能量连续传递的超分子人工光捕获系统构筑及其在光催化反应中应用

光捕获系统在自然界光合作用过程中起着至关重要的作用.模拟自然界的光捕获体系,在生物成像、发光器件、光催化以及解决人类面临的能源问题等方面均具有重要意义[1].目前,在水相中构筑高效的人工光捕获系统已取得一系列重要进展[2].然而,为了更好地理解并模拟自然界中以多通道信息通讯为特征的捕光天线系统[3],构筑具有多步连续能量转移特征并能实现光能到化学能转化的人工光捕获体系仍然是一项具有挑战性的工作.     

Selection of Planar Chiral Conformations between Pillar[5,6]arenes Induced by Amino Acid Derivatives in Aqueous Media

Chiral α-amino acids play critical roles in the metabolic process in nearly all life forms. So far, chiral recognition of α-amino acids has mainly focused on the determination of l /d enantiomers. Herein, selection of planar chiral conformations between water-soluble pillar[5]arene WP5 and pillar[6]arene WP6 was observed due to α-side chain or ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides binding with WP5 and WP6 , respectively. Therefore, α-side chain and ethyl ester moieties of l -α-amino acid ethyl ester hydrochlorides were recognized by observing the induced CD signal and its inversion. This is a rare example of being able to detect the chiral region around α-carbon of a chiral α-amino acid molecule.     

Signatures of spin-glass freezing in Co/CoO nanospheres and nanodiscs

We present a study of the magnetic properties of Co nanoparticles having a combination of both spherical and disk shapes. The hcp Co nanospheres with an average diameter of 11 nm and nanodiscs of dimensions ∼2.5×15 nm² were prepared by thermal decomposition of di-cobalt octacarbonyl in the presence of an amine surfactant. The as-synthesized nanoparticles were oxidized to grow an antiferromagnetic layer. High resolution transmission electron microscopy showed the presence of a ferromagnet/antiferromagnet (Co/CoO) interface with a 2.2-nm thick CoO shell on the spherical nanoparticles and 0.5 nm thick on nanodiscs. We report the temperature and field dependent DC magnetization, frequency, field, and temperature dependent AC susceptibility, and the radio frequency transverse susceptibility. A low temperature paramagnetic behavior was observed in the DC magnetization at high fields and is assigned to defects in the CoO shell that are not coupled to the antiferromagnetic lattice. Our results support the existence of a low temperature frozen, disordered magnetic state, characterized by a strong exchange coupling between the structurally disordered, spin-glass CoO shell and Co core.     

Electroanalytical and spectral investigation of organic receptors as colorimetric and absorption ratiometric anion chemosensor

Colorimetric receptors R1 and R2 have been designed and synthesized by Schiff base condensation and characterised by standard spectroscopic techniques. Anion binding ability of the receptors have been investigated quantitatively through optical, electrochemical and ¹HNMR titration studies. UV-vis spectra of receptor R1 and R2 exhibited a significant red shift for F^? and AcO^? ions with a visual color response. Receptor R1 exhibited selective response towards AcO^? ion in the presence of HEPES buffer media. Incremental color change of receptor R2 with the higher equivalence of AcO^? ions clearly represent the ratiometric response. Cyclic voltammetric studies of R1 and R2 exhibits shift in oxidation and reduction peak with successive addition of AcO^? ions indicating the anion induced oxidation of -NH and reduction of the keto group and nitro species. Electrooptical and ¹H NMR titration studies of R2 collectively reflects the anion induced change of chromophore from C=N to N=N indicative of azo-hydrazone tautomeric signaling in the presence of AcO^? ions. Lower detection limit of 2.1 and 0.41 ppm achieved with sodium salt of AcO^? ion with R1 and R2 reflects their utility as colorimetric chemosensor.