萜品油烯的DeMayo光环加成产物的反应研究

通过萜品油烯和2，6-二氧代戊酸甲酯的de Mayo反应，使[2 + 2]环加成产物 3-6经retro-aldol重排，开环生成取代环己烯7和12。在不同反应介质中对开环产 物进行再环合，并对其反应机理进行研究。在碱性条件下，经分子内Claisen缩合 反应形成螺环化合物；以对甲本碘酸为催化剂的环合，除生成正常的Claisen缩合 产物以外，7和12均发生烯键亲核加成反应，生成具有二环[3.3.1]结构的桥环化合 物9-11和二环[3.2.1]结构的桥环化合物16-18。所得新化合物的化学结构均经IR, ~1H NMR，~(13)C NMR及元素分析予以确定。     

New fabrication approach to develop a high birefringence photo-crosslinked film based on a sulfur-containing liquid crystalline molecule with large temperature dependence of birefringence

ABSTRACT

We present a new fabrication approach to achieve a high birefringence film by means of photopolymerization based on an alkylthio-containing rod-like liquid crystalline molecule exhibiting large temperature dependence of birefringence. We designed a new reactive mesogen having alkylthio linkages (BPM–S). It was found that BPM–S had a larger increment of birefringence with decreasing temperature, relative to commercially available alkoxy analog LC242. This result could be thought to be due to enhanced intermolecular attractive interaction for an alkylthio mesogen implied by the proximity of laterally neighboring molecules and cybotactic nematic tendency based on wide-angle X-ray measurement. The uniaxially-aligned photo-polymerized film for BPM–S showed higher birefringence than that for LC 242.     

Supramolecular graphyne: a C(sp)-H...N hydrogen-bonded unique network structure of 2,4,6-triethynyl-1,3,5-triazine

The crystallization of 2,4,6-triethynyl-1,3,5-triazine (2) leads to a pi-stacked layered structure of a C(sp)-H...N hydrogen-bonded unique hexagonal network structure, which may be regarded as a supramolecular analogue of a hitherto unknown graphyne network: in-plane intermolecular interactions are short and linear H...N contacts (2.31 and 2.34 A) and the interlayer separation is 3.23 A.     

Synthesis of MoVNbTe(Sb)O(x) composite oxide catalysts via reduction of polyoxometalates in an aqueous medium

The synthesis of MoVNbTe(Sb)O(x)() composite oxide catalysts based on the self-organization of polyoxometalates (POMs) was investigated. The catalysts which were synthesized via reduction of POMs by using reducing agents under mild conditions and/followed by calcination in an O(2)-excluded atmosphere which superior performance for propane (amm)oxidation. It was suggested that the metastable phase formed at an elevated temperature with a specific oxidation state corresponds to the catalytic activity.     

Design and modeling of microwave photonic devices

Different types of finite element methods (FEMs) for microwave and optical waveguides are reviewed and are utilized for modeling of a traveling-wave (TW) optical modulator, as one of the typical microwave photonic devices. Using the quasi-TEM and the full-wave vector FEM solvers for microwave waveguides and the scalar FEM solver for optical waveguides, the behaviour of a TW Z-cut Ti:LiNbO3 Mach–Zehnder optical modulator with a ridge structure is investigated.     

The influence of oxygen on the continuum emission from ion-bombarded metal surfaces

Spectral scans of 12 metals: Al, Co, Cr, Cu, Fe, Mg, Mo, Ni, Pd, Si, Ti and W under Ar⁺ ion bombardment have been taken with and without backfilled oxygen in the target chamber to study the effect of oxygen on the emission of continuum radiation. Some of the observed broad band features can be attributed to sputtered metal-oxide molecular emission while other continua remain unidentified. In all cases except Pd, increasing the partial pressure of oxygen enhances the continuum emission.     

New synthetic method for orsellic acid type macrolides by intramolecular alkylation of protected cyanohydrin. The synthesis of (±)-zearalenone.

Zearalenone was synthesized by a general cyclization method of orsellic acid type macrolides having ketone moiety using the intramolecular alkylation of the protected cyanohydrin. This alkylation tolerates the presence of ester group and requires short reaction time.