Pseudo Jahn-Teller Effect in Puckering and Planarization of Heterocyclic Compounds

The goal of this brief partly review paper is to summarize the results of the works published over the last few years regarding the origin of the out-of-plane distortions (puckering) of heterocyclic compounds. In all the papers devoted to this problem, it is shown that the instability of planar configurations of heterocyclic molecules leading to symmetry breaking and distortions is induced by the pseudo Jahn-Teller effect (PJTE). Special attention in this work is paid to the mechanism of suppression and enhancement of the PJTE distortions of heterocycles by oxidation, reduction, and chemical substitutions. It is demonstrated that oxidation of 1,4-dithiine containing compounds leads to suppression of the PJTE and to restoration of their planar nuclear configurations. An example of a dibenzo[1,2]dithiine molecule is used to demonstrate the mechanism of enhancement of the PJTE by reduction. It is shown that the reduction of the neutral C12H8S2 molecule up to the dianion (C12H8S2)2- enhances the PJTE, followed by the S-S bond cleavage and significant structural distortions of the system. The change of the PJTE by chemical substitutions, accompanied either by puckering or by planarization of heterocyclic compounds, is discussed using as examples 1,4-ditinine and its S-oxygenated derivatives.

青蒿素在亚铁离子催化下的裂解产物-3-羟基脱氧青蒿素

用硫酸亚铁引发青蒿素的自由基裂解反应,对主产物之一的3-羟基脱氧青蒿素进行了单晶培养和X射线的表征,运用环Puckering分析方法对结构中环的构象进行了半定量描述。其中六元环分别呈现微扭曲的椅式构象、严重扭曲的椅式构象及半椅式构象;五员环的构象呈信封式,为探索构效关系、开发新型抗疟药物提供了必要的理论依据。

Is there a relationship between dopamine and rhegmatogenous retinal detachment?

Dopamine and its receptors have been widely studied in the neurological conditions and in the retina. In this study, we evaluated the possible role of dopamine in rhegmatogenous retinal detachment(RRD) by comparing the amount of 3,4-dihydroxyphenylacetic acid(DOPAC), a surrogate index of retinal dopamin levels, in the vitreous sample of patients affected by RRD with those affected by macular pucker and vitre ous hemorrhage. Our results showed that significantly higher levels of DOPAC were found in the vitreou sample of patients affected by RRD compared with those affected by vitreous hemorrhage and macula pucker(P = 0.002). Specifically, no trace of the substance was found in vitreous hemorrhage and macula pucker samples. A slightly significant positive correlation was found among DOPAC and post-operativ best corrected visual acuity(r = 0.470, P = 0.049). No correlation was found between DOPAC and the day elapsed between diagnosis and surgery(P = 0.317). For the first time our findings suggest that DOPAC i released in RRD, but not in other retinal diseases such as vitreous hemorrhage and macular pucker. More over, we showed a correlation between visual acuity outcome and the amount of DOPAC in the vitreous This might have a potential, although still unknown, implication in the pathogenesis of the disease and/o in the associated photoreceptors loss. This study was approved by the Ethics Committee of Rome Tor Ver gata University Hospital(R.S.92.10) on September 24, 2010.

The impact of macular surgery in different grades of epiretinal membrane

AIM：To assess the impact of macular surgery on the functional and anatomic outcomes of the patients in different grades of epiretinal membrane（ERM）.METHODS：Seventy-one eyes of 71 patients who underwent 23-gauge transconjunctival sutureless pars plana vitrectomy for primary isolated ERM were evaluated in this study.RESULTS：There were 38 females（53.5%） and 33 males（46.5%）.The average age of the patients was 68.1 y（range 42-89 y）.Mean follow up period was 14 mo（range 6-26 mo）.The cases were divided into two subgroups of cellophane maculopathy（CM） and macular pucker（MP）.An improvement was observed in the postoperative best-corrected visual acuity（BCVA）,as well as a decrement in central foveal thickness（CFT） in both groups（both of these being statistically significant;P=0.001）.In comparison between two groups,it was found that there was a significant improvement on BCVA and CFT in CM group than MP group（P=0.01）.Furthermore,the postoperative fundus findings regarding RPE alterations and macular edema were significantly higher in MP group when compared to the CM group（P=0.01）.CONCLUSION：ERM and internal limiting membrane peeling surgery can lead to a significant reduction of CFT and visual improvements in idiopathic ERM.A long-term ERM persistence will cause unrecoverable retinal damage and visual loss.

