorption behavior of the crown conformer of calix[4]resorcinarenes (CRAs), cyclic tetramers of resorcinol and aliphatic aldehydes, and theirO-carboxymethoxylated and O-hydroxyethyloxylated derivatives on a quartz surface was investigated. The adsorption of the macrocyclic amphiphiles from solutions of less polar solvents such as toluene at concentrations of >10â3 mol dmâ3 obeyed the Langmuir equation to give monomolecular layers. The absorption equilibrium constant for CRA was two orders of magnitude greater than that of the corresponding resorcinol. Such efficient adsorptivity of the macrocyclic compounds arises from their characteristic structures which possess eight hydrogen-donating polar residues on the same rim of the cylindrical molecular skeleton. CRA molecules are also adsorbed on the surface of a poly(vinyl alcohol) thin film, suggesting that these cyclic tetramers provide a general procedure to give monomolecular layers deposited on polar surfaces of amorphous solids.
Urea-functionalized Resorcinarenes: Preparation, Self-folding, and Their CD Phenomena Caused by Chiral Urea Termini through Intramolecular Hydrogen Bonding Interactions
Self-folding resorcinarenes bearing optically active urea moieties showed unique circular dichroism (CD) phenomena on the macrocyclic skeleton, which were caused by their chiral urea termini through intramolecular hydrogen bonding interactions in chloroform. These characteristic CD bands were disappeared upon complexation with anions such as chloride and bromide.
含有光学活性脲分子的自折叠间苯二酚在大环骨架上显示出独特的圆二色性(CD)现象,这是由其手性脲末端在氯仿中通过分子内氢键相互作用引起的。与氯化物和溴化物等阴离子络合后,这些特征性 CD 带消失了。
Flotation of Uranium from Seawater with Phosphate Esters of C-Undecylcalix[4]resorcinarene
Table-type chelating surfactants ([4]ArmX-R12, mX means the number of phosphates (P), carboxylic acid (Ac), and hydroxamic acid (Hx), respectively) have been derived from the calix[4]resorcinarene bearing tetradodecyl sidechains ([4]Ar-R12), and applied to a collector of uranium flotation. The surface tension of the aqueous solution was 35 mN m−1 for [4]Ar5.6P-R6 (Rn means the alkylchain length), 52 mN