A Computational Model for the Prediction of Seam Pucker

This paper reports on a computational model established based on discriminant analysis for predicting the occur-rence of seam pucker and advising on the correction of causing variables (e. g. fabric properties) to prevent seam pucker. The model has a self - updating feature, viz. automatically up - dating model parameters to im-prove the reliability of the model as new data becomes available. It has been successfully implemented in a re-cently developed sewability system.

醚桥联二聚体合成的关键中间产物-9,10-脱水青蒿素

以二氢青蒿素为反应原料在制备不对称醚桥联二聚体时得到了关键的中间产物9,10-脱水青蒿素。9,10-脱水青蒿素保留了母体化合物青蒿素中的过氧基团并且含有一个C=C双键,其抗疟活性与蒿乙醚的抗疟活性相似。9,10-脱水青蒿素在合成蒿醚类衍生物时,是关键的中间产物。培养9,10-脱水青蒿素的单晶,通过X射线表征其结构。运用Puckering分析方法对9,10-脱水青蒿素结构中环的构象进行了半定量描述。其中几个六元环分别呈现椅式、扭船式、信封式构象。

Synergistic lubricating effect of graphene/ionic liquid composite material used as an additive

We prepared a graphene/ionic liquid(G/IL)composite material by the hybridization of G and an IL for use as a lubricating oil additive.The friction coefficient and wear volume of a base oil containing 0.04 wt%of the G/IL composite was reduced by 45%and 90%,respectively.Furthermore,the base oil containing the G/IL composite exhibited better lubricating properties than the base oil containing G,IL,or a mixture of IL and G at the same mass fraction.A synergistic lubrication mechanism was also revealed.The G/IL composite was adsorbed and deposited on the wear surface,forming a more ordered protective film and a unique tribochemical reaction film during rubbing.Therefore,the G/IL composite exhibited the synergistic lubricating effects of G and IL,which significantly improved the lubricating performance of the base oil.This study also suggested a way to limit the out-of-plane puckering of G at the macroscale.

rac-11-t-Butoxy-1,4-dihydro-1,4-methanoanthracene:A two-dimensional framework structure built from C-H…O and C-H…π hydrogen bonds

The title compound rac-11-t-butoxy-l,4-dihydro-l,4-methanoanthracene （C19H200, Mr = 264.35） has been synthesized and characterized by FT-IR, 1H NMR, HRMS spectra and single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/n, with a = 13.5240（10）, b = 8.3453（6）, c = 13.9604（9） A,β = 100.0190（10）°. The structure of the title compound comprises a norbornene unit with a t-butoxy g, roup, having a naphthalene ring fused on one side. The naphthalene is essentially planar with a maximum deviation of 0.032（2） A for atom C（3）. In the crystal, inversion-related molecules are linked by pairs of C- H...O hydrogen bonds, forming a cyclic dimer with R2z （16） graph-set motif. The C-H-..~r interactions are also observed, linking the molecules into a continuous two-dimensional framework structure.

Monolayer puckered pentagonal VTe_(2):An emergent two-dimensional ferromagnetic semiconductor with multiferroic coupling

Two-dimensional(2D)magnetic crystals have been extensively explored thanks to their potential applications in spintronics,valleytronics,and topological superconductivity.Here we report a novel monolayer magnet,namely puckered pentagonal VTe_(2)(PP-VTe_(2)),intriguing atomic and electronic structures of which were firmly validated from first-principles calculations.The PP-VTe_(2) exhibits strong intrinsic ferromagnetism and semiconducting property distinct from the half-metallic bulk pyrite VTe_(2)(BP-VTe_(2))phase.An unusual magnetic anisotropy with large magnetic exchange energies is found.More interestingly,the multiferroic coupling between its 2D ferroelasticity and in-plane magnetization is further identified in PP-VTe_(2),lending it unprecedented controllability with external strains and electric fields.Serving as an emergent 2D ferromagnetic semiconductor with a novel crystal structure,monolayer PP-VTe_(2) provides an ideal platform for exploring exotic crystalline and spin configurations in low-dimensional systems